WO2010057672A1

WO2010057672A1 - Device for physiological, dynamic in-vitro cell stretching

Info

Publication number: WO2010057672A1
Application number: PCT/EP2009/008348
Authority: WO
Inventors: Christoph Bourauel; James Deschner; Andreas Jäger; Ludger Keilig; Birgit Rath-Deschner; Susanne Reimann
Original assignee: Rheinische Friedrich-Wilhelms-Universität Bonn
Priority date: 2008-11-24
Filing date: 2009-11-24
Publication date: 2010-05-27
Also published as: DE102008058782A1

Abstract

The invention relates to a device (1) for physiological, dynamic in-vitro cell stretching, comprising a stretching unit (2a, 2b), which has at least one ram (3), and at least one cell cultivation dish (4), which has a removable cover (5) and a flexible membrane (6) as the bottom, on which cells can be grown, wherein the ram (3) presses against the membrane (6) so as to stretch it, the ram (3) and the membrane (6) are arranged so they can be moved relative to one another in a linear movement, and the membrane (6) is supported on the ram (3) in a substantially unstretched state, and the device comprises an electric motor-driven linear drive, by means of which mechanical pressure can be applied to the cover (5) of the cell cultivation dish (4) by way of a transfer means (8), so that the cell cultivation dish (4) with the membrane (6) thereof is pressed against the ram (3) and is stretched depending on the pressure.

Description

Apparatus for physiological, dynamic in vitro cell dilatation

The invention relates to a device for physiological dynamic in vitro cell elongation, comprising an expansion unit having at least one punch, and at least one cell cultivation tray having a removable lid and a flexible membrane as a bottom, can be attracted to the cells, wherein the punch presses against the diaphragm to stretch it.

Cell culture dishes are well known. An arrangement of six such trays, as they can be used in the context of the invention is known from US Pat. Nos. 6,048,723 and 6,472,202 B1.

There are various approaches to deform cells in vitro. These different approaches can be summarized in the following five groups.

In a first approach, an elongation of a carrier material can take place on which cells have grown. This can be stretched longitudinally, transversely or radially symmetrically. There are several techniques for creating this stretch: The backing is clamped on two opposite sides and stretched. It can be stretched by the introduction of a liquid under the substrate or pulled by vacuum or gravity over a pressure plate / plunger. Here, the shape of the plunger has a decisive influence on the distribution of the strains of the Support material. For example, introduced liquids cause a non-linear strain distribution of a radially symmetric carrier material.

A second approach is to generate shear stress by flushing liquid around a stationary substrate with grown cells.

In a third approach, a hydrostatic overpressure is created in a chamber in which cells have grown. This can e.g. be a cell culture bottle.

A fourth approach is manipulating individual cells under the microscope with micro-pipettes.

Finally, a fifth group includes combinations of these techniques.

Of these methods, the first three are suitable for cell culture. Of these, the first system has the advantage that the cells can be kept in a clearly defined state of elongation or shear. In contrast, shear in a flowing fluid creates an uncontrollable superposition of various modes of deformation. With method 3 experimental approaches, only compression can be generated. On the other hand, tensile cell elongation is the primary mode of deformation for cells in cartilage, tendons, ligaments, muscles, skin and lung tissue.

The known methods have the following disadvantages: The strain distributions over a carrier material on which cells have grown are non-linear in almost all systems. Among other things, the strains are not precisely defined in all places. Furthermore, commercial systems are expensive. Vacuum systems are loud due to the pumps and need a lot of space. The pumps generate gases / oil vapor in the ambient air and require relatively much energy. In addition, they are maintenance intensive. Incidentally, their handling is sometimes very complicated and expensive. This is the case in particular when using vacuum stamping. From US Patent 4,940,853 a device for physiological, dynamic in vitro cell expansion is known in which the elongation is effected by an electromotive linear drive. In this case, a plate with round recesses is provided. The underside of this plate is covered with a flexible membrane, on the inside of the recesses cells can be cultivated. Below the membrane, a bottom plate is arranged, which closes the recesses downwards substantially, with the individual recesses central holes are provided in the bottom plate, through which a pin from below into the individual recesses can be inserted. Several such pins are mounted on a liftable plate. By lifting this plate, the pins are moved through the holes of the bottom plate and abut on the underside of the membrane of the individual recesses, so that the membranes in the recesses are each raised and stretched. The pins have a small diameter compared to the diameter of the recesses, so that the predominant surface of the membrane is inclined by the elongation. There are cylindrical, net-like support rings are provided which can be inserted into the recesses and rest on the inside of the recesses. The cell cultures can also grow on these support rings. Centrally under the assembly there is provided a stepper motor mounted on a support plate from which a central spindle extends against the plate supporting the plate at a central point of that plate. The cell cultivation plate is connected to the holding plate via side walls, so that the cell cultivation plate together with the membrane is counteracted by the force exerted by the stepping motor with which the pins press against the membranes. The pins supporting plate is guided in these parallel side walls.

