Decellularization reduces immunogenicity of sheep pulmonary artery vascular patches

Objectives: Allograft vascular tissue is important in the repair of complex structural lesions of the heart and great vessels, but induces a deleterious immune response that might shorten the effective lifespan of the tissue and sensitize the recipient. We hypothesized that decellularizing allograft vascular tissue reduces the host allogeneic immune response. Methods: Allograft ovine pulmonary artery patches were decellularized, cryopreserved, and implanted into the descending thoracic aorta. The humoral immune response was measured by means of flow cytometry at regular intervals over 6 months. Graft histology, immunohistochemistry, and calcification were assessed after 4 weeks or 6 months. Results: Leukocyte infiltration was reduced in decellularized grafts. A trend toward decreased in-patch calcification was observed in the decellularized group ( 7.6 +/- 4.3 vs 40.0 +/- 15.9 mg of calcium/mg of protein, P = .107). Decellularization reduced IgG antibody binding to donor splenocytes ( 9.8% +/- 3.3% vs 57.8% +/- 13.7% [control value], P = .010), as assessed by means of flow cytometry. All cytokines examined were detected in nondecellularized tissues after 4 weeks but not at 6 months, indicating complete graft rejection at that time. In contrast, transforming growth factor beta 1 and interleukin 10 were the only prominent cytokines in all decellularized grafts at 4 weeks after transplantation. Conclusions: Decellularization of allograft vascular tissue minimized the recipient cellular immune response and eliminated the production of anti-donor antibodies in recipients. (J Thorac Cardiovasc Surg 2011;141:1056-62)