Structure, production and function of erythropoietin: implications for therapeutical use in cardiovascular disease

Erythropoietin (EPO) is a 30,400 daltons glycoprotein, consisting of 165 amino acids produced mainly in the kidney and in the liver and regulating erythrocyitosis. It primarily acts on erythroid precursor cell at colony-forming units-erythroid stage inhibiting the apoptosis. EPO binds on a specific membrane receptor thereby activating at least three specific intracellular signaling pathways, such as phosphatidylinositol 3-kinase/ protein kinase B, Ras-mitogen-activated protein kinase and some members of the signal transducers and activators of transcription family. In addition to kidney and liver, EPO mRNA has been detected in other tissues; accordingly EPO receptor has been identified in several type of cells and recent reports have suggested new roles for EPO in non-haematopoietic tissues with a robust evidence for neuroprotective and cardioprotective activity. In different animal models, in vitro, in isolated perfused heart and in vivo, recombinant human erythropoietin protects heart from ischemia reperfusion injury and reduces myocardial damage. EPO tissue protective activity can be separated from erythropoietic activity. Molecules owing the first property but not the second one have been described. In patients with acute myocardial infarction serum EPO level correlates inversely with infarct size. Acute coronary syndrome, extracorporeal circulation and percutaneous coronary intervention are potential fields of application for tissue protective EPO activity to reduce myocardial damage, increase cardiac function ad improve outcome.