Mechanism of BMP and TG2 in mesenchymal stem cell osteogenesis.

OBJECTIVE: To study the interactive effects of Type II glutamine transaminase (TG2) and bone morphogenetic protein-9 (BMP-9) in the induction of osteogenesis in mice mesenchymal stem cells (MSCs) C3H10T1/2 model. MATERIALS AND METHODS: Batches of MSCs C3H10T1/2, divided into two groups, were treated with BMP-9 (control group) or BMP-9 and TG2 (experimental group) under oxygen deficient conditions. The secreted alkaline phosphatase (SEAP) chemiluminescence and the histochemical staining methods were used to detect the alkaline phosphatase (ALP) expression. The alizarin red S staining was used to detect the calcium salt precipitation and the caspase-3 protein expression was monitored using Western blot. Flow cytometry was employed to identify cell cycle, and trypan blue exclusion method to count the living cells and monitor cell proliferation. RESULTS: The levels of ALP expression in the experimental group were much higher than that of the control group. The level of expression of advanced caspase-3 protein was significantly lower (p < 0.05) in the experimental group than in the control group. The highest fraction of cells in the experimental group was in the phase M while cells in the control group were in the interphase. Moreover, cell number in the experimental group was significantly increased (p < 0.05) relatively to the control group. CONCLUSIONS: BMP-9 interacts with TG2 in osteogenesis of MSCs C3H10T1/2 cells. Further studies are needed to understand the exact mechanism of BMP9/PG2 interactions in osteogenesis.