JP2013094168A - Method and apparatus for myocardial toxicity test and cardiomyocyte evaluation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for a myocardial toxicity test and a cardiomyocyte evaluation.SOLUTION: Cardiomyocyte populations 10-10are arranged on a transparent substrate 1, and the quality of cardiomyocites is evaluated from a cardiomyocyte response to forced pulsation stimulation given to myocardial pulsating cells. The cardiomyocyte populations 10-10are arranged on the transparent substrate 1 and exposed to the flow of liquid containing drug so that the drug acts on the cells composing a network. The level of cardiac toxicity caused by the drug is evaluated from fluctuation measurement obtained from the comparison of the adjacent myocardial pulsating cells of the network.

Description

  The present invention relates to a method and apparatus for myocardial toxicity testing and cardiomyocyte evaluation.

  Bioassays are often used to observe changes in the state of cells and the response of cells to drugs and the like. Conventional bioassays often use cultured cells in general. In this system, since the assay is performed using a plurality of cells, the average value of the value of the cell population has been observed as if it were a characteristic of one cell.

  In reality, however, cells rarely have a synchronized cell cycle in the population, and each cell expresses a protein in a different cycle. For this reason, the problem of fluctuations always accompanies when analyzing the results of responses to stimuli.

  That is, since there is a response fluctuation universally possessed by the cell reaction mechanism itself, only an average response can always be obtained. In order to solve these problems, techniques such as synchronized culture have been developed, but using a group of cells that are always in the same stage means that such cells must always be supplied. It is an obstacle to the widespread spread of bioassays.

  In addition, there are two types of stimulation (signal) for cells: those given by the amount of signal substances, nutrients and dissolved gas contained in the solution around the cells, and those by physical contact with other cells and cell-cell interactions. Therefore, it was actually difficult to judge fluctuations.

  The problem of physical contact of cells and cell-cell interaction can be solved to some extent by performing a bioassay on a cell mass such as a tissue fragment. However, in this case, unlike cultured cells, a uniform cell mass cannot always be obtained. Therefore, there are problems that the obtained data varies and information is buried in the group.

  In order to measure an information processing model in which each cell of a cell group is a minimum structural unit, the inventors of the present application specify a cell as shown in JP-A-2006-94703 (Patent Document 1) and the like. Configure multiple cell culture compartments to be confined in a spatial arrangement, connect adjacent compartments with grooves or tunnels that cannot pass through cells, and if necessary, grooves or tunnels or cells We proposed an aggregate cell microarray (bioassay chip) having a structure with multiple electrode patterns for measuring cell potential changes in the culture compartment.

  In addition, as an evaluation method of an electrocardiogram acquired by reflecting a complicated function of the heart, a method of analyzing an electrocardiogram by applying a method used for normal nonlinear dynamics measurement has been proposed. For example, the most commonly used electrocardiogram analysis is the Poincare plotting method (Non-patent Document 1). One point in the plot indicates information of two adjacent pulsation data. For example, the pulsation rate at a point in time on the X-axis and the previous pulsation rate on the Y-axis. Thus, the fluctuation of the heart beat is estimated by quantifying the distribution of points on the graph. Other methods for measuring fluctuations in heart beat include a correlation dimension method, a nonlinear predictability (non-patent document 2), and an approximate entropy method (non-patent document 3).

  Regarding the evaluation of cardiotoxicity, there is also an evaluation of side effects of drugs in terms of how the contractile force of cardiomyocytes, that is, the stroke volume of blood, changes with the administration of drugs. At present, in vivo measurement is mainly used, and at present, a cell-based in vitro screening system has not been established.

JP 2006-94703 A

Brennan M, Palaniswami M, Kamen P. Do existing measures of Poincare plot geometry reflect non-linear features of heart rate variability? Biomedical Engineering, IEEE Transactions on, Proc.IEEE Transactions on Biomedical Engineering, 2001, 48, 1342-1347 Kanters JK, Holstein-Rathlou NH, Agner E (1994). "Lack of evidence for low-dimensional chaos in heart rate variability". Journal of Cardiovascular Electrophysiology 5 (7): 591-601.PMID 7987529. Storella RJ, Wood HW, Mills KM et al. (1994). "Approximate entropy and point correlation dimension of heart rate variability in healthy subjects". Integrative Physiological & Behavioral Science 33 (4): 315-20.PMID 10333974.

  In conventional bioassays, cells were either treated as tissue fragments or treated as one cell like cultured cells. If the number of cells is too large, the information obtained is averaged as described in the section of the prior art, and there is a problem that a response to a drug or the like cannot be obtained accurately. When cells are used one by one, cells that originally function as cells of a multicellular tissue are used as separated and independent cells, so that the influence of cell-to-cell interaction does not appear. Again, there are problems in obtaining accurate drug response or bioassay data.

  Looking at cardiomyocytes and fibroblasts, propagation of pulsation from adjacent cardiomyocytes or fibroblasts can accurately measure cell potential and cell morphology in units of one cell, and drug toxicity test for cardiomyocytes is 1 It is important to develop devices and systems that can accurately measure cell potential and cell morphology.

  In order to use cardiomyocytes differentiated from human stem cells such as human iPS cells or human ES cells for drug discovery screening or regenerative medicine, the cardiomyocytes have the same quality as the cardiomyocytes in the human heart. It is necessary to quantitatively evaluate whether it exists from the functional aspect of the cell.

The present invention further provides the following apparatus and method for simultaneously measuring the electrophysiological characteristics and mechanical characteristics of cardiomyocytes and quantitatively evaluating these relationships to evaluate cardiotoxicity.
(1) substrate,
A cell population comprising a plurality of cardiomyocytes to be evaluated or a non-cardiomyocyte such as fibroblasts and the like, which are placed on the substrate and perform stable pulsation;
A wall for filling a cell culture solution formed on the substrate so as to surround the periphery of the cell population;
One or more microelectrodes carrying one cell of the cell population or a local part of the cell population;
A reference electrode provided in the region for filling the cell culture medium surrounded by the wall,
A potential measuring means for measuring a cell potential placed on the microelectrode by using a lead wire connected to each of the microelectrodes and a lead wire connected to the comparison electrode;
Control / recording means for controlling electrical stimulation sent to the microelectrode and recording potential data measured by the potential measuring means;
Microparticles having a particle size of about 1 μm or more and about 50 μm or less (eg, polystyrene microparticles) having optical properties different from those of the cell population including the myocardial cells arranged on the cell population or at one or more locations in the population with a spatial distance Glass fine particles, gold fine particles),
Displacement data including an irradiation light source for optically measuring the fine particles, an optical microscope, and an image acquisition camera, and the position and position change of the fine particles including temporal movement amount data and angle change data in the movement direction. As an optical measurement system, and recording means for recording the potential data and the displacement data in correlation with each other,
A cardiotoxicity evaluation device.
(2) substrate,
A cell population comprising a plurality of cardiomyocytes to be evaluated or a non-cardiomyocyte such as fibroblasts and the like, which are placed on the substrate and perform stable pulsation;
A wall for filling a cell culture solution formed on the substrate so as to surround the periphery of the cell population;
One or more microelectrodes carrying one cell of the cell population or a local part of the cell population;
A reference electrode provided in the region for filling the cell culture medium surrounded by the wall,
A potential measuring means for measuring a cell potential placed on the microelectrode by using a lead wire connected to each of the microelectrodes and a lead wire connected to the comparison electrode;
Control / recording means for controlling electrical stimulation sent to the microelectrode and recording potential data measured by the potential measuring means;
Fine particles having a particle size of about 1 μm or more and about 50 μm or less having optical properties different from those of the cell population including the cardiomyocytes arranged on the cell population or at one or more locations in the population with a spatial distance.
An objective lens having a numerical aperture of about 0.3 or less and a zoom lens in the subsequent stage for continuously measuring the position and position change of the fine particles as displacement data including temporal movement amount data and angle change data in the movement direction. An optical measuring means arranged with a system, and a recording means for correlating and recording the potential data and displacement data,
A cardiotoxicity evaluation device.
(3) The cardiotoxicity evaluation apparatus according to (1) or (2) above, further comprising a culture solution supply / discharge channel for supplying and / or discharging the cell culture solution into the region surrounded by the wall.
(4) The cardiotoxicity evaluation apparatus according to any one of (1) to (3), wherein the microelectrode includes a stimulation electrode for stimulating a cell and a measurement electrode for measuring a cell potential.

The present invention also provides the following apparatus and method for evaluating cardiotoxicity using extracellular potential measurement of cardiomyocytes.
(5) Using the cardiotoxicity evaluation apparatus described in (1) above,
As a cell to be measured, generation of sharp inward current of Na ion within about 20 ms after the start of depolarization accompanied by a sharp and clear depolarization without adding a drug, and subsequent depolarization start The extracellular potential is determined using cardiomyocytes that have a slow Ca ion inward current generation within about 100 ms and a significant K ion outward current observed after about 100 ms after depolarization is started. A cardiotoxicity evaluation method characterized by measuring.
(6) Using the cardiotoxicity evaluation apparatus described in (2) above,
As a cell to be measured, generation of sharp inward current of Na ion within about 20 ms after the start of depolarization accompanied by a sharp and clear depolarization without adding a drug, and subsequent depolarization start The extracellular potential is determined using cardiomyocytes that have a slow Ca ion inward current generation within about 100 ms and a significant K ion outward current observed after about 100 ms after depolarization is started. A cardiotoxicity evaluation method characterized by measuring.
(7) The above (5) or (6), wherein the cardiotoxicity evaluation apparatus further comprises a culture solution supply / discharge channel for supplying and / or discharging the cell culture solution into the region surrounded by the wall. Cardiotoxicity assessment method.
(8) The cardiotoxicity evaluation method according to any one of (5) to (7), wherein the microelectrode includes a stimulation electrode for stimulating a cell and a potential measurement electrode for measuring a cell potential.

  Changes in the response of cardiomyocytes and fibroblasts to drugs can be accurately evaluated from cell fluctuation measurements.

  Conventionally, the field potential duration (FPD) (see the explanation below) and the magnitude of fluctuations of adjacent pulsations of cardiomyocytes (for example, short-term variability (STV)) are independently used as indicators. I did not test myocardial toxicity in combination with both. According to the myocardial toxicity test method of the present invention, by evaluating not only the extension of the FPD waveform but also the increase in fluctuation (STV) of adjacent pulsations of cardiomyocytes, a more accurate evaluation of myocardial toxicity can be performed. It becomes possible.

  Furthermore, according to the present invention, an in vitro system capable of evaluating the electrophysiological response and mechanical response of a cardiomyocyte population in combination is provided, and measurement at an in vitro cardiomyocyte level capable of being evaluated closer to the individual level. Is possible.

