EP4153718A1

EP4153718A1 - Cell culture apparatus

Info

Publication number: EP4153718A1
Application number: EP21710314.2A
Authority: EP
Inventors: Patrick Kugelmeier; Martin Meier; Guillaume Jung
Original assignee: Kugelmeiers Ag
Current assignee: Kugelmeiers Ag
Priority date: 2020-05-19
Filing date: 2021-03-11
Publication date: 2023-03-29
Also published as: IL298176A; WO2021233585A1; AU2021276361A1; CA3182327A1; CN115605575A; JP2023527703A; US20230193179A1; KR20230012525A

Abstract

The invention relates to a cell culture apparatus for cultivating cell spheroids, comprising at least one compartment having n compartment walls which define a compartment base area and a volume V_K above the compartment base area and a multiplicity of microwells having p top edges and a volume V_M, wherein the microwells are arranged in the compartment base area such that the compartment base area outside the microwells merely has inclined surfaces, the number of microwells is chosen such that the entire compartment base area is covered with microwells, all the microwells have the same volume VM and the microwells have the shape of a pyramid or a cone having a rounded tip for accommodation of cells and additionally rounded edges between the tip and the base of the pyramid or the cone.

Description

Cell culture device

Field of invention

The present invention relates to devices for the in vitro aggregation of cells. The devices are distinguished by the fact that they contain specially shaped cavities which enable the aggregation of individual cells to form cell spheroids when a cell suspension is seeded onto the device. The present invention also relates to a method for the aggregation of cells and the use of the devices according to the invention for the aggregation of cells.

Background of the invention

Stem cell research deals with the principles of tissue regeneration processes in order to develop methods for regenerative medicine. A very important factor in stem cell biology is the constant communication between the stem cells themselves and the interaction between the stem cells and the surrounding tissue, the so-called stem cell niche. Together, these cells form organizational units, called cell clusters, cell spheroids or organoids, which in large numbers and with a sophisticated architecture ultimately form a whole organ.

Various experimental environments allow the analysis of such processes, the standard here being the use of "hanging drops". The development of stem cells is simulated by adding a certain amount of stem and other cells to a drop, which then develop into cell clusters that can be analyzed. The disadvantages of this widespread technology are that only a limited number of cell clusters can be generated in this way and that only a limited change of medium can be carried out. This would be important, however, since the differentiation of stem cells depends on the presence of certain cytokines at a certain point in time, which could be added when the medium is changed.

In the clinical setting, the possibility of large-scale production of cell clusters of a defined size with the possibility of changing the medium for various therapeutic approaches, such as, for example, islet cell transplantation, would be very desirable. In this technique, small islets are diffusible in the early post-transplant time due to the limited supply of nutrients and oxygen better than large islets as large islets die off due to lack of oxygen after transplantation. As a result, two to three transplants are required until there are enough functional islets in the patient that he no longer needs injected insulin (Lehmann R. et al., Diabetes. 2007 Mar; 56 (3): 594- 603). It would therefore be desirable to create many small islands instead of a few large islands. Mathematically, a transplant would be sufficient for a diabetic to be functionally cured and no longer need to inject insulin. For the successful production of small islets and clinical application, however, islets would have to be dissociated into individual cells and re-aggregated into small "pseudoislets". Approximately 1,000,000 pseudoislets would be required for transplantation, a number that cannot be achieved with the hanging drop technique.

In WO 2008/106771 a device for setting up cell aggregates is described. This device is sold under the tradename Aggrewell (Stemcell Technologies, Vancouver, BC, Canada V5Z 1 B3). However, this was only developed as a laboratory product and not as a medical device, which is why it should only be used for human application if the user accepts the risk.

In addition, the device described is of limited use for stem cell cluster production, since the microwells have a purely inverted pyramid shape or the shape of a pyramid with a flat bottom. In any case, however, the side edges of the pyramid are not rounded. The cultivated cells are therefore forced into a pointed pyramid shape or into the corresponding side edges instead of a round spheroid / cluster shape. This contradicts the basic physical principles of "free energy minimization" to which all cell processes are subject. In addition, in this form of microwells, the cells are not supported in forming a round cell spheroid, but instead forced into an unnatural conformation.

