Abstract
A method for replicating a structure of a biological tissue provides a plastically deformable film that is subjected to a pressure in order to press it into a mold. The mold comprises formations for pit-like depressions, recesses and notches. The recesses each border on at least one of the pit-like depressions and are opened up. The notches form at least one film hinge in the film. The shaped film is folded into a stack having at least two layers of film, the film hinge forming the folding edge for the folding process. The pit-like depressions are closed along their direction of extension by a neighboring layer of the stack and form each time a capillary. At least two of the opened recesses are arranged one on top of another and form a canal arranged perpendicular to the plane of extension of the film.
Claims
1. A method for producing a molding for replicating a structure of a biological tissue, comprising the following steps: providing of a plastically deformable film; subjecting the film to a pressure in order to press it into a mold, the mold comprising formations for pit-like depressions, for recesses and for notches, wherein the pit-like depressions are formed in the plane of extension of the film, while the recesses each border on at least one of the pit-like depressions and each have a bottom, at which they are opened, so that each time an opening is produced, and the notches form at least one film hinge in the film; and folding of the formed film to produce a stack comprising at least two layers of the film, the film hinge forming the folding edge for the folding, whereby the pit-like depressions are closed along their direction of extension by a neighboring layer of the stack and form a capillary, and whereby at least two of the opened recesses are arranged one on top of the other and form a canal arranged perpendicular to the plane of extension of the film.
2. The method according to claim 1, wherein the film is heated prior to the pressing into the mold to a temperature between 140° C. and 180° C.
3. The method according to claim 1, wherein each time one of the pit-like depressions of one of the layers is arranged congruently across one of the pit-like depressions of the layer located above it, so that the capillary formed between them is symmetrically formed between the two layers.
4. The method according to claim 1, wherein the recesses are opened up at their bottoms in that they are molded far enough into the film that the film rips at the bottoms of the recesses.
5. The method according to claim 1, wherein the recesses are opened up at their bottoms by dissolving the bottoms of the recesses in an etching bath.
6. The method according to claim 1, wherein prior to the folding of the shaped film the following step is carried out: colonizing of biological cells at least on one of the two sides of the shaped film.
7. The method according to claim 1, wherein prior to the molding of the film the following step is carried out: applying of a layer of a cell attractant (23) or a cell repellent to the formations of the mold.
8. The method according to claim 1, wherein the film is subjected to the pressure indirectly through a sacrifice film.
9. The method according to claim 1, wherein the provided film has pores with a diameter between 500 nm and 2 μm.
10. A molding for replicating a structure of a biological tissue, comprising a film, which is configured in the form of a stack of at least two layers; wherein the film has pit-like depressions, which are closed along their direction of extension by a neighboring layer of the stack, so that capillaries are formed; wherein the film has recesses which are open at their bottoms, while several of the recesses are arranged one on top of another within the stack, so that a canal arranged perpendicular to the plane of extension of the film is formed by the open recesses arranged one on top of another, which borders at least on one of the capillaries; and wherein the layers are connected in pairs at one edge of the stack by a film hinge which is formed in the film.
11. The method according to claim 2 wherein each time one of the pit-like depressions of one of the layers is arranged congruently across one of the pit-like depressions of the layer located above it, so that the capillary formed between them is symmetrically formed between the two layers.
12. The method according to claim 2, wherein the recesses are opened up at their bottoms in that they are molded far enough into the film that the film rips at the bottoms of the recesses.
13. The method according to claim 2, wherein the recesses are opened up at their bottoms by dissolving the bottoms of the recesses in an etching bath.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Further benefits, details, and modifications of the invention will emerge from the following description of preferred embodiments of the invention, making reference to the drawing. There are shown:
[0045] FIG. 1 is a method for pressing a film into a mold according to one preferred embodiment of the method according to the invention;
[0046] FIG. 2 is the film shown in FIG. 1 in a modified embodiment after the molding process;
[0047] FIG. 3 is the film shown in FIG. 2 prior to the folding process according to a first preferred embodiment;
[0048] Fig. : is the film shown in FIG. 3 in the folded state;
[0049] FIG. 5 is the film shown in FIG. 2 prior to a folding process according to a second preferred embodiment;
[0050] FIG. 6 is the film shown in FIG. 5 in the folded state;
[0051] FIG. 7 is the film shown in FIG. 4 with biological cells introduced;
[0052] FIG. 8 is the film shown in FIG. 1 according to another preferred embodiment;
[0053] FIG. 9 is the placement of a cell attractant on the mold shown in FIG. 8;
[0054] FIG. 10 is a liver structure being replicated by the method according to the invention;
[0055] FIG. 11 is a sinusoid of a hepatic lobule being replicated by the method according to the invention;
[0056] FIG. 12 is the replication shown in FIG. 11 in seven-fold iteration;
[0057] FIG. 13 is a punch used for the replication shown in FIG. 12;
[0058] FIG. 14 is another sinusoid of a hepatic lobule replicated by the method according to the invention;
[0059] FIG. 15 is the replication shown in FIG. 11 in seven-fold iteration; and
[0060] FIG. 16 is a punch used for the replication shown in FIG. 15.
