Abstract 17132: Inhibition of Sonic Hedgehog Signaling Attenuates Proliferation of Vascular Cells and Prevents Neointimal Lesion Formation
Purpose: De-differentiation and proliferation of smooth muscle cells (SMC) and fibroblasts are hallmarks of vascular proliferative diseases. Sonic hedgehog (Shh) is a regulator of vasculogenesis and has recently also been implicated in proliferation of vascular cells and differentiation of perivascular stem cells in the adult. Moreover, Shh acts as a potent chemoattractive factor for the recruitment of inflammatory cells. The aim of the study was to investigate the role of Shh in vascular proliferative diseases.
Methods and Results: Wire-mediated injury of the femoral artery was performed in C57BL/6 mice to induce neointimal lesion formation. Shh was significantly up-regulated in neointimal SMC and perivascular cells at 4 and 7 days after injury compared to sham-operated arteries, as determined by qPCR and immunohistochemistry (IHC). Moreover, we detected a prominent espression of Shh in the adventitia of human atherosclerotic plaques as compared to healthy mammalian arteries using IHC. In vitro, stimulation of human fibroblasts and human coronary artery SMC with Platelet-derived growth factor (PDGF-BB) and Tumor necrosis factor (TNF-α) resulted in a significant up-regulation and secretion of Shh to the supernatant. Incubation of fibroblasts and SMC with recombinant Shh dose-dependently induced cell proliferation. The specific Shh inhibitor GDC-0449 (Vismodegib) was not only effective in attenuating Shh signaling but also prevented the Shh/PDGF-BB induced proliferation in fibroblasts and SMC in a dose-dependent manner. Following wire-induced injury, local application of GDC-0449 via a self-degrading Pluronic® F-127 Gel significantly reduced neointimal lesion formation (neointima/media ratio: 2.19±0.17 vs. 0.88±0.19, n=5, P<0.001). This was associated with a reduced accumulation of leukocytes as well as reduced proliferation of SMC and perivascular cells. The effects of Shh inhibition on the downstream signaling pathways are currently investigated.
Conclusions: Shh signaling is critically involved in neointimal lesion formation by augmenting the proliferation of SMC and perivascular cells. Therefore, these data add significantly to our understanding of vascular proliferative diseases.
- © 2013 by American Heart Association, Inc.