A disadvantage of this arrangement according to US Patent 4,940,853 on the one hand, the narrow design of the pins, so that the bottom of the recesses forming membrane with the largest part of your cells bearing surface is inclined relative to the horizontal. As a result, the cell cultures, together with the liquid introduced, flow into the marginal area where they collect. A uniform distribution of cell cultures on the inside surface of the membrane and thus a homogeneous cell culture is possible. A further disadvantage is that in the case of damage to a membrane, liquid and cell material are the mechanical can contaminate moving parts of the arrangement. Cleaning and disinfecting these parts is difficult and possible with great effort. Another disadvantage is the central storage of the pins holding plate. On the one hand, the plate can tilt when dirt inserts between the plate and the inside sliding surfaces of the side walls. On the other hand, there is a risk that in the case of a not exactly aligned horizontally to the cell culturing plate, the pins holding plate no uniform pressure on all the individual membranes of the recesses is exerted, so that the different membranes are stretched differently. It is therefore an object of the invention to uniformly stretch cells in an in vitro cell culture in a physiologically as large as possible area, with a simple, easy-to-use, low-cost and low-maintenance device for cell expansion to be created, which allows dynamic expansion of the cells.

This is achieved by the features of claim 1. Advantageous embodiments of the invention are formulated in the subclaims and are explained below.

There is proposed a device for physiological dynamic in vitro cell elongation, comprising an elongation unit having at least one punch, and at least one cell cultivation tray having a removable lid and a flexible membrane as a bottom on which cells can be attracted the plunger for expanding the membrane presses against it by the plunger and the membrane are arranged in a linear movement relative to each other movable and the membrane in the substantially unstretched state on the stamp, in particular resiliently supported, and the device comprises an electromotive linear drive, by means of which a mechanical pressure can be exerted on the cover of the cell cultivation dish via a transfer means, so that the cell cultivation dish (4) is pressed with its membrane (6) against the stamp (3) and is stretched as a function of the pressure. The application of pressure to the lid of the cell culture dish causes the die to be pressed against the flexible membrane and thereby stretch it. The stamp is increasingly moved into the cell cultivation dish. As a result, the cells attracted to the membrane are also stretched. This physiological stretch can be between 3% and 25%.

The force acting on the lid or on the stamp can be adjusted automatically by the electromotive linear drive, extremely precise and preferably dynamically according to a predeterminable expansion profile. Thus, a particularly variable adjustability of the degree of expansion including its temporal change is possible with the device according to the invention. Compared to the conventional method of stretching cells, for example the known vacuum method, the proposed device is robust and less maintenance intensive.

The combination of commercially available cell culture plates, as they are produced, for example, under the name Bioflex ^® the manufacturer Flexcell International Corporation, Hillsborough, NC, United States and marketed with an easy-to-use mechanical stretching unit represents a significant advantage over other (commercial) systems ,

It is particularly advantageous in the proposed device that the expansions of the Bioflex® support material can be realized by pressure on the lid of the cell culture plate. As a result, the cell culture membrane is pressed over the stamp so that it at least partially rests in the cell cultivation dish.

In an advantageous development of the invention, the expansion unit can have a frame in which the cell cultivation dish is held. The frame encompasses the cell culture dish on the outside. The pressure generated by the linear drive is transmitted to the frame. By the stroke of the frame, the strain is set so that can be spoken by a motor-driven frame. Preferably, the transfer means may be a support which is placed on the frame or directly on the lid of the line cultivation tray or rests in the pressure-transmitting state on the frame. In the case of the frame, the pressure from the frame is transferred to the lid, so that can be spoken of a motor-driven lid. The transmission means is preferably U-shaped, so that it can be placed on three peripheral sides of the frame. This causes the pressure to be evenly distributed on the frame so that the bottom of the cell culture dish is pressed evenly against the punch and uniform elongation of the membrane is achieved. This ensures that even the cells are stretched evenly. The uniform application of the pressure to the frame is particularly important in arranging several cell culture dishes in a cell culture plate so that the elongation of the membranes of each cell culture dish is the same.

