Magnesium ions facilitate integrin alpha 2-and alpha 3-mediated proliferation and enhance alkaline phosphatase expression and activity in hBMSCs

Magnesium metal and its alloys have been proposed as a novel class of bone implant biomaterials because of their biodegradability and mechanical properties. The purpose of this study was to determine whether magnesium ions, which are released abundantly from alloys, affect proliferation and differentiation of human bone marrow-derived stromal cells (hBMSCs). High levels of magnesium ions did not induce cytotoxicity in hBMSCs, but treatment with 2.5-10mM magnesium ions for 48-72 h significantly increased hBMSC proliferation. The expression of integrins alpha 2 and alpha 3, but not beta 1, was upregulated compared with the control and shifted from alpha 3 to alpha 2 in hBMSCs treated with magnesium ions. Knockdown of integrins alpha 2 and/or alpha 3 significantly reduced magnesium-induced proliferation of hBMSCs. Magnesium exposure profoundly enhanced alkaline phosphatase (ALP) gene expression and activity even at a relatively low magnesium concentration (2.5mM). Exposure to magnesium ions facilitated hBMSC proliferation via integrin alpha 2 and alpha 3 expression and partly promoted differentiation into osteoblasts via the alteration of ALP expression and activity. Accordingly, magnesium could be a useful biomaterial for orthopaedic applications such as bone implant biomaterials for repair and regeneration of bone defects in orthopaedic and dental fields. Copyright (C) 2014 John Wiley & Sons, Ltd.