Furthermore, such a device prevents the natural communication mechanisms of cells, since in the cell clusters formed in this way, due to their irregular shape, there are different concentrations of oxygen and signal molecules for the individual cells. This device is therefore unsuitable for cell therapies, since the shape of the microwells can cause a disruption of the signal pathways, which can lead to incorrect programming and, in later applications with stem cells, ultimately to tumor formation. In addition, a solution must be found in this device Reduction of cell attachment can be used. This solution is not clinically approved, so that for this reason too the device is not suitable for clinical use.

From the prior art, only a single device is known so far which enables cell clusters to be grown on the required scale (WO 2010/142755 A2). This has a large number of microwells with one design. The disadvantage here, however, is that, due to technical limitations, the microwells do not cover the entire bottom surface of the device, but rather an essentially horizontal edge remains along the compartment wall, on which individual cells can potentially be deposited. To avoid this, WO 2010/142755 A2 proposes the use of inserts that are placed on the protruding edge.

However, this system carries the risk that, if handled carelessly, individual cells get under the edge of the insert on the edge, which in the case of stem cells can grow uncontrollably, which in the worst case can lead to tumor formation in the patient treated with this cell product.

There is therefore still a need for cell culture devices which, due to their design, prevent individual cells from settling outside the microwells and being able to differentiate there in an uncontrolled manner.

Technical problem to be solved

The object to be solved objectively is therefore to provide a cell culture device which is constructed in such a way that all introduced cells are cultivated under defined conditions and growth of individual cells outside the microwells is prevented.

Summary of the invention

The object is achieved by a cell culture device for cultivating cell spheroids, comprising at least one compartment with n compartment walls and a volume V ″, which define a compartment floor area, and a multiplicity of microwells with p upper edges and a volume VM, the microwells being arranged in the compartment bottom surface in such a way that the compartment bottom surface outside the microwells only has sloping surfaces, the number of microwells is selected so that the entire compartment bottom surface is covered with microwells, all microwells have the same volume V _M and the microwells have the shape of a pyramid or a cone with a rounded tip for receiving the cells and furthermore rounded edges between the tip and the base of the pyramid or the cone.

The object is also achieved by a method for producing cell spheroids, the cell spheroids being cultivated in a cell culture device according to the invention.

Brief description of the figures

1 shows two side views, two sectional views and a top view of a cell culture device according to the invention.

2 shows an isometric view, a top view and a sectional view and two detailed views of the arrangement of the microwells in one embodiment of the device according to the invention Base G and d the diameter of the rounded tip.

Fig. 3 shows a sectional view of part of a device according to the invention. G denotes the base area of a microwave, ß the angle between the compartment wall and the compartment floor area.

4 shows an isometric view of a pyramid-shaped microwave with a rounded tip according to an embodiment of the device according to the invention. G denotes the base area of the microwave, S the side area of the microwave, c the upper edges of the base area G, f the side area edges, d the diameter of the rounded tip, d _fi the diameter of the rounded edge of the side surface edge near the base area G and de the diameter of the rounded edge the side face edge near the top of the pyramid. 5 shows a plan view, an isometric view and a side view of microwells of a device according to the invention with p equal to 3, 4, 6 or infinitely large.

6 shows a top view of an arrangement of microwells according to the present invention and a top view, sectional view and isometric view of a microwell, where p is 3 and n is 6.

FIG. 7 shows a top view of an arrangement of microwells according to the present invention and a top view, sectional view and isometric view of a microwell, where p equals 4.

8 shows a top view and isometric view of an arrangement of microwells according to the present invention and a top view, sectional view and isometric view of a microwell, where p equals 4.

9 shows a top view of an array of microwells in accordance with the present invention and a top, sectional and isometric view of a microwell, where p is equal to 6 and n is approaching infinity.

