Understanding the effect of magnesium degradation on drug release and anti-proliferation on smooth muscle cells for magnesium-based drug eluting stents

[Display omitted] •The degradation of Mg-alloy substrate would improve the in vitro rapamycin release on a Mg alloy based drug-eluting system.•Quantitative analyzation distinguished that the improved drug release was mainly caused by H2 evolution, while pH played a trivial role.•Mg-based PLGA/RAPA drug-loading system exhibited more pronounced long-term inhibition for the proliferation of smooth muscle cells. To understand the possible influence of substrate degradation on the drug-loading system of magnesium alloy-based drug-eluting stents, a rapamycin drug-loading poly(lactic-co-glycolic acid) coating was prepared on Mg-Nd-Zn-Zr stents for a systematic investigation in a phosphate buffer system. Mg degradation accelerated the drug release kinetics prominently, which was mainly attributed to H2 evolution in the diffusion-controlled phase while thereafter to PLGA erosion. Although physiochemical stability of the released rapamycin