Novel Markers for the Isolation of Primary Bone Marrow Derived MSC with Multi-Lineage Differentiation Capacity.

We have previously described a novel culture protocol to grow MSC from bone marrow (BM) and non-amniotic placenta (PL) with an immature phenotype and multi-lineage differentiation capacity (1). Using the low affinity nerve growth factor receptor (CD271) (2) as a key marker for isolation of MSC derived from femur shaft bone marrow cells (BM-MSC) of patients undergoing a total hip replacement, we could identify two CD271+ distinct populations: CD271dull and CD271bright cells. Two-color flow cytometer analysis revealed that only the CD271bright population coexpressed the mesenchymal markers CD10, CD13, CD73, and CD105, but was negative for CD45. CD271dull cells were positive for CD45 and HLA-DR but negative for the other markers. To analyze the mesenchymal stem cell potential, colony-forming-unit fibroblast (CFU-F) assays were performed. Not surprisingly, the CFU-F were exclusively detected in the CD271bright but not in the CD271dull fraction. By screening a battery of antibodies against known and unknown antigens, we identified several reagents that selectively detected the CD271brightCD45- population but no other bone marrow cells. These markers included the PDGF-RB (CD140b), the embryonic stem cell marker TRA-1-49, the clustered markers HER-2/erbB2 (CD340), the recently described W8B2 antigen (3), as well as the cell surface antigens defined by the antibodies W1C3, W3D5, W4A5, W5C4, W5C5, W7C6, 9A3, 58B1, F9-3C2F1, and HEK-3D6. In conclusion we identified several novel markers for the prospective isolation and characterization of BM-MSC.