Angiogenesis and vasculogenesis in systemic sclerosis.

In addition to inflammatory infiltrates and an accumulation of extracellular matrix proteins, vascular changes are a hallmark in the pathogenesis of systemic sclerosis (SSc). Consistent with the ongoing endothelial cell apoptosis, several markers of EC damage are up-regulated in the serum of SSc patients. Surprizingly, vascular endothelial growth factor (VEGF), a very potent angiogenic molecule, is overexpressed in SSc patients despite the insufficient angiogenesis. VEGF can protect patients from fingertip ulcers, but a prolonged overexpression of VEGF might have paradoxical effects leading to the formation of irregular vessels similar to that observed in SSc. Besides defective angiogenesis, recent studies suggest that vasculogenesis is also impaired in SSc patients with reduced numbers and functional defects of endothelial progenitor cells.