Preparation of tissue equivalents by contraction of a collagen gel layered on a collagen gel

• US 5,536,656 A
• Filed: 02/09/1994
• Issued: 07/16/1996
• Est. Priority Date: 09/15/1989
• Status: Expired due to Term

• Current Assignee: Organogenesis Inc. (Organogenesis Holdings, Inc.)
• Original Assignee: Organogenesis Inc. (Organogenesis Holdings, Inc.)
• Inventors: Kemp, Paul, Kagan, David T., Mason, Valerie, Cavallaro, John, Bell, Eugene
• Primary Examiner(s): Naff, David M.
• Application Number:
  US08/193,809
• Time in Patent Office: 888 Days
• Field of Search: 435/177, 435/180, 435/240.2, 435/240.23, 435/240.243, 435/285, 623/1, 424/422, 424/423
• US Class Current: 435/371
• CPC Class Codes: A61L 27/60 Materials for use in artificial skin
• CPC Class Codes: C12M 25/04 in combination with well or multiwell plates, i.e. culture inserts
• CPC Class Codes: C12N 2502/094 keratinocytes
• CPC Class Codes: C12N 2502/1323 Adult fibroblasts
• CPC Class Codes: C12N 2533/54 Collagen; Gelatin
• CPC Class Codes: C12N 5/0698 Skin equivalents

Abstract

Tissue equivalents are produced by applying a solution of collagen without cells to a permeable membrane, gelling to produce a collagen gel on the membrane, applying a mixture of collagen and a contractile agent to the collagen gel, gelling the mixture and allowing the resultant gel to undergo radial contraction which is controlled by the collagen gel on the membrane. A suitable contractile agent is fibroblast cells. A skin tissue equivalent is produced by disposing human epidermal cells on the contracted collagen gel and allowing epidermalization to occur. A nutrient medium can be supplied to the cells. An absorbent member may be disposed adjacent the permeable membrane opposite the collagen gel on the membrane. The permeable membrane can be the bottom of an inner well disposed in an outer well for containing a nutrient medium in contact with the membrane. The nutrient medium may be contained in the outer well in an agarose gel in contact with the membrane.

Claims

1. A method of producing a tissue equivalent in an apparatus, the apparatus comprising at least one container for the tissue equivalent, the container comprising:

(i) an inner well comprising one or more walls;

(ii) a permeable membrane defining the bottom of the inner well; and

(iii) an outer well within which the inner well is disposed, the outer well being arranged for containing a nutrient medium in contact with the permeable membrane,

wherein, the method comprises;

(a) applying a solution comprising collagen in the absence of cells to the permeable membrane of the apparatus;

(b) maintaining the solution of step (a) under conditions which permit the collagen solution to gel and to form a first collagen gel on the permeable membrane;

(c) applying a mixture comprising collagen and at least one contractile agent to the first collagen gel; and

(d) forming a tissue equivalent by maintaining the mixture of step (c) under conditions which permit (i) the mixture to gel and form a second collagen gel on the first collagen gel, and (ii) radial contraction of the second gel by the contractile agent to form a contracted collagen lattice on the first collagen gel, wherein the radial contraction is controlled by the first collagen gel.

2. The method of claim 1, wherein the contractile agent comprises fibroblast cells and the outer well contains a nutrient medium.

3. The method of claim 2, wherein the mixture of step (c) contains fibroblast cells at a concentration of about 1.25×

5×

10⁴ cells/ml and collagen at about 0.5 to 2.0 mg/ml.

4. The method of claim 1, wherein the solution of step (a) comprises collagen at a concentration of about 0.5 to 2.0 mg/ml.

5. The method of claim 4, wherein the mixture of step (c) and the solution of step (a) are used at a ratio of about 3:

1 to 1;

3, volume;

volume.

6. The method of claim 1, wherein an absorbent member is disposed adjacent the permeable member opposite the first collagen gel.

7. The method of claim 6, wherein the absorbent member comprises a fibrous pad or a gel.

8. The method of claim 7, wherein the fibrous pad is cotton.

9. The method of claim 1, wherein a gel comprising agarose is disposed in the outer well of the apparatus and in contact with the permeable member.

10. The method according to claim 1, wherein the apparatus further comprises a cover means, the means being removably sealable to the inner or outer well.

11. The method according to claim 1, wherein the inner well is provided with at least one opening, the opening communicating with the region defined by the outer container.

12. The method according to claim 1, wherein the inner container comprises butadiene-styrene polymer.

13. The method according to claim 1, wherein the outer well comprises a nutrient medium and further comprising step (e) of disposing human epidermal cells on the tissue equivalent formed in step (d) and maintaining the tissue equivalent and epidermal cells under conditions which permit epidermalization to form a skin tissue equivalent,

14. The method of producing a skin tissue equivalent according to claim 13, wherein the outer well comprises a nutrient medium and further comprising step (f) of providing the outer well with at least one cotton pad to provide contact between the cotton pad and the permeable member, and maintaining the epidermalized tissue equivalent of step e under conditions which permit cornification.

15. The method according to claim 1, wherein the first collagen gel is about 1 to 5 mm thick.

16. The method according to claim 15, wherein the first collagen gel is about 2 to 3 mm thick.

17. The method of claim 1, wherein the permeable membrane is a hydrophilic membrane.

18. The method of claim 17, wherein the hydrophilic membrane has a pore diameter from about 1 to about 10 μ

.

19. The method of claim 18, wherein the hydrophilic membrane is a polycarbonate membrane having a pore size of about 3 to 10 μ

.

20. A tissue equivalent produced by the method of claim 1.

21. A skin tissue equivalent produced by the method of claim 13.

22. A skin tissue equivalent produced by the method of claim 14.