It is generally accepted that adult bone marrow(BM) contains both hematopoietic stem cells(HSCs) and mesenchymal stem cells (MSCs). Recently, a rare population of stem cells different from HSCs and MSCs were identified in murine BM and human cord blood (CB), named as very small embryonic like(VSEL) stem cells. These cells are tiny round and CXCR4+ Sca-1+ Lin- CD45-, expressing SSEA-1/4, Oct-4 and Nanog, which have potent of differentiation into all three germ-layer lineages, such as cardiomyocytes, neural and pancreatic cells.