Division of Cardiovascular Research, St. Elizabeth’s Medical Center, Tufts University School of Medicine, Boston, MA 02135, USA

We have identified a subpopulation of stem cells within adult human bone marrow (BM), isolated at the single-cell level, that self-renew without loss of multipotency for more than 6 to 9 months of continuous cultures and exhibit the capacity for differentiation into cells of three germ layers. Based on surface marker expression, these clonally expanded human bone marrow-derived multipotent stem cells (hBMSCs) do not appear to belong to previously described BM-derived stem or progenitor cell populations.