ARTERIAL HEPARAN-SULFATE PROTEOGLYCANS INHIBIT VASCULAR SMOOTH-MUSCLECELL-PROLIFERATION AND PHENOTYPE CHANGE IN-VITRO AND NEOINTIMAL FORMATION IN-VIVO

Purpose: The aim of this study was to determine whether heparan sulfat e proteoglycans (HSPGs) from the normal arterial wall inhibit neointim al formation after injury in vivo and smooth muscle cell (SMC) phenoty pe change and proliferation in vitro. Methods: Arterial HSPGs were ext racted from rabbit aortae and separated by anion-exchange chromatograp hy. The effect of HSPGs, applied in a periadventitial gel, on neointim al formation was assessed 14 days after balloon catheter injury of rab bit carotid arteries. Their effect on SMC phenotype and proliferation was measured by point-counting morphometry of the cytoplasmic volume f raction of myofilaments (Vvmyo) and H-3-thymidine incorporation in SMC s in culture. Results: Arterial HSPGs (680 mu g) reduced neointimal fo rmation by 35% at 14 days after injury (P =.029), whereas 2000 mu g of the low-molecular-weight heparin Enoxaparin was ineffective. HSPGs at 34 mu g/mL maintained subconfluent primary cultured SMCs with the sam e high Vvmyo (52.1% +/- 13.8%) after 5 days in culture as did cells fr eshly isolated from the arterial wall (52.1% +/- 15.1%). In contrast, 100 mu g/mL Enoxaparin was ineffective in preventing phenotypic change over this time period (Vvmyo 38.9% +/- 14.6%, controls 35.9% +/- 12.8 %). HSPGs also inhibited 3H-thymidine incorporation into primary cultu red SMCs with an ID50 value of 0.4 mu g/mL compared with a value of 14 mu g/ml; for Enoxaparin (P <.01). Conclusion: When used periadventiti ally in the rabbit arterial injury model, natural arterial HSPGs are e ffective inhibitors of neointimal formation. In vitro, the HSPGs maint ain SMCs in a quiescent state by inhibiting phenotypic change and DNA synthesis. This study suggests that HSPGs may be a natural agent for t he treatment of clinical restenosis.