MULTIWELL, MICROSCOPE-COMPATIBLE DEVICE FOR HIGH-THROUGHPUT ANALYSIS OF CELL INVASION

Abstract

The invention is related to a device (1) for receiving a biological sample (3) wherein the device (1) comprises a plurality of wells (10) wherein each well (10) comprises an inner surface (14) facing a volume (60) for receiving a biological sample (3). The inner surface (14) comprises a top section (20) and a bottom section (30). The top section (20) and the bottom section (30) are connected via a circumferential step (40). The circumferential step (40) forms a stop for a tip of a pipette (70).

Claims

1. A device (1) for receiving a biological sample (3) comprising: a plurality of wells (10), wherein each well (10) comprises an inner surface (14) facing a volume (60) for receiving a biological sample (3), wherein the inner surface (14) comprises a top section (20) and a bottom section (30), characterized in that the top section (20) and the bottom section (30) are connected via a circumferential step (40) forming a stop for a tip of a pipette (70).

2. The device (1) according to claim 1, characterized in that the circumferential step (40) comprises an inner edge (44) marking a predefined lower portion of the volume (62).

3. The device (1) according to claim 1, characterized in that the bottom section (30) comprises a concave curvature.

4. The device (1) according to claim 1, characterized in that the bottom section (30) comprises a spherical curvature.

5. The device (1) according to claim 1, characterized in that the bottom section (30) comprises a flat bottom (34).

6. The device (1) according to claim 5, characterized in that the bottom section (30) comprises a lateral portion (36) connected to the bottom (34).

7. The device (1) according to claim 6, characterized in that the lateral portion (36) is cylindrical.

8. The device (1) according to claim 6, characterized in that the lateral portion (36) comprises four rectangular sides (38).

9. The device (1) according to claim 1, characterized in that a first angle (50) enclosed by the top section (20) and the circumferential step (40) is in the range from 90° to 135°, in particular from 100° to 130°, in particular from 115° to 125°, wherein particularly the first angle (50) is 120°.

10. The device (1) according to claim 1, characterized in that each well (10) extends along a longitudinal axis (13), wherein the circumferential step (40) is configured such that the circumferential step (40) encloses an acute angle (a1) with the longitudinal axis (13).

11. The device (1) according to claim 10, characterized in that the acute angle (a1) lies in the range from 5° to 85°, in particular in the range from 15° to 75°, in particular in the range from 30° to 60°.

12. The device (1) according to claim 1, characterized in that each well (10) extends along a central axis (12) and is rotationally symmetrical with respect to the central axis (12).

13. The device (1) according to claim 1, characterized in that each well (10) comprises or is formed out of a transparent material.

14. The device (1) according to claim 1, characterized in that the device (1) is configured to be arranged on a stage of a microscope (90).

15. The device (1) according to claim 1, characterized in that the bottom section (30) comprises a coating for reducing adhesion of cells.

16. The device (1) according to claim 1, characterized in that the device (1) comprises at least 6, particularly at least 10, particularly at least 20, particularly at least 30, particularly at least 40, particularly at least 50, particularly at least 60, particularly at least 70, particularly at least 80, particularly at least 90, particularly at least 96 wells (10), wherein particularly the plurality of wells (10) forms an array of wells.

17. The device (1) according to claim 1, characterized in that the top section (20) comprises a lower top section (202) and an upper top section (204), wherein the lower top section (202) and the upper top section (204) are connected via a further circumferential step (400).

18. The device (1) according to claim 17, characterized in that the further circumferential step (400) encloses a further acute angle (a3) with the longitudinal axis (13), in particular wherein the further acute angle (a3) is between 5° and 85°, in particular between 15° and 75°, in particular between 30° and 60°.

19. The device (1) according to claim 17, characterized in that the further circumferential step (400) and the circumferential step (40) run in parallel to each other.

20. The device (1) according to claim 17, characterized in that the further circumferential step (400) comprises a further inner edge (404) marking a predefined extended lower portion (63) of the volume (60).

21. The device (1) according to claim 2, characterized in that the predefined lower portion of the volume (62) is at least 10% of the volume (60), in particular at least 15% of the volume (60), in particular at least 20% of the volume (60).

22. The device (1) according to claim 17, characterized in that the predefined lower portion of the volume (62) is at least 5% of the volume (60), in particular at least 7.5% of the volume (60), in particular at least 10% of the volume (60).

