We postulated that combining erythropoietin (EPO) infusion with bone marrow 
mesenchymal stem cells (MSC) delivery may give better prognosis in a rat 
infarcted heart. Acute myocardial infarction (MI) model was developed by 
coronary artery ligation. Animals were grouped (n=18) to receive intramyocardial 
injection of 30 microl saline solution without cells (EPO and control groups) or 
with 3x10(6) MSC from transgenic green fluorescent protein (GFP)+ male mice (MSC 
and MSC-EPO groups). The animals received either 5000 U/kg body weight EPO (EPO 
and MSC-EPO groups) or saline solution (MSC and control groups) for 7 days after 
MI. Cardiac functions were measured by echocardiography and cardiac tissue was 
harvested for immunohistological studies 3 weeks after surgery. We observed 
regeneration of MSC in and around the infarcted myocardium in MSC and MSC-EPO 
groups. Capillary density was markedly enhanced with significantly smaller 
infarct size and reduced fibrotic area in MSC-EPO group as compared with other 
three groups. A smaller left ventricular (LV) diastolic dimension and a higher 
LV fractional shortening were observed in MSC-EPO group than in other three 
groups. Transplantation of MSC combined with cytokine EPO is superior to either 
of the monotherapy approach for angiomyogenesis and cardiac function recovery.