Figure 3

Scheme indicating that a combination of 5 osteoblast-related parameter levels/activity (Ca ⁺⁺ deposition, ALP activity, and RANKL, BSP, OPN gene expression) can be used as an indicator of the stage of MSC differentiation into osteoblasts. Using this setting, 4 stages were defined: (i) undifferentiated MSC (=native stage) expressed high RANKL levels, but no BSP, no OPN, no ALP and no mineralization activity, (ii) osteoprogenitors (=early stage observed after 7 days of DAG treatment) expressed high BSP, moderate RANKL, moderate OPN levels, but had low ALP and no mineralization activity, (iii) mature osteoblasts (=intermediate stage reached after 14 days of DAG treatment) had a high ALP activity, expressed high BSP, high OPN, moderate RANKL levels and had low mineralization activity, and (iv) late osteoblasts (=late stage obtained after 21 days of DAG treatment) had a high mineralization activity, expressed high BSP, high OPN and moderate RANKL levels and had moderate ALP activity.