DETAILED DESCRIPTION
[0061] FIG. 1 shows one step of a preferred embodiment of the method according to the invention. During this step, a thermoplastic film 01 is pressed with the aid of a forming gas (not shown) into a mold 02 fashioned as a negative mold. The mold 02 has a formation 03 for a pit-like depression, so that a pit-like depression 04 is produced in the film 01. Furthermore, the mold has a deeper formation 06 for a recess, so that a recess 07 is produced in the film 01. The film 01 is pressed far enough into the recess 06 until the film 01 rips open in the area of a bottom 08 of the recess 07. Furthermore, the mold has formations (not shown) for notches, so that several notches 09 (shown in FIG. 2) are produced in the film 01.
[0062] FIG. 2 shows the film m01 shown in FIG. 1 in a modified embodiment after the molding process in a partial perspective view. The modification consists in the arrangement of the pit-like depressions 04, the recesses 07 and the notches 09.
[0063] FIG. 3 shows the film 01 shown in FIG. 2 prior to a folding process according to a first preferred embodiment. The folding process being carried out is symbolized by an arrow 11. The folding is done at the central notch 09, which functions here as a film hinge.
[0064] FIG. 4 shows the film 01 shown in FIG. 3 in the folded state. One half of the film 01 has been pivoted by 180° about the central notch 09, so that this meets the other half of the film 01 in congruent manner. In this way, the pit-like depressions 04 are brought together at their long sides, so that they form a capillary 12 pairwise each time. At the same time, the open recesses 09 have been placed one on top of another, so that they form a canal 13 pairwise each time, which extends perpendicular to the capillaries 12 and to the film 01. Two of the notches 09 remain unused in this embodiment. The folded film 01 forms the molding being produced according to the invention.
[0065] FIG. 5 shows the film 01 shown in FIG. 2 prior to a folding process according to a second preferred embodiment. The folding process being done involves a first step, which is symbolized by two arrows 14, and a second step, which is symbolized by an arrow 16. The folding is done in the first step at the two outer notches 09, each of which acts as a film hinge, and in the second step it is done at the central notch 09, which then acts likewise as a film hinge.
[0066] FIG. 6 shows the film 01 shown in FIG. 5 in the folded state. The two outer quarters of the film 01 have been pivoted in a first step 14 (shown in FIG. 5) by 180° about the two outer notches 09 and 180° inwardly, so that these meet the two inner quarters of the film 01 in congruent manner. In this way, the pit-like depressions 04 are joined in pairs along their long sides, so that they each form one of the capillaries 12. At the same time, the open recesses 09 have been placed one on top of another in pairs, so that they form part of the canal 13, which extends perpendicular to the capillaries 12. In the second step 16 (shown in FIG. 5), the two already folded halves of the film 01 have been pivoted by 180° about the inner notches 09, so that these meet each other in congruent manner. In this way, the already formed parts of the canal 13 are placed one on top of another, so that the canal 13 is completely formed.
[0067] None of the notches 09 remained unused in this embodiment. The folded film 01 forms the molding being produced according to the invention.
[0068] FIG. 7 shows the folded film 01 shown in FIG. 4, i.e., the molding being produced according to the invention in a detail view, where in particular one of the capillaries 12 is shown in cross section. This embodiment of the molding according to the invention serves to replicate liver tissue, for which biological cells, namely hepatocytes 21 and endothelial cells 22, have been introduced into the molding. The endothelial cells 22 have been introduced into the capillary 12, while the hepatocytes 21 were colonized in the areas outside of the capillary 12. The colonization of the biological cells 21, 22 is preferably controlled by a cell attractant 23 (shown in FIG. 9).
