[The gene expression patterns of bone-marrow mesenchymal stem cells under different osteogenic induction].

OBJECTIVE

To investigate the molecular mechanism of osteogenetic differentiation of bone-marrow mesenchymal stem cells (BMSCs) and the probability using the BMSCs to gene therapy for bone fractures.

METHODS

By gradient centrifugation and adherence to the culture plastic, the MSCs were separated and purified from mouse bone marrow. The BMSCs then were cultured and sub-cultured in the osteogenetic medium (100 nmol/L Dexamethasone, 10 mmol/L beta-glycerophosphate and 50 mg/mL ascorbic acid, osteogenic supplements, OS-medium) or the recombinant human bone morphogenetic protein-2 (rhBMP-2, 500 ng/mL) for the mineralized inductions of osteogenesis, and stained by alizarin red in inducing week 1 and 2 for the identification of calcium nodule formed. The gene expressions of Runx2, Osx, OCN, and Col I were detected by RT-PCR on day 1, 2 and 3 after doing the osteogenetic inductions.

RESULTS

The BMSCs induced by OS-medium and rhBMP-2 were both of positive Ca nodules with alizarin red. However, the Ca nodule induced by OS-medium formed in 1 inducing week, but the one done by rhBMP-2 occurred in 2 inducing weeks, which meant it was a late for one week. In the OS-group, the mRNA of Runx2 could not be detected on inducing day 1, 2 and 3, but the Osx mRNA appeared on inducing day 2 and 3, and also the mRNAs of OCN and Col I could be detected in all the three inducing days. In rhBMP-2 group, the Runx2 gene expressed on inducing day 2, the Osx gene expressed on inducing day 2 and 3, the OCN and Col I genes expressed on inducing day 1, 2 and 3.

CONCLUSION

The BMSCs induced by OS-medium are more likely to form bone nodules than that of rhBMP-2, because of their simpler mechanisms to differentiate into osteoblasts.