10 shows top and isometric views of an array of microwells in accordance with the present invention and top, sectional and isometric views of a microwell, where p approaches infinity.

Description of the invention

The invention relates to a cell culture device comprising at least one compartment with n compartment walls which define a compartment bottom surface, and a plurality of microwells with p top edges and a volume VM, the microwells being arranged in the compartment bottom surface in such a way that the compartment bottom surface outside the microwells only has sloping surfaces has, the number of microwells is selected so that the entire compartment floor area is covered with microwells, and all microwells have the same volume V _M.

According to the present definition, a cell culture device is suitable for the cultivation of eukaryotic cells, in particular stem cells, and differs from assay plates, inter alia, in the material used, which Surface quality, attachment properties, sterility, gas permeability, light permeability, and the refractive index.

In a preferred embodiment, the cell culture device consists of a material that prevents cell adhesion. Such materials include, for example, specifically suitable plastics (e.g., polystyrene, polycarbonate), and glass, with or without coatings to reduce cell adhesion. In a particularly preferred embodiment, the cell culture device consists of cycloolefin copolymers.

The cell culture device according to the invention comprises at least one compartment with n compartment walls. The cell culture device according to the invention is thus delimited on all sides by a compartment wall, so that a liquid, e.g. cell culture medium, can be held within the compartment. The compartment walls can all have the same or different heights. The typical height of a compartment wall is from 1 to 100 mm, preferably 10 to 30 mm. In any case, the compartment walls are smooth, i.e. they have no protrusions.

The compartment walls define a compartment floor area. This extends over the entire area delimited by the compartment walls and is delimited by the compartment walls. In a preferred embodiment, the compartments of the cell culture device according to the invention are open at the top, i.e. the side opposite the compartment bottom surface is not closed, so that the compartments are directly accessible. The compartment volume V «is located above the compartment floor area.

The compartments of the cell culture device according to the invention have an n-cornered opening. n can be any natural number. In a preferred embodiment, n is so large that the opening of the compartment is approximately circular. In a further preferred embodiment, n is 3, 4, or 6, particularly preferably 4. Such a geometry facilitates production.

In a further embodiment, two opposing compartment walls are each of the same length, so that the compartment has a symmetrical opening. In a preferred embodiment, all compartment walls are the same long, so that the compartment has an opening in the shape of an equilateral triangle, hexagon or, particularly preferably, a square.

In a preferred embodiment, the compartment walls are essentially perpendicular to the compartment bottom surface outside the microwells. Any wall angle β from 90 ° to 110 ° to the compartment floor surface is referred to herein as essentially perpendicular.

The cell culture device according to the invention comprises at least one compartment, but can also comprise several, e.g. 2, 3, 4, 5, 6, 8, 10, 12, 18, 24, 48, 96, 384, 1536, 3456 or 9600 compartments. The cell culture device preferably comprises 4, 6, 12, 24, 96, 384 or 1536 compartments. In a particularly preferred embodiment, the cell culture device comprises 6 compartments.

The cell culture device according to the invention furthermore comprises a multiplicity of microwells with p upper edges c. Microwells are defined as depressions in the compartment floor area in which cells can settle, approach one another and grow as cell clusters. Microwells can also be referred to herein as picowells, nanowells, microcavities and depressions.

The microwells of the cell culture device according to the invention have a square base. The base G is an opening through which the cells can slide into the interior of the microwells. The opening has p upper edges c, which border the opening p can be any natural number. In a preferred embodiment, p is so large that the base area G is approximately a circle. In a further preferred embodiment, p is 3, 4 or 6, particularly preferably 4.

In one embodiment, p is equal to n. In a preferred embodiment, p is equal to n is equal to 4. This ensures optimal use of the available floor space. In a further embodiment, n is 6 and p is 3. In a further embodiment, n is so large that the opening of the compartment is approximately circular, and p is 4 or 6. In yet another embodiment, n and p approach infinity.

