Inhibition of human vascular smooth muscle cell growth by heparin

We examined the inhibitory effect of heparin on vascular smooth muscle cell (VSMC) outgrowth from cultured coronary artery explants of primary atherosclerotic lesions and of undiseased regions from the same patients, compared with explant outgrowth from control patients (idiopathic cardiomyopathy) with no evidence of atherosclerosis. For undiseased tissue regardless of origin, heparin significantly delayed half-maximum percentage explant outgrowth time (mean difference from control treatment 2·1 [SE 0 8] days for atherosclerosis patients and 2 3 [10] days for control patients). For plaque tissue, heparin had no such effect. Thus the proliferative state of the cells involved in outgrowth may influence the activity of heparin.