It is the perspective view which showed typically an example of the structure of the myocardial toxicity test | inspection apparatus based on the Example of this invention. It is a perspective view which shows typically an example of a structure of the cell holding | maintenance part CH of the myocardial toxicity test | inspection apparatus shown in FIG. FIG. 3 is a diagram illustrating an optical system that optically detects the cells held in the cell holding unit CH of the myocardial toxicity testing apparatus shown in FIG. (A), (b) and (c) is a figure which shows the signal regarding measurement of a cell potential. The horizontal axis represents time, and the vertical axis represents the cell potential obtained between the microelectrode 2 and the comparative electrode _2C . (A), (b) and (c) is a figure which shows the signal regarding the result of having measured the volume change accompanying the pulsation of a cell with an optical system. (A) is a figure which shows the cell potential change accompanying the inflow / outflow amount of the Na ^<+> ion, Ca ^{< 2+ >} ion, and K ^<+> ion component of the target cell in the normal state in which a drug is not contained in a culture solution, (b) is culture | cultivation. It is a figure which shows the cell potential change accompanying the inflow / outflow amount of the Na ^<+> ion of a target cell, Ca ^{< 2+ >} ion, and K ^<+> ion component in the state in which the drug was contained in the liquid. It is a figure explaining an example of arrangement | positioning of the optical system which detects the cell of a myocardial toxicity test | inspection apparatus optically, and a movable electrode. It is a schematic diagram explaining generation | occurrence | production of the electrical signal of a cell. (A) is a figure which shows an example of the cell potential change by addition of a chemical | medical agent, (b) is an example of the Poincare plot which evaluates the homology of two adjacent pulsations about the cell potential change at each pulsation. FIG. (A) is a schematic diagram which shows an example of the reentry circuit created by the cyclic | annular network of the myocardial cell using the cell arrangement technique in the 1-cell level, (b) is an example which has actually arrange | positioned the cell on a microelectrode. FIG. (A) is a schematic diagram which shows an example of the reentry circuit by the cyclic | annular network of a myocardial cell using a cell population of fixed width, (b) is the microscope picture which shows an example which has actually arrange | positioned the cell on a microelectrode. (C) is a photomicrograph showing an example in which cell populations are actually arranged in a ring shape on a microelectrode array. (A) is a schematic diagram which shows an example of the reentry circuit measuring apparatus using a ring electrode, (b) is the graph which showed the normal pulsation data and the abnormal pulsation data actually measured with the electrode. (A) is a schematic diagram showing an example of the arrangement of an electrode and a cell for measuring the potential of one cell, and (b) is a photograph on the electrode of an isolated one cell actually measured with the electrode and its pulsating electrical data, (C) is the graph which showed the photograph on the electrode of the measured cell population, and the pulsation electrical data of 1 cell in a cell population. It is a schematic diagram explaining the Example which used the camera light-receiving element for the electric potential measurement of 1 cell by this invention. It is a schematic diagram explaining an example of the mechanism which can measure a some sample with the cell measuring system of this invention. It is a schematic diagram explaining the heart information which can be measured with the cell measurement system of this invention. It is an example of the graph explaining the change with respect to the addition of the drug of the field potential signal waveform of the cell which can be measured with the cell measurement system of the present invention. Regarding the elapsed time (FPD: field potential duration) from the sodium ion release time at the peak position of potassium ion release in the cell field potential signal waveform that can be measured by the cell measurement system of the present invention, the potassium ion channel inhibitor E4031 It is an example of the graph explaining an example of the average value of the change with respect to addition. About the elapsed time (FPD: field potential duration) from the sodium ion release time at the peak position of potassium ion release in the cell field potential signal waveform of the cell that can be measured by the cell measurement system of the present invention, the magnitude of the fluctuation is adjacent. It is an example of the graph and formula explaining one of the methods of evaluating quantitatively the short-term fluctuation of the pulsation to be performed based on a Poincare plotting. With respect to the elapsed time (FPD: field potential duration) from the sodium ion release time at the peak position of potassium ion release of the cell field potential signal waveform that can be measured by the cell measurement system of the present invention, the magnitude of the fluctuation is pointed. It is an example of the graph and formula explaining one of the methods of evaluating quantitatively based on plotting. The elapsed time from the sodium ion release time (FPD: field potential duration) at the peak position of potassium ion release in the field potential signal waveform of the cardiomyocyte that can be measured by the cell measurement system of the present invention is caused by the addition of E4031. An example of the magnitude of fluctuation is shown by pointe plotting (a), and STV is summarized for this (b). It shows FPD and STV when a drug known to have various cardiotoxicity and a comparative drug are added to cardiomyocytes that can be measured by the cell measurement system of the present invention. FIG. 2 shows an example of FPD point plotting with respect to drug addition due to the difference in the shape of the cardiomyocyte network that can be measured by the cell measurement system of the present invention and the difference in position. (A) is the microscope picture which showed an example of an actual cell network, (b) shows the graph which measured the change in the point of A, B, C, D of (a). The figure shows an example of the point-in-time plotting of the transmission time from the pacemaker region to the local with respect to drug addition due to the difference in the shape of the cardiomyocyte network that can be measured by the cell measurement system of the present invention and the difference in position. (A) is the microscope picture which showed an example of an actual cell network, (b) shows the graph which measured the change in the point of A, B, C, D of (a). (C) is a formula for calculating STV. In cardiomyocyte network measurement that can be measured by the cell measurement system of the present invention, the relationship between the conventional in vitro measurement method and the in vivo measurement method, and the relationship between the FP waveform of one cell and the FP composite waveform of the cell network are schematically shown. It is a figure. Configuration of an apparatus having a function of estimating a cell potential from an FP waveform of a cell obtained from each electrode and a function of synthesizing an electrocardiogram comparison waveform from an FP composite waveform of the cell network in cardiomyocyte network measurement that can be measured by the cell measurement system of the present invention FIG. In the cardiomyocyte network measurement that can be measured by the cell measurement system of the present invention, the FP waveform (B) of cells obtained from each electrode of the cardiomyocyte network (A) arranged in a ring and the synthesized FP waveform (C) ) Is an example. In this example, a pulsation signal is normally transmitted from the PM region. In the cardiomyocyte network measurement that can be measured by the cell measurement system of the present invention, the FP waveform (B) of cells obtained from each electrode of the cardiomyocyte network (A) arranged in a ring and the synthesized FP waveform (C) ) Is an example. In this example, a pulsation signal is abnormally transmitted from the PM region. It is a graph which shows an example of the relationship between the beating frequency (Beating Frequency) of a cardiac muscle cell, and FPD in the cardiac muscle cell network measurement which can be measured with the cellular measurement system of this invention. It is a graph which shows an example of the time change of FPD when forced pulsation is given to a cardiac muscle cell in cardiac muscle cell network measurement which can be measured with the cellular measurement system of the present invention. It is a microscope picture which shows the example of a cell network arrangement | positioning in the case of measuring cardiomyocyte network which can be measured with the cell measurement system of this invention, and giving a forced pulsation to a cardiomyocyte and measuring FPD. FIG. 4 is a schematic diagram showing an example of a mechanism using a mechanism for maintaining a microelectrode at a constant potential by using feedback control of a microelectrode potential for FP measurement of a myocardial cell in cardiomyocyte network measurement that can be measured by the cell measurement system of the present invention. . In the cardiomyocyte network measurement which can be measured with the cell measurement system of the present invention, a graph showing an example of the relationship of the response of the pulsation cycle of the cardiomyocyte population when forced pulsatile stimulation is given to a partial region of the cardiomyocyte population is there. It is a graph which shows an example of the change of the length of FPD when forced pulsatile stimulation is given to the partial area | region of the cardiomyocyte population in the cardiomyocyte network measurement which can be measured with the cell measuring system of this invention. (A) is an example of the relationship between the change in the FP waveform caused by the forced pulsatile stimulation and the change in the length of the FPD, and (b) is the length of the FPD according to the change in the stimulation interval of the forced pulsatile stimulus. It is a graph which shows an example of a change of. In the cardiomyocyte network measurement that can be measured by the cell measurement system of the present invention, the results shown in FIG. 33 and FIG. 34 for an example of the response of the cell population when forced pulsatile stimulation is applied to a partial region of the cardiomyocyte population. It is a summary table. 2 schematically shows a differential circuit between a reference electrode and a microelectrode for noise removal in the electrode potential measurement of the present invention. (A) It is a schematic diagram of an example of the circuit which showed the principle. 2 schematically shows a differential circuit between a reference electrode and a microelectrode for noise removal in the electrode potential measurement of the present invention. (B) It is a circuit diagram of an example of the amplifier circuit incorporating this difference circuit. 2 schematically shows a differential circuit between a reference electrode and a microelectrode for noise removal in the electrode potential measurement of the present invention. (C) It is a figure which shows the example by which the noise was reduced by the circuit. It is a figure which shows typically the example of the comprehensive evaluation method of the cardiotoxicity evaluation method of this invention. (A) From the FPD data of the cells, the extent of FPD extension is plotted on the X axis, and the magnitude of FPD temporal fluctuation is plotted on the Y axis. (B) shows an example of an average of the results plotted in an XY diagram. It is a schematic diagram which shows an example of a structure of the system which measures the cardiotoxicity of this invention. It is the model and photograph which show an example of a structure of the cell culture measurement chamber in the system which measures the cardiotoxicity of this invention. It is the figure which showed the cross section of the cell culture measurement plate typically. It is a figure which illustrates typically the composition of the electrode wiring of the electrode arrangement arranged on the multi-electrode substrate. It is the schematic diagram which showed the example of the electrode arrangement | positioning on a multi-electrode board | substrate. It is the schematic diagram which showed an example of the system configuration | structure of this invention which measures the mechanical property and electrical property of a cardiac muscle cell simultaneously. It is an example of the data acquisition monitor screen which showed an example of the data acquired from an example of the system configuration | structure of this invention which measures the mechanical characteristic and electrical characteristic of a cardiac muscle cell simultaneously. It is an example of the data acquired from an example of the system configuration | structure of this invention which measures the mechanical characteristic and electrical property of a cardiac muscle cell simultaneously. It is a figure explaining an example of acquisition of the direction data of cell displacement acquired from an example of the system configuration of the present invention which measures the mechanical property and electrical property of a cardiac muscle cell simultaneously. It is a figure explaining the example of the spatial arrangement | positioning of the cardiomyocyte network in the system of this invention which measures the mechanical characteristic and electrical characteristic of a cardiomyocyte simultaneously. It is a figure explaining the example of the waveform pattern of the extracellular potential of the cell which measures the electrical property of a cardiac muscle cell. It is a figure which shows an example of the fluctuation | variation of the drug response of the cell potential of a cardiac muscle cell, and a hERG ion channel. It is a figure explaining the principle of the cell stimulation method in the arbitrary positions by the stimulation potential superposition from a stimulation electrode array. It is a figure explaining the effect at the time of combining an objective lens with a numerical aperture of 0.3 or less and a zoom lens system about optical measurement of fine particles.

  FIG. 1 is a perspective view schematically showing an example of the structure of a myocardial toxicity test apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view schematically showing an example of the configuration of the cell holding unit CH of the myocardial toxicity testing apparatus shown in FIG. FIG. 3 is a diagram illustrating an optical system that optically detects the cells held in the cell holding unit CH of the myocardial toxicity testing apparatus shown in FIG.

With reference to FIGS. 1 and 2, the myocardial toxicity testing apparatus 100 is configured mainly with components constructed on a transparent substrate 1. The transparent substrate 1 is an optically transparent material, for example, a glass substrate or a silicon substrate. The microelectrode 2 is a transparent electrode made of ITO, for example, and is disposed on the transparent substrate 1. Reference numeral 2 ′ denotes a lead wire for the microelectrode 2. 3 ₁ , 3 ₂ , 3 ₃ and 3 ₄ are agarose gel walls, which are arranged around the microelectrode 2 with gaps 4 ₁ , 4 ₂ , 4 ₃ and 4 ₄ . Walls 3 ₁ , 3 ₂ , 3 _3, and 3 ₄ formed by agarose gel are notched at the center to form a space for cell storage. If necessary, a microelectrode 2 is disposed on the transparent substrate 1 in the space serving as a cell storage portion formed by the walls 3 ₁ , 3 ₂ , 3 ₃ and 3 ₄ formed of agarose gel. Regardless of the presence or absence of the microelectrode 2, one cell 10 can be stored in the cell storage portion. In FIG. 2, a microelectrode 2 is disposed on a transparent substrate 1 in a space serving as a cell storage portion formed by walls 3 ₁ , 3 ₂ , 3 ₃ and 3 ₄ formed of agarose gel, and cardiomyocytes 10 are disposed thereon. It is stored. A state in which the lead wire 2 ′ is connected to the microelectrode 2 and drawn out is shown. Cells such as collagen adhere to the electrode surface and the transparent substrate on the cell placement surface when the cells are placed directly on the transparent substrate 1 without providing the cell placement surface of the microelectrode 2 and the microelectrode 2. It is better to apply materials that will help. The cells in the cell storage part formed by the walls 3 ₁ , 3 ₂ , 3 ₃ and 3 ₄ by the agarose gel are not adhered to the cells, so that the walls 3 ₁ , 3 ₂ , 3 ₃ and 3 also ₄ height as same extent as cells, cell 10 can not move over a wall. Further, the gaps 4 ₁ , 4 ₂ , 4 ₃ and 4 ₄ around the cell storage portion formed by cutting out the central portions of the walls 3 ₁ , 3 ₂ , 3 ₃ and 3 ₄ by the agarose gel are determined by the size of the cells. Since it is assumed to be small, the cell 10 does not move through the gaps 4 ₁ , 4 ₂ , 4 ₃ and 4 ₄ .

