The effects of heparin on cultured explants of varicose long saphenous vein

Objective. To examine the effects of heparin on smooth muscle cells (SMCs) in explants of varicose, long saphenous vein (LSV). Procedures. Explants of varicose LSV were cultured for 7 days either alone, or with heparin at 10, 100 or 1000 IU/ml (Monoparin). At 7 days, cultured explants were analysed for changes in intimal and medial thickness and by i mmuno-histochemistry. Comparisons were made with explants at initial isolat ion and with similar, cultured explants of normal LSV. Results. In normal LSV, by day 7, SMC-derived neointimal hyperplasia develo ped (p<0.01) with an increase in intimal thickness (p<0.02) and a decrease in medial thickness (p<0.001). Heparin at 10 and 100 IU/ml further enhanced this neo-intima formation (p<0.001). In contrast, at 1000 IU/ml, heparin i nhibited neo-intima formation. In varicose explants, the pattern of intimal and medial changes was different. At isolation, varicose LSVs had substant ially thicker intimal layers (p<0.001). When cultured alone, a thicker medi a developed (p<0.001) but there was little change in intimal thickness. Hep arin at all concentrations had no effect on the thicker medial development seen in controls but did, however, reduce intimal thickness (p<0.005). Conclusions. The response to heparin in explants of varicose LSV is differe nt from that of normal LSV, which is biphasic and complex.