ObjectiveTo investigate the role of kinase insert domain containing receptor (KDR) positive cells in the formation of cardiospheric structure, myocardium and vessels.MethodsTwenty-four Wistar rats weighting 250 g were selected. Cardiosphere-derived cells were isolated by enzymatic digestion of rat hearts, and their immunological phenotypes were analyzed by using fluorescence-activated cell sorting (FACS). The cardiomyogenic and vasculogenic potential was diagnosed by immunohistochemistry.ResultsKDR positive cells grew exponentially and formed cell clusters. It also could generate myocardial precursor cells (cardiac troponin T positive). And these cells can develop spontaneous contraction activity in vitro. Meanwhile, KDR positive cells formed many vessel-like structures through a budding process.ConclusionKDR positive cells form cardiospheric structure in vitro culture, and exhibit differentiation potential towards the cardiac and vascular cells. Therefore, KDR positive cells may have a broad prospect of clinical application as cell donors.