In FIG. 1, cell holding parts CH ₁ , CH ₂ , CH ₃ and CH _n hold one cardiomyocyte or fibroblast 10 ₁ , 10 ₂ , 10 ₃ and 10 _n in the cell storage part respectively. Although it is not clear, each has a microelectrode 2 and lead lines 2 ′ ₁ , 2 ′ ₂ , 2 ′ ₃ and 2 ′ _n are led out. These cardiomyocytes or fibroblasts constitute a cell communication channel CCC arranged in series. Here, n is 20, for example. Further, the distribution of the 20 serially arranged cardiomyocytes and fibroblasts may be random, but the cells of the cell holding part CH _{1 and} the cells of CH ₂₀ should be cardiomyocytes. A cardiomyocyte population holding region including a cell population 10 _{G in} which 3 × 3 cell holding portions CH _G are formed at the left end of the cell communication channel CCC and the cardiomyocytes 10 are held in the respective cell holding portions CH. Exists. This cell population 10 _G functions as a pacemaker that performs stable pulsation. In the cell population 10 _G , only one cell holding part CH of the cell population 10 _G is provided with the microelectrode 2, and the lead line 2 ′ _G is drawn out. Further, the right of the central cell holder CH of the cell population 10 _G are configured so as to be opposed to the cell holder CH ₁ of the cell communication channel CCC. Barrier 11 _a is provided between the left end of the right and cell communication channel CCC of the cell population 10 _G. The barrier 11 _a small opening 11 _b in the lower portion of the central portion is formed. The opening 11 _b on both sides has a cell holder CH ₁ of the cell population 10 cells holder CH right center of _G and cell communication channel CCC that opposing the, with a gap 4 around the respective cell storage unit It is configured to allow physical contact and cell-cell interaction of the cells held in each. The bottom of the cell population 10 _G reference electrode 2 _C is provided, is drawn out lead wire 2 _'C.

Reference numeral 7 denotes a wall surrounding the periphery, which surrounds the cell population 10 _{G, the} cell communication channel CCC, and the reference electrode 2 _C. 8 ₁ and 8 ₂ are pipes for supplying the cell culture solution to the region inside the wall 7 and discharging the cell culture solution from the region inside the wall 7. to near the bottom surface of the substrate 1 is supplied culture solution from the pipe 8 ₁ that is stretched, the culture medium from the pipe 8 ₂ that is stretched to near the bottom surface of the substrate 1 is discharged. Pipe 8 ₃ is coupled near the outlet of pipe 8 ₁ of culture medium supplying the culture solution, the drug to be allowed to act on cells via the pipe 8 ₃ is supplied. Thus, cells 10 while being exposed to cultures of cells that is supplied to the area inside the wall 7 by pipe 8 _1, is stably held on the microelectrode 2. When it is no longer necessary to expose the cells in the culture solution may be discharged culture solution from the interior of the region of the wall 7 by pipe 8 _2. In addition, when exchanging the culture solution with a new one, the culture solution may be supplied after or while discharging the culture solution. Meanwhile, when it is desired to effect the agent to a cell, while discharging the culture solution by a pipe 8 _2, the drug to be allowed to act on cells via pipe 8 ₃ In addition to the culture medium, supplied together with the culture solution by a pipe 8 ₁ do it. In this case, by providing the barrier 11 _a between the cell population 10 _G and the cell communication channel CCC, when culture medium containing the drug is supplied into the region of the wall 7 by pipe 8 _1, cell communication channel Compared to the degree to which the CCC cells are affected by the drug, the degree to which the cells of the cell population 10 _G are affected by the drug is low. That is, when the culture medium containing the drug is supplied by a pipe 8 _1, is supplied to the culture barrier 11 _a gap and the barrier 11 _a cell population 10 _G overcame upper surface of the both side walls 7 of The cells of the cell population 10 _G are also affected by the drug. However, since the effect is indirect compared with that of the cell communication channel CCC on cells, it does not affect the function as a pacemaker. Note that the configuration and arrangement of the pipes 8 ₁ , 8 _2, and 8 ₃ may be arbitrarily changed depending on the measurement method. For example, pipes 8 ₁ and the pipe 8 ₃ may be one which is separated, the pipe 8 ₂ is omitted, the pipe 8 ₁ feed, or as being used for both the discharge.

PC is a personal computer (potential measuring means, control / recording means), and measures and records the cell potential between the lead wire 2 'of the microelectrode 2 and the lead wire 2' of the comparison electrode _2C of the cell holding part CH. . An operation signal Ms from the operator is applied to the personal computer 9.

The myocardial toxicity test apparatus 100 can be placed on the XY stage 15 of the optical observation apparatus 200 to observe the pulsation of an arbitrary cell 10 in the cell communication channel CCC using an optical system. The XY stage 15 is optically transparent and is moved to an arbitrary position by the XY driving device 16 in accordance with a signal given by the personal computer PC in accordance with an operation signal Ms of the operator. FIG. 3 shows an example in which the state of pulsation of the cell 10 _n of the cell communication channel CCC is observed. Reference numeral 12 denotes a culture solution.

Reference numeral 22 denotes a light source for a phase contrast microscope or differential interference microscope, and a halogen-based lamp is generally used. Reference numeral 23 denotes a band-pass filter that transmits only light having a specific wavelength from light from a light source for observation of a stereoscopic microscope such as a phase difference. For example, in the case of the cell 10 _n of the observation, it is possible to prevent damage of the cells 10 _n by using light of a narrow band near the wavelength 700 nm. Reference numeral 24 denotes a shutter, which has a function of blocking light irradiation while image measurement is not being performed, such as when the XY stage 15 is moved. A condenser lens 25 introduces a phase difference ring for phase difference observation, and introduces a polarizer for differential interference observation. A myocardial toxicity test apparatus 100 formed on the substrate 1 is placed on the XY stage 15, and the XY stage 15 is moved by an XY drive device 16, so that an arbitrary position of the myocardial toxicity test apparatus 100 is set. Observe and measure. The state of pulsation of the cell 10 _n in the myocardial toxicity test apparatus 100 is observed with the objective lens 17. The focal position of the objective lens 17 can be moved in the Z-axis direction by the driving device 18 in accordance with a signal from the personal computer PC. The objective lens 17 having a magnification of 40 times or more can be used. What is observed by the objective lens 17 is a phase difference image or differential interference image of the cell 10 _n by the light transmitted from the light source 22. Only the phase-contrast microscope image or the differential interference microscope image is observed by the camera 21 by the dichroic mirror 19 and the band-pass filter 20 that reflect light having the same wavelength as that transmitted through the band-pass filter 23. The image signal observed by the camera 21 is introduced into the personal computer PC. Although not shown, the image can be displayed on a monitor or display connected to the personal computer.

An example of the main size of the structure of the myocardial toxicity test apparatus 100 shown in FIG. 1 is as follows. This is an example in which the cell size is 10 μmφ. The transparent substrate 1 has a size of 100 mm × 150 mm, the microelectrode 2 has a size of 8 μm × 8 μm, and the individual sizes of the walls 3 ₁ , 3 ₂ , 3 ₃ and 3 ₄ by agarose gel are 20 μm × 20 μm × 10 μm (high The space 4 ₁ , 4 ₂ , 4 ₃ and 4 _{4 having} a width of 2 μm, and the space serving as the cell storage part formed by the walls 3 ₁ , 3 ₂ , 3 ₃ and 3 ₄ by agarose gel is a cylindrical shape of 12 μmφ, The outer shape of the wall 7 is 5 mm × 5 mm and the height is 5 mm. The height of the barrier 11a is 1 mm. Here, the microelectrode 2 has a square of 8 μm × 8 μm, but the entire wall 3 ₁ , 3 ₂ , 3 ₃ and 3 ₄ and the width of the gaps 4 ₁ , 4 ₂ , 4 ₃ and 4 ₄ are formed by agarose gel. It is good also as a circular electrode of 10 micrometers diameter used as the storage part of the cell comprised by these.

  Hereinafter, a configuration example of the myocardial toxicity test apparatus 100 of the present invention and a specific measurement example using the same will be described.

4 (a), 4 (b), and 4 (c) are diagrams showing signals related to measurement of cell potential. The horizontal axis represents time, and the vertical axis represents the cell potential obtained between the microelectrode 2 and the comparative electrode _2C . 4 (a) is a cell potential based on the pulsation of the cell population 10 _G. Here, the potential between the cell population 10 _{G C} pulled out lead wire 2 from one 'leader line 2 and _G were drawn from the reference electrode 2 _C' of the shown in Figure 1. As shown in the figure, it shows stable pulsation and it can be understood that it can function as a pacemaker. FIG. 4 (b) shows the cell potential due to the pulsation of the target cell in a normal state where no drug is contained in the culture solution. Here, the target cells measured with the cell 10 _n of the cell communication channel CCC, the potential between the _C 'lead wire 2 led from the reference electrode 2 _C and _n' to draw wire 2 drawn out from the cell 10 _n It is measured. As is apparent from the comparison with the waveform of FIG. 4A, it is observed that the cell communication channel CCC is delayed by the time Δt required for transmission of pulsation by the cell 10. On the other hand, FIG. 4C shows the cell potential due to the pulsation of the target cell in a state where the culture solution contains the drug. Again, the target cell for measurement is the cell 10 _n of the cell communication channel CCC, and the comparison with FIG. 4B is made clear. As apparent from the comparison with the waveforms in FIGS. 4 (a) and 4 (b), the delay of time Δt + α is not a delay of time Δt required for transmission of pulsation by the cells 10 of the cell communication channel CCC. It is observed that This means that the magnitude of Na ion inhibition due to the action of the drug on the cells of the cell communication channel CCC appears as an increase in the delay of + α. That is, the toxicity of a drug to cardiomyocytes can be evaluated as Na ion inhibition.
Note that the microelectrode used for observation may be referred to as an observation electrode.

FIG. 5A, FIG. 5B, and FIG. 5C are diagrams showing signals related to the result of measuring the volume change accompanying the pulsation of the cells by the optical system. FIG. 5A shows the volume change accompanying the pulsation of the cells of the cell population 10 _G. One pulsation of cells of the cell population 10 _G is optically detected in the form shown in FIG. The contraction and expansion associated with the pulsation of cells are recognized as changes appearing in pulses. The period of this waveform is the same as the period of change in cell potential associated with the pulsation shown in FIG. FIG. 5 (b) shows the volume change associated with the pulsation of the target cell in a normal state where the drug is not contained in the culture solution, and the lower part shows a time differential value in order to evaluate this as an electrical signal. Waveform is shown. Again, the target cell for measurement is the cell 10 _n of the cell communication channel CCC, and the pulsation of the cell 10 _n is optically detected in the form shown in FIG. As apparent from the comparison with the waveform in FIG. 5A, it is observed that the cell communication channel CCC is delayed by a time Δt required for transmission of pulsation by the cell 10. On the other hand, FIG. 5 (c) is an explanatory diagram for evaluating the volume change accompanying the pulsation of the target cell in the state where the drug is contained in the culture solution. FIG. 5 (a) and FIG. The time axis is shown in an enlarged form as compared with (). The upper part is a waveform corresponding to the upper part of the waveform in FIG. 5B, and as is apparent from the waveform in FIG. 5A, the time Δt required for transmission of pulsation by the cell 10 of the cell communication channel CCC. It is observed that the delay is further increased by β. The effect of the volume change accompanying the pulsation of the target cell due to the drug is characterized in that the slope of the volume change becomes smaller than the increase in the delay. This can be clearly seen when compared with the volume change in the culture solution containing no drug shown in the lower part of FIG. 5C as a reference waveform. The middle part of FIG. 5C shows a waveform when processed as a time differential value in order to evaluate the upper waveform. As can be seen by comparing this time differential value with that in the lower part of FIG. 5B, the peak value becomes smaller and the slope becomes gentler. This means that the contraction rate of the myocardium is reduced by the drug, and the cardiac output is reduced. That is, the toxicity of a drug to cardiomyocytes can be evaluated as a decrease in contraction rate.

FIG. 6 (a) shows changes in cell potential associated with the inflow and outflow amounts of Na ⁺ ions, Ca ²⁺ ions, and K ⁺ ion components of target cells in a normal state in which no drug is contained in the culture solution. FIG. 6 (b) shows changes in cell potential associated with the inflow / outflow amount of Na ⁺ ion, Ca ²⁺ ion, and K ⁺ ion component of the target cell in a state where the drug is contained in the culture solution. As can be readily seen by comparing FIG. 6A and FIG. 6B, a QT delay appears and the waveform extends in the time axis direction. Furthermore, the waveform is greatly deformed with the inflow and outflow of K ⁺ ions. In order to evaluate this as an electric signal, the durations of values of 30%, 60% and 90% are set to APD30, APD60 and APD90 with respect to the values between “0” and “100” indicated by broken lines in the figure. Detect as. Here, APD is an expression taken from the initials of Action Potential Duration. If the magnitude and ratio of these values are evaluated, the influence of the drug on the inflow / outflow amount of Na ⁺ ion, Ca ²⁺ ion, and K ⁺ ion component can be evaluated.