23. The device (1) according to claim 20, characterized in that the predefined extended lower portion (63) of the volume (60) is at least 20% of the volume (60), in particular at least 30% of the volume (60), in particular at least 40% of the volume (60).

24. The device (1) according to claim 1, characterized in that the top section (20) tapers towards the circumferential step (40).

25. A method for propagating biological samples (3) using a device (1) according to claim 1, comprising the steps of: providing a suspension of cells (3) in a culture medium (5) in a plurality of wells (10) of the device (1), incubating the cells (3), placing a tip of a pipette (70) on the respective circumferential step (40), and removing culture medium (5) by means of the pipette (78) such that culture medium (5) and cells (3) remain in a lower portion of the volume (62) of the respective well (10).

Description

[0164] In the following, further features, advantages and embodiments of the present invention are explained with reference to the Figures, wherein

[0165] FIG. 1 shows a schematic top view of an embodiment of a device comprising 96 wells,

[0166] FIG. 2 shows a schematic side view (A), a schematic cross section view (B) and a schematic top view (C) of a well comprising a curved bottom section,

[0167] FIG. 3 shows schematic cross section views of four wells comprising a curved bottom sections (A-D),

[0168] FIG. 4 shows schematic perspective views (A, C), schematic cross section views (B, D) and a schematic top view (E) of a well comprising a flat bottom,

[0169] FIG. 5 shows a schematic side view of a well wherein the circumferential step has a conic shape and a tip of a pipette is placed into the well (A, B),

[0170] FIG. 6 shows a schematic side view of a well wherein the circumferential step has the shape of a circular ring and a tip of a pipette is placed into the well,

[0171] FIG. 7 shows a schematic cross section view of a well comprising a curved bottom section,

[0172] FIG. 8 shows a schematic perspective view of a well comprising a curved bottom section,

[0173] FIG. 9 shows a schematic cross section view of a well comprising a curved bottom section, a circumferential step and a further circumferential step,

[0174] FIG. 10 shows a schematic perspective view of a well comprising a curved bottom section, a circumferential step and a further circumferential step, and

[0175] FIG. 11 shows a schematic cross section view of a well a circumferential step and a further circumferential step, wherein a tip of a pipette is put on the circumferential step (A) or the further circumferential step (B).

[0176] FIG. 1 shows a top view of a device 1 that comprises a plurality of wells 10, here as an example 96 wells 10. The device 1 can have a rectangular ground area. The wells 10 can be arranged in an array comprising e.g. eight rows wherein each row comprises e.g. 12 wells 10. Each individual well 10 can have a circular cross-sectional area. All wells 10 can be configured identically.

[0177] The device 1 can be placed on the stage of a microscope 90, in particular on the stage of a fluorescence microscope.

[0178] A well 10 can comprise a bottom section 30 that comprises a concave curvature, hereafter also referred to as curved bottom section 30. Exemplary embodiments of a well 10 comprising a curved bottom section 30 are shown in FIGS. 2, 3, 5, 6, 7, 8, 9, 10 and 11.

[0179] In an alternative embodiment, a well 10 can comprise a bottom section 30 that comprises a flat bottom 34; hereafter also referred to as flat bottom section 30 (shown in FIG. 4).

[0180] As can be seen in FIGS. 2 to 11, the well 10 can extend along a central axis 12. The well can extend along a longitudinal axis 13. The longitudinal axis 13 can be the central axis 12. The well 10 can be rotationally symmetrical with respect to the central axis 12 (FIGS. 2, 3, 5-11).

[0181] The well 10 can comprise an inner surface 14 that faces a volume 60 for receiving a biological sample 3. The inner surface 14 comprises a top section 20, a bottom section 30 and a circumferential step 40 that connects the top section 20 and the bottom section 30. The circumferential step 40 can be a rim, particularly a circumferential rim.

[0182] The top section 20 can extend parallel or coaxially to the central axis 12. In an embodiment, the top section 20 can have the shape of an open cylinder. In an embodiment, the top section 20 can have the shape of an open circular right cylinder (FIGS. 2, 3, 5, 6, 7, 8). In another embodiment, the top section 20 can comprise four rectangular sides 26 wherein each two adjacent rectangular sides 26 can be arranged perpendicular to each other (FIG. 4). All four rectangular sides 26 can be configured identically, in particular, each rectangular side 26 can have the same width and height. In a further embodiment, the top section 20 can taper towards the bottom section 30 (FIGS. 9-11).