The microwells have a pyramid or conical shape, the tip of the pyramid being located within the compartment floor area and the base area of the pyramid or cone forming the opening of the microwells. In other words, extends the volume V of the microwells from the surface of the compartment floor area into the compartment floor area. In the context of the invention, the tip of the pyramid or the cone is therefore also referred to as the bottom B of a microwell. The triangular side edges f, which delimit the side surfaces S, are located between the tip and the base G of a microwave, more precisely between the corners of the opening and the base B.

The tips are used to receive the cells. Rounding them off promotes the formation of regular spheroids. In one embodiment, all the tips of the microwells in a compartment are equidistant from one another. This is important to maintain communication between the spheroids. The cells communicate using messenger substances. The information transmitted depends on the concentration of the messenger substances. These principles of morphogen gradients and lateral inhibition make it necessary that the distances between the cell spheroids are the same so that the cell spheroids develop at the same rate. Safe use in cell therapy is only possible if all cell spheroids are at the same stage of development during transplantation.

In one embodiment, the microwells are in the shape of a pyramid. In a preferred embodiment, the tip of the pyramid is rounded with a diameter d _B.

In an embodiment in which p is so large that the base G is approximately a circle, the microwells have the shape of a cone. In a preferred embodiment, the tip of the cone is rounded with a diameter d _ß.

In a preferred embodiment, the tip of the cone or the pyramid has a diameter d _ß between 2 pm and 500 pm, preferably 5 pm to 400 pm and particularly preferably 70 pm to 200 pm. In a preferred embodiment, the diameter d _ß 90 μm. In a further preferred embodiment, the diameter d _B 180 pm or 270 pm.

In other words, the tip of the pyramid or the cone of the microwell has a radius r _B between 1 and 250 pm, preferably 2.5 pm to 200 pm and particularly preferably 35 pm to 100 pm. In a preferred embodiment, the radius r _{B is} 45 μm. In a further preferred embodiment, the radius r _{B is} 90 pm or 135 pm. The microwells have a depth h. The depth is between 10 pm and 2000 pm, preferably 50 pm to 1000 pm, more preferably 100 pm to 500 pm and most preferably 200 pm to 400 pm. In a further preferred embodiment, the depth is 600 μm to 700 μm, particularly preferably 641 μm.

The upper edges c have a length between 0 μm to 5 mm, preferably 200 μm to 2 mm, and most preferably 400 μm to 1200 μm. In a preferred embodiment, all of the upper edges are of the same length.

In a preferred embodiment, the triangular side edges f, ie the edges between the side surfaces of the pyramid, are rounded. In a particularly preferred embodiment, the rounding of the triangular side edges f increases progressively from the opening to the pyramid top or bottom of the microwell, where s, ie the diameter d _{fi of} the rounding near the opening of the microwell differs from the diameter de near the top of the Pyramid or the bottom of the microwave. In a particularly preferred embodiment, d _{fi is} smaller than d _f 2. In a preferred embodiment, d _fi is 0 and d _f 2 is d _ß .

The side surfaces S form a wall angle a with the base surface G or the imaginary surface in the opening of the microwells or with the compartment bottom surface. a is between 35 ° to 75 °, preferably 40 ° to 70 °, more preferably 50 ° to 60 ° and most preferably 54.7 °. This angle ensures that all cells slide down to the bottom or into the tip B and that optimal conditions exist to support the cells in forming a natural cell spheroid, but at the same time not to constrict or force them into an unnatural conformation.

According to the invention, the depth of the microwells and the length of the upper edges depend on the radius or diameter d _ß and the angle α. In a particularly preferred embodiment with a equal to 54.7 °, p is 4 and the diameter d _ß is 90 μm, the length of the upper edges is c 500 μm and the depth h is 320 μm. In a further preferred embodiment, with a equal to 54.7 °, the diameter d _ß 180 pm, the length of the upper edges c 1000 pm and the depth h 641 pm.