[0069] FIG. 8 shows the mold 02 shown in FIG. 1 in a modified preferred embodiment, which is suitable as a positive mold especially for the producing of the molding to replicate liver tissue. For this, the mold 02 comprises hexagonally arranged raised formations 03 for the pit-like depressions, at whose center the raised formation 06 for the recess is arranged. Thus, the mold 02 configured as a positive mold constitutes a punch.
[0070] FIG. 9 shows the placement of the cell attractant 23 on the mold 02 shown in FIG. 8. For this, the cell attractant 23 is at first arranged on a backing 24, such as one of PDMS or glass. Next, the mold 02 with the raised formations 03, 06 is pressed with a slight pressure against the cell attractant 23, whereby the latter comes to adhere to the raised formations 03, 06. During the subsequent pressing of the film 01 into the mold 02 (shown in FIG. 1), which in the case of the mold 02 shown here and configured as a positive mold can be done by pressing the mold 02 against the film 01, once again the cell attractant 23 is placed in the pit-like depressions 04 and in the recesses 07 of the film 01 (shown in FIG. 1). The areas outside of the pit-like depressions 04 and the recesses 07 are not provided with cell attractant 23 in this process.
[0071] Instead of the mold 02, as an alternative the molded film 01 can also be pressed directly onto the cell attractant 23 on the backing 24. Instead of the cell attractant 23, a cell repellant can also be applied in the described manner to the mold 02 or the molded film 01.
[0072] FIG. 10 shows a liver structure being replicated according to the method of the invention. The structure comprises four hexagonally shaped hepatic lobules 26, at whose centers there is situated a Vena centralis 27 each time. A sectional view A-A represents hepatocytes 28 in particular. At the outer corners of the hepatic lobules 26 is found a Glisson trias 29 with an Arteria interlobularis 31, a Vena interlobularis 32 and a Doctuli interlobularis 33, which are shown in particular in a detail representation 34 of one of the Glisson trias 29.
[0073] FIG. 11 shows a sinusoid of one of the hepatic lobules 26 (shown in FIG. 10) replicated by the method according to the invention with the canal 13 for replicating the Vena centralis 27 (shown in FIG. 10).
[0074] FIG. 12 shows the replication shown in FIG. 11 in a seven-fold iteration in hexagonal arrangement, so that a larger portion of the liver tissue is replicated.
[0075] FIG. 13 shows the mold 02 used for the replication represented in FIG. 12, being designed as a punch. The mold 02 comprises the formations 03 for the pit-like depressions and the formations 06 for the recesses.
[0076] FIG. 14 shows another sinusoid of one of the hepatic lobules 26 (shown in FIG. 10) replicated by the method according to the invention with the several canals 13 for replicating the Glisson trias 29 (shown in FIG. 10).
[0077] FIG. 15 shows the replication shown in FIG. 14 in a seven-fold iteration in hexagonal arrangement, so that a larger portion of the liver tissue is replicated.
[0078] FIG. 16 shows the mold 02 used for the replication represented in FIG. 15, being designed as a punch. The mold 02 comprises the formations 03 for the pit-like depressions and the formations 06 for the recesses.
LIST OF REFERENCE NUMBERS
[0079] 01 Film
[0080] 02 Mold
[0081] 03 Formation for pit-like depression
[0082] 04 Pit-like depression
[0083] 05—
[0084] 06 Formation for recess
[0085] 07 Recess
[0086] 08 Bottom
[0087] 09 Notch
[0088] 10—
[0089] 11 Arrow
[0090] 12 Capillary
[0091] 13 Canal
[0092] 14 Arrows
[0093] 15—
[0094] 16 Arrow
[0095] 21 Hepatocytes
[0096] 22 Endothelial cells
[0097] 23 Cell attractant
[0098] 24 Backing
[0099] 25—
[0100] 26 Hepatic lobule
[0101] 27 Vena centralis
[0102] 28 Hepatocytes
[0103] 29 Glisson trias
[0104] 30—
[0105] 31 Arteria interlobularis
[0106] 32 Vena interlobularis
[0107] 33 Doctuli interlobularis
[0108] 34 Detail