[0183] The upper edge of the top section 22 can delimit an opening of the well 16. The opening of the well 16 can have a circular shape (FIGS. 2, 3, 5-11). Alternatively, the opening of the well 16 can have a rectangular shape, in particular a squared shape (FIG. 4). The volume 60 can be accessed via the opening of the well 16. The lower edge of the top section 24 can border the circumferential step 40. The lower edge of the top section 24 can abut the circumferential step 40.

[0184] The circumferential step 40 can extend along the entire circumferential direction 110 and can form a circumferential surface (FIGS. 2C, 4E, 8, 10). Further, the circumferential step 40 can comprise an outer edge 42 and an inner edge 44. The outer edge 42 can be adjacent to the lower edge of the top section 24. The lower edge of the top section 24 can abut the outer edge 42 of the circumferential step 40.

[0185] The inner edge 44 of the circumferential step 40 borders the bottom section 30.

[0186] The inner edge 44 can have the shape of a circle comprising a center of that circle 46 (FIGS. 2, 3, 5-11). The well 10 can be configured such that the center of the circle determined by the inner edge 46 is located on the central axis 12. The inner edge 44 can have a diameter d1 (FIGS. 2, 3, 5, 6, 7, 9).

[0187] In an embodiment the circle described by the inner edge 44 of the circumferential step can have the diameter d1 in a range from 3.5 mm to 6.5 mm, in particular from 5 mm to 6 mm. In an embodiment, the diameter d1 of the circle described by the inner edge 44 of the circumferential step can be 5.94 mm.

[0188] In another embodiment, the inner edge 44 can have the shape of a square (FIG. 4). The square described by the inner edge 44 of the circumferential step can comprise a diagonal in a range from 4 mm to 10 mm, in particular from 4.24 mm to 8.5 mm.

[0189] The center of the square determined by the inner edge 46 can be located on the central axis 12.

[0190] The top section 20 and the circumferential step 40 can enclose a first angle 50. In an embodiment, the first angle 50 can be an obtuse angle (FIGS. 2B, 4A, 4B, 5A, 5B). In particular, the first angle 50 can be in a range between 115° and 125°.

[0191] In an embodiment, the circumferential step 40 encloses an acute angle a1 with the longitudinal axis 13 (see e.g. FIGS. 2B, 5B, 7). The circumferential step 40 can enclose the acute angle a1 with the central axis 12 (see e.g. FIGS. 2B, 5B, 7).

[0192] The circumferential step 40 can taper in a direction from the outer edge 42 to the inner edge 44 (FIGS. 2, 4A, 4B, 5A, 5B). The diameter d1 related to the inner edge 44 of the circumferential step 40 can be smaller than a diameter related to the outer edge 42 of the circumferential step 40. In an embodiment, the circumferential step 40 comprises a conical shape (FIGS. 2B, 5A, 5B, 8, 10). In another embodiment, the circumferential step 40 can have the shape of a frustum, in particular of a square frustum (FIGS. 4A, 4B).

[0193] In an embodiment, the first angle 50 can be an angle of 90° (FIGS. 3A-D; 4C, 4D, 6). This means that the top section 20 and the circumferential step 40 are arranged perpendicular to each other.

[0194] The inner edge 44 of the circumferential step borders the bottom section 30. The inner edge 44 marks a predefined lower portion of the volume 62 (indicated by a dashed grey line in FIGS. 2 to 6). Further, the lower portion of the volume 62 is confined by the bottom section 30.

[0195] The lower portion of the volume 62 can be between 10 μl and 120 μl, in particular between 15 μl and 50 μl, in particular 30 μl.

[0196] According to an embodiment, the lower portion of the volume 62 is at least 10% of the volume 60. According to an embodiment, the lower portion of the volume 62 is 20% of the volume 60.

[0197] The volume 60 can comprise the lower portion of the volume 62 and an upper portion of the volume 66. In an embodiment, the volume 60 consist of the lower portion of the volume 62 and the upper portion of the volume 66.

[0198] In an embodiment, the upper portion of the volume 66 comprises a topmost portion 67 of the volume 60.

