[Effects of high glucose on expression of core binding factor alpha1 and osteocalcin in vascular smooth muscle cells]

To investigate the effects of high glucose on expression of core binding factor alpha1 (cbfalpha-1) and osteocalcin (OC) in vascular smooth muscle cells (VSMCs), and discuss the mechanism of small vessels calcification induced by high glucose (GS) in vitro.

The primary cultured VSMCs from rats' aortic segments were divided into three groups, including normal control group (5 mmol/L D-glucose), high glucose group (25 mmol/L D-glucose) and mannitol group (5 mmol/L D-glucose plus 25 mmol/L mannitol). We measured quantitatively the calcium deposition in VSMCs and investigated the calcium extent of VSMCs by alizarin red stain in each group. The mRNA levels of cbfalpha-1 and OC were measured by real-time PCR, and the protein expression levels of cbfalpha-1 and OC were examined by Western blot. The activity of alkaline phosphatase was measured by alkaline phosphatase activity testing kit, and the protein level of alpha-smooth muscle actin (a-SMA) was detected by immunohistochemistry.

When compared with the normal group and mannitol group, the high glucose group showed that the calcium deposition and calcium extent of VSMCs increased obviously, the mRNA and protein levels of cbfalpha-1 and OC also increased significantly (P < 0.05), while the protein level of alpha-SMA decreased (P < 0.05), which were in a dose-dependent manner. The level of alkaline phosphatase activity of VSMCs was approximately doubled in high glucose group.

The mechanism of high glucose induced calcification in VSMCs may be due to the increased expression of cbfalpha-1 and OC. High glucose decrease the expression of alpha-SMA in VSMCs, which could induce the transdifferentiation from RVSMCs to osteoblast-like cells.