ARE LONG-TERM CRYOPRESERVATION AND PATENCY OF VEIN ALLOGRAFT TRULY ACHIEVABLE

Despite extensive experimental work, neither the effect of long term c ryopreservation on vein graft architecture nor the failure of allovein s due to graft rejection have yet been investigated. Herein, we invest igated ultrastructurally: a) the integrity of rabbit jugular veins fol lowing 1, 2 and 3 months of cryopreservation; b) the outcome of the th ree-month cryopreserved vein auto- and allografts after 1 month of imp lantation in the rabbit carotid artery; and c) the immunologic respons e to cryopreserved vein allografts with and without seeded autologous endothelium. Prior to implantation, the cryopreserved rabbit veins wer e well-maintained except for endothelial cell damage. Following implan tation, the cryopreserved vein autografts were comparable to fresh vei ns with a complete endothelial lining. Conversely, only one of the all ograft was still patent with features of acute rejection. After seedin g with autologous endothelium, these explants failed shortly after sur gery. We found absence of endothelium and necrosis of the media compon ents with neutrophil infiltration. Although three months of cryopreser vation does not affect vein graft architecture significantly, endothel ial cells are damaged irrespective of the time of cryopreservation. Ve in autografts promptly healed after one month of implantation at which time a viable endothelial cell lining was restored from the host arte ry. Conversely, vein allografts, with and without seeded autologous en dothelium, failed due to graft rejection. This study highlights that c urrent methods of cryopreservation do not reduce antigenicity of venou s allografts significantly.