Background and aim of the study: The remodeling process of the decellularized allograft after implantation remains unclear. Herein, the hemodynamics, recellularization and immunological response of the decellularized allograft were evaluated at four weeks after implantation in a mini-pig model, and compared with a cryopreserved allograft.
Methods: Six porcine pulmonary allografts were harvested from mini-pigs, and cryopreserved for four weeks. In two pigs, the grafts were decellularized with Triton X solution, after which static reseeding of the valve surface was performed for 48 h with autologous endothelial cells harvested from a leg artery. Decellularization, but not reseeding, was carried out in two mini-pigs, and cryopreservation alone in two mini-pigs. Whilst under right heart bypass, the right ventricular outflow tract was replaced in six mini-pigs. The grafts were explanted

after four weeks; analysis included direct pressure measurement, echocardiography, macroscopy, light microscopy with hematoxylin and eosin staining, and immunohistochemical studies to identify macrophages, T lymphocytes, and endothelial cells.
Results: Hemodynamically and macroscopically, there were no major differences between the three groups. In the cryopreservation-only group, immunohisto-chemistry showed an influx of macrophages, and T lymphocytes at the cusps. Endothelial cell coverage was found in the decellularized and decellularized + cell-seeded groups, but no macrophages and T lymphocytes were found at the cusps.
Conclusion: Decellularization of the cryopreserved allograft may reduce the inflammatory response and improve its long-term durability.
The Journal of Heart Valve Disease 2004;13:984-990