Fig. 1

Osteogenic differentiation of MSCs. The MSC population proliferates actively at the initial stages of osteogenesis. As MSCs commit to osteoblasts their proliferation rate decreases while they start expressing osteogenic markers such as alkaline phosphatase secreted by early osteoblasts (matrix maturation phase) and osteocalcin secreted by late osteoblasts (mineralization phase). At the end of the bone forming phase, they can become BLCs or osteocytes or undergo apoptosis