FIG. 7 is a diagram for explaining an example of the arrangement of an optical system for optically detecting cells of the myocardial toxicity test apparatus and movable electrodes. For example, an example of observing the pulsation state of a cell 10 _{n to be} measured is shown. Yes. Reference numeral 12 denotes a culture solution. Reference numeral 22 denotes a light source for a phase contrast microscope or differential interference microscope, and a halogen-based lamp is generally used. Reference numeral 221 denotes a fluorescent light source for measuring fluorescence of cells, and a mercury lamp, a monochromatic laser, an LED light source or the like is generally used. Reference numeral 23 denotes a band-pass filter that transmits only light having a specific wavelength from light of a light source for observation of a stereoscopic microscope such as a phase difference. Reference numeral 231 denotes a band that transmits only light having an excitation wavelength that excites specific fluorescence from the fluorescent light source 221. It is a path filter. For example, in the case of observing a shape change such as pulsation accumulation change information of the cell 10 _n , an image passing through the band-pass filter 20 that transmits only light having a wavelength for measuring the cell shape is measured in real time by the camera 21. However, damage to the cell 10 _n can be prevented by using a narrow band light having a wavelength near 700 nm for measurement. Reference numerals 24 and 241 denote shutters, which have a function of blocking light irradiation while image measurement is not performed, for example, when the XY stage 15 is moved. A condenser lens 25 introduces a phase difference ring for phase difference observation, and introduces a polarizer for differential interference observation. In the case of fluorescence measurement, for example, when measuring intracellular calcium release, a combination of a band pass filter that selectively transmits light at an excitation wavelength of about 500 nm and a fluorescence measurement wavelength of about 600 nm is used, and only the light of the fluorescence wavelength is used. The fluorescence image that has passed through the band-pass filter 201 that selectively transmits is measured by the camera 201. At this time, when measuring the temporal relationship of calcium release per cell in the cell network and measuring the signal transmission path in the cell network, the measurement time resolution of the camera is 0.1 ms or more. High-speed continuous images can be acquired. A myocardial toxicity test apparatus 100 formed on the substrate 1 is placed on the XY stage 15, and the XY stage 15 is moved by an XY drive device 16, so that an arbitrary position of the myocardial toxicity test apparatus 100 is set. Observe and measure. The state of pulsation of the cell 10 _n in the myocardial toxicity test apparatus 100 is observed with the objective lens 17. The focal position of the objective lens 17 can be moved in the Z-axis direction by the driving device 18 in accordance with a signal from the personal computer PC. The objective lens 17 having a magnification of 40 times or more can be used. What is observed by the objective lens 17 is a phase difference image or differential interference image of the cell 10 _n by the light transmitted from the light source 22. Only the phase-contrast microscope image or the differential interference microscope image is observed by the camera 21 by the dichroic mirror 192 and the band-pass filter 20 that reflect the light having the same wavelength as that transmitted through the band-pass filter 23. The image signal observed by the camera 21 is introduced into the personal computer PC. In this embodiment, the movable electrode 27 for stimulating the cells is arranged, and the coordinates of the movable electrode can be adjusted not only at an arbitrary position on the same plane as the XY stage but also at an arbitrary height. A position control mechanism is provided. By using this position control mechanism and moving the tip of the movable electrode to the position of one specific cell or several cells in the cell network, any specific cell or several cells can be stimulated. The movable electrode is made of a specific electrode or only a few cells near the tip of the movable electrode, such as a metal electrode with insulation coating on the portion other than the tip, and a glass electrode with a tip opening size of about 5 microns or less. An electrode having a configuration capable of applying electrical stimulation can be used. When using a metal electrode, electrical stimulation can be effectively transmitted to the cells by adding platinum black or the like to the tip surface. The position of the tip of the movable electrode is adjusted according to the degree of response of the cell to the electrical stimulation, and may be in contact with the cell or may be disposed in the very vicinity of the cell. In addition, the electrode 2 for cell potential measurement may be used as a ground electrode by switching at the moment of applying an electrical stimulus in order to apply the stimulus of the stimulus electrode to a specific target cell appropriately, or separately. The ground electrode 28 may be disposed. Furthermore, in order to stimulate specific cells, the existing microelectrode 2 may be used as a stimulation electrode. In that case, what is normally connected to the electrical signal measuring circuit 30 is connected to the electrical stimulation circuit 31 by switching switching at the moment of applying a stimulus by switching of the switching circuit 29 to which the microelectrode is connected. Thus, a rectangular wave stimulation signal can be applied to the microelectrode 2. In addition, at the moment of applying a stimulus using the movable electrode 27, the switching circuit 29 can be switched to the ground. On the other hand, the movable electrode can be used not only as a stimulation electrode but also as an electrode for measuring an electrical signal of a cell or as a ground electrode. In that case, the movable electrode is connected to the switching circuit 291, and the cell potential is measured by switching to the electric signal measuring circuit 301 by switching according to the use as the cell potential measurement, cell stimulation, and ground electrode, respectively. Alternatively, it can be used as a ground electrode by connecting to an electrical stimulation circuit 311 to give a rectangular wave stimulation signal to a cell, or by grounding the cell. The timing of electrical stimulation given to the cells by the electrical stimulation circuits 31 and 311 can be mainly used in the following two applications. One is a cell network with autonomous pulsation function, which gives irregular stimulation during the pulsation interval of the normal cardiomyocyte network, and the other is a cardiomyocyte network without autonomous pulsation ability. Gives a beat interval. In both cases, it is possible to track changes in the response of the cell network when the period of the beat interval (the time difference between two beats) is gradually shortened in units of 5 ms. For this purpose, the electrical stimulation circuits 31 and 311 can perform feedback control that analyzes the pulsation period information obtained by the electrical signal measurement circuits 30 and 301 and determines the timing of stimulation based on the result. . Further, when the movable electrode 27 is used for electric signal measurement, the same measurement can be performed without the microelectrode 2 in the present system. This is because it is possible to measure the pulsation period of each cell in the cell network by optical measurement configured in the system, so it is not possible for the pulsation period to change from a stable state to an unstable state such as arrhythmia. In this case, the data of the electrical characteristics of a specific cell is obtained using a movable electrode as necessary from the result of measurement with an optical measurement device arranged in the system. A large cell network can be constructed more freely as long as optical measurement is possible without being restricted by the number of microelectrodes arranged in advance.

  FIG. 8 is a schematic diagram showing an example of generation of an electrical signal of a cell. First, the influx of sodium ions from the sodium ion channel in the cell membrane occurs into the cell, the cell potential drops rapidly, then, after a short delay, the cell potential decreases due to the inflow of calcium ions, As the next step, the cell potential rises due to the discharge of potassium ions to the outside of the cell. The change in cell potential is caused by the difference in characteristics of various ion channels having different response characteristics existing in the cardiomyocyte membrane. When the position of the peak of the potential change caused by each ion channel is analyzed as the characteristic time of each ion channel, each ion channel is blocked by the influence of the drug, so that it blocks according to the characteristic of the drug. The change of the waveform of the electric signal according to the type of the ion channel can be measured, and thereby the inhibitory effect of the drug on the ion channel can be estimated. The ion channels that are particularly important for drug evaluation are the four ion channels FastNa, SlowNa, Ca, IKr, and IKs, and the block states of these four types of ion channels can be measured.

  FIG. 9A shows changes in the electrical signal of the cell shown in FIG. 8 when reagent E-4031 that actually selectively inhibits potassium ion channels is added at various concentrations. Since the IKr ion channel responsible for the extracellular discharge function of K ions that raise the cell potential is inhibited, it can be seen that the change in the positive cell potential is gradually delayed as the drug concentration increases. FIG. 9A shows specific one-beat data of the cell response. Actually, the magnitude of the fluctuation width of the response in each adjacent beat is important for estimating the influence of the drug. Index. FIG. 9B shows an example of this, which is an analysis method for comparing the correlation between adjacent beat data called Poincare plot. Here, a plot is made with the position of the response time of a specific ion channel at the nth beat on the X axis and the position of the response time of the same ion channel at the (n + 1) th beat on the Y axis. . Then, when the characteristics of adjacent beats are the same, the plots are arranged on Y = X drawn with a dotted line in the graph, but there is a large fluctuation in the response between adjacent beats In this case, a large distribution of plots is observed from Y = X to a position away from it. In fact, in this example, the control time without addition of the drug has a delay in response time with the addition of 40 nM, but the homology between adjacent beats is maintained. On the other hand, when the drug is added up to 400 nM, in addition to the further delay of the response time, the homology between adjacent pulsations is broken and an unstable pulsation cycle is generated. it can. This result is consistent with the result of QT prolongation measurement showing cardiotoxicity, and the occurrence of QT prolongation is estimated by using the Poincare plot as an index of the measurement of fluctuation of each adjacent pulsation at the 1 cell level. be able to. This phenomenon is caused when a specific ion channel is blocked by a drug, and if the degree of blocking is slight, the instability of the cellular response has not yet occurred, but only the phenomenon of reduced ion ejection capacity can be seen. On the other hand, when the degree of blocking becomes severe, the number of functioning ion channels decreases drastically, so that the ion discharge ability of the cells is the same cell but has a large fluctuation with low reproducibility. The result will come out. The magnitude of this fluctuation can be used as an index of the ease with which QT extension occurs.

  FIG. 10 (a) is a schematic diagram showing an example of a reentry circuit drug based on a cyclic network of cardiomyocytes using a cell placement technique at the level of one cell. A ring network of cells created only from cardiomyocytes becomes a normal network model. In the case of a pathological model such as cardiac hypertrophy, it is realized by incorporating fibroblasts into the cell network. Then, fibroblasts mixed in the network cause a delay or attenuation of the transmission rate of the cardiomyocyte network, and as a result, occurrence of extra-systole can be predicted. FIG. 10B is a photomicrograph showing an example in which cardiomyocytes are actually arranged on the microelectrode. Actually, as shown in this photograph, when the cells are arranged on the microelectrode in units of one cell, the signal transmission delay between adjacent cardiomyocytes can be measured. Since this transmission speed depends on the magnitude of the first electrical signal generated at the time of pulsation, this signal transmission delay data can be used as an inhibitory effect on the Na ion channel.

  FIG. 11A is a schematic diagram illustrating an example of a reentry circuit using a cyclic network of cardiomyocytes using a cell population having a certain width. In the cyclic cell network in the unit of one cell shown in FIG. 10, the pulsation signal of the cardiomyocyte is unique in its passage, and the same as long as there is no fluctuation of the pulsation of the cell itself as shown in FIG. Maintaining properties, cells transmit pulsatile signals between adjacent cells. On the other hand, as shown in FIG. 11, when cells are arranged with a certain width to form a circular network, the cell population has different paths for each pulsation as indicated by a solid line 35, a broken line 36, and a dotted line 37. Will have the freedom to take. In particular, as described with reference to FIG. 9, when a large fluctuation occurs in the response characteristics of each cardiomyocyte due to the addition of the drug, each time the stimulation signal circulates in the cyclic network, the easily responding cells change each time. The difference in route becomes more prominent. This is the same mechanism as the extra-systolic mechanism that leads to the death of the heart, called spiral reentry, so by using a cyclic network based on such a cell population, spiral reentry Measurement is possible. FIG. 11B is a photomicrograph showing an example in which a cell population is actually arranged on a microelectrode. A cell population in which about 60% of fibroblasts are mixed with about 60% of cardiomyocytes is arranged. In fact, with such an arrangement, the fluctuation of the transmission speed between adjacent electrodes increases between adjacent pulsations, and the increase in the fluctuation becomes significant with the addition of a drug. The occurrence of spiral reentry can be estimated from the change in the fluctuation width of the transmission speed. FIG. 11C is a photomicrograph showing an example in which cell populations are actually arranged in a ring shape on the microelectrode array. For the actual spiral reentry measurement, the calcium firing of each cell in the cell population network can be estimated at the single cell level by using the high-speed fluorescence measurement camera shown in FIG. It is possible to actually analyze the change of the route in each lap, as to which route of signal transmission is proceeding.

  FIG. 12A is a schematic diagram showing an example of a reentry circuit measuring device using an annular electrode. In this example, one annular electrode 38 formed in a ring shape having a diameter of 1 to 3 mm and having a width of 50 to 100 microns is arranged on the bottom surface of each 96-well plate 42, and the cell population is only 41 on the electrode surface. Is arranged in a ring shape, and the bottom surface of the periphery excluding the electrode is coated with a material having no cell adhesiveness such as agarose. A concentric reference electrode ring 39 is disposed in a region coated so that the cells do not adhere, and a channel 40 through which the reagent can enter and exit is disposed. By using such an electrode, it is possible to easily measure abnormal pulsations of cardiomyocytes. FIG. 12B is a graph showing normal pulsation data and abnormal pulsation data actually measured with electrodes. In the present embodiment, the annular electrode is used. However, by using the optical measurement system shown in FIG. 7, the same system as that of the present annular electrode can be used to optically measure abnormal pulsations. Can do. In that case, when measuring an electrical signal, the electrical signal can also be acquired by bringing the moving electrode shown in FIG. 7 into contact with the annular cell network.