Each compartment of the cell culture device according to the invention has a large number of microwells. A large number is defined here as a natural number between 1 and 1,000,000. A compartment therefore comprises between one and 1,000,000 microwells. ok

In a preferred embodiment, a compartment comprises more than one microwell. In a further preferred embodiment, a compartment comprises exactly one microwell.

According to the invention, the compartment floor area of a compartment is completely covered with microwells. The microwells are arranged in such a way that there is as little space as possible between them. In one embodiment, the microwells are arranged in regular columns and rows. In the context of the invention, there is little space between two microwells if the surface of the edge between the two microwells has a width of less than 15 μm.

In one embodiment, each microwell has at least one upper edge in common with each neighboring microwell.

A common upper edge is to be understood here as meaning that the openings of the microwells lie seamlessly next to one another. In the embodiment in which n is equal to p is equal to 4, a microwell x, which is located between four further microwells Xi, X2, X3, X4, has with each of the four adjacent microwells between x and Xi, x2, X3 and X4 together, ie with Xi the upper edge Ci, with X2 the upper edge c ₂ , with x ₃ the upper edge c ₃ and with x the upper edge c. A microwell y, which is located in a row or column adjoining a compartment wall, has a common upper edge with the three neighboring microwells. A microwell z, which is located in a corner of the compartment floor area, has a common upper edge with the two neighboring microwells. The same applies to values of n and p not equal to 4.

The common upper edge prevents cells from remaining between the microwells, where they could develop in an uncontrolled manner. In the cell culture device according to the invention, due to the special geometry and arrangement of the microwells, all cells are directed into the interior of a microwell, so that each cell can develop correctly in the desired environment.

The upper edges of the microwells y and z, which are not shared with the neighboring microwells, are flush with the compartment walls. Flush is defined here as form-fitting, so that there is no flat edge at the transition between the upper edge and the compartment wall on which individual cells can settle. In the context of the invention, it applies here that an upper edge is flush with a compartment wall when the resulting edge has a maximum width of 15 μm. In one embodiment, this edge is not horizontal, that is to say parallel to the compartment bottom surface, but rather beveled.

Because each microwell has at least one edge in common with each neighboring microwell, and the top edges of the outer microwells are flush with the compartment walls, the compartment floor area outside the microwells only has sloping surfaces on which no cells can settle. Thus, in the device according to the invention, no cells can grow outside the microwells in an uncontrolled manner.

According to the invention, all microwells have the same volume V. In other words, the corresponding upper edges of all microwells are each of the same length. To put it another way, the cell culture device according to the invention does not have any cut-off microwells. This ensures that the same growth conditions prevail in all microwells.

According to the invention, all of the microwells in a compartment are in fluid connection with one another. As a result, the same growth conditions prevail in all microwells.

The invention further relates to the use of the cell culture device described for the cultivation of cells. Due to the special geometry of the microwells, when using suitable starting cells and cultivation conditions, cell clusters can arise from the cultivated cells.

Cell spheroids, cell clusters, organoids or 3D cell colonies are regularly or irregularly shaped aggregates of cells that extend in all spatial directions. Spherical cell clusters are also known as cell spheroids. The terms cell cluster, cell accumulation and cell aggregate are used synonymously herein.

The cell culture devices according to the invention are therefore particularly suitable for 3D cell culture with the aim of obtaining cell spheroids. In contrast to conventional 3D cultivation methods, the cultivation method according to the invention does not require any further devices, reactors or special skills on the part of the experimenter in order to reliably obtain cell spheroids. Instead, the cells can like are applied on a conventional cell culture plate and automatically form cell spheroids as a result of the special geometry of the microwells, which are characterized by a high degree of homogeneity in size and functionality.

This distinguishes the devices according to the invention from devices already known in which the cells can grow in cell clusters of any shape. As a result, this leads to an uneven distribution of oxygen and nutrients within the cell clusters, to the death of individual clusters and thus to less functional cell clusters as a whole.

