In addition, the reduction in myocardial fibrosis in these animals is also an important indicator for improved heart function since late reperfusion of infarcted vascular beds attenuates left ventricular remodeling including infarct expansion. In addition to myogenesis, vasculogenesis and antiapoptotic effects of the Byakangelicin paracrine factors Procyanidin-B2 secreted by hematopoietic stem cells, our findings also indicate that the hematopoietic stem cells home to injured sites besides their usual destinations such as lung, liver, spleen and bone marrow. This phenomenon therefore suggests that both trans-differentiation and paracrine mechanisms might be operational in our therapeutic approach. Nanofiber expanded stem cells express significantly more CXCR4 and high concentrations of SDF-1 in ischemic or damaged tissues, which may be responsible for increased homing as CXCR4 is a natural receptor for SDF-1. As we report, hematopoietic stem cells home to the injured heart besides the usual destinations such as the lung, liver, spleen and bone marrow. In this homing of stem cells both transdifferentiation and paracrine mechanisms might be involved. In cardiac tissues, infused stem cells differentiate into endothelial cells and integrate into the inner lining of microvasculature under influence of microenvironment. We have previously demonstrated that nanofiber expanded stem cells maintain the ability to multi-potentially differentiate into endothelial and smooth muscle cells, hence, contributing to vasculogenesis. A recent report indicated that hematopoietic stem cells integrated into rat myocardial ischemic tissues and organs could be detected even one month after injection. The involvement of paracrine mechanisms to mediate the therapeutic effects of stem cells in various ischemia models have also been demonstrated. In murine ischemic models, bone marrow stromal cells have been shown to enhance collateral flow recovery and remodeling, thereby attenuating muscle atrophy. Moreover in rat myocardial infarction models, collaterals and improved cardiac function have been demonstrated using CD34+ stem cell therapy.