JP2020078356A - Cell culture apparatus, cell culture method, and culture tank - Google Patents

Abstract

To make culture medium replacement of a floating cell culture system easier.SOLUTION: A cell culture apparatus comprises: a culture tank capable of housing culture medium and cells inside thereof; culture medium supply means for supplying culture medium into the culture tank; and culture medium discharge means for discharging culture medium from the culture tank, in which the culture tank comprises: a partition wall which can divide the internal space into an upper space and a lower space in a gravity direction; a supply port for allowing the culture medium supply means to supply culture medium to the inside; and a discharge port for allowing the culture medium discharge means to discharge culture medium from the inside. The discharge port opens for the upper space, and the partition wall can switch an internal space of the culture tank to a state where the upper space and the lower space are divided, or a state where the upper space and the lower space are communicated.SELECTED DRAWING: Figure 7

Description

  TECHNICAL FIELD The present invention relates to a cell culture device, a cell culture method, and a culture tank capable of exchanging a culture medium during cell culture.

  In recent years, with the progress of stem cell research/regenerative medicine and the development of biopharmaceuticals such as antibody drugs, it has been required to culture a large amount of cells. When culturing a large amount of cells, use a culture tank such as a bioreactor (Patent Document 1) or a bag-shaped culture bag (Patent Document 2) made of a gas permeable material instead of culturing in a flask or a petri dish. Is increasing.

JP, 2011-188777, A Japanese Patent Laid-Open No. 2000-125848

The cells take in components necessary for growth such as oxygen and nutrients during culture, and discharge carbon dioxide and waste products. Therefore, when the cells are cultured for a long period of time, the medium deteriorates and it is necessary to replace the medium regularly. Replacing the medium requires labor and cost for the operator, and causes a risk that the cell culture system is contaminated with bacteria and the like.
For example, in order to prepare cells for clinical use, culturing that meets strict standards is required, and culturing in a closed system is effective to reduce the risk of contamination, etc., but it is not necessary to change the medium during culturing in a closed system. Very difficult.
Further, when the culture target is floating cells, it is necessary to separate the medium and the cells by centrifugation or the like when exchanging the medium, which complicates the work and further increases the burden on the operator.

  The present invention has been made in view of the above circumstances, and in a culture system using a culture tank such as a bioreactor, a cell culture device, a cell culture method, and a culture tank that can easily exchange the medium Is intended to provide.

In order to achieve the above object, the present invention provides the following means.
One aspect of the present invention, a culture tank capable of containing a medium and cells inside,
Medium supply means for supplying a medium to the culture tank,
Medium discharging means for discharging the medium from the culture tank,
A cell culture device comprising:
The culture tank has a partition wall that divides the internal space into an upper space and a lower space in the direction of gravity, a supply port for supplying the culture medium to the inside by the culture medium supply means, and a culture medium discharge means from the inside to the culture medium. And a discharge port for discharging
The discharge port opens to the upper space,
The partition wall provides a cell culture device capable of switching the internal space of the culture tank to a state in which the upper space and the lower space are divided or a state in which the upper space and the lower space are in communication.

  According to this aspect, when culturing a large number of floating cells, it is possible to easily exchange the medium. That is, the medium can be exchanged without separating the floating cells by a complicated operation such as centrifugation.

  In the reference example of the present invention, the partition wall includes an elastic member having an opening, and the size of the opening increases when an external force is applied to the elastic member, so that the upper space and the lower space communicate with each other. When the external force is not applied to the elastic member, the size of the opening may be reduced and the upper space and the lower space may be divided. As a result, the upper space and the lower space can be divided with a simple structure, and the floating cells and the medium can be separated.

  In the reference example of the present invention, a valve that closes the opening of the elastic member from the lower space side may be provided. As a result, the flow of the medium from the lower space to the upper space can be stopped when the medium is discharged from the upper space, and the risk of outflow of cells can be reduced.

  The reference example of the present invention may be provided with a partition wall pressing means formed by a net-like member that spreads the opening of the elastic member and allows the medium and cells to freely pass therethrough. As a result, the upper space and the lower space can be divided with a simple structure, and the floating cells and the medium can be separated.

  In the above aspect of the present invention, the partition wall includes a plurality of members, at least a part of the partition wall is opened or closed by changing the relative position of the plurality of members, the internal space of the culture tank, It is possible to switch between a state in which the upper space and the lower space are divided, or a state in which the upper space and the lower space are in communication. As a result, the upper space and the lower space can be divided with a simple structure, and the floating cells and the medium can be separated.