[0199] In an embodiment, the bottom section 30 is a curved bottom section 30 (FIGS. 2, 3, 5-11). The curved bottom section 30 can comprise a lowest point 32. The lowest point 32 is characterized in that the distance from the lowest point 32 to the opening of the well 16 parallel to the central axis 12 is greater than the distance from any other point of the bottom section 30 to the opening 16 parallel to the central axis 12. In an embodiment, the lowest point 32 is located on the central axis 12.

[0200] The lower portion of the volume 62 can be characterized by a height of the lower portion 64 (FIG. 7, 9; also indicated by the dot-and-dashed line in FIG. 2B) wherein the height of the lower portion 64 is the distance from the lowest point 32 to the center of the circle determined by the inner edge 46. The height of the lower portion 64 can be in the range from 1 mm to 4 mm, in particular from 2 mm to 3 mm. In an embodiment, the height of the lower portion 64 can be 2.97 mm.

[0201] The bottom section 30 can comprise a concave curvature. In particular the bottom section 30 can be curved concavely. This means that the distance between the bottom section 30 and a virtual first plane 100 that comprises the lowest point 32 and that extends perpendicular to the central axis 12, increases with increasing distance from the lowest point 32.

[0202] In an embodiment, the bottom section 30 can be hemispherical (FIG. 3A). In another embodiment, the bottom section 30 can have the shape of a segment of a spheroid (FIG. 3B, C). In an embodiment, the bottom section 30 can comprise the shape of a segment of an oblate, i.e. flattened, semi-spheroid (FIG. 3B). In an alternative embodiment, the bottom section 30 can comprise the shape of a segment of a prolate, i.e. elongated, semi-spheroid (FIG. 3C). In another embodiment the bottom section 30 can have the shape of a spherical segment (FIG. 2, FIG. 3D).

[0203] In an alternative embodiment, the bottom section 30 can be a flat bottom section 30 (FIG. 4). A flat bottom section 30 can comprise a flat bottom 34 that extends in a plane, in particular in the first plane 100. In addition, the flat bottom section 30 can comprise a circumferential lateral portion 36 wherein the lateral portion 36 can comprise four rectangular sides 38. Each two adjacent rectangular sides 38 of the bottom section 30 can be arranged perpendicular to each other. The lateral portion 36 can be connected to the bottom 34. Further, the lateral portion 36 can connect the bottom 34 and the circumferential step 40. In an embodiment, the lateral portion 36 can extend perpendicular to the bottom 34.

[0204] A height of the lower portion of a well comprising a flat bottom section 30 can be in the range from 1 mm to 6 mm.

[0205] A top view of a well 10 (FIG. 2C) illustrates that a well 10 can have a circular cross section. In an embodiment, the diameter of the circle determined by the top section 20, in particular by the upper edge of the top section 22, is greater than the diameter d1 of the circle determined by the inner edge 44 of the circumferential step 40. The diameter of the circle that is determined by the upper edge of the top section 22 can be in the range from 6 mm to 7.5 mm, in particular between 6.5 mm and 7 mm. In an embodiment, the diameter of the circle that is determined by the upper edge of the top section 22 can be 6.94 mm.

[0206] In another embodiment, the well 10 can have a squared cross section (FIG. 4E). The diagonal of the square determined by the upper edge 22 can be in the range from 7 to 10 mm.

[0207] FIG. 5 and FIG. 6 as well as FIG. 11 show cross section views of a well 10 wherein a tip of a pipette 70 is placed into the well 10. In FIG. 5A and FIG. 5B, a well 10 comprising an obtuse first angle 50 is shown. In FIG. 6, a well 10 comprising a right first angle 50 is presented. The bottom section 30 can be a curved bottom section 30 that comprises the shape of a segment of a sphere (FIG. 5A and FIG. 5B) or a spheroid (FIG. 6).

[0208] A biological sample 3 can be placed into the volume 60 (FIG. 5A). In particular, the biological sample 3 can be located in the lower portion of the volume 62, in particular in the lower portion of the volume 62 close to the lowest point 32.

[0209] The lowest point 32 is located on the central axis 12. Hence, the biological sample 3 is located centrally. If the biological sample 3 is located centrally, it is visually easy to access. This is an advantage for a further analysis of the biological sample 3, in particular for the inspection of the biological sample by means of a microscope.

