The long-term objective of this research is to provide a gene therapy method for the sustained delivery of erythropoietin to treat the anemia of patients with chronic renal failure. We will evaluate an appropriate pre-clinical sheep model of erythropoietin gene transfer using retrovirally transduced autologous vascular smooth muscle cells seeded in a prosthetic vascular graft. Grafts seeded with transduced erythropoietin-secreting smooth muscle cells will be implanted as arteriovenous fistulae across the carotid artery and jugular vein to treat the anemia of sheep with surgically induced stable uremia. This research may be applied to patients with chronic renal failure who are subject to dialysis and require prosthetic access grafts. Such grafts can be preseeded with autologous vascular smooth muscle genetically modified to deliver human erythropoietin. In the USA the estimated annual cost of recombinant erythropoietin for the 85,000 patients with anemia of chronic renal failure is about $500 million. The ability to treat these, and other patients with erythropoietin-responsive anemias, by gene therapy would provide major clinical and economic benefits. Overall, this research will provide a broadly applicable method for the long-term systemic delivery of erythropoietin to treat anemias responsive to this hormone and also other therapeutic proteins such as cytokines and clotting factors.
The specific aims i nclude: the construction of novel three gene vectors, synthesis of recombinant Epo, and ELISA construction, the development of optimal graft seeding procedures and their evaluation in normal sheep and animals with surgically created stable uremic anemia.
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