In Vivo Evaluation of the Effects of a New Ice-Free Cryopreservation Process on Autologous Vascular Grafts

Abstract

Conventionally cryopreserved vascular grafts have performed poorly as arterial grafts. One possible mechanism that causes the poor function is the extracellular ice damage in tissue. We used a novel new ice-free cryopreservation (namely, vitrification) method for prevention of ice formation in cryopreserved venous grafts. This study was designed to evaluate the in vivo effects of the vitrification process on autologous vascular grafts using a short-term transplantation model and to examine the morphology and patency of vitrified grafts in correlation with control grafts. New Zealand White rabbits underwent a right common carotid interposition bypass graft. Fresh and vitrified reversed ipsilateral external jugular veins were used as autologous grafts. Animals were sacrificed at either 2 or 4 weeks after implantation, and fresh and vitrified vein grafts were harvested for histology studies. The results, comparing the patency of fresh and vitrified grafts, demonstrated similar short-term patency rates (approximately 90%). There were no signs of media disruption, aneurysm, or graft stenosis in vitrified vein grafts. Vitrification had not altered the pathophysiological cascade of events that occur when a vein graft is inserted into the arterial system. The vitrification process had no adverse effects locally or systemically in vivo. In addition, vitrification has preserved endothelial cell and smooth muscle cell integrity posttransplantation. In conclusion, this study, using an autologous animal model, clearly demonstrated a significant benefit of vitrification for preservation of graft function, and vitrification may be an acceptable approach for preservation of blood vessels or engineered tissue constructs.