The long-term objective of this research proposal is to develop technology and devices for the cryopreservation and drying of human allograft saphenous veins and ultimately bioprosthetic heterograft vessels which allow storage in a non-frozen state (4o - 22oC). Veins will be preserved by vitrification with incorporation of naturally occurring dry protectant sugars and dried by molecular distillation in a manner quantitatively related to the water phases present. Evaluation will be made by light and electron microscopy, strength/elasticity and flow measurements, biochemical assays, and immunological tests for Class I and II major histocompatibility antigens. The potential advantages of such veins would be longer and more convenient storage pregraft, and significantly reduced structural damage during processing which, it is anticipated, would result in reduced thromboembolic risk post graft and longer graft life spans. In addition, advantage will be taken of the ability of the processing method to maintain transient partial endothelial cell function, but not viability. This should allow endothelial cells to cover the intima for a limited period thereby avoiding immediate thrombo-occlusion, but these compromised cells would ultimately be replaced by autologous endothelial cells. Later, Phase II studies will focus on animal implant models, the feasibility of scale- up, and design of a prototype commercial processing machine.
