Effect of high glucose levels on the calcification of vascular smooth muscle cells by inducing osteoblastic differentiation and intracellular calcium deposition via BMP-2/Cbfα-1 pathway

In this paper, we investigate the effect and the possible mechanism of high glucose levels on the calcification of human aortic smooth muscle cells (HASMCs). HASMCs were divided into four groups: normal glucose group (NG), osmolality control group (OC), high glucose group (HG, HASMCs culture medium containing 30 mmol/L glucose), and high glucose plus recombinant human Noggin protein (bone morphogenetic protein-2 (BMP-2) antagonist) group (HN). The mRNA levels and the protein expressions of BMP-2 and core binding factor alpha-1 (Cbf alpha-1) were measured by real-time quantitative polymerase chain reaction (PCR) and Western blot. After induced by 10 mmol/L beta-glycerol phosphoric acid, cells were harvested for assessments of alkaline phosphatase (ALP) activities at Days 1, 2, and 3, and intracellular calcium contents at Days 7 and 14, respectively. High glucose levels increased the mRNA levels and the protein expressions of BMP-2 and Cbf alpha-1 (P < 0.05). The expression of Cbf alpha-1 was partially blocked by Noggin protein (P < 0.05), while BMP-2 was not (P > 0.05). After being induced by beta-glycerol phosphoric acid, high glucose levels increased the ALP activity [(48.63 +/- 1.03) vs. (41.42 +/- 2.28) U/mg protein, Day 3; P < 0.05] and the intracellular calcium content [(2.76 +/- 0.09) vs. (1.75 +/- 0.07) mu mol/mg protein, Day 14; P < 0.05] in a time-dependent manner when compared with the NG group, while the ALP activity could not be blocked by Noggin protein [(48.63 +/- 1.03) vs. (47.37 +/- 0.97) U/mg protein, Day 3; P > 0.05]. These results show that high glucose levels can evoke the calcification of HASMCs by inducing osteoblastic trans-differentiation and intracellular calcium deposition via the BMP-2/Cbf alpha-1 pathway, which can be partially blocked by Noggin protein.