Treatment of collagenous tissue

Claim 2

A process for the treatment of collagenous tissue to adapt it for use in a prosthetic implant and to promote the growth of endothelial cells thereon after implantation, characterized in that it comprises the steps of: (a) contacting said tissue with at least one surfactant for a time sufficient to substantially completely remove deleterious material and open up the fibrous structure of the collagenous tissue; (b) washing the resulting fibrous matrix to remove substantially all surfactant; (c) fixing the washed tissue with glutaraldehyde; (d) treating the glutaraldehyde-fixed tissue with a calcification-inhibiting agent, an agent which inhibits infiltration and attack by phagocytic cells upon implantation and/or an agent which inhibits infection; and, (e) treating the resulting agent/matrix tissue with a reducing agent to stabilize the bonding of the glutaraldehyde of step (c) and the agent of step (d) to the tissue.

Claim 3

A process according to claim 1, characterized in that the surfactant is a mixture of 1% by weight sodium dodecyl sulfate and 1% by weight octylphenoxy polyethoxy ethanol and/or 1% by weight polyoxyethylene (20) sorbitan monooleate and the collagenous tissue is contacted with said surfactant solution for about three hours at room temperature.

Claim 4

A process according to claim 1, or claim 2 characterized in that the collagenous tissue is prewashed with saline solution to remove excess blood and plasma proteins, prior to treatment with surfactant.

Claim 5

A process according to any one of the preceding claims, characterized in that the fibrous matrix of tissue resulting from the surfactant treatment is soaked in 0.5% by weight glutaraldehyde solution in the presence of 0.1 M acetate buffer for a period of about three and a half hours, after which excess glutaraldehyde is washed from the tissue.

Claim 6

A process according to claim 4, characterized in that the glutaraldehyde-fixed tissue is treated with an agent which inhibits calcification for a time sufficient to bond substantially all the free reactive groups of the bonded glutaraldehyde molecules to the reactive amino groups of the calcification-inhibiting agent and said calcification-inhibiting agent is an amino diphosphonate selected from compounds of the formula:- and

Claim 7

A process according to claim 4, characterized in that the glutaraldehyde-fixed tissue is treated with (i) a sporin antibiotic having a free reactive amino group or methotrexate or (ii) cephalosporin C.

Claim 8

A process according to claim 5 or 6, characterized in that tissue is further treated with sodium borohydride to stabilize the treated tissue.

Claim 9

A process for the treatment of collagenous tissue to adapt it for use in a prosthetic implant and to promote the growth of endothelial cells thereon after implantation characterized in that it comprises the sequential combination of the following steps: (1) contacting the tissue with at least one surfactant for a time sufficient to substantially completely remove deleterious material and open up the fibrous structure to form a matrix substantially free from lipids, red blood cells, plasma protein, organelles, and dead cell fragments; (2) rinsing the cleaned fibrous matrix resulting from step 1 with distilled water or saline solution to remove substantially all surfactant; (3) soaking said matrix in aqueous glutaraldehyde solution for a time sufficient to bond the glutaraldehyde molecules to substantially all the reactive amino groups present in the protein molecules of the tissue; (4) washing the glutaraldehyde-fixed tissue to remove excess glutaraldehyde; (5) treating the fixed tissue with an aqueous solution of amino diphosphonate containing reactive amino groups for a time sufficient to bond substantially all the free reactive groups of the bonded glutaraldehyde molecules to the reactive amino groups of the amino diphosphonate; (6) washing to remove excess amino diphosphonate; and, (7) treating the diphosphonate-bonded tissue matrix with sodium borohydride to stabilize the bonding of the amino diphosphonate and glutaraldehyde to the protein molecules of the tissue; and (8) washing to remove excess sodium borohydride and, if desired, storing the resulting treated tissue in aqueous formaldehyde for subsequent use.

Claim 10

A process for the treatment of collagenous tissue to adapt it for use in a prosthetic implant and to promote the growth of endothelial cells thereon after implantation characterized in that it comprises the sequential combination of the following steps: (1) contacting the tissue with at least one surfactant for a time sufficient to substantially completely remove deleterious material and open up the fibrous structure to form a matrix substantially free from lipids, red blood cells, plasma protein, organelles, and dead cell fragments; (2) rinsing the cleaned fibrous matrix resulting from step 1 with distilled water or saline solution to remove substantially all surfactant; (3) soaking said matrix in aqueous glutaraldehyde solution for a time sufficient to bond the glutaraldehyde molecules to substantially all the reactive amino groups present in the protein molecules of the tissue; (4) washing the glutaraldehyde-fixed tissue to remove excess glutaraldehyde; (5) treating the fixed tissue with an aqueous solution of amino diphosphonate containing reactive amino groups for a time sufficient to bond substantially all the free reactive groups of the bonded glutaraldehyde molecules to the reactive amino groups of the amino diphosphonate; (6) washing to remove excess amino diphosphonate; and, (7) treating the diphosphonate-bonded tissue matrix with sodium borohydride to stabilize the bonding of the amino diphosphonate and glutaraldehyde to the protein molecules of the tissue; and (8) washing to remove excess sodium borohydride and, if desired, storing the resulting treated tissue in aqueous formaldehyde for subsequent use.

Claim 11

A process according to any one of the preceding claims, characterized in that the collogenous tissue is bovine or porcine pericardial tissue; dura mater; fascia lata; valve tissue or vascular graft tissue.

Claim 12

A fixed and stabilized collagenous tissue adapted for use in a prosthetic implant produced by a process according to any one of the preceding claims.