O pénis e o endotélio. Aspectos extra genitais da disfunção eréctil

The endothelium is a metabolically highly active layer of cells lining all blood vessel walls, playing important structural and functional roles in regulating vascular homeostasis. Endothelial cells (ECs) are the first to sense humoral changes, to which they respond by releasing a variety of factors. If the balanced release of these mediators is disrupted, EC dysfunction ensues. Loss of functional endothelium plays an integral role in the pathogenesis of atherosclerotic and cardiovascular diseases, in which several vascular risk factors, act by directly injuring ECs. These vascular comorbidities are associated with the increased incidence of erectile dysfunction (ED), demonstrating the crucial role of cavernosal ECs. Vascular repair mechanisms, of angiogenesis and adult vasculogenesis, are usually activated to regenerate affected endothelium. The angiogenic process refers to the proliferation and migration of adjacent ECs to injured sites, repairing them. During vasculogenesis, Endothelial Progenitor Cells (EPCs) are mobilized to neovascular sites, where they differentiate into mature ECs. The Vascular Endothelial Growth Factor (VEGF) is the central regulator of these processes, mediating its functions by engagement with its receptors on ECs and EPCs. It is thought, that in ED both local and sistemic vascular repair mechanisms may be impaired. The expression of VEGF and its receptors may be altered in cavernosal endothelium, conditioning its angiogenic functions. It was also suggested that EPCs are present in reduced number in the peripheral circulation of individuals with ED. Treatment with phosphodiesterase type 5 inhibitors, induced the mobilization of EPCs, highlighting their vasculoprotective role. It remains to define the molecular alterations involved in this response, and the role of the VEGF/VEGFR system in the improvement of the endothelization capability of EPCs. Further studies, will provide valuable insight into the angiogenic and vasculogenic mechanisms that govern erectile function, leading to new tailored-treatment strategies.