The Response to High Magneto-Gravitational Environment of Different Differentiating-Stage Osteoblasts

Abstract: To investigate the effects and possible mechanism of high magneto-gravitational environment (HMGE) on the differentiation of different differentiating stage MC3T3-E1 osteoblasts， the 4 d or 7 d osteogenic differentiating MC3T3-E1 osteoblasts were cultured under μ g [9 Tesla(T)]， 1 g (16 T)， 2 g (12 T) and control (1 g， geomagnetic field) conditions for 12 h respectively. The alkaline phosphatase (ALP) activity was analyzed by p-nitrophenyl phosphate colorimetric assay. Alizarin red s staining was used to detect mineralized nodule formation. Real time RT-PCR was applied to detect the mRNA expression of osteogenic genes including ALP， runt-related transcription factor 2 (Runx2)， type I collagen α1 (Col Iα1)， osteocalcin (OC) and dentin matrix protein 1 (DMP1). The results showed that 12 h treatment of μ g and 1 g condition significantly increased the ALP activity of 7 d differentiating MC3T3-E1 cells (P<0.001， P<0.01) compared with control condition， while HMGE did not affect the ALP activity of 4 d differentiating MC3T3-E1 cells. Alizarin red S staining showed that the mineralized nodule formation of 7 d differentiating MC3T3-E1 cells increased under μ g and 1 g condition. Real time RT-PCR results showed that the expressions of osteogenic genes (ALP， Runx2， OC， Col Iα1 and DMP1) were significantly up-regulated by 12 h treatment of μ g and 1 g condition while down-regulated under 2 g condition (P<0.05， P<0.01， P<0.001) in both 4 d and 7 d osteogenic differentiating cells. These results demonstrate that 4 d and 7 d different differentiating stage MC3T3-E1 cells show different sensitivity to 12 h treatment of HMGE while 7 d mineralizing stage cells are more sensitive to HMGE and suggest the promotion effect of magnetic field on osteoblast differentiation.

CSTR: 32200.14.cjcb.2013.07.0008