From the oxygen to the organ protection: erythropoietin as protagonist in internal medicine.

Erythropoietin (EPO), already known as the stimulating hormone for erythropoiesis, has shown different and interesting pleiotropic actions. It does not only affect erythroid cells, but also myeloid cells, lymphocytes and megakaryocytes. This hormone can also enhance phagocytic function of the polymorphonuclear cells and reduce the activation of macrophages, thus modulating the inflammatory process.Moreover, hematopoietic and endothelial cells probably have the same cellular origin, and the discovery of erythropoietin receptors (EPO-R) also on mesangial and myocardial cells, smooth muscle fibrocells and neurons has prompted the study of the non-erythropoietic functions of this hormone.The interaction between EPO and VEGF may be of particular importance in neovascularization and wound healing. Different studies have demonstrated that EPO has an important direct hemodynamic and vasoactive action, which does not depend exclusively on any increase in hematocrit and viscosity. Moreover EPO showed protective effects on myocardial cells against apoptosis induced by ischemia/repefusion injury, but it could negatively affect pulmonary hypertension in patient with chronic cor pulmonale.This review aims to stress the importance of the increasing interest in EPO applications and the necessity of further studies to gain a deeper knowledge of this hormone and its pleiotropic and complex actions.