Furthermore, the expansion unit may have a shell, at the bottom of which the stamp is supported. In particular, the stamp may be molded to the bottom, i. be integrally formed with this. The use of a shell has the advantage here that liquid substances introduced into the cell culture dish and / or cell material are collected and do not pollute or contaminate other non-mechanical parts of the device.

The shell can be firmly connected or connectable to a plate on which the linear drive is fixed. The plate thus absorbs the force transmitted via the cover to the punch and sets it against a corresponding counter force which is exerted by the punch. This causes a linear relative movement of the punch and the membrane to each other, wherein the membrane is placed over the punch, so that they and thus at the same time the cells stretch or stretch. Alternatively, the stamp can be supported directly on a plate on which the linear drive is fixed.

The plate may preferably be formed of aluminum, which as an inert material is resistant to humid and chemical environments, easy to disinfect and suitable for an incubator. In the embodiment in which the stretching unit of the device according to the invention has a frame on which the pressure generated by the linear drive is exerted and a cup with the punch, the cell cultivation dish is arranged between the frame and the cup. This results in a compact and easy-to-use arrangement that can be prepared outside the device and then inserted into the device as a whole unit. The cell culture dish is movably guided in the shell of the expansion unit so that the pressure exerted by the transfer means on the frame can be absorbed.

For a precise setting of the pressure and thus the degree of expansion, the linear drive can have a stepping motor, which can be moved in increments of 0.1 micrometers.

The setting of a specific pressure, in particular its time change, can preferably take place automatically and programmatically. For this purpose, the linear drive can be connected to a computer on which a program for controlling the linear drive can be executed or executed. The program is set up to change the duration and / or the amount of pressure exerted dynamically, in particular according to a predetermined profile. Preferably, the amplitude and / or frequency of the pressure may be controlled by the program. The membrane of the cell culture plate can be stretched linearly and frequency-dependent in a range of 3% to 25%.

Furthermore, it is advantageous to manufacture the stamp from an inert material, in particular from polyoxymethylene (POM) and / or aluminum. Aluminum can serve in particular for reinforcement. Polyoxymethylene and aluminum are chemically inert and can be used in wet environments and in contact with biological materials.

According to the invention, the expansion unit and / or the transmission means (8) may comprise at least one contact sensor for detecting the contacting of the transmission means with the cover or the frame. Alternatively or additionally, the stretching unit and / or the transmission means may be at least a pressure sensor for detecting the pressure exerted by the transfer means on the lid or the frame pressure. Furthermore, a display means for indicating the contacting of the transmission means may be provided with the lid or the frame.

The device according to the invention has a number of advantages. For example, the costs can be kept within an adequate range compared to other systems, with the pure material costs being low. Furthermore, all materials for the production of the system are commercially available. The application software can be adapted with relatively little effort to special wishes of a user. The dimensions are such that the load unit fits into a commercial incubator and the associated controller and PC require minimal space so that they can be placed on the incubator. The system is thus also suitable for small laboratories. The system is easy to handle, easy to clean and disinfect. The calculated strain is uniformly distributed linearly over the entire membrane, whereby the cells grown on it are stretched homogeneously.

The invention will be explained in more detail with reference to an embodiment and the accompanying drawings.

Show it:

Figure 1: Results of the FEA (Finite Element Analysis).

Figure 2A: Dismantled expansion unit and BioFlex ^® -Zellkulturplatte (right).

2B: BioFlex ^® -Zellkulturplatte on the loading base.

Figure 2C: Assembled stretching unit exposing cells to permanent biophysical elongation. Figure 3: Overview of the system for dynamic cell expansion.

Biomechanical stress is fundamental to the development, maintenance and repair of a variety of cells. Recent studies have shown that dynamic biomechanical forces can have anti-inflammatory effects and affect other features of diseases such as osteoarthritis can. In addition, dynamic and static mechanical stress can differently regulate fibrochondrocyte gene expression and protein synthesis.

