Method for preparing porous collagen matrices

1. A process for preparing a porous collagen matrix from a connective tissue, comprising: providing a connective tissue having a surface ranging from 20 mm 2 to 2 m 2 ; swelling said connective tissue with an acidic solution by at least 50% in volume to form a swollen connective tissue comprising soaking said connective tissue in said acidic solution, and concurrently squirting a liquid into said connective tissue, or concurrently treating the connective tissue with ultrasound, wherein the acidic solution has a pH of 2-6 and is substantially free of salt; and washing said swollen connective tissue to remove non-collagenous material, thereby forming a porous collagen matrix

2. The process of claim 1 , wherein the connective tissue has a size of 25 mm 2 to 900 cm 2 .

3. The process of claim 1 , wherein the acidic solution contains an acid selected from the group consisting of formic acid, carboxylic acids, oxalic acid, acetic acid, citric acid, lactic acid, malic acid, boric acid, phosphoric acid, and a mixture thereof.

4. The process of claim 3 , wherein the acidic solution has a pH value of 2 to 4.

5. The process of claim 4 , wherein the acidic solution contains acetic acid at a concentration of 0.1-6 M.

6. The process of claim 1 , wherein in the swelling step, the connective tissue is swollen by 100%-500% in volume.

7. The process of claim 1 , wherein said washing step comprises soaking said swollen connective tissue in a wash solution containing a detergent, a proteolytic enzyme, or a mixture thereof.

8. The process of claim 7 , wherein said soaking step further comprises concurrently squirting a liquid into said swollen connective tissue.

9. The process of claim 7 , wherein said soaking step further comprises concurrently treating the swollen connective tissue with ultrasound.

10. The process of claim 1 , further comprising, prior to the swelling step, treating the connective tissue with a solvent containing an organic solvent and optionally water, wherein the organic solvent is selected from the group consisting of alcohol, ketone, acetone, acetonitrile, chloroform, N,N-dimethylformamide, dimethyl sulfoxide, and a mixture thereof.

11. The process of claim 10 , wherein the solvent contains both the organic solvent and water at a volume ratio of 1:4 to 9:1.

12. The process of claim 1 , wherein the connective tissue contains a plurality of hairs or hair roots, and the process further comprises, prior to the swelling step, treating the connective tissue with a proteolytic enzyme to loosen the hairs or hair roots.

13. The process of claim 12 , wherein the proteolytic enzyme is selected from the group consisting of dispase, trypsin, papain, pepsin, chymotrypsin, bromelain, ficin, and a mixture thereof.

14. The process of claim 1 , wherein the connective tissue is derived from dermis or tendon.

15. The process of claim 1 , further comprising, after the washing step, drying the porous collagen matrix.

16. The process of claim 1 , wherein the washing step is performed by treating the swollen connective tissue with a first wash solution containing a detergent, a chelating agent, or a mixture thereof, and with a second wash solution containing a proteolytic enzyme.