Decellularization reduces immunogenicity of sheep pulmonary artery vascular patches

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.

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.

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 β1 and interleukin 10 were the only prominent cytokines in all decellularized grafts at 4 weeks after transplantation.

Decellularization of allograft vascular tissue minimized the recipient cellular immune response and eliminated the production of anti-donor antibodies in recipients.