  FIG. 13A is a schematic diagram showing an example of the arrangement of the microelectrode 2 for measuring the potential of one cell and the cell. One cell to be measured is placed on the microelectrode 2 having a diameter of 10 to 50 microns. This shows a method of measuring only cells. Also in this example, as in the other examples, a material such as agarose that inhibits cell adhesion is coated around the electrode so that cells on the electrode are held in place. FIG. 13 (b) shows a photograph on the electrode of an isolated single cell actually measured with the microelectrode 2 and its pulsation electrical data, but the signal of the isolated single cell is unstable and is shown in the graph. It pulsates with a large fluctuation. On the other hand, as shown in FIG. 13 (c), one cell is arranged on the microelectrode 2 in the same manner as in FIG. 13 (b), but by forming a cell population connected to other cells. As can be seen from the pulsation signal graph, the stability of the pulsation cycle is realized. In actual pulsation measurement at the level of one cell, as shown in FIG. 9, since the magnitude of fluctuation between adjacent pulsations is an index, cell grouping as shown in this embodiment is performed. Only one cell to be measured is placed on the microelectrode so that pulsation data of one cell can be acquired while realizing stabilization by the above, and other cardiomyocytes are placed in order to maintain the stability of this specific cell. A measurement system using a configuration in which the electrode is not placed on the electrode is useful.

  FIG. 14 is a schematic diagram for explaining an example in which the camera light-receiving element is used for measuring the potential of one cell in the present invention. Usually, a camera light receiving element converts an optical signal into an electric signal on a photoelectric conversion surface and uses this electric signal for measurement. By removing this photoelectric surface and using an electric signal array portion, It becomes possible to acquire an electric signal in two dimensions. As a result, since an electrode array having a size of one cell level can be used, for example, cells having a certain width shown in FIG. 11 that require simultaneous measurement of electrical signals of cells in a cell population. It is possible to measure the occurrence of spiral reentry, which is a change in signal transmission path in a collective network. In actual measurement, the pixel measurement interval needs to be about 1 / 10,000 second, and it is necessary to use a camera light receiving element of a high-speed camera with a shutter speed of 1/10000 second. In this case, the acquired cell signal data can be directly applied to an image processing technique used in an existing camera, and real-time processing using an image processing FPGA becomes possible. In addition, feedback stimulation to the stimulation electrode can be performed based on the data obtained by the real-time processing.

  FIG. 15 is a schematic diagram illustrating an example of a mechanism capable of measuring a plurality of samples with the cell measurement system of the present invention. The system of this embodiment includes an analysis module, a multistage incubator, an electrical analysis module, and an online analysis module connected by an online network. Here, the analysis module includes a phase-contrast microscope or differential interference microscope that measures changes in cell shape, optical measurement using fluorescence microscope and camera imaging analysis, and agarose can be locally dissolved on a micron scale using a microscope system. It consists of agarose processing technology. A multi-stage incubator has a plurality of cell culture tanks, and a microelectrode chip is arranged in the cell culture tank, and the measurement of electrical signals and electrical stimulation of each cell are performed in parallel in the incubator. Can be processed continuously. The obtained electrical signal is measured in real time by the electrical analysis module, and the data is recorded in an online accessible storage with the same time stamp as the optical measurement data and electrical measurement data results. It is possible to analyze the recorded data by appropriately accessing the recorded data online.

  FIG. 16 is a schematic diagram illustrating cardiac information that can be measured by the cell measurement system of the present invention. By measuring the electrical signal of one cell on a microelectrode, it is possible to measure the signal data of ion channels such as Na, Ca, IKr, and IKs. From the measurement of the rate of signal transmission between adjacent cardiomyocytes, Na Inhibition of ion channels can be measured. In addition, the occurrence of arrhythmia can be measured and the cardiac output can be estimated by optical measurement of the shape change of one cell. Furthermore, it is possible to measure the occurrence of reentry by arranging the cell network in a ring shape, and it is possible to measure as a pathologic heart model such as cardiac hypertrophy by adding fibroblasts to the cell arrangement.

FIG. 17 is a graph illustrating an example of a change in the field potential (FP) signal waveform of a cell obtained from autonomously beating cardiomyocytes with respect to drug addition in the cell measurement system of the present invention. The cell field potential signal waveform shows changes in cell potential generated by ions flowing into and out of the cell as shown in FIG. 8, and the differential value of the cell potential, that is, ions per unit time. In this case, inward ionic currents such as sodium and calcium in the process leading to depolarization are negative, and outward ionic currents such as potassium in the subsequent repolarization process are positive. ing. Normally, with respect to the FP signal waveform of this cell, rather than focusing on the difference between adjacent pulsations as shown in FIG. 17, a plurality of adjacent waveforms are averaged to obtain a noise component and each adjacent waveform. One FP waveform is extracted as an average value excluding the influence of differences and the like, and is used to estimate the state of each ion channel by detailed analysis of one waveform reflecting the average value. However, in the present invention, the average value of adjacent FP signal waveforms is not acquired, but a portion depending on the fluctuation of the response of the ion channel is compared and extracted from the difference between adjacent FP signal waveforms, and the magnitude of this fluctuation is Based on this, the blocked amount of the ion channel is estimated quantitatively. The meaning of this can be understood from the fact that the magnitude of fluctuation is generally indicated by the inverse [1 / (n) ^1/2 ] of the square root of element n. That is, when the number of ion channels on the cell surface is functioning, for example, 10 ⁴ , the magnitude of functional fluctuation as the sum of ion channels is 1% [1 / (10 ⁴ ) ^1/2 ]. However, if the number of ion channels that function up to 10 ² decreases due to blocking by the drug, the magnitude of the fluctuation of the function will rapidly increase to 10% [1 / (10 ² ) ^1/2 ]. Increasing and adjacent FP waveforms will cause significant changes. That is, if the fluctuation magnitude can be estimated by comparing changes in adjacent FP waveforms, the total amount of blocked ion channels can be estimated from the fluctuation magnitude.

  Focusing on the location of the peak of the outward ion current generated by the release of potassium ions, for example, regarding the change in the adjacent waveform, for example, the inflow time of sodium ions into the cell is set as a reference (zero), and from that time, potassium ions When the time to the peak of the release of the FPD is defined as the field potential duration (FPD), the change in the length of the FPD is the peak value of the inflow of potassium ions following the inflow and outflow of ions such as sodium and calcium. The fluctuation of the position of the FPD can be noted as an indicator of the amount of change as the sum of changes in ions entering and exiting when various ion channels of the cell are blocked by the drug. Fluctuations in adjacent FP waveforms of ion channels of all relevant cells The thing that reflects the sum total. In fact, the position of the FPD in FIG. 17 (the position of the red arrowhead) was confirmed. By adding E4031, a potassium ion channel inhibitor, the FPD was between 425-450 ms before the addition, but 10 nM was added. 642-645ms, 663-694ms with the addition of 100nM, 746-785ms with the addition of 1μM, the FPD value increases monotonously with the addition of the inhibitor, and adjacent FPDs are not the same value, It will take different values that reflect fluctuations.

  FIG. 18 shows an example of the experimental result depending on the concentration of E4031 regarding the extension of FPD when the potassium ion channel of the cell is inhibited by the drug E4031 having the function of specifically inhibiting the potassium ion channel. . Here, it can be presumed that the outflow of ions is delayed by inhibition of the potassium ion channel, and FPD is extended in a concentration-dependent manner. Consider the case where the fluctuation measurement is similarly performed on the experimental result.

FIG. 19 shows how the FPDs of adjacent pulsations are in a homologous state when focusing on FPD fluctuations by using the Poincare plotting, which generally measures the rhythm fluctuations of an electrocardiogram, to evaluate the FPD values in the FP waveform. Among the points of interest in the method of estimating the deviation, it explains how to estimate the magnitude of fluctuation of adjacent beats (short-term variability (STV)). In FIG. 19A, the diagonal line where X = Y is located when adjacent beats FPD _n and FPD _{n + 1} have the same FPD size, and the difference between two FPDs (FPD _n The vertical distance from the diagonal line with the size of _{+ 1−} FPD _n ) is the magnitude of fluctuation of the adjacent pulsation itself normalized, and particularly for the k number of samplings, it is shown in FIG. It can be evaluated by an equation such as equation 1).

On the other hand, FIG. 20 shows the point of view in the method of estimating how much the FPD of the adjacent pulsations deviates from the homologous state when focusing on the fluctuation of the FPD using the Poincare plotting. The magnitude of the fluctuation of the beat in terms of how much it deviates from the average value of the beat (the sum of all samples corresponds to the ideal value of the ion channel response) (LTV: Long-term variability) It explains how to estimate. In FIG. 20A, an average value FPD _{mean of} FPDs arranged on a diagonal line where X = Y and a difference between two FPDs of distances between adjacent beats FPD _n and FPD _{n + 1} [(FPD _{n +1} −FPD _mean ) + (FPD _n −FPD _mean )], the vertical distance from the diagonal line is standardized, and the magnitude of fluctuation from the average value of the FPD. On the other hand, it can be evaluated by an equation such as (Equation 2) in FIG. This indicates a deviation from the symmetry of X = −Y, and this magnitude is an index for finding out whether the pulsation is merely a fluctuation around the average value or has a history. be able to.

  FIG. 21 is a summary of the fluctuations of FPD shown by the Poincare plotting as an example of the response of cardiomyocytes when E4031 is actually added stepwise, and the fluctuations as STV quantitatively. It is presumed that the ion channel is blocked in response to the addition of E4031 by extending the length of time of FPD, and it can be seen that the value of STV increases abruptly with the addition of a high concentration.

  FIG. 22 shows the ratio (%) in which the extension of FPD corresponding to conventional QT extension measurement is observed on the X axis using myocardial cells, and the ratio (%) in which the increase in STV is observed on the Y axis. Evaluations were made on drugs known to have toxicity and drugs known to have no cardiotoxicity. For conventional drug toxicity tests, evaluation was based only on the results of FPD data on the X-axis, but when the evaluation was performed with the results of STV on the Y-axis, as shown in the figure, a two-dimensional In the mapping on the graph, the distribution is the same as the known literature results in the three areas of high risk, high risk, low risk, and no risk. I understand that. From this, it can be seen that the addition of STV in addition to the conventional FPD makes it possible to more accurately and easily estimate the possibility of the cardiotoxicity of the drug.

  FIG. 23 shows the difference in STV response for FPD to drug addition. In FIG. 23 (a), as an example, a local FPD pointe plotting (A, B) in the case where a circular cardiomyocyte network is constructed, and a two-dimensional myocardial sheet are constructed and the local pointe plots are plotted. (B) shows the result of measuring the Ting (C, D). In this example, B and D are located in the vicinity and A and C are located far from the pager area PM. In (b), FPD that was distributed on the diagonal line of Poincare plotting X = Y before the addition of the drug caused large fluctuations in the cyclic models (A, B) due to the addition of a low-volume cardiotoxic drug. Although an increase in STV is observed, the two-dimensional sheet model (C, D) hardly fluctuates. In addition, for medium-volume drug addition, the pulsation shifts to the fibrillation state or the stop state in the annular model (A, B), but in the region C far from the PM in the two-dimensional sheet model (C, D). Although an increase in STV is observed, it is observed that the amount of increase in STV is still lower than that in region C in the nearby region D. As can be seen from this example, for the prediction of drug cardiotoxicity by STV measurement of FPD, a cell population (network) arranged linearly from the pacemaker region is more than a cell population (network) of a two-dimensional sheet. It can be seen that the effect of the drug is accurately reflected.

