Engineered Blood Vessels

The field of tissue engineering has has made significant progress in the past 20 years. Of the many tissues and organs in development, the area of vascular tissue engineering is now one of the most mature. In that regard, we have developed a novel tissue engineered vascular graft (human acellular vessel [HAV]) that addresses many of the limitations of native vein harvest and the performance of both synthetic ePTFE and autologous vein grafts. The HAV is manufactured in a laboratory by culturing human vascular cells within a biodegradable scaffold that forms a mechanically robust tissue engineered blood vessel. The cells are then completely removed (decellularization), leaving behind a non-immunogenic human collagen-based vascular tissue that can be stored on the shelf for months at a time and ready for immediate implantation into any patient. The HAV is currently being evaluated in Phase II and Phase III clinical trials in the U.S., E.U. and Israel as an arteriovenous vascular access graft for hemodialysis in patients with end-stage renal failure and as an arterial substitute for patients in need of vascular bypass for peripheral arterial disease or vascular trauma. Following clinical implantation, we have observed repopulation and remodeling of the manufactured vessel with the hosts' own cells. We hypothesize that the biological composition of the HAV, compared to synthetic vascular grafts, promotes its physiological integration into host tissue including support of normal host cell infiltration and function. Host cells that identify histologically similar to vascular smooth muscle cells appear to repopulate the middle of the vessel and recipient cells characterized as endothelial cells appear to cover the luminal surface of the implanted vessel. Clinical observations of the Phase II trials have demonstrated excellent vessel durability and a freedom from both early and delayed infection. Based on the success of the Phase II studies, a Global Phase III study is underway for patients in need of dialysis access shunts and vascular programs for vascular (arterial) bypass and trauma are expanding.