Biphasic responses of human vascular smooth muscle cells to magnesium ion

Magnesium-based alloys are promising in biodegradable cardiovascular stent applications. The degradation products of magnesium stents may have significant impacts on the surrounding vascular cells. However, knowledge on the interactions between magnesium ion and vascular cells at the molecular and cellular levels is still largely missing. Vascular smooth muscle cell (SMC) plays an important role in the pathogenesis of restenosis and wound healing after stent implantation. This study evaluated the short-term effects of extracellular magnesium ion (Mg²⁺) on the cellular behaviors of SMCs. Cellular responses to Mg²⁺ were biphasic and in a concentration-dependent manner. Low concentrations (10 mM) of Mg²⁺ increased cell viability, cell proliferation rate, cell adhesion, cell spreading, cell migration rate, and actin expression. In contrast, higher concentrations (40-60 mM) of Mg²⁺ had deleterious effects on cells. Gene expression analysis revealed that Mg²⁺ altered the expressions of genes mostly related to cell adhesion, cell injury, angiogenesis, inflammation, coagulation, and cell growth. Finding from this study provides some valuable information on SMC responses toward magnesium ions at the cellular and molecular levels, and guidance for future controlled release of magnesium from the stent material.