Development of Serum‐Free Quality and Quantity Control Culture of Colony‐Forming Endothelial Progenitor Cell for Vasculogenesis

Quantitative and qualitative impairment of endothelial progenitor cells (EPCs) limits the efficacy of autologous cell therapy in patients with cardiovascular diseases. Here, we developed a serum‐free quality and quantity control culture system for colony‐forming EPCs to enhance their regenerative potential. A culture with serum‐free medium containing stem cell factor, thrombopoietin, vascular endothelial growth factor, interleukin‐6, and Flt‐3 ligand was determined as optimal quality and quantity culture (QQc) in terms of the most vasculogenic colony‐forming EPC expansion, evaluated by the newly established EPC colony formation assay. The QQc of umbilical cord blood‐CD133+ cells for 7 days produced a 52.9‐fold increase in total cell number and 3.28‐fold frequency in definitive EPC colony development, resulting in a 203.9‐fold increase in estimated total definitive EPC colony number in vitro. Pre‐ or post‐QQc cells were intramyocardially transplanted into nude rats with myocardial infarction (MI). Echocardiographic and micromanometer‐tipped conductance catheter examinations 28 days post‐MI revealed significant preservation of left ventricular (LV) function in rats receiving pre‐ or post‐QQc cells compared with those receiving phosphate‐buffered saline. Assessments of global LV contractility indicated a dose‐dependent effect of pre‐ or post‐QQc cells and the superior potency of post‐QQc cells over pre‐QQc cells. Furthermore, immunohistochemistry showed more abundant formation of both human and rat endothelial cells and cardiomyocytes in the infarcted myocardium following transplantation of post‐QQc cells compared with pre‐QQc cells. Our optimal serum‐free quality and quantity culture may enhance the therapeutic potential of EPCs in both quantitative and qualitative aspects for cardiovascular regeneration.