Are Long Term Cryopreservation and Patency of Vein Allograft Truly Achievable?

Despite extensive experimental work, neither the effect of long term cryopreservation on vein graft archi tecture nor the failure of alloveins due to graft rejection have yet been investigated. Herein, we investigated ul trastructurally: a) the integrity of rabbit jugular veins following 1, 2 and 3 months of cryopreservation; b) the outcome of the three-month cryopreserved vein autoand allografts after 1 month of implantation in the rabbit carotid artery ; and c) the immunologic response to cryopreserved vein allografts with and without seeded autologous endothelium. Prior to implantation , the cryopreserved rabbit veins were well-maintained except for endothelial cell damage. Following implantation , the cryopreserved vein autografts were comparable to fresh veins with a complete endothelial lining. Conversely , only one of the allograft was still patent with features of acute rejection . After seeding with autologous endothelium , these explants failed shortly after surgery. We found absence of endothelium and necrosis of the media components with neutrophil infiltration. Although three months of cryopreservation does not affect vein graft architecture significantly, endothelial cells are damaged irrespective of the time of cryopreservation. Vein autografts promptly healed after one month of implantation at which time a viable endothelial cell lining was restored from the host artery . Conversely, vein allografts, with and without seeded autologous endothelium, failed due to graft rejection . This study highlights that current methods of cryopreservation do not reduce antigenicity of venous allografts significantly.