[0210] Further, the predefined lower portion of the volume 62 can be filled with a solution, e.g. a culture medium 5 (FIG. 5A). The circumferential step 40 and the lower portion 62 of the volume 60 can be configured for growing spheroids and medium exchange.

[0211] The circumferential step 40 can act as a stop for the tip of the pipette 70. This includes that the circumferential step 40 can control a depth the pipette 78, in particular the tip of the pipette 70, can be inserted into the respective well 10. The tip of the pipette 70 comprises a face side 76 that can comprise an edge of the pipette 74 that delimits an opening of the pipette 72. The tip of the pipette 70 can be placed in the well 10 such that the face side 76, in particular the edge of the pipette 74, can touch the circumferential step 40.

[0212] The opening of the pipette 72 and the circumferential step 40 can enclose a second angle 80. This means that the plane in that the face side 76 extends and the circumferential step 40 can enclose a second angle 80. The tip of the pipette 70 can be arranged such that the edge of the pipette 74 can be in contact with the circumferential step 40 and such that the second angle 80 is an acute angle (FIG. 5B, FIG. 6). In particular, the second angle 80 can be in the range from 3° to 60°, in particular from 5° to 45°.

[0213] In FIG. 5B the first angle 50 is an obtuse angle and the tip of the pipette 70 is arranged such in the well 10 that the opening of the pipette 72 extends perpendicular to the central axis 12 such that the second angle 80 is an acute angle.

[0214] In FIG. 6 the first angle 50 is a right angle and the tip of the pipette 70 is arranged such in the well 10 that the face side 76 extends with in inclination with respect to the central axis 12. This means that the tip of the pipette 70 is arranged such that the opening of the pipette 72 does not extend perpendicular to the central axis 12. The second angle 80 is an acute angle.

[0215] In FIG. 5A, the first angle 50 is an obtuse angle and the tip of the pipette 70 is arranged such in the well 10 that the face side 76 extends with in inclination with respect to the central axis 12. In particular the tip of the pipette 70 is arranged such in the well 10 that the face side 76 extends parallel to the circumferential step 40.

[0216] In FIG. 9 a cross section view of a well 10 is illustrated that comprises a circumferential step 40 and a further circumferential step 400. FIG. 10 shows a perspective view of a well 10 comprising the circumferential step 40 and the further circumferential step 400.

[0217] The circumferential step 40 connects the top section 20 and the bottom section 30. The top section 20 can comprise a lower top section 202 and an upper top section 204. The upper top section 204 can be connected with the lower top section 202 via the further circumferential step 400. The lower top section 202 can connect the circumferential step 40 and the circumferential step 400.

[0218] In an embodiment, the upper top section 204 has a cylindrical shape (FIGS. 9, 10). Along the central axis 12, the upper top section 204 can extend parallel to the central axis 12.

[0219] In an alternative embodiment, the upper top section has a conical shape, wherein the upper top section tapers towards the further circumferential step.

[0220] According to an embodiment, the lower top section 202 can have a conical shape. The lower top section 202 can taper in direction from the further circumferential step 400 towards the circumferential step 40. The lower top section 202 can enclose a tapering angle a2 with the central axis 12. The lower top section 202 can enclose a tapering angle a2 with the longitudinal axis 13. The tapering angle a2 can be an acute angle.

[0221] In the illustrated embodiment, the tapering angle a2 is smaller than the acute angle a1. The tapering angle a2 can be smaller than the further acute angle a3. In an embodiment, the tapering angle a2 is smaller than the acute angle a1 and the further acute angle a3.

[0222] In an embodiment, in direction towards the bottom section 30, the lower top section 202 declines steeper than the circumferential step 40. In direction towards the bottom section 30, the lower top section 202 can decline steeper than the further circumferential step 400.

[0223] In an alternative embodiment, the lower top section has a cylindrical shape.

[0224] The further circumferential step 400 can enclose a further acute angle a3 with the longitudinal axis 13 and/or with the central axis 12. In an embodiment according to the invention, the acute angle a1 and the further acute angle a3 are equal. The circumferential step 40 and the further circumferential step 400 can run in parallel.

[0225] In an embodiment, the further circumferential step 400 extends along the entire circumferential direction 110 and can form a further circumferential surface (FIG. 10).

[0226] The further circumferential step 400 can comprise a further outer edge 402 and a further inner edge 404. The further outer edge 402 can be adjacent to a lower edge of the upper top section 204.