In order to distinguish the different effects of static and dynamic forces on cells, a novel device 1 for loading cells with defined strains was developed. Since biological systems are generally dynamic, the device 1 has been developed for dynamic strain loads. Important criteria here were the smallest possible space requirement, the suitability for an incubator and cost efficiency. To achieve this and a standardized procedure, the commercial BioFlex ^® -Zellkulturplatte were 11 (Flex Cell International, NC, USA), see Figure 2A, used.

The following technical requirements were set for the remaining materials: (1) they should be moisture resistant, since the device 1 must be resistant to relatively humid environments, (2) they should be chemically inert, as the system must be easy to disinfect, and ( 3) they should be biologically inert as they are intended for contact with cell materials.

As mechanical requirements it was stated that the strain should be evenly distributed over the cell membranes 6. The strains should be between 3% and 25%, ie. H. within the physiological range. The motor 7, which is used in the dynamic system for expanding the cell culture plates, works with very high positioning accuracy and repeatability. In addition, the device 1 is intended for use by various scientists. The application of the device 1 is easy to learn and easy to adapt to different experimental arrangements.

Cellbiomechanical research requires a standardized procedure. Therefore, the widespread, commercial BioFlex ^® -Zellkulturplatte 11, see Fig. 2A used for the biological tests. Often these cell culture plates 11 are stretched with a vacuum system. In order to control the strain distribution prior to the construction of the devices, a finite element analysis (FEA) was performed at a membrane 6 of a cell culturing dish 4 of a BioFlex ^{® "11} carried out under vacuum cell culture plate. This revealed that the displacements and therefore the strains the cell culture plate membrane 6 were not evenly distributed, See Fig. 1. Based on these results, it has been found that evenly distributed strains are achieved when the membrane 6 is pulled over a cylindrical die 3. For this configuration, the strains are easy to calculate.

FIG. 2A shows an expansion unit 2a, 2b in which uniform expansions of the membrane 6 are achieved. The stretching unit 2a, 2b consists of a lower part 2a, which serves as a load base, and an upper part 2b, which serves as a load frame. The lower part 2a forms a shell 2a with six cylindrical interchangeable punches 3, which are arranged on the bottom of the shell 2a. 2a the shell, a commercially available BioFlex ^® -Zellkulturplatte 11 (Flex Cell International Corporation, Hillsborough, NC, USA) record having six Zeilkultivierungsschalen 4, the bottom of which is closed each with a flexible membrane 6, which serves as a substrate for the cultivated cells. The cell culture plate 11 is located in the shell and is movably guided therein by the relative movement of the punches 3 and cell cultivation shells 4. The cell culture plate 11 can be covered with a removable, transparent lid 2b, so that the view of the cell culture plate 11 remains. The upper part 2b forms a frame 2b, which encompasses the cell culture plate 11 on the outside. The frame 2b can be connected to the shell 2a via screws 12 and screw heads 13 made of brass. Characterized the BioFlex ^® -Zellkulturplatte 11 is moved downward, whereby the flexible bottom of each cell culture dish 4 is forced to conform to the stamps. 3 By screwing of frame 2b and shell 2a, a static Zeildehnungsapparatur is formed, which is shown in Figure 2C. For the use of the arrangement of shell 2a, cell cultivation plate 11 and frame 2b, no screwing takes place. The screws 12 guide the frame 2b as it moves perpendicular to the shell 2a. They lie in corresponding holes 14 of the frame 2b.

The frame 2b lies on its lower side on the lid 5 and thus transmits a pressure force exerted on it to the cell culture plate 11, which in turn is pressed against the punches 3, as a result of which the membrane 6 is stretched. The shell 2a, including the dies 3, and the frame are made of white polyoxymethylene (POM). This has a chemically and biologically inert property and Moisture resistance. POM is characterized by high strength, hardness and rigidity over a wide temperature range. It has a high abrasion resistance, a low friction coefficient and a low water absorption.

The punches 3 are fixed in the shell 2a by a cylindrical interference fit. Depending on the amount of the stamps used, for example, 13.5 and 16.0 mm, the membranes 6, the BioFlex ^® -Zellkulturplatte 11 are continuously stretched by 3% and 20%. The construction of the expansion unit 2a, 2b is such that the BioFlex ^® -Zellkulturplatte 11 can be inserted into the loading frame 2b, the punch 3 below the cell cultivation trays 4, the so-called "wells" can be positioned centrally. FIG. 2B shows the cell culture plate 11 with lid 5 inserted into the dish 2b. FIG. 2C shows the assembled stretching unit 2a, 2b with cell culture plate 11 arranged between loading frame 2b and loading base 2a. All components can be disinfected with alcohol and introduced into an autoclave.

