Bone Marrow Is a Reservoir for Cardiac Resident Stem Cells

Resident cardiac stem cells (CSCs) represent a responsive stem cell reservoir within the adult myocardium and have a significant function in myocardial homeostasis and injury. However, the distribution, origin, homing and possible therapeutic benefits of CSCs are still under discussion. Here we investigated whether bone marrow (BM) stem cells could contribute to repopulating the pool of CSCs in heart. The engraftment of BM cells in heart was detected at a low level after BM transplantation (BMT) and ischemia/reperfusion (I/R) could increase BM cells engraftment but not significant. We clarified that more than 50% CSCs are derived from BM and confirmed that BM-derived CSCs have similar characteristics with the host CSCs. Furthermore, we transplanted BM-derived CSCs into heart ischemia models and presented evidence for the first time that BM-derived CSCs can differentiate into cardiomyocytes in vivo. In conclusions, BM stem cells could be a potential back-up source of CSCs for restoring heart function after injury or maintaining homeostasis of CSCs.