[0227] The further inner edge 404 can have a circular shape with a further diameter d2. The diameter d2 can be greater than the diameter d1 (determined by the inner edge 44 of the circumferential step 40).

[0228] The upper top section 204 and the further circumferential step 400 can enclose a second angle 52. In an embodiment, the second angle 52 is an obtuse angle (FIG. 9).

[0229] In an embodiment, the further circumferential step 400 encloses an acute angle a3 with the longitudinal axis 13 (FIG. 9). The further circumferential step 400 can enclose the acute angle a3 with the central axis 12 (FIG. 9).

[0230] The further circumferential step 400 can taper in a direction from the further outer edge 402 to the further inner edge 404 (FIGS. 9, 10). The diameter d2 related to the further inner edge 404 of the further circumferential step 400 can be smaller than a diameter related to the further outer edge 402 of the further circumferential step 400. In an embodiment, the further circumferential step 400 comprises a conical shape (FIG. 10). With respect to the upper top section 204, the further circumferential step 400 can be directed inwards, i.e. towards the central axis 12. The upper portion of the volume 66 can comprise the topmost portion 67 of the volume 60.

[0231] The further inner edge 404 can mark a predefined extended lower portion 63 of the volume 60.

[0232] The predefined extended lower portion 63 of the volume 60 can comprise the lower portion 62 of the volume 60 and a further portion 620 of the volume 60. In particular, the predefined extended lower portion of the volume 63 can consist of the lower portion 62 of the volume 60 and the further portion 620 of the volume 60 (FIG. 10).

[0233] Further, the predefined extended lower portion 63 of the volume 60 can be confined by the bottom section 30 and the lower top section 202.

[0234] According to an embodiment, the predefined extended lower portion 63 of the volume 60 is at least 5% of the volume 60. According to an embodiment, the predefined extended lower portion 63 of the volume 60 is 10% of the volume 60.

[0235] The volume 60 can comprise the predefined extended lower portion 63 and an upper portion of the volume 66. In an embodiment, the volume 60 consist of the extended lower portion 63 of the volume 60 and the upper portion of the volume 66.

[0236] Along the central axis 12, the circumferential step 40 and the further circumferential step 400 can be arranged distant to each other. Along the central axis 12, a distance 624 can be between the circumferential step 40 and the further circumferential step 400. The further portion 620 of the volume 60 can be confined by the distance 624. The further portion 620 of the volume 60 can be confined by the tapering angle a2. The further portion 620 of the volume 60 can be confined by the diameter d1. The further portion 620 of the volume 60 can be confined by the diameter d2.

[0237] The predefined extended lower portion 63 of the volume 60 determined by the lower portion 62 of the volume 60, the distance 624, the tapering angle a2, the diameter d1 and or the diameter d2.

[0238] In an embodiment, the further circumferential step 400 is arranged in a precise chosen distance 624 from the circumferential step 40. The dimensions of the well can define different volumes in the respective well 10 separated by the steps 40, 400. In particular, the lower portion 62, the extended lower portion 63, the further portion 620 and the upper portion 66 can be defined. The ratios between the lower portion 62, the extended lower portion 63, the further portion 620 and the upper portion 66 of the volume 60 can be predefined. The circumferential step 40 and the further circumferential step 400 can be configured and arranged such that the predefined ration between the volumes, in particular the lower portion 62, the extended lower portion 63, the further portion 620 and the upper portion 66 of the volume 60 are met. This can advantageously provide mixing predefined volume of solution with a particular concentration with a further predefined volume of polymer at a predefined further concentration. After polymerization, solidified matrix can be overlaid with medium. The further circumferential step 400 can facilitate the medium exchange.

[0239] The predefined lower portion of the volume 62 can be filled with a solution, e.g. a culture medium 5 (FIG. 11A). The circumferential step 40 can act as a stop for the tip of the pipette 70.

[0240] The extended lower portion 63 of the volume 60 can be filled with a solution, e.g. a culture medium 5 (FIG. 11B). The further circumferential step 400 can act as a stop for the tip of the pipette 70.

[0241] According to an embodiment, the further circumferential step 400 can be arranged and configured for medium exchange of matrix-embedded cultures. The further circumferential step 400 can be configured to prevent the sucking-up of matrix during medium exchange.

