Inhibition of patched-1 prevents injury-induced neointimal hyperplasia.

OBJECTIVE To determine the role of patched receptor (Ptc)-1 in mediating pulsatile flow-induced changes in vascular smooth muscle cell growth and vascular remodeling. APPROACH AND RESULTS In vitro, human coronary arterial smooth muscle cells were exposed to normal or pathological low pulsatile flow conditions for 24 hours using a perfused transcapillary flow system. Low pulsatile flow increased vascular smooth muscle cell proliferation when compared with normal flow conditions. Inhibition of Ptc-1 by cyclopamine attenuated low flow-induced increases in Notch expression while concomitantly decreasing human coronary arterial smooth muscle cell growth to that similar under normal flow conditions. In vivo, ligation injury-induced low flow increased vascular smooth muscle cell growth and vascular remodeling, while increasing Ptc-1/Notch expression. Perivascular delivery of Ptc-1 small interfering RNA by pluronic gel inhibited the pathological low flow-induced increases in Ptc-1/Notch expression and markedly reduced the subsequent vascular remodeling. CONCLUSIONS These results suggest that pathological low flow stimulates smooth muscle cell growth in vitro and vascular remodeling in vivo via Ptc-1 regulation of Notch signaling.