Acellular vascular products
A product comprising a natural acellular xenogenic vascular tissue matrix having at least an 80% reduction in DNA content as compared to an untreated control vascular tissue matrix and being antigenically inert by being substantially free of epitopes capable of reacting with pre-formed human antibodies and also without having the ability to substantially activate complement. The invention also includes methods of preparing such products and uses of the products especially in bypass surgery.
1. A method of preparing a natural acellular vascular tissue, the method comprising obtaining a suitable donor blood vessel and subjecting it to the following methodological steps, wherein steps (iii) through (vi) are in the following order:
(i) an incubation with 200 mM ethylenediaminetetraacetic acid (EDTA);
(ii) a disinfection wash;
(iii) at least two cycles of an incubation with a hypotonic buffer and an anionic detergent;
(iv) a nuclease treatment;
(v) a hypertonic wash; and
(vi) a terminal sterilization process.
2. The method according to claim 1 , wherein steps (i) and (ii) are performed in a reverse order.
3. The method according to claim 1 , wherein the incubation with EDTA is performed in a hypertonic buffer solution.
4. The method according to claim 1 , wherein the disinfection wash comprises a wash in a hypotonic buffer solution comprising vancomycin, gentamicin and polymyxin.
5. The method according to claim 1 , wherein the anionic detergent is sodium dodecyl sulfate (SDS).
6. The method according to claim 1 , wherein the nuclease treatment of step (iv) comprises an incubation in a nuclease solution comprising a hypotonic buffer including a DNAase and a RNAase.
7. The method according to claim 1 , wherein the hypertonic incubation of step (v) comprises an incubation in a hypertonic buffer comprising TRIS and NaCl.
8. The method according to claim 1 , wherein the terminal sterilization process provides viral clearance and a reduction of bioburden.
9. The method according to claim 1 , wherein the terminal sterilization process is one or more processes selected from the group comprising incorporation or coating of an antimicrobial agent, treatment with a cross-linking agent, treatment with a sterilizing agent, irradiation and treatment with supercritical CO 2 .
10. The method according to claim 1 , further including a step of coating an internal and/or external surface of the natural acellular vascular tissue with a material selected from the group comprising anticoagulants, synthetic pentasaceharide inhibitors, direct thrombin inhibitors, Vitamin K antagonists, Factor Xa inhibitors, silver, collagen IV, elastin, glycoproteins, glycosaminoglycans, synthetic or natural peptides and mixtures thereof.
11. The method according to claim 1 , further including a step of seeding the natural acellular vascular tissue with a single or mixed population of cells elected according to a transplant site and selected from the group comprising epithelial cells, smooth muscle cells, pluripotent and multipotent stem cells and fibroblasts.
12. The method according to claim 1 , wherein porcine donor blood vessel is up to 30 cm in length and bovine donor blood vessel is up to 80 cm in length.