  FIG. 24 shows the difference in the response of STV with respect to the transmission speed (V) of the pulsatile stimulus from the PM region to the addition of the drug. This is because Torsad Pointes (TdP), which occurs as cardiotoxicity, is a transmission abnormality in cardiomyocyte tissue, and by confirming how much fluctuation in the transmission rate from the PM region actually occurs, drug toxicity It is a technique to estimate In this case, as shown in (Formula 3) of FIG. 24C, the definition of STV is changed to FPD, and the transmission time T from the PM region (or the distance from the PM is divided by this transmission time). The measurement is performed using the apparent transmission speed V) at the observation point. The definition of LTV is the same as STV, but FPD is changed to T or V. In FIG. 24 (a), as an example, when the cardiomyocyte network is constructed in a ring shape, the pointe-care plotting (A, B) of the local transmission time T and the myocardial sheet spread in two dimensions are constructed and the local FIG. 24 (b) shows the result of measuring the Poincare plotting (C, D). In this example as well as FIG. 23, B and D are located in the vicinity and A and C are located far from the pager area PM. In FIG. 24 (b), the FPD distributed on the diagonal line of Poincare plotting X = Y before the addition of the drug is greatly fluctuated in the cyclic model (A, B) due to the addition of the low-volume cardiotoxic drug. Is observed and an increase in STV showing a large fluctuation in transmission time is observed, but the two-dimensional sheet model (C, D) hardly causes fluctuation. In addition, for medium-volume drug addition, the pulsation shifts to the fibrillation state or the stop state in the annular model (A, B), but in the region C far from the PM in the two-dimensional sheet model (C, D). Although an increase in STV is observed, it is observed that the amount of increase in STV is still lower than that in region C in the nearby region D. As can be seen from this example, the cardiotoxicity of a drug by STV measurement of the transmission time T (or apparent transmission speed V in each region) is determined from the pacemaker area by using a two-dimensional sheet-like cell population (network). It can be seen that the linearly arranged cell population (network) reflects the influence of the drug more accurately, and at the same time, it is possible to more effectively measure the occurrence of spatially dependent fluctuations.

  FIG. 25 shows an FP waveform, a conventional in vitro measurement technique (for example, patch clamp method), and a conventional in vivo measurement technique (for example, when the electrical FP waveform is acquired from each cardiomyocyte in the cardiomyocyte network of the present invention. The relationship with the electrocardiogram) is schematically illustrated. The waveform obtained by the FP measurement of the cell of the present invention indicates the magnitude of ion flow per unit time entering and exiting the cell, and becomes cell potential change information (electrically ionic current). The cell potential obtained by the conventional cell-based in vitro measurement has a differential / integral relationship as depicted in FIG. Next, the FP waveform measured from one electrode obtained from each cell (or local area of the cell network) is superposed on each FP waveform obtained from a plurality of electrodes arranged in a plurality of regions of the cell network. A synthetic FP waveform of the cell network can be obtained, which is homologous to the electrocardiogram data of the QT region corresponding to the response of the ventricular tissue portion of the electrocardiogram which is a potential change signal waveform obtained from the heart.

  FIG. 26 schematically shows the configuration of the apparatus system for estimating the correlation between the information measured by the conventional technique described in FIG. 25 and the FP data obtained by the apparatus of the present invention. Is. FP data acquired in units of one electrode from a plurality of microelectrodes arranged so as to measure a local FP on one cell or cell network can be accumulated, and the cell potential can be estimated by differentiating each FP data. An arithmetic circuit having a function or an arithmetic circuit capable of comparing with the electrocardiogram waveform (Q-T portion) of the ventricular portion of the electrocardiogram by superimposing each electrode data. In particular, it is not only possible to analyze FP data of a single electrode using a superposition circuit but also to synthesize data of a plurality of microelectrode arrays arranged at equal intervals on a cell network arranged in series, for example. In addition, data reflecting not only the result of FP of cells on each electrode but also the state of transmission between cells will be displayed. In particular, in estimating arrhythmia, which is an abnormal transmission between cardiomyocytes, the abnormal transmission is synthesized. Since it is reflected in the FP waveform, the result of this superposition circuit is moved to the direct prediction mechanism of the occurrence of extrasystole, and the same prediction as the electrocardiogram analysis can be performed from this result. The cell potential data obtained from the other differentiating circuit is also used to estimate the state of ion channels having different activation states depending on the cell potential.

  27 and 28 show an example in which the FP data from each electrode is actually overlaid by the arithmetic circuit described in FIG. In FIG. 27, as shown in FIG. 27A, the cardiomyocyte network is arranged in a ring shape, and microelectrodes are arranged at regular intervals along the network. In the annular cardiomyocyte network in which the pacemaker (PM) region is at the position of the electrode R1, the pulsation signal is transmitted from R2 → R8 or L1 → L8 can be seen from the FP waveform of each electrode in FIG. The waveform obtained by superimposing these becomes the waveform of the lower S. FIG. 27C shows the result of actual measurement and synthesis over a long period of time. This is a composite FP waveform including FP transmission information necessary for estimating the waveform in the QT region of the actual electrocardiogram. As can be seen from this figure, when a pulsation signal is normally transmitted from the PM region, the synthesized waveform is also a smooth waveform as can be seen from FIG. On the other hand, as can be seen from FIG. 28 (B), FIG. 28 shows a distorted waveform when the pulsation signal from the PM region is not transmitted regularly, and the S which becomes the composite FP also becomes a very distorted waveform, and corresponds to an electrocardiogram. In 28 (C), a waveform having the same shape as that of the arrhythmia can be seen as a synthesized FP waveform. It should be noted here that when predicting an arrhythmia from only one electrode data of each microelectrode in FIG. 28B, depending on the electrode to be observed (for example, L5), it is not possible to predict the occurrence of a significant arrhythmia. It is difficult, and it can be seen that it is possible to predict more accurately by using a synthesized FP waveform as seen in FIG.

FIG. 29 shows the relationship of the size of the FPD to the pulsation cycle of the cardiomyocytes. A black circle is a result of measuring FPD in cardiomyocytes having various autonomous pulsations with the apparatus system of the present invention. As can be seen from this result, it can be seen that the cell changes the value of FPD depending on its pulsation cycle. This is because when the measurement is performed using cardiomyocytes using autonomous pulsation, when the pulsation cycle of the cell changes, stops pulsating, or becomes unstable due to the drug, this side effect causes the original ion channel. This suggests that the FPD may change due to a cause that is not a block. The red X indicates the FPD value when the pulsation cycle of the cell is forcibly changed by forced pulsation. The pulsation cycle can be maintained for a certain period of time or longer by continuous external stimulation. It can be seen that a stable FPD is obtained.

  FIG. 30 shows an example of temporal changes in the FPD of cardiomyocytes when forced pulsatile stimulation is applied from the outside to the cardiomyocytes that are actually autonomously pulsating using the system of the present invention. As can be seen in this example, when a cell with an autonomous pulsation interval of about 4 seconds gives a forced pulsatile stimulus of 1 Hz, the FPD value changes greatly immediately after that, and the position of 550 ms is about 30 seconds after the start of stimulation. It can be seen that it stabilizes. It can also be seen that even after the forced pulsatile stimulation is completed, the autonomic pulsation period is different, and the FPD becomes gradually longer. As can be seen from these results, it is desirable to conduct a drug toxicity test after 30 seconds from the start of stimulation until the FPD is stabilized after the forced pulsatile stimulation is started.

  FIG. 31 shows an example of cell arrangement in the case where FPD, transmission time T, or transmission speed V is actually measured by applying a forced pulsatile stimulus from the outside using the system of the present invention. FIG. 31A shows an example of stimulus measurement using a cell population arranged to cover at least two microelectrodes. For example, while applying a forced stimulation signal at a constant interval of 60 beats per minute from the stimulation electrode, the FPD of the cell at the adjacent measurement electrode, or the transmission time T of the pulsation signal from the stimulation time of the stimulation electrode to the cell on the measurement electrode, Alternatively, the transmission speed V to the cell on the measurement electrode is measured. FIG. 31 (b) shows a forced stimulation pulsation provided by stimulation microelectrodes arranged at the end points of a linearly arranged cardiomyocyte network, and this transmission is performed with a minute arrangement arranged along the cardiomyocyte network at regular intervals. The electrode array measures the FPD, T, V of myocardial cells on each electrode, predicts not only the data of each electrode with respect to the stimulation signal of the stimulation electrode but also the prediction of the occurrence of arrhythmia by the combined FP of each recording electrode FP, The relationship between T and V can be estimated. However, what is shown here is merely an example of the cell arrangement, and the same measurement can be performed by giving a forced pulsation to the PM region of the circular cell network shown in FIG. It is also possible to measure FPD with the minimum number of cells by using the stimulation electrode as a measurement electrode in the upper cell.

  In all of the examples so far, only a part of the myocardium has been mentioned for the myocardial cell network, but the addition of fibroblasts so as to have the same properties as the living tissue is included.

  FIG. 32 schematically shows that a potential clamp type feedback control mechanism that keeps the potential of the electrode 2 constant can be used to perform the FP measurement of the cells arranged on the microelectrode 2. . Here, the FP of the cell does not measure by amplifying the signal from the conventional electrode, but monitors the current supplied from an external power source in order to maintain the potential of the electrode 2, and displays the result in real time. It is estimated by analyzing with. Here, zero is normally selected as the potential to be kept constant, but when the cell state is changed, such as changing the depolarization potential, the potential can be adjusted to a different one.

  FIG. 33 shows the pulsation cycle of a cell population when forced pulsatile stimulation is applied to a partial region of the cell population actually differentiated from human ES cells into cardiomyocytes using the system of the present invention described above. It is a graph of an example of the result of having measured change. As can be seen from this graph, in a normal myocardial cell population, when a forced stimulation of, for example, 0.6 Hz to 1.8 Hz is given as in this example, in response to the forced stimulation linearly in all of this range. It can be seen that the beat follows.

In FIG. 34 (a), since the pulsation of the cell population has the same period as the interval of the forced pulsation stimulation when the forced pulsation stimulation is actually applied, the cardiomyocyte population in this forced pulsation stimulation state is shown in FIG. The change of the waveform of FP and the change of the length of FPD are shown. As can be seen from the graph, it can be seen that the FP waveform is changed and the length of the FPD is shortened by increasing the forced pulsation stimulation interval. Therefore, as shown in FIG. 34 (b), when this change in FPD is shown in a graph, this shortening depends on the period (RR) of the forced pulsation interval. From the study of the relationship between QT interval length and heart rate in Japan (Patrick Davey, How to correct the QT interval for the effects of heart rate in clinical studies. Journal of Pharmacological and Toxicological Methods 48 (2002) 3-9) correction, i.e. correction since the length of the QT by the difference in the speed of the beating is not to cause a relative comparison changes, the length of QT during myocardial pulsation pulsation cycle 60 beats per minute (QT _C) those converted as _{QT C = QT / (RR)} 1/3 in order to, or if it matches the one that calculated as _{QT C = QT / (RR)} 1/2 where Bazett advocated is important. As explained above, the length of QT in vivo corresponds to the overlap of the length of FPD measured in the entire cell network measured by this system, that is, the FPD itself of each cell is , above, suggest that it should fall within the scope of correction of Fredericia or Bazett, indeed, the results shown in FIG. 34 (b) is a _{QT C = QT / (RR)} 1 / 2.5 You can see that it is between the Fredericia and Bazett corrections. FIG. 35 is a table showing the data shown in the graphs of FIGS.

These results show that the quality of cardiomyocytes actually used in screening and regenerative medicine can be confirmed by measuring the response of cardiomyocytes when forced pulsatile stimulation is applied to the cardiomyocytes. Yes. 1) Giving forced pulsatile stimulation to a cardiomyocyte or myocardial cell population, confirming whether the cell or cell population responds to the forced pulsatile stimulation at the same interval as the forced pulsatile stimulation, and Measure whether the response corresponds to the frequency range of the forced pulsatile stimulation, and confirm that the pulsation can follow, and determine that it satisfies one of the sufficient conditions for healthy cardiomyocytes Or, more specifically, it is determined that the following of the response satisfies, for example, at least 1.8 Hz by satisfying one of the sufficient conditions for a healthy cardiomyocyte.
2) In the above-mentioned frequency range in which the follow-up of the pulsation of the cell can be confirmed with respect to the forced pulsation stimulation interval (RR), the change in the FPD with respect to the forced pulsation stimulation is FPD / (RR) ^1/3 / (RR) ^Judge that one of the sufficient conditions for healthy cardiomyocytes is satisfied by confirming that it is between ^1/2 .

By using the above procedure, the quality of cardiomyocytes can be controlled. A healthy cardiomyocyte is a cell capable of stable pulsation. Here, for the cell population to be evaluated, the cell population subjected to differentiation induction may be used as it is, or the cardiomyocytes subjected to differentiation induction may be dispersed and measured and evaluated in units of one cell. Alternatively, these dispersed cardiomyocytes may be repopulated and measured, or these dispersed cardiomyocytes may be mixed with human heart-derived fibroblasts to be measured and evaluated as a new cell population. .
These cardiomyocytes can be used for myocardial toxicity tests.

  FIG. 36A shows a comparison between the microelectrode 2 on which the cell 10 is placed and the bare cell on which the cells arranged in the vicinity of the microelectrode 2 are not placed in order to reduce the noise of the cell signal electronically. The circuit which outputs the difference value of the electric potential between the electrodes 2c is shown typically. In fact, as shown in FIG. 36B, by incorporating this circuit in the first stage of the amplifier circuit, it can be seen that noise is reduced without depending on a specific frequency as shown in FIG. 36C. . At this time, it is desirable that the position of the comparison electrode 2c with respect to the microelectrode is closer, for example, those arranged at a distance of 50 μm can perform a sufficient function but can provide a noise reduction function up to a distance of 1 mm. .