[0242] The well 10 can be configured such that a fluid 5 can be removed from the volume 60 such that the fluid 5 remains in the predefined lower portion 62 of the volume 60 exclusively (see e.g. FIG. 11A). In particular, the tip 70 of the pipette 78 can be positioned on the circumferential step 40 and fluid 5 can be removed. The fluid 5 will remain in the predefined lower portion 62 of the volume 60.

[0243] The well 10 can be configured such that the fluid remains in the extended lower portion 63 of the volume 60 exclusively. In other words this means that the well can be configured such that fluid can be removed from the upper portion 66 of the volume 60. In particular, the tip 70 of the pipette 78 can be positioned on the further circumferential step 400 and fluid can be removed. The fluid will remain in the extended lower portion 63 of the volume 60.

[0244] The well 10 can be configured such that a polymerised matrix 6 remains in the extended lower portion 63 of the volume 60 exclusively.

[0245] In the following a further aspect of the present invention as well as embodiments thereof are stated as items, wherein the reference numerals in parentheses relate to the Figures. These items may also be formulated as claims of the present invention.

[0246] Item 1: A method for propagating biological samples (3) using a device (1) according to one of the preceding claims, comprising the steps of: providing a suspension of cells (3) in a culture medium (5) in a plurality of wells (10) of the device (1); incubating the cells (3); placing a tip of a pipette (70) on the respective circumferential step (40); and removing culture medium (5) by means of the pipette (78) such that culture medium (5) and cells (3) remain in a lower portion of the volume (62) of the respective well (10).

[0247] Item 2: The method according to item 1, wherein a portion of the culture medium (5) is replaced by fresh culture medium (5) at least once or several times.

[0248] Item 3: The method according to item 1 or 2, wherein the method comprises the step of: adding a compound to the culture medium in the respective well (10) such that the culture medium (5) polymerizes.

[0249] Item 4: The method according to one of the items 1 to 3, wherein the method further comprises the step of: adding a solution to the culture medium in a plurality of wells (10) wherein the solution is a control medium (5), or wherein the solution comprises one of: a stimulating compound for stimulating the biological sample (3), an inhibiting compound for inhibiting the biological sample (3), a combination of a stimulating and an inhibiting compound.

[0250] Item 5: The method according to one of the items 1 to 4, wherein the method further comprises the steps of: adding a fluorescent dye to the culture medium in a plurality of wells (10); putting the device (1) on the stage of a microscope (90), in particular a fluorescence microscope; and acquiring images of cells (3) in the respective well (10) by means of the microscope.

[0251] Item 6: The method according to one of the items 1 to 5, wherein the tip of the pipette (70) comprises an opening (72), wherein the tip of the pipette (70) is placed such that the opening of the pipette (72) and the circumferential step (40) enclose a second angle (80), wherein the second angle (80) is in the range from 0° to 75°, in particular in the range from 5° to 45°.

LIST OF REFERENCE NUMERALS

[0252] 1 device [0253] 3 biological sample or cells [0254] 5 medium [0255] 6 matrix [0256] 10 well [0257] 12 central axis [0258] 13 longitudinal axis [0259] 14 inner surface [0260] 16 opening of the well [0261] 20 top section [0262] 22 upper edge of the top section [0263] 24 lower edge of the top section [0264] 26 rectangular side of the top section [0265] 30 bottom section [0266] 32 lowest point [0267] 34 flat bottom [0268] 36 lateral portion [0269] 38 rectangular side of the bottom section [0270] 40 circumferential step [0271] 42 outer edge [0272] 44 inner edge [0273] 46 center of the circle determined by the inner edge [0274] 50 first angle [0275] 52 second angle [0276] 60 volume [0277] 62 lower portion of the volume [0278] 63 extended lower portion of the volume [0279] 64 height of the lower portion [0280] 66 upper portion of the volume [0281] 67 topmost portion of the volume [0282] 70 tip of a pipette [0283] 72 opening of a pipette [0284] 74 edge of a pipette [0285] 76 face side of a pipette [0286] 78 pipette [0287] 80 second angle [0288] 90 stage of a microscope [0289] 100 first plane [0290] 110 circumferential direction [0291] 202 lower top section [0292] 204 upper top section [0293] 400 further circumferential step [0294] 402 further outer edge [0295] 404 further inner edge [0296] 620 further portion of the volume [0297] 624 distance