Statins Enhance Clonal Growth of Late Outgrowth Endothelial Progenitors and Increase Myocardial Capillary Density in the Chronically Ischemic Heart Wen Wang1, Jennifer K. Lang 2 , Gen Suzuki2, John M. Canty Jr.2, Thomas Cimato2* 1 Department of Pathophysiology, Capital Medical University, Beijing, China, 2 Department of Medicine/Cardiovascular Medicine, School of Medicine and Biomedical Sciences, SUNY at Buffalo, Buffalo, New York, United States of America Abstract Background: Coronary artery disease and ischemic heart disease are leading causes of heart failure and death. Reduced blood flow to heart tissue leads to decreased heart function and symptoms of heart failure. Therapies to improve heart function in chronic coronary artery disease are important to identify. HMG-CoA reductase inhibitors (statins) are an important therapy for prevention of coronary artery disease, but also have non-cholesterol lowering effects. Our prior work showed that pravastatin improves contractile function in the chronically ischemic heart in pigs. Endothelial progenitor cells are a potential source of new blood vessels in ischemic tissues. While statins are known to increase the number of early outgrowth endothelial progenitor cells, their effects on late outgrowth endothelial progenitor cells (LOEPCs) and capillary density in ischemic heart tissue are not known. We hypothesized that statins exert positive effects on the mobilization and growth of late outgrowth EPCs, and capillary density in ischemic heart tissue. Methodology/Principal Findings: We determined the effects of statins on the mobilization and growth of late outgrowth endothelial progenitor cells from pigs. We also determined the density of capillaries in myocardial tissue in pigs with chronic myocardial ischemia with or without treatment with pravastatin. Pravastatin therapy resulted in greater than two-fold increase in CD31+ LOEPCs versus untreated animals. Addition of pravastatin or simvastatin to blood mononuclear cells increased the number of LOEPCs greater than three fold in culture. Finally, in animals with chronic myocardial ischemia, pravastatin increased capillary density 46%. Conclusions: Statins promote the derivation, mobilization, and clonal growth of LOEPCs. Pravastatin therapy in vivo increases myocardial capillary density in chronically ischemic myocardium, providing an in vivo correlate for the effects of statins on LOEPC growth in vitro. Our findings provide evidence that statin therapy can increase the density of capillaries in the chronically ischemic heart. Citation: Wang W, Lang JK, Suzuki G, Canty JM Jr, Cimato T (2011) Statins Enhance Clonal Growth of Late Outgrowth Endothelial Progenitors and Increase Myocardial Capillary Density in the Chronically Ischemic Heart. PLoS ONE 6(9): e24868. doi:10.1371/journal.pone.0024868 Editor: Gangjian Qin, Northwestern University, United States of America Received April 7, 2011; Accepted August 23, 2011; Published September 13, 2011 Copyright: 2011 Wang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: Funding was provided by the American Heart Association-Scientist Development Grant: Thomas Cimato, U.S. Department of Veterans Affairs, National Institutes of Health/NHLBI, and the New York State Stem Cell Science ESSC Board: John Canty, Gen Suzuki, and Thomas Cimato. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: tcimato@buffalo.edu Introduction Coronary artery disease is the leading cause of heart failure in the United States [1]. The primary goal of therapy in patients with heart failure or weakened cardiac muscle function due to coronary artery disease is to restore blood flow to prevent damage to heart muscle from chronic ischemia and prevent death of cardiac myocytes. In some patients coronary artery disease persists unidentified, or cannot be revascularized, resulting in chronically ischemic myocardium, with regional contractile dysfunction. These clinical findings can result in heart failure manifesting as shortness of breath with exertion, weight gain, and retention of fluid. Therapies to promote improved heart muscle function are an important goal to improve symptoms and prevent death in patients with coronary artery disease and heart failure. Therapy with HMG-CoA reductase inhibitors (statins) is an important component of medical treatment for coronary artery disease primarily for their cholesterol lowering benefits to prevent the progression and recurrence of disease in the heart. However, statins have additional non-cholesterol lowering benefits that are less well described. In our prior study, we found that therapy with the HMG-CoA reductase inhibitor pravastatin mobilized c-kit+ bone marrow cells to the heart in animals with chronic myocardial ischemia with regional myocardial dysfunction, leading to improved contractile function without significantly affecting myocardial blood flow [2]. However, the effects of statins on endothelial progenitor cells and myocardial capillary density in the chronically ischemic heart are not known, and somewhat controversial. Some have suggested that therapy with statins impairs angiogenesis in the chronically ischemic heart [3]. There are several potential sources of new blood vessels in the heart including differentiation of local resident vascular progenitor cells [4] via vasculogenesis, formation of new vessels by recruitment of endothelial progenitor cells from the blood stream, PLoS ONE | www.plosone.org 1 September 2011 | Volume 6 | Issue 9 | e24868