  FIG. 37 is a diagram schematically showing an example of a comprehensive evaluation method for cardiotoxicity evaluation of the present invention. Regarding FPD values obtained from the results of cardiomyocyte cell potential measurement after the addition of a specific concentration of drug, first, the aggregated results of the extent of FPD extension are taken as values on the X axis, and the above FPD time The fluctuation is set as the value on the Y-axis from the Poincare plotting to STV, and the result is plotted. FIG. 37 (b) is an example of various drugs plotted in the XY diagram as a result. As can be seen from the figure, a drug in the region where FPD prolongation and fluctuation (STV) increase are small can be judged to have QT prolongation but no cardiotoxicity, and FPD prolongation and fluctuation (STV) increase simultaneously In cases (upper right in XY drawing), it can be predicted that there is cardiotoxicity such as TdP.

  FIG. 38 is a schematic diagram showing an example of the configuration of a system for actually measuring cardiotoxicity. The system of this embodiment is composed of a liquid feeding unit, a cell culture measurement unit, and a cell analysis / stimulation unit.

  The liquid feeding section can be fed by a syringe pump system, a peristaltic pump system, or an HPLC pump system that continuously feeds the culture solution to each cell culture chamber cultured in the cell culture measurement section. In addition, a resistance heating wiring for temperature adjustment is wound around the outer periphery of the pipe of the liquid feeding section, and the liquid temperature in the pipe is continuously monitored by a heat detection mechanism such as a micro K-type thermocouple or thermistor, so that the liquid temperature to be introduced can be controlled. By adjusting the degree of resistance heating to be controlled, a solution at a constant temperature is always introduced. In addition, a mechanism such as a merging pipe and a switching pipe is arranged in the pipe for adding the drug to be tested in this liquid feeding section, so that a drug having a desired concentration can be introduced into each cell culture chamber. Can do. In addition, in order to quantitatively confirm the concentration of the chemical solution to be introduced, a part of the liquid introduction tube is optically transparent and can be quantitatively evaluated by absorption spectroscopic measurement in the wavelength range of 280 nm to 800 nm. It is desirable that a mechanism is added. Similarly, for the waste liquid, it is desirable that a part of the waste liquid tube is optically transparent and that a mechanism capable of quantitative evaluation is added by absorption spectroscopic measurement in the wavelength range of 280 nm to 800 nm. In addition, the control temperature of the chemical solution is usually desirably a temperature close to the normal temperature of the human body, and from this point of view, it is desirable to be able to control the temperature in the range of 30 to 45 degrees Celsius.

  FIG. 39 is a schematic diagram and a photograph showing an example of the configuration of the cell culture measurement chamber in the system for measuring cardiotoxicity of the present invention. A multi-electrode substrate 4201 (see FIG. 40) on which a plurality of cell potential measurement electrodes are arranged is bonded to a cell culture container 4202 on which a culture solution introduction mechanism / discharge mechanism is arranged, so that eight samples can be measured simultaneously. It is a possible cell culture measurement plate. As schematically shown in the cross section of the cell culture measurement plate in FIG. 40, in this cell culture container 4202, the solution inlet is arranged in a fan-like shape on the bottom surface closest to the multi-electrode substrate 4201. On the other hand, the liquid discharge mechanism is developed in a fan shape in the same direction as the interface direction of the liquid level at a position that determines the height 4204 of the upper liquid level.

  FIG. 41 is a diagram schematically illustrating the configuration of the electrode wiring in the electrode arrangement arranged on the multi-electrode substrate. In the present invention, a transparent electrode such as ITO is used as an electrode for observing the shape of a cell. However, since the transparent electrode has a higher resistance value than a normal metal electrode as a characteristic of the transparent electrode, it is particularly multi-electrode. When the substrate becomes large, such as a plate, the wiring becomes long and the impedance becomes very large. In order to avoid this, if the metal layer is arranged on the transparent electrode with the same wiring as the transparent electrode, the resistance value can be lowered by the conductivity of the metal electrode. Actually, in the region where cells are cultured, wiring using the transparent electrode 4302 on the glass substrate 4301 is arranged for optical observation, and in the region where cells are not observed, the wiring is overlapped with the transparent electrode. A metal layer 4303 is disposed on the upper surface of the metal layer 4303 and the upper surface thereof is covered with an insulating film. As the metal electrode material used here, for example, gold, platinum, titanium, copper, aluminum or the like may be used.

  FIG. 42 is a schematic diagram showing an example of electrode arrangement on a multi-electrode substrate. First, in FIG. 42A, a stimulation electrode 4401 for locally stimulating one end of a cardiomyocyte network arranged in series in the cell culture region 4404, and a measurement electrode 4402 for measuring excitatory conduction of cardiomyocytes stimulated by this stimulation electrode. A reference electrode 4403 for noise removal is arranged. The results of a plurality of local responses of the cardiomyocyte network obtained from each measurement electrode 4402 can be measured, and fluctuations in the transmission speed can be obtained by comparative analysis of the transmission poisoning degree between the measurement electrodes. . In FIG. 42 (b), the measurement electrodes are connected in a straight line. With this configuration, a waveform similar to the electrocardiogram waveform in the ST region (ventricular region) of the electrocardiogram can be measured. In FIG. 42 (c), a part of the above FIG. 42 (b) is cut away to make it easy to obtain the FP waveform of local cardiomyocytes. FIG. 42 (d) is an example of an electrode arrangement for measuring cells arranged in a ring shape on the ring electrode. These measure the cardiomyocyte network arranged in a ring shape as shown in FIG. 11 and FIG. 12, but a part of the ring-shaped measurement electrode is lost and a local forced stimulation is applied to the site. A stimulation electrode is arranged, and a reference electrode for noise removal is arranged. Further, in FIG. 42 (e), the measurement electrodes are also divided so that the response of the local cardiomyocytes can be measured.

  FIG. 43 is a schematic diagram showing an example of the system configuration of the present invention for simultaneously measuring the mechanical characteristics and electrical characteristics of cardiomyocytes. The system includes (1) a cell network chip in which a plurality of microelectrodes capable of culturing a cell population and acquiring cell potential data of a microregion in the population are arranged on a substrate; A chip mounter that fixes the chip and is electrically connected to the cell stimulation / cell potential measurement system, and (3) an environmental control vessel that can control the temperature, humidity, oxygen concentration, carbon dioxide concentration, etc. of the cell population to be cultured. (4) a micro multi-electrode potential measurement system capable of stimulating specific cardiomyocytes in a cell population and simultaneously measuring cell potentials of various micro regions in the cell population; and (5) the cell network described above When the particle size arranged in the cell population is about 0.1, 0.2 μm or less by culturing by mixing with the surface of the cardiomyocyte population in the chip or in the cell population, 0. μm, 0.4μm, 0.5μm, 0.6,0μm. 7 μm, preferably about 0.8 μm, more preferably about 0.9 μm, most preferably about 1 μm up to about 500 μm, 400 μm, 300 μm, preferably about 200 μm, more preferably about 100 μm, most preferably about 50 μm The shape and shape of myocardial cells whose brightness and birefringence can be easily distinguished with an optical microscope from cardiomyocytes such as plastic microparticles, glass microparticles, gold microparticles, etc. An optical image comprising one or more position coordinate probe fine particles for measurement, (6) the illumination light source for optically measuring the fine particles, an optical microscope, and an image acquisition camera for acquiring the image. Acquisition system and (7) Cell potential measurement by analyzing potential waveform and cell displacement measurement by image analysis and analysis , A computer system is capable our image analysis and cell potential for analysis and stimulus control and integration data recording which performs feedback stimulus based on the results. In the measurement using this device, for stimulation for causing depolarization of cardiomyocytes, (A) the measurement using the conduction of autonomous pulsation of the cardiomyocyte population is performed, and (B) in the cardiomyocyte population. Applying a forced electrical stimulus to a specific cell from the outside and measuring the conduction; (C) a relationship between a cell potential value and a delay time based on the measured cell potential data for a specific cell in the cardiomyocyte population. It is possible to apply a stimulus by mainly selecting from three means of giving a feedback stimulus at a specific timing satisfying the condition and measuring its conduction.

  FIG. 44 is an example of a data acquisition monitor screen showing an example of data acquired from an example of the system configuration of the present invention for simultaneously measuring the mechanical characteristics and electrical characteristics of cardiomyocytes. In this example, a large number of polystyrene fine particles are arranged on the surface of the cardiomyocyte population, and a probe fine particle displacement observation window is set for the polystyrene fine particles to be used as five probes, and the fine particles in the window are arranged. As the center of gravity of the window moves with the movement, the displacement of a specific probe fine particle can be continuously measured as a vector time change in the X-axis direction and the Y-axis direction. In addition, by measuring the cell potential data of a specific target cardiomyocyte at the position where optical measurement is being performed, changes in the conduction stimulation response of the Na ion channel, Ca ion channel, and K ion channel, and changes in the cell shape Can be correlated and measured. In particular, it is possible to simultaneously measure the displacement of a plurality of probe microparticles and to measure the displacement direction in addition to the displacement amount, thereby producing a drug caused by variations in response characteristics of each cardiomyocyte in the cell population It is also possible to quantitatively estimate whether the change in shrinkage strength due to addition occurs uniformly or nonuniformly.

  FIG. 45 is an example of data acquired from an example of the system configuration of the present invention for simultaneously measuring the mechanical characteristics and electrical characteristics of cardiomyocytes. As can be seen from the figure, in addition to the cell potential data, it is possible to obtain the displacement amount of the myocardial cells at the same time and displacement speed data obtained by time-differentiating the displacement amount.

  FIG. 46 is a diagram for explaining an example of acquisition of cell displacement direction data acquired from an example of the system configuration of the present invention for simultaneously measuring the mechanical characteristics and electrical characteristics of cardiomyocytes. It is a continuous image showing the time change of the probe fine particles arranged in the upper cell, and this displacement data is acquired as an (X, Y) component, and this is obtained by using a polar coordinate system (r, By converting into θ), it is possible to quantitatively estimate the effect of the medicine using two indexes of displacement and angle change. The graph below shows an example of a phenomenon in which it is observed that the fluctuation of the angle change of the fine particle displacement is actually increased by the addition of the drug.

  FIG. 47 is a diagram for explaining an example of the spatial arrangement of the cardiomyocyte network in the system of the present invention that simultaneously measures the mechanical characteristics and electrical characteristics of the cardiomyocytes. (A) shows one minute cardiomyocyte cluster arranged on one minute electrode, (b) shows two-dimensionally arranged cells arranged in a two-dimensional cardiomyocyte sheet. (C), the cardiomyocytes are arranged linearly on a microelectrode array arranged linearly in one dimension, and arranged so that the firing of the cardiomyocytes at the end points is conducted to the other end, (d) Is a cardiomyocyte network arranged in a ring on a microelectrode array arranged in a ring, and the cardiomyocyte network arranged in a ring is connected in a closed loop, or arranged in a ring Some of them are arranged so that a part of the cell network is cut to form an open loop. Here, particularly when the cells are arranged in a straight line as shown in (c), if the adhesion of the cardiomyocytes to the substrate surface is not sufficient, the substrate surface of the cardiomyocytes as shown in (e) Since the contraction force between cardiomyocytes is too strong for adhesion to the cells, the cells gradually contract and the spatial arrangement of the cell network cannot be maintained, resulting in a cell mass. In order to avoid this, it is effective to dispose the cells in a ring shape as shown in FIG. It is also effective to use collagen vitrigel instead of conventional collagen for the collagen layer on the substrate surface.

  FIG. 48 shows cell potential (Action Potential) graphs of human stem cell-derived cardiomyocytes (upper three types) classified based on actually well-known cardiomyocyte cell potential measurements, and their cell potentials are time-differentiated. Fig. 3 shows extracellular potential (Field Potential) graphs (lower three types). The left graph shows atrial muscle cells, the middle graph shows ventricular muscle (Purkinje cells) cells, and the right graph shows atrioventricular nodal cells. Therefore, when measuring the drug response of the ventricular muscle or the conduction response in the ventricular muscle, it is desirable to measure the characteristics shown in the graph in the lower center using the cells measured by the extracellular potential. This is characterized by the generation of a sharp inward current of Na ions within 20 ms after the start of depolarization accompanied by rapid and clear depolarization in the absence of a drug, and within 100 ms after the start of subsequent depolarization. There is a generation of a slow Ca ion inward current and a significant K ion outward current observed after 100 ms after the start of depolarization.

