Characterization of Human Mesenchymal Stem Cells from bone marrow

Human mesenchymal stem cells from bone marrow (hMSC) show self-renewal capacity and multipotency. hMSC are easily isolated based on their adherence to a plastic surface. Another particular feature of hMSC is their ability to survive without serum. This study shows that, in these conditions, hMSC remain arrested at the G0/G1 phase of the cell cycle, keeping their surface markers expression, as well as their proliferative and differentiation potentials, even after prolonged periods. Based on this advantage, the signals involved in hMSC survival, migration, adhesion, proliferation and differentiation were characterized under these conditions by identifying the endogenous expression of receptors to different growth factors and by manipulating their pathways exogenously. These assays demonstrate that BMP and Wnt pathways are involved in survival. In addition, whereas Erk pathway activation promotes proliferation, migration and differentiation to osteoblasts or adipocytes, RA causes a mesenchymal to ectodermal transition (including the de novo expression of neuronal markers) that leads to a loss of these hMSC characteristics including their capacity to survive in serum-free medium.