Reduction in vascular lesion formation by hirudin secreted from retrovirus-transduced confluent endothelial cells on vascular grafts in baboons

Background-The hypothesis that thrombin mediates the formation of neointima l vascular lesions at sites of mechanical vascular Injury has been tested i n baboons by measurement of the effects of hirudin delivered by retrovirus- transduced hirudin-secreting vascular endothelial cells (ECs) lining surgic ally implanted arterial vascular grafts (AVGs). Methods and Results-The antithrombotic efficacy of baboon ECs transduced wi th cDNA encoding hirudin was assessed in vitro and in vivo on thrombogenic segments in chronically exteriorized femoral arteriovenous (AV) shunts. Bil ateral brachial AVGs lined with hirudin-transduced versus nonhirudin contro l ECs at confluent density were surgically implanted, and vascular lesion f ormations at distal graft-vessel anastomoses were compared after 30 days. H irudin-transduced ECs secreted 20 +/- 6 ng.10(6) cells(-1).24 h(-1) (range, 14 to 24 ng.10(6) cells(-1).24 h(-1)) hirudin in supernatants of static cu ltures. Hirudin-secreting ECs on segments of collagen-coated graft interpos ed in chronic AV shunts decreased the accumulation of In-111-labeled platel ets to 0.52 +/- 0.34 x 10(9) platelets, compared with 0.82 +/- 0.49 x 10(9) platelets in controls (P = 0.03) and reduced platelet deposition in propag ated thrombotic tails extending downstream from segments of vascular graft from 1.38 +/- 0.41 x 10(9) platelets in controls to 0.59 +/- 0.22 x 10(9) p latelets (P = 0.04). ECs recovered from 30-day AVG implants generated 17 +/ - 9 ng.10(6) cells(-1).24 h(-1) (range, 9 to 25 ng.10(6) cells(-1).24 h(-1) ) hirudin. Hirudin-secreting ECs reduced neointimal lesion formation at dis tal graft-vessel anastomoses, ie, 1.02 mm(2) (range, 0.88 to 1.95 mm(2)) ve rsus 1.82 mm(2) (range, 0.88 to 2.56 mm(2)) in contralateral AVGs bearing n onhirudin control ECs (P < 0.01). Conclusions-Viral vector-directed secretion of hirudin from ECs lining impl anted AVGs significantly reduces the formation of thrombus and neointimal v ascular lesions.