Inhibition of vein graft intimal proliferative lesions in the rat by heparin.

The authors investigated the effect of heparin on the development of myointimal proliferative lesions in a rat vein graft model. Intimal thickening in this model was most pronounced in the anastomotic regions, and was composed principally of vascular smooth muscle cells, as identified by immunocytochemistry with anti-muscle actin antibody, HHF-35. Medial thickening was less cellular, and evenly distributed throughout the grafts. Continuous, intravenous infusion of whole heparin at 0.3 mg/kg/hr effectively inhibited the development of myointimal proliferative lesions, although with no effect on medial thickening. The authors suggest that heparin, through its antiproliferative activity for vascular smooth muscle cells, may have a potentially important pharmacologic role in preventing vein graft failure, which most commonly results from the development of myointimal proliferative lesions.