  Further, in the above aspect, the partition wall includes a plate-shaped member that can be folded in a bellows shape, and by expanding or folding the foldable plate-shaped member, the inner space of the culture tank is set to the upper space. And the lower space may be divided, or the upper space and the lower space may communicate with each other. As a result, the upper space and the lower space can be divided with a simple structure, and the floating cells and the medium can be separated.

  Further, in the above aspect, the partition wall includes a plate-shaped member fixed to a column, and by rotating the plate-shaped member around the column, the inner space of the culture tank is divided into the upper space and the upper space. The lower space may be divided, or the upper space may communicate with the lower space. As a result, the upper space and the lower space can be divided with a simple structure, and the floating cells and the medium can be separated.

  According to the present invention, floating cells and medium can be separated by a simple operation without complicated operations such as centrifugation, and the medium replacement work is simplified, so that the burden on the operator can be reduced. At the same time, the risk of contamination of the cell culture system by bacteria or the like can be reduced.

It is an explanatory view showing a schematic structure of a cell culture device concerning a reference embodiment of the present invention. It is explanatory drawing which shows schematic structure of the partition of the cell culture apparatus concerning reference embodiment of this invention. It is explanatory drawing which shows schematic structure of the partition of the cell culture apparatus concerning reference embodiment of this invention. It is explanatory drawing which shows schematic structure of the modification of the cell culture apparatus concerning reference embodiment of this invention. It is explanatory drawing which shows schematic structure of the modification of the cell culture apparatus concerning reference embodiment of this invention. It is explanatory drawing which shows schematic structure of the partition of the cell culture apparatus concerning reference embodiment of this invention. It is explanatory drawing which shows schematic structure of the cell culture apparatus concerning 1st Embodiment of this invention. It is explanatory drawing which shows schematic structure of the partition of the cell culture apparatus concerning 1st Embodiment of this invention. It is explanatory drawing which shows schematic structure of the shelf part of the cell culture apparatus concerning 1st Embodiment of this invention. It is explanatory drawing which shows schematic structure of the partition of the cell culture apparatus concerning 1st Embodiment of this invention. It is explanatory drawing which shows schematic structure of the cell culture apparatus concerning 2nd Embodiment of this invention. It is explanatory drawing which shows schematic structure of the culture medium exchange using the cell culture apparatus concerning 2nd Embodiment of this invention.

A cell culture device according to an embodiment of the present invention will be described below with reference to the drawings.
(Reference embodiment)
The cell culture device 100 according to the present embodiment is a device used when culturing cells in a culture tank such as a bioreactor, and has the configuration shown in FIG. 1.
The cell culture device 100 holds a cell and a medium inside, and a culture tank 1 capable of culturing cells while maintaining an internal environment in a state suitable for cell culture, and a medium for supplying the culture medium to the culture tank 1. It comprises a supply means 3 and a medium discharge means 4 for discharging the medium from the culture tank 1.

The culture tank 1 includes a partition wall 2 that divides the inner space into upper and lower parts in the gravity direction. The partition wall 2 is arranged inside the culture tank 1 so as to divide the interior of the culture tank 1 into an upper space 1c and a lower space 1d in the gravity direction. There is. At least a part of the partition wall 2 is made of an elastic member, and the elastic member has a small opening 2a. When an external force is applied to the elastic member, the opening 2a expands and becomes a large opening, and when the external force is removed, the opening 2a returns to an opening smaller than the elastic force of the elastic member.
When the opening 2a is a large opening, the medium and cells can freely pass therethrough, but when the opening 2a is small, the passage of the medium and cells is blocked.

Next, an example of a method for applying an external force to the elastic member of the partition wall 2 will be described with reference to FIG.
FIG. 2 shows an example in which the partition pressing means 11 applies an external pressure. The partition pressing means 11 includes a spherical portion 11a and a support 11b. When the spherical portion 11a is pressed against the opening 2a of the elastic member and pushed down by the column 11b, the elastic member is pressed downward and protrudes toward the lower space 1d, and at the same time, the spherical portion 11a opens the opening 2a. It will be pushed out. Here, the spherical portion 11a forms an open space through which the culture medium and cells can freely pass, and the upper space 1c and the lower space 1d can be in a state of communicating with each other via the spherical portion 11a. The spherical portion 11a may be formed of, for example, a mesh-like member through which the medium and cells can freely pass, and may have a strength that can withstand the pressure of pushing the opening 2a. The shape of the spherical portion 11a is not limited to a spherical shape, and may be, for example, a conical shape.

