Minoxidil inhibits proliferation and migration of cultured vascular smoothmuscle cells and neointimal formation after balloon catheter injury

The goal of the study was to investigate the in vitro and in vivo inhibitio n of minoxidil on smooth muscle cell (SMC) proliferation and migration as w ell as neointimal formation. The in vitro effect of minoxidil was investiga ted by Boyden chamber assay and cell-cycle analysis. To evaluate the in viv o effect, we treated the animals with minoxidil in their drinking water bef ore and after balloon catheter injury to carotid artery. Results showed tha t minoxidil inhibited SMC migration across type I collagen membrane in a do se-related manner (13.5% by 0.01 mg/ml; p < 0.05; 16.8% by 0.05 mg/ml; p < 0.01; 40.4% by 0.25 mg/ml: p < 0.001; and 65.8% by 1.25 mg/ml; p < 0.001). Minoxidil (0.8 mg/ml) increased the number of SMCs in G(1) phase (p < 0.05) and decreased the number of SMCs in S phase (p < 0.001). In vivo minoxidil treatment reduced neointimal mass by 31.7% (120 mg/L) and 42.3% (200 mg/L) , respectively. Data demonstrate that minoxidil inhibits vascular SMC proli feration and migration both in vitro and in vivo, and therefore may be usef ul to inhibit SMC hyperplasia that occurs in restenosis and other vascular diseases.