COMPOSITE TISSUE-ENGINEERED INTERVERTEBRAL DISC WITH SELF-ASSEMBLED ANNULAR ALIGNMENT

• US 20150238657A1
• Filed: 05/12/2015
• Published: 08/27/2015
• Est. Priority Date: 05/05/2009
• Status: Active Grant

• Current Assignee: Cornell University
• Original Assignee: Cornell University
• Inventors: Bonassar, Lawrence J., Hartl, Roger, Bowles, Robert D., Gebhard, Harry H.
• Granted Patent: US 9,662,420 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2002/4435 Support means or repair of the natural disc wall, i.e. annulus, e.g. using plates, membranes or meshes
• CPC Class Codes: A61F 2002/444 for replacing the nucleus pulposus
• CPC Class Codes: A61F 2002/4445 Means for culturing intervertebral disc tissue
• CPC Class Codes: A61F 2002/445 Intervertebral disc tissue harvest sites
• CPC Class Codes: A61K 35/32 Bones; Osteocytes; Osteoblasts; Tendons; Tenocytes; Teeth; Odontoblasts; Cartilage; Chondrocytes; Synovial membrane
• CPC Class Codes: A61L 2430/38 for reconstruction of the spine, vertebrae or intervertebral discs
• CPC Class Codes: A61L 27/20 Polysaccharides
• CPC Class Codes: A61L 27/22 Polypeptides or derivatives thereof , e.g. degradation products
• CPC Class Codes: A61L 27/24 Collagen
• CPC Class Codes: A61L 27/3658 Intervertebral discs mechanical aspects and structures of intervertebral discs A61F2/442
• CPC Class Codes: A61L 27/3691 characterised by physical conditions of the treatment, e.g. applying a compressive force to the composition, pressure cycles, ultrasonic/sonication or microwave treatment, lyophilisation
• CPC Class Codes: A61L 27/3817 Cartilage-forming cells, e.g. pre-chondrocytes
• CPC Class Codes: A61L 27/3856 Intervertebral discs mechanical aspects and structures of intervertebral discs A61F2/442
• CPC Class Codes: A61L 27/3886 comprising two or more cell types
• CPC Class Codes: A61L 27/44 having a macromolecular matrix
• CPC Class Codes: A61L 27/52 Hydrogels or hydrocolloids
• CPC Class Codes: C08L 5/04 Alginic acid; Derivatives thereof

Abstract

The present invention relates to a tissue-engineered intervertebral disc (IVD) suitable for total disc replacement in a mammal and methods of fabrication. The IVD comprises a nucleus pulposus structure comprising a first population of living cells that secrete a hydrophilic protein and an annulus fibrosis structure surrounding and in contact with the nucleus pulposus structure, the annulus fibrosis structure comprising a second population of living cells and type I collagen. The collagen fibrils in the annulus fibrosis structure are circumferentially aligned around the nucleus pulposus region due to cell-mediated contraction in the annulus fibrosis structure. Also disclosed are methods of fabricating tissue-engineered intervertebral discs.

Claims

1. A method of fabricating a tissue-engineered intervertebral disc (IVD) suitable for total disc replacement in a mammal, said method comprising:

providing a first gel comprising a first population of living cells that secrete a hydrophilic protein;

forming the first gel into a predetermined shape and size;

providing a second gel comprising a second population of living cells and type I collagen;

contacting the formed first gel with the second gel at a region that extends circumferentially around the first gel; and

storing the first and second gels under conditions effective for the collagen in the second gel to align circumferentially around the first gel by self-assembly of collagen due to cell-mediated gel contraction in the second gel, wherein the first gel forms a nucleus pulposus structure and the second gel forms an annulus fibrosus structure surrounding and in contact with the nucleus pulposus structure, thereby fabricating a tissue-engineered IVD suitable for total disc replacement in a mammal.

2. The method according to claim 1, wherein the first gel is an alginate gel comprising about 0.5% to about 10% (w/v) alginate.

3. The method according to claim 1, wherein the first population of cells is present in the first gel at a concentration of about 1×

10⁶ to about 50×

10⁶ cells/ml.

4. The method according to claim 1, wherein the first population of cells secrete a proteoglycan.

5. The method according to claim 1, wherein the first populations of cells comprises nucleus pulposus cells.

6. The method according to claim 1, wherein the first gel further comprises type II collagen.

7. The method according to claim 1, wherein the nucleus pulposus has an isotropic structure.

8. The method according to claim 1, wherein the second population of cells comprises annulus fibrosus cells.

9. The method according to claim 1, wherein the second population of cells are present in the second gel at a concentration of about 0.1-5.0×

10⁷ cells/ml.

10. The method according to claim 1, wherein the second gel comprises type I collagen at a concentration of about 1 mg/ml to about 30 mg/ml.

11. The method according to claim 1, wherein the annulus fibrosus has an anisotropic structure.

12. The method according to claim 1, wherein the IVD is permeable to allow nutrient transport to developing tissue.

13. The method according to claim 1 further comprising:

cross-linking the first gel.

14. The method according to claim 1, the second gel is formed at a temperature of about 25°

C. to about 37°

C.

15. The method according to claim 1, wherein said storing is carried out for about 3 to about 28 days.

16. The method according to claim 1, wherein said forming is carried out by injection molding or by cutting samples from a sheet.

17. A method of fabricating a tissue-engineered intervertebral disc (IVD) suitable for total disc replacement in a mammal, said method comprising:

providing a first gel comprising a first population of living cells that secrete a hydrophilic protein;

providing a second gel comprising a second population of living cells and type I collagen;

forming the second gel around a central mandrel structure;

storing the second gel under conditions effective for the collagen in the second gel to align circumferentially around the central mandrel by self-assembly of collagen due to cell-mediated gel contraction in the second gel;

replacing the central mandrel with the first gel, wherein the first gel forms a nucleus pulposus structure and the second gel forms an annulus fibrosus structure surrounding and in contact with the nucleus pulposus structure, thereby fabricating a tissue-engineered IVD suitable for total disc replacement in a mammal.

18. The method according to claim 17, further comprising:

forming the first gel into a predetermined shape and size.

19. The method according to claim 17, wherein the mandrel comprises plastic or metal.

20. The method according to claim 17, wherein said forming is carried out by injection molding or by cutting samples from a sheet.