Another advantage of using the cell culture device according to the invention is that all cells applied to the cell culture device inevitably grow in cell clusters, since no individual cells remain outside the microwells and can grow there in an uncontrolled manner. This is of enormous importance especially in therapeutic applications in which the (stem) cell clusters obtained are to be transplanted into a patient. This is equally beneficial in research to ensure that only cells with the same properties are present.

In principle, all types of cells in the invention

Cell culture device are cultured. However, the cultivation of eukaryotic cells is particularly preferred. All animal cells can be cultivated with the cell culture device according to the invention, in particular mammalian cells, particularly preferably human cells.

In a preferred embodiment, the cell culture device is used to cultivate stem cells. By using the invention

Cell culture devices can be obtained from stem cells, stem cell spheroids which are suitable for use in regenerative medicine. Such stem cell spheroids have already been used successfully experimentally for the regeneration of various organs and tissues, including the heart, lungs, liver, salivary glands, bone tissue, skin, thymus and nerve cells (Ong CS, Zhou X, Han J, et al. In vivo therapeutic applications of cell spheroids. Biotechnology Advances. 2018 Mar-Apr; 36 (2): 494-505.). The transplantation of such stem cell spheroids, however, carries the risk of tumor formation if the cell spheroids are programmed incorrectly. The geometry of the microwells and the arrangement in the device according to the invention can prevent incorrect programming of the stem cells, see above that the stem cell spheroids obtained in this way are safe for therapeutic use.

In a further preferred embodiment, the cell culture device is used to cultivate islet cells. The term “islet cells” is familiar to the person skilled in the art and refers to a group of insulin-producing cells from the human pancreas. With the transplantation of these cells, diabetes can be functionally cured. Islet cell spheroids known from the prior art are usually too large, which is why they largely die off during transplantation due to a lack of oxygen. By using the cell culture device according to the invention, the size of the spheroids can be standardized and their survival rate can be improved, since oxygen can diffuse into the center if the size is optimal.

In a further preferred embodiment, the cell culture device is used to cultivate tumor cells. According to current medical knowledge, tumor cells are degenerate stem cells (so-called "cancer stem cells"). The cell culture device according to the invention can therefore also be used to obtain tumor cell spheroids. For example, tumor cells isolated from patients can be grown as spheroids that show exactly the same properties as the patient's tumor. This means that therapies can be tested outside the body (ex vivo), e.g. which chemotherapy should be used in the patient. These tumor cell spheroids also offer great potential for drug development and can thus reduce the number of animal experiments required.

The invention further relates to cell spheroids which can be obtained using the cell culture device described. These cell spheroids can be used for medical applications such as medicine. The invention accordingly also relates to methods for treating the human body in which cell spheroids are administered which are cultured by means of the devices according to the invention. The range of applications is enormous and includes practically all organ systems, e.g. the treatment of heart attacks, cardiac insufficiency, liver failure, strokes, wound healing, pulmonary fibrosis or vascular diseases.

Preferred embodiments of the present invention are described below with reference to the figures. In the embodiment shown in FIGS. 1 and 2, the cell culture device has six compartments with n equal to four. The microwells p are equal to 4. The microwells are arranged in such a way that each microwell has a common upper edge with each adjacent microwell (cf. FIG. 3A). In addition, the microwells have the same volume V and a rounded tip with a diameter d _B or radius r _B. G denotes the imaginary base of the pyramid, c the upper edges that delimit the base. The side surfaces of the microwells form an angle α with the base.

3 shows a sectional view of a device according to the invention at the transition between the compartment bottom surface and the compartment side wall. The angle β, which is approximately 90 ° C., is present between the compartment bottom surface and the compartment side wall. There is no edge between the compartment side wall and the adjacent microwell.