  FIG. 49 is a diagram showing an example of fluctuations in fluctuations in cell potential of cardiomyocytes and drug response of hERG ion channel. As shown in FIG. 49 (A), when the drug E4031 that specifically inhibits the hERG ion channel is added, the response of the extracellular potential (Field Potential: FP) varies between adjacent pulsation cycles as described above. However, using human stem cell-derived cardiomyocytes, the cell potential (AP) has the same tendency and degree of fluctuation as FP. It can be seen that it is generated. Therefore, even when using electrophysiological cell potential measurement methods such as the conventional patch clamp method, rather than taking the average value of each response, the observation is quantitatively measured. It is also possible to estimate by doing. At this time, in order to adjust the stability of the cell response, for example, in the case of measurement using the patch clamp method, one cell in the cardiomyocyte population is measured rather than measurement with one isolated cardiomyocyte. It is desirable to do. FIG. 49 (B) shows an example of the result of measuring the change in cell potential of the whole cell against inhibition by E4031 in the same manner for CHO cells in which only the hERG ion channel is forcibly expressed. As can be seen from this result, the average value of the measured data is shown in the conventional tail current measurement. However, when the block of the ion channel advances, the current itself decreases and the measurement becomes difficult. However, when the fluctuation of the cellular response is measured, the increase in fluctuation increases rapidly when the hERG ion channel block rate increases. When measurement based on current is difficult due to an increase in size, combined measurement of two methods of measuring by fluctuation measurement is effective.

FIG. 50 is a diagram for explaining the principle of the cell stimulation method at an arbitrary position by superimposing stimulation potentials from the stimulation electrode array. As shown in FIG. 50 (A), a number of stimulation electrode arrays capable of controlling the electrode potential and phase between adjacent electrodes are two-dimensionally arranged on the substrate, and each electrode is separated from a single electrode. Stimulation of the cell outputs a weak potential change that does not cause depolarization of the cell, and by superimposing these, a superposition potential sufficient to give the cell stimulation is generated specifically at a specific position on the two-dimensional plane Therefore, it is possible to calculate the electric field strength and phase pattern of each electrode that each electrode needs to generate based on the rules of Fourier synthesis, and to give a stimulus only to a specific place. As an example, for example, as shown in FIG. 50B, an electrode array is arranged in a circular ring shape, and by controlling them with the above method, it is possible to give a stimulus by a focused electric field at the center of the ring. It is. When this electrode array is arranged in a form floating spatially in the Z-axis direction from the XY plane (R-axis direction) that is the cell culture layer, specifically, the plane (R-axis) on which the electrode array is arranged Direction) and the electric field irradiation direction (Z-axis direction) in the plane of the electric field focusing, the arrangement of the stimulation electrode array is as follows. First, when the electric field is focused on the point Z _f on the Z axis, the distance from R ₀ to Z _f is mλ, where R ₀ is the foot of the perpendicular drawn from the focal point Z _f to the R axis plane. To do. Here, λ is the wavelength of the stimulation signal wave based on the conduction velocity in the cell population generated from each stimulation electrode, and m is a natural number. When the stimulation electrode is arranged at the position of R ₀ , the radius of each of the microelectrodes arranged concentrically is R _n when the radius of the _{nth in-} phase location from the center is R _n .
Can be put. However, the position R _n indicates the position of the concentric circle of the n-th stimulation electrode, and its width is about ± λ / 4 at most in terms of conduction velocity in terms of the distance from the position of the focal point where the stimulation is applied. Naturally, even if the reference stimulation electrode is not arranged at the position of R ₀ , it is possible to specifically stimulate the focal position of the concentric circle, and Z _f is the same as the substrate on which the cell network is arranged. A stimulation electrode array may be arranged on the substrate so that Z _f = 0. In addition, when the focal position deviates from the center of the circle, the phase of the stimulation signal of each stimulation electrode is converted from the conduction velocity and changed according to the deviation, so that it can be changed to any specific position in the stimulation ring electrode. It is possible to give a stimulus. In the above description, the myocardial cell network is taken as an example, but the same processing is possible for all cells having the ability to transmit excitatory conduction between cells.

  FIG. 51 illustrates the effect of combining an objective lens having a numerical aperture of 0.3 or less and a zoom lens system for optical measurement of fine particles. In an ordinary optical system, an image from an objective lens is directly formed on an image recording element such as a CCD camera and observed. In this case, the depth of focus corresponding to the numerical aperture (NA) of the objective lens is observed. Thus, when the magnification is enlarged, there is a problem that the depth of focus at which the image is not blurred becomes shallow. In order to solve this, an image acquired with an objective lens having a low magnification (that is, a low numerical aperture) may be enlarged with a zoom lens system added to the subsequent stage. Although the spatial resolution of the image is defined by the numerical aperture, in the present invention, probe fine particles whose shape is already known are used. Therefore, if the fine particle image is not blurred, accurate fine particles can be obtained even if spatial resolution is somewhat sacrificed. There is no problem because the spatial coordinates of can be acquired. FIG. 51A shows an example of the configuration of the optical system of the present invention. A zoom optical system is arranged after the objective lens, and a video camera is arranged after the objective lens. FIG. 51B is a result of actually observing fine particles directly using an objective lens having various magnifications (numerical apertures) and observing image blur in the depth direction. As can be seen from this result, with a 10 × (numerical aperture of 0.3) objective lens, an image with a focal depth of 15 μm can be observed without blur, but 20 × (numerical aperture of 0.4) and 40 ×. In both cases (numerical aperture 0.6), it is not possible to obtain an image in which blurring occurs only in the depth direction of about 5 μm. FIG. 51C is an observation result of an optical system image obtained by actually adding a zoom system to a 10 × objective lens (numerical aperture 0.28). As can be seen from this result, even when the zoom system is used to enlarge the magnification ratio (positional coordinate resolution) equivalent to 20 times the objective lens and 40 times the objective lens, the depth of focus is maintained at about 25 μm, and particularly the contraction. In a cardiomyocyte network that moves, even a large displacement in the depth direction can be tracked with the position coordinate resolution using the same image processing without losing sight of the coordinates of the probe fine particles.

  According to the present invention, it is possible to evaluate whether a cardiomyocyte differentiated from a stem cell such as an iPS cell is a healthy cardiomyocyte that can be used for drug discovery screening or regenerative medicine.

1 ... transparent substrate, 2 ... microelectrode, 2c ... reference electrode, 2 '... lead wire microelectrode _2, 3 _1, 3 2, _{3 3} and _{3 4} ... Wall by agarose _gel, 4 _1, 4 2, _{4 3} And 4 ₄ ... Gap, 7... Surrounding wall, 8 ₁ , 8 ₂ , 8 ₃ ... Pipe, PC ... PC, Ms ... PC operation signal 10, 10 ₁ , 10 ₂ , 10 ₃ , --- 10 n _... cardiomyocytes or fibroblasts, 15 ... transparent stage of optical observation apparatus, 16 ... X-Y drive apparatus, 18 ... Z drive _{apparatus, CH 1, CH 2, CH} 3 and CH n _... cell holder, CCC ... cell communication channel, 10 _G ... cell population, 11 _a ... barrier, 11 _b ... aperture, 19, 191, 192, 193 ... dichroic mirror, 20, 201 ... bandpass filter, 21, 211 ... camera, 22 ... light source, 221 Fluorescent light source 23, 231 ... band pass filter, 24, 241 ... shutter, 25 ... condenser lens, 26 ... objective lens, 27 ... movable electrode, 28 ... ground electrode, 29, 291 ... switching circuit, 30, 301 ... electrical signal Measurement circuit 31, 311 ... Electrical stimulation circuit, 32 ... Cardiomyocyte, 33 ... Fibroblast, 34 ... Pipette for cell placement, 35 ... N-th round transmission path, 36 ... (N + 1) round-th round transmission path, 37 ... (N + 2) circular transmission path, 38 ... measurement electrode, 39 ... reference electrode, 40 ... liquid feeding system, 41 ... annularly arranged cell population, 42 ... 96 well plate, 43 ... camera light receiving element, 44 ... Cell, 45 ... Cell stimulation electrode, 100 ... Myocardial toxicity test apparatus, 4201 ... Multi-electrode substrate, 4202 ... Cell culture container, 4203 ... Flow of solution, 4204 ... Height of liquid surface, 4301 ... Glass substrate, 4302 ... Transparent Pole, 4303 ... metal layer, 4304 ... insulating film, 4401 ... stimulation electrodes, 4402 ... Measurement electrodes, 4403 ... reference electrode, 4404 ... cell culture area.

Claims (8)

substrate,
A cell population comprising a plurality of cardiomyocytes to be evaluated or a non-cardiomyocyte such as fibroblasts and the like, which are placed on the substrate and perform stable pulsation;
A wall for filling a cell culture solution formed on the substrate so as to surround the periphery of the cell population;
One or more microelectrodes carrying one cell of the cell population or a local part of the cell population;
A reference electrode provided in an area for filling the cell culture medium surrounded by the wall,
A potential measuring means for measuring a cell potential placed on the microelectrode by using a lead wire connected to each of the microelectrodes and a lead wire connected to the comparison electrode;
Control / recording means for controlling electrical stimulation sent to the microelectrode and recording potential data measured by the potential measuring means;
Fine particles having a particle size of about 1 μm or more and about 50 μm or less, which are different in optical properties from the cell population containing cardiomyocytes, arranged on the cell population or at one or more locations in the population at a spatial distance,
Displacement data including an irradiation light source for optically measuring the fine particles, an optical microscope, and an image acquisition camera, and the position and position change of the fine particles, including temporal movement amount data and angle change data in the movement direction. As an optical measurement system, and recording means for correlating and recording the potential data and the displacement data,
A cardiotoxicity evaluation device. substrate,
A cell population comprising a plurality of cardiomyocytes to be evaluated or a non-cardiomyocyte such as fibroblasts and the like, which are placed on the substrate and perform stable pulsation;
A wall for filling a cell culture solution formed on the substrate so as to surround the periphery of the cell population;
One or more microelectrodes carrying one cell of the cell population or a local part of the cell population;
A reference electrode provided in an area for filling the cell culture medium surrounded by the wall,
A potential measuring means for measuring a cell potential placed on the microelectrode by using a lead wire connected to each of the microelectrodes and a lead wire connected to the comparison electrode;
Control / recording means for controlling electrical stimulation sent to the microelectrode and recording potential data measured by the potential measuring means;
Microparticles having a particle size of about 1 μm or more and about 50 μm or less having optical characteristics different from that of the cell population including the cardiomyocytes arranged on the cell population or at one or more locations in the population at a spatial distance;
An objective lens having a numerical aperture of about 0.3 or less and a zoom lens in the subsequent stage for continuously measuring the position and position change of the fine particles as displacement data including temporal movement amount data and angle change data in the movement direction. An optical measuring means arranged with a system, and a recording means for correlating and recording the potential data and displacement data,
A cardiotoxicity evaluation device.   Furthermore, the cardiotoxicity evaluation apparatus of Claim 1 or 2 provided with the culture solution supply / discharge channel which supplies and / or discharges | emits the said cell culture solution in the area | region enclosed by the said wall.   The cardiotoxicity evaluation apparatus according to claim 1, wherein the microelectrode includes a stimulation electrode for stimulating a cell and a measurement electrode for measuring a cell potential. Using the cardiotoxicity evaluation apparatus according to claim 1,
As a cell to be measured, in a state where no drug is added, a sharp inward current of Na ions is generated within 20 ms after the start of depolarization accompanied by a sharp and depolarization, and the subsequent depolarization is started. Measure the extracellular potential using cardiomyocytes that have a slow Ca ion inward current generation within 100 ms and a significant K ion outward current observed after 100 ms after depolarization starts. Cardiotoxicity evaluation method characterized by Using the cardiotoxicity evaluation apparatus according to claim 2,
As a cell to be measured, in a state where no drug is added, a sharp inward current of Na ions is generated within 20 ms after the start of depolarization accompanied by a sharp and depolarization, and the subsequent depolarization is started. Measure the extracellular potential using cardiomyocytes that have a slow Ca ion inward current generation within 100 ms and a significant K ion outward current observed after 100 ms after depolarization starts. Cardiotoxicity evaluation method characterized by   The cardiotoxicity evaluation method according to claim 5 or 6, wherein the cardiotoxicity evaluation apparatus further includes a culture solution supply / discharge channel for supplying and / or discharging the cell culture solution into an area surrounded by the wall.   The cardiotoxicity evaluation method according to claim 5, wherein the microelectrode includes a stimulation electrode for stimulating a cell and a potential measurement electrode for measuring a cell potential.