Next, another example of a method for applying an external force to the elastic member of the partition wall 2 will be described with reference to FIG.
FIG. 3 shows an example in which an external pressure is applied by the partition pressing means 12. The partition pressing means 12 includes a tubular portion 12a, a support 12b arranged inside the tubular portion 12a, and a stirring means 12c installed on the support 12b.
When the tip of the tubular portion 12a is pressed against the opening 2a of the elastic member, the elastic member receives downward pressure and projects toward the lower space 1d, and at the same time, the tubular portion 12a opens. It will be in the state where it was pushed open. Here, the tubular portion 12a forms an open space through which the medium and cells can freely pass, and the upper space 1c and the lower space 1d can be in a state of communicating with each other via the tubular portion 12a. The tubular portion 12a may be formed of, for example, a mesh-like member through which the medium and cells can freely pass, and may have a strength that can withstand the pressure of pushing the opening 2a. The culture medium can be stirred by the stirring means 12c inside the tubular portion 12a. For example, the stirring means 12c may be rotated by applying a rotational force to the support column 12b to stir the medium.

The culture tank 1 includes a supply port 1 a to which the medium is supplied from the medium supply unit 3 and a discharge port 1 b to which the medium is discharged to the medium discharge unit 4. The supply port 1a and the discharge port 1b are open to the upper space 1c.
The discharge port 1b is preferably opened near the bottom surface of the upper space 1c so that almost all the medium in the upper space 1c can be discharged.
The supply port 1a may be installed at any place, but it is preferable that the supply port 1a is opened at a position where the medium can be supplied so as to be dropped from the upper part of the upper space 1c. By doing so, it is possible to prevent backflow of the medium and reduce the risk of contamination (contamination) of the medium upstream thereof. Further, in FIG. 1, the supply port 1a is opened in the upper space 1c, but it may be opened in the lower space 1d.

Next, an example of a procedure for culturing cells using the cell culture device 100 according to the present embodiment will be described.
The user of this device first presses the elastic member of the partition wall 2 by the partition wall pressing means to bring the upper space 1c and the lower space 1d into communication with each other via the partition wall pressing means. In this state, a medium and cells to be cultured (floating cells) are placed in the culture tank 1, and cell culture is started while maintaining the temperature inside the culture tank 1 (eg, 37° C.) suitable for cell culture. At this time, it is preferable that the stirring means 5 appropriately stir the medium and cells.
When the medium needs to be replaced, the user first stops the stirring means 5 and stops the flow of the medium to precipitate the cells by gravity. The cells in the upper space 1c precipitate toward the partition wall 2, but since the elastic member is in a state of protruding toward the lower space 1d, the cells slide down toward the opening 2a, pass through the opening 2a, and pass through the lower space 1d. Settles on the bottom of the.
In the state where the cells are sufficiently settled, the user slowly pulls up the partition wall pressing means upward to release the external force applied to the elastic member to close the opening 2a, and separate the culture tank 1 into the upper space 1c and the lower space 1d. To do. At this time, most of the cells are settled in the lower space 1d, and only a few cells remain in the medium in the upper space 1c.
The user discharges the medium in the upper space 1c from the culture tank 1 by the medium discharging means 4, and then supplies a new medium by the medium supplying means 3.
The user presses the elastic member of the partition wall 2 by the partition wall pressing means to bring the upper space 1c and the lower space 1d into communication with each other via the partition wall pressing means. The stirring means 5 is actuated to appropriately stir the medium and cells to restart the culture.
According to the above process, the medium retained in the upper space 1c can be replaced with a new medium, and the deterioration rate of the culture medium can be slowed.

Next, a modified example of the present embodiment will be described. The cell culture device 200 according to this modification has the configuration shown in FIG.
In this modification, the partition wall 22 is separable from the culture tank 21. The partition wall 22 includes a frame portion 22a and an elastic member 22b fitted in the frame portion 22a, and the elastic member 22b has an opening 22c. The frame portion 22 a has a shape that fits inside the culture tank 21.
A shelf portion 21a is fixed to a wall surface inside the culture tank 21, and when the partition wall 22 is inserted into the culture tank 21, the frame portion 22a is placed on the shelf portion 21a, and the inside space of the culture tank 21 becomes an upper space. 21c and the lower space 21d can be separated.
As shown in FIG. 5, the cell culture device 200 can perform cell culture in the same manner as the cell culture device 100 of the reference embodiment. Although FIG. 5 shows an example using the partition pressing means 11, the partition pressing means 12 may be used.

  In the present embodiment and the modified example, as shown in FIG. 6, the partition wall may be provided with a valve 2b that prevents the flow of the medium from the lower space to the upper space. The valve 2b may have a size that can close the opening when the external force applied to the elastic member is removed and the opening becomes a small opening. This makes it possible to prevent the medium from flowing from the lower space to the upper space when the medium in the upper space is discharged from the culture tank, and reduce the risk of discharging cells.

In the present embodiment and the modification, the example in which the discharge port is opened to the upper space is shown, but the discharge port may be further opened to the lower space. This makes it easier to collect the medium and cells when the culture is completed.

(First embodiment)
The cell culture device 300 according to the present embodiment is a device having a configuration shown in FIG. 7, and differs from the reference embodiment in that a partition 32 is provided instead of the partition 2. Other than that, it is the same as the reference embodiment.

  Unlike the partition wall 2 of the reference embodiment, the partition wall 32 does not include an elastic member, and by moving the plate-shaped member forming the partition wall 32, the upper space 1c and the lower space 1d can be communicated with or separated from each other. It is a partition that can.

  An example of the partition wall 32 is shown in FIG. The partition wall 32 is provided with two propeller-like plate-shaped members 32a and 32b, which are rotatable relative to each other around the axis with the pillar 33 being coaxial. By relatively rotating such two plate-like members, the upper space 1c and the lower space 1d are communicated with each other (FIG. 8B), or the upper space 1c and the lower space 1d are separated (see FIG. 8(c)).

For example, when the plate-shaped member 32a is fixed to the inner wall of the culture tank and the plate-shaped member 32b is fixed to the support column 33, the plate-shaped member 32b rotates relative to the plate-shaped member 32a when the support column 33 is rotated about the shaft. 8B and FIG. 8C can be brought into the state of FIG. 8B and FIG. 8C.
At this time, in order to dispose the plate-shaped member and the supporting column at a predetermined place inside the culture tank, a shelf may be installed inside the culture chamber and the plate-shaped member and the supporting column may be arranged there. For example, as shown in FIG. 9, the shelf portion is composed of two ring-shaped members 34 fixed to the inner wall of the culture tank at predetermined intervals, and the plate-shaped member 32a and the plate-shaped member 32b are two ring-shaped members. It may be arranged between 34. At this time, the plate-shaped member 32a may be fixed to the ring-shaped member 34, and the plate-shaped member 32b fixed to the support column 33 may be movably arranged between the two ring-shaped members 34. By doing so, the plate-shaped member 32b can be rotated around the support column 33 as an axis, and the state shown in FIG. 8B or FIG.

Next, an example of a procedure for culturing cells using the cell culture device 300 according to the present embodiment will be described.
The user of this device first rotates the support column 33 to relatively rotate the two plate-shaped members, and establishes a state in which the upper space 1c and the lower space 1d are in communication with each other (FIG. 8B). In this state, a medium and cells to be cultured (floating cells) are placed in the culture tank 1, and cell culture is started while maintaining the temperature inside the culture tank 1 (eg, 37° C.) suitable for cell culture. At this time, it is preferable that the stirring means 5 appropriately stir the medium and cells.
When the medium needs to be replaced, the user first stops the stirring means 5 and stops the flow of the medium to precipitate the cells by gravity. The cells in the upper space 1c pass through the openings of the partition walls 32 and settle on the bottom surface of the lower space 1d.
In a state where the cells are sufficiently settled, the user rotates the support column 33 to relatively rotate the two plate-shaped members, so that the upper space 1c and the lower space 1d are separated (FIG. 8C). .. At this time, most of the cells are settled in the lower space 1d, and only a few cells remain in the medium in the upper space 1c.
The user discharges the medium in the upper space 1c from the culture tank 1 by the medium discharging means 4, and then supplies a new medium by the medium supplying means 3.
The user rotates the support column 33 to relatively rotate the two plate-shaped members so that the upper space 1c and the lower space 1d communicate with each other (FIG. 8B). The stirring means 5 is activated to appropriately stir the medium and cells to restart the culture.
According to the above process, the medium retained in the upper space 1c can be replaced with a new medium, and the deterioration rate of the culture medium can be reduced.

Another example of the partition wall 32 is shown in FIG. The partition wall 32 includes a plate-shaped member 32c that can be folded in a bellows shape. The plate-shaped member 32c is fixed to the support column 33, and can be expanded or folded while rotating around the support 33. For example, one end of the plate-shaped member 32c is fixed to the inner wall of the culture tank, and the plate-shaped member 32c can be expanded or folded by rotating the support column 33 as an axis to connect the upper space 1c and the lower space 1d. It can be separated (FIG. 9A) or separated (FIG. 9B).
At this time, in order to dispose the plate-shaped member 32c and the support column 33 at predetermined positions inside the culture tank 1, a shelf portion 35 may be installed inside the culture tank 1.

(Second embodiment)
The cell culture device 400 according to the present embodiment is a device having the configuration shown in FIG. 11, and also has a discharge port 41e in the lower space 41d, and the medium is discharged to the medium discharge means 46 via the discharge port 41e. It is different from each of the above-described embodiments in that Other than that, it is the same as each of the above-described embodiments.

  The cell culture device 400 holds a cell and a medium inside, and a culture tank 41 capable of culturing cells while maintaining an internal environment in a state suitable for cell culture, and a medium for supplying the culture medium to the culture tank 1. It comprises a feeder 43, a medium discharging means 44 and a medium discharging means 46 for discharging the medium from the culture tank 1.

  The culture tank 1 is provided with a partition wall 42 that divides the inner space into upper and lower parts in the gravity direction. There is. The partition 42 may be the partition shown in the reference embodiment or the first embodiment.

The culture tank 41 has a supply port 41a to which the medium is supplied from the medium supply unit 43, a discharge port 41b to which the medium is discharged to the medium discharge unit 44, and a discharge port to which the medium is discharged to the medium discharge unit 46. 41e. The supply port 41a and the discharge port 41b open to the upper space 41c, and the discharge port 41e opens to the lower space 41d.
The discharge port 41b is preferably opened near the bottom surface of the upper space 41c so that almost all the medium in the upper space 41c can be discharged. The discharge port 41e is preferably opened near the bottom surface of the lower space 41d so that almost all the medium in the lower space 41d can be discharged.
Although the supply port 41a may be installed at any place, it is preferable that the supply port 41a be opened at a position where the medium can be supplied so as to be dripped from the upper portion of the upper space 41c. By doing so, backflow of the medium can be prevented. Further, in FIG. 10, the supply port 41a is opened in the upper space 41c, but it may be opened in the lower space 41d.

Next, an example of a procedure for culturing cells using the cell culture device 400 according to this embodiment will be described with reference to FIG.
The user of this device first opens the partition wall 42 to bring the upper space 41c and the lower space 41d into communication with each other. In this state, the culture medium and cells to be cultured (floating cells) are placed in the culture tank 41, and cell culture is started while maintaining the temperature inside the culture tank 41 (for example, 37° C.) suitable for cell culture. At this time, it is preferable that the medium and cells are appropriately stirred by the stirring means 45 (a).
When the medium needs to be replaced, the user first stops the stirring means 45 and stops the flow of the medium to precipitate the cells by gravity. The cells in the upper space 41c pass through the openings of the partition wall 42 and settle on the bottom surface of the lower space 41d.
In a state where the cells are sufficiently precipitated, the user closes the opening of the partition wall 42 to separate the culture tank 41 into an upper space 41c and a lower space 41d. At this time, most of the cells are settled in the lower space 41d, and only a few cells remain in the medium in the upper space 41c (b).
The user collects the medium and cells in the lower space 41d from the culture tank 41 by the medium discharging means 46 (c).
The user opens the partition wall 42 to bring the upper space 41c and the lower space 41d into communication with each other, and moves the medium in the upper space 41c to the lower space 41d (d).
The user supplies a new medium to the culture tank 41 by the medium supply means 43, operates the stirring means 45, appropriately stirs the medium and cells, and restarts the culture (e).
According to the above process, the cells precipitated in the lower space 41d can be collected, and the cell culture can be continued based on the cells remaining in the upper space 41c (corresponding to passage of cells). At this time, the medium corresponding to the amount discharged from the lower space 41d can be replaced with a new medium, and the deterioration rate of the culture medium can be slowed.

  The culture tank of the present invention may be a large one such as a bioreactor or a small culture container such as a flask. In addition, a bag-shaped culture bag may be used as a disposable bioreactor.

According to the present invention, a partition wall capable of accommodating a medium and cells inside and capable of switching the internal space into a state in which it is divided into an upper space and a lower space in the direction of gravity, or a state in which the upper space and the lower space communicate with each other A method for culturing a suspension cell using a culture tank provided with, the method comprising repeating the following steps.
・Step of culturing the floating cells in the culture tank ・Step of precipitating the floating cells ・Step of dividing the inner space of the culture tank into upper space and lower space by gravity in the direction of gravity ・Step of replacing the medium in the upper space with a new medium・Step of connecting upper space and lower space

According to the present invention, a partition wall capable of accommodating a medium and cells inside and capable of switching the internal space into a state in which it is divided into an upper space and a lower space in the direction of gravity, or a state in which the upper space and the lower space communicate with each other. A method for culturing a suspension cell using a culture tank provided with, the method comprising repeating the following steps.
・Step of culturing the floating cells in the culture tank ・Step of precipitating the floating cells ・Step of dividing the inner space of the culture tank into the upper space and the lower space by gravity in the direction of gravity ・Step of collecting medium and cells in the lower space ・Step of connecting upper space and lower space ・Step of supplying new medium to upper space

DESCRIPTION OF SYMBOLS 1 culture tank 2 partition walls 3, 43 medium supply means 4, 44, 46 medium discharge means 5, 45 stirring means 11 partition wall pressing means 12 partition wall pressing means 21 culture tank 22 partition wall 32 partition wall 33 column 34 ring member 35 shelf 41 culture Tank 42 partition

Claims (12)

A culture tank capable of containing a medium and cells,
Medium supply means for supplying a medium to the culture tank,
Medium discharging means for discharging the medium from the culture tank,
A cell culture device comprising:
The culture tank has a partition wall that divides the internal space into an upper space and a lower space in the direction of gravity, a supply port for supplying the culture medium to the inside by the culture medium supply means, and a culture medium discharge means from the inside to the culture medium. And a discharge port for discharging
The discharge port opens to the upper space,
The partition wall includes a plurality of members, and at least a part of the partition wall is opened or closed by changing the relative positions of the plurality of members, and the inner space of the culture tank communicates with the upper space and the lower space. The cell culture device that can be switched to a closed state or a state in which the upper space and the lower space are divided.   The cell culture device according to claim 1, wherein the plurality of members are plate-shaped members. The plate-shaped member can be folded in a bellows shape,
By expanding or folding the plate-shaped member, the inner space of the culture tank can be switched to a state in which the upper space and the lower space are divided or a state in which the upper space and the lower space communicate with each other. The cell culture device according to claim 2.   The plate-shaped member is fixed to a support, and by rotating the plate-shaped member around the support, the inner space of the culture tank is divided into the upper space and the lower space, or The cell culture device according to claim 2, wherein the upper space and the lower space are switched to communicate with each other.   The said plate-shaped member is provided with the 1st plate-shaped member fixed to the inner wall of the said culture tank, and the 2nd plate-shaped member centered on the said support|pillar rotatably arrange|positioned. Cell culture device.   The cell culture device according to any one of claims 1 to 5, wherein the culture tank comprises a stirring means for stirring the medium in the lower space.   The cell culture device according to claim 1, wherein the culture tank has a second outlet in the lower space. Culturing the floating cells in a culture tank,
Precipitating the floating cells,
A step of dividing the inner space of the culture tank into an upper space and a lower space along the gravity direction by using a partition wall;
Discharging the medium in the upper space and supplying a new medium to the upper space,
A step of opening the partition wall to communicate the upper space and the lower space with each other.   The cell culture method according to claim 8, comprising a step of collecting cells precipitated in the lower space. The step of culturing the floating cells in the culture tank includes a step of stirring the medium in the culture tank,
The cell culture method according to claim 8 or 9, wherein the step of precipitating the floating cells includes a step of precipitating the floating cells in the lower space by stopping the stirring. A culture tank capable of containing a medium and cells therein,
The culture tank is
A partition wall that can divide the inner space of the culture tank into an upper space and a lower space in the direction of gravity,
A supply port for supplying a medium to the inside of the culture tank,
An outlet for discharging the medium from the inside of the culture tank,
Equipped with
The discharge port opens to the upper space,
The partition wall includes a plurality of members, and at least a part of the partition wall is opened or closed by changing the relative positions of the plurality of members, and the upper space and the lower space communicate with the inner space of the culture tank. A culture tank that can be switched to a closed state or a state where the upper space and the lower space are divided.   The culture tank according to claim 11, wherein the plurality of members are plate-shaped members.

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