FIG. 4 shows an embodiment of a single microwell in which the microwell has the shape of a pyramid (FIG. 4A) or a cone (FIG. 4B) with a rounded tip. In the case of the pyramid, the edges f between the side surfaces S are rounded, the diameter of the rounding d _fi near the opening or base area G being smaller than the diameter de near the tip of the pyramid. It can be seen that de corresponds _{approximately to d B.}

5 shows different embodiments of the microwells according to the invention. For example, p is equal to 3 and the microwell has the shape of a three-sided pyramid with a rounded tip. In a further embodiment, p is equal to 4 and the microwell has the shape of a four-sided pyramid with a rounded tip. In a further embodiment, p is equal to 6 and the microwell has the shape of a six-sided pyramid with a rounded tip. In another embodiment, p is so large that the base area G of the microwell is approximately circular and the microwell has the shape of a cone with a rounded tip. As can be seen from FIG. 5, in all of these embodiments the triangular side edges f are rounded, the diameter of the rounding d _fi near the opening or base G being smaller than the diameter de near the pyramid or cone apex. 6 shows a device according to the invention with p = 3 and n = 6. The microwells have the shape of a three-sided pyramid with a rounded tip and rounded edges between the side surfaces (cf. FIG. 6A).

7 shows a device according to the invention with p = 4 and n = °°. The microwells have the shape of a four-sided pyramid with a rounded tip and rounded edges between the side surfaces (cf. FIG. 7A).

8 shows a further arrangement of microwells with p = 4 in a device according to the invention. The microwells have the shape of a four-sided pyramid with a rounded tip and rounded edges between the side surfaces (cf. FIG. 8A). 9 shows a device according to the invention with p = 6 and n = °°. The microwells have the shape of a six-sided pyramid with a rounded tip and rounded edges between the side surfaces (cf. FIG. 9A).

10 shows an arrangement of microwells in a device according to the invention with p = ^00. The microwells have the shape of a cone with a rounded tip (cf. FIG. 10A). Here, too, the microwells have a common upper edge with each neighboring microwell.

Claims

Expectations

1. Cell culture device for cultivating cell spheroids comprising at least one compartment with n compartment walls defining a compartment floor area and a volume V «above the compartment floor area and a plurality of microwells with p upper edges and a volume VM, the microwells being arranged in the compartment floor area that the compartment floor area outside of the microwells only has sloping surfaces, the number of microwells is selected so that the entire compartment floor area is covered with microwells, all microwells have the same volume V _M and the microwells have the shape of a pyramid or a cone with a rounded one Have tip for receiving cells and further rounded edges between the tip and the base of the pyramid or the cone.

2. Cell culture device according to claim 1, wherein all tips of the microwells of a compartment have the same distance from one another

3. The cell culture device according to claim 1, wherein the microwells have side surfaces and the side surfaces form an angle of 54.7 ° with the compartment bottom surface.

4. Cell culture device according to one of the preceding claims, wherein each compartment wall is arranged flush with at least one upper edge of at least one microwell.

5. Cell culture device according to one of the preceding claims, wherein each microwell has a common upper edge with each neighboring microwell.

6. Cell culture device according to one of the preceding claims, wherein two opposing compartment walls are of equal length.

7. Cell culture device according to one of the preceding claims, wherein all upper edges of the microwells are of the same length.

8. Cell culture device according to one of the preceding claims, wherein n and / or p is 3, 4 or 6.

9. Cell culture device according to one of the preceding claims, wherein n and / or p are so large that the compartment and / or the microwells have an approximately round bottom surface or base.

10. Cell culture device according to one of the preceding claims, wherein n is equal to p.

11. Cell culture device according to one of the preceding claims, comprising 1,

2, 4, 6, 12, 24, 96, 384, 1536, 3456 or 9600 compartments.

12. A method for the production of cell spheroids, wherein the cell spheroids are cultivated in a cell culture device according to one of claims 1 to 12.

13. Use of a cell culture device according to one of claims 1 to 12 for the cultivation of stem cell spheroids.

14. Cell spheroids obtained by culturing cells in a cell culture device according to one of claims 1 to 12.

15. Cell spheroids according to claim 15, wherein the cells are islet cells, stem cells or tumor cells.