Fig. 6. Model of elastin-vascular smooth muscle cell interactions in development and disease. (A) During normal development, vascular smooth muscle cells synthesize and secrete elastin polymers that form concentric rings of elastic lamellae around the arterial lumen. Elastin provides mechanical support to the vessel wall, and signals vascular smooth muscle cells to localize around the elastic lamellae and remain in a quiescent, contractile state. (B) In the absence of elastin, this morphogenic signal is lost resulting in pervasive subendothelial migration and proliferation of vascular smooth muscle cells that occludes the vascular lumen. (C) This leads us to propose that the focal disruption and/or destruction of elastin in the mature artery by vascular injury releases smooth muscle cells to dedifferentiate, migrate and proliferate, and contributes to neointimal formation.