FIG. 3 shows the overall arrangement of the device 1 according to the invention with an electromotive stepping motor as a linear drive 7, by means of which a mechanical pressure is exerted on the cover 5 of the cell cultivation shells 4 via a transmission means 8 so that the cell cultivation shells 4 press against the plunger 3 with their membrane 6 and are stretched as a function of the pressure. The stretching unit 2a, 2b has three pressure sensors 10 for detecting the pressure exerted on the lid 5 by the transmission means 8. Furthermore, the transmission means 8 comprises a contact sensor, not shown, for detecting the contacting of the transmission means 8 with the frame 2b. Display means 15 indicate the contacting of the transmission means 8 with the frame (2b).

The device 1 according to the invention has the advantage that an automatic adjustment of the elongation with a computer program, separate adjustment of the loaded and unloaded exposure duration as well as the adjustment of the test duration by time and cycle number is possible. The loading base 2a is fixed on an aluminum base plate 9. The transmission means 8 is also made of aluminum.

A high-resolution linear micro stage (M-126, Physik Instrumente (PI) GmbH & Co. KG, Karlsruhe, Germany) represents the drive system and is combined with the Apollo stepper motor controller from PI (C-630, Physik Instrumente). This cost-effective micro stage is equipped with a 2-phase stepper motor, which allows a smallest step size of 0.1 μm and a high repeatability of 1 μm. The control of the motor can be done directly via the Apollo control. The engine system is built into an aluminum strut and attached to the base plate 9. This positioning system actuates the loading frame 2b of the device 1, which causes the expansion of the cell culture plate. The control program was written using the LabView ™ 8.0 software (National Instruments Corporation (NI), Austin, TX). For easy adjustment are built into the frame three contact sensors 10, the pressure on the lid 5 of the BioFlex ^® cell culture plate 11 exerts. The contact between the load frame 2b and the lid 5 is indicated by diodes which light up red when not in contact and green when in contact. This visual control facilitates the determination of the time at which the respective strain load can begin. Hereinafter, a measurement performed for cell dilation and practical experience with the device of the present invention will be explained. In a first step, the membrane elongation of the BioFlex ^® cell culture plate 11 was controlled. For this purpose, the plate membrane 6 was marked with small dots. Thereafter, the membrane was stretched 3% and 20%, respectively, in a static cell dilator of Figure 2C, and the strain was measured in randomly selected fields under ten times primary magnification with a Nikon microscope (H800, Dusseldorf, Germany) with a CCD camera (DXP). 9100P 3CCD color video; Sony, Tokyo, Japan) and Lucia imaging software (LIM Laboratory Imaging, distributed via Nikon). Thereafter, the strains of adult human periodontal ligament (PDL) cells were controlled. After fixation with 1: 1 methanol / acetone at -20 ⁰ C for 5 minutes and washing with phosphate buffered saline (PBS), the cells were incubated with a monoclonal anti-actin antibody (1: 200 in PBS; clone AC40, Sigma) at 4 ° C dyed overnight. After more After washing several times with PBS, a Alexa488-conjugated goat anti-mouse IgG2a secondary antibody (Invitrogen) at a 1: 400 dilution in PBS was allowed to act at room temperature for one hour. The labeled cell elongations were measured analogously to the previously described method. The performance of the dynamic straining apparatus 11 according to FIG. 3 was controlled in a continuous loading test. The device 1 worked for 48 hours at 37 ⁰ C in 5% CO ₂ with maximum dynamic strains. In the first part of the experiments it could be verified that the principle of loading with these punches works satisfactorily: The elongations of the marked cell culture plate membrane, which were effected by the punches, corresponded exactly with the given and calculated strains.

The dynamic device 1 proved to be reliable and durable in the dry and humid environment of an incubator. It could be confirmed that the device 1 is practical and easy to operate. The visual control provided by the transparent lid 5 proved to be useful to define the starting point of the loading cycles.

In general, a decrease in gene expression after exercise was found to be dependent on the level and duration of exercise. The difference between gene expression of stretched and unstretched cells was found to be statistically significant at a level of p <0.05.

The calculated strain is evenly distributed over the entire membrane. The device 1 operates with a predetermined elongation per trial. This makes it possible to regulate the strains on the cell culture plates 11 very reliable. The device 1 is characterized by a high repeatability. It is practical, easy to clean and sterilize. The adaptation to further requirements is possible by minor modifications of the arrangement. In contrast to vacuum-driven cell dilation apparatus, the described device 1 produces linear and homogeneous membrane deformations.

The device 1 according to the invention is a new device for applying tensile strains to cells. Since biological systems are dynamic, the in FIG 3 apparatus shown an automatic dynamic device 1 for simulating a dynamic biological environment for cell culturing. In order to ensure a standardized process are, in the apparatus commercially available BioFlex ^® -Zellkulturplatten 11 (Flex Cell International, NC, USA) with six cell cultivation trays 4 with cell adhesion Membranes 6 used at the bottom. In the present system, the membranes 6 are pulled over cylindrical dies 3 to achieve evenly distributed strains. The device 1 consists predominantly of polyoxymethylene (POM) and is reinforced with aluminum. The device 1 comprises a high-resolution, linear micro stage computer-controlled by means of a program written in LabView ™. Different cell types were loaded with different strains over different time periods and first results could be determined. Measurements of the 3% stretched cell culture plate membrane and the cells grown on them gave cell elongations of 3.7%. The results showed a high repeatability.

Claims

claims

A device (1) for physiological dynamic in vitro cell dilatation comprising a stretching unit (2a, 2b) having at least one punch (3) and at least one line cultivating dish (4) comprising a removable lid (5) and a flexible membrane (6) as a bottom, can be attracted to the cells, wherein the punch (3) for stretching the membrane (6) presses against this, characterized in that the punch (3) and the membrane (6) in one Linear movement relative to each other are arranged movable and the membrane (6) in a substantially unstretched state on the punch (3) is supported, wherein the device (1) (1) comprises an electromotive linear drive (7), by means of which a transmission means (8 ) a mechanical pressure on the lid (5) of the line cultivation tray (4) is exercisable, so that the cell cultivation tray (4) with its membrane (6) pressed against the punch (3) and is stretched in dependence of the pressure.

2. Device (1) according to claim 1, characterized in that the

Stretching unit (2a, 2b) has a frame (2b) in which the cell cultivation dish (4) is held.

3. Device (1) according to claim 2, characterized in that the

Transmission means (8) is a support which rests on the frame (2b), wherein the frame (2b) transmits the pressure on the lid (5).

4. Device (1) according to claim 1, 2 or 3, characterized in that the punch (3) on a plate (9) is supported, on which the linear drive (7) is fixed.

5. Device (1) according to one of the preceding claims, characterized in that the stretching unit (12a, 2b) has a shell (2b), at the bottom of the punch (3) is supported, in particular is formed.

6. Device (1) according to claim 5, characterized in that the shell (2b) fixedly connected to a plate (9) or is connectable, on which the linear drive (7) is fixed.

7. Device (1) according to claim 5 or 6, characterized in that the cell cultivation dish (4) between the frame (2b) and the shell (2a) is arranged.

8. Device (1) according to one of claims 5 to 7, characterized in that the cell cultivation dish (4) in the shell (2a) of the expansion unit (2a, 2b) is movably guided.

9. Device (1) according to one of the preceding claims, characterized in that the linear drive (7) is in communication with a computer on which a program for controlling the linear drive (7) is executable.

10.Vorrichtung (1) according to claim 8, characterized in that the

Program is set to change the duration and / or the amount of pressure applied dynamically.

11. Device (1) according to claim 9, characterized in that the program is adapted to control the amplitude and / or the frequency of the pressure.

12. Device (1) according to one of the preceding claims, characterized in that the punch (3) is made of an inert material, in particular of polyoxymethylene and / or aluminum.

13. Device (1) according to one of the preceding claims, characterized in that the stretching unit (2a, 2b) and / or the transmission means (8) at least one contact sensor (10) for detecting the contacting of the transmission means (8) with the lid ( 5) or the frame (2b).

14. Device (1) according to one of the preceding claims, characterized in that the expansion unit (2a, 2b) and / or the transmission means (8) at least one pressure sensor (10) for detecting the of the transmission means (8) on the lid ( 5) or the frame (2b) applied pressure.

15. Device (1) according to one of the preceding claims, characterized by indicating means (15) for indicating the contacting of the transmission means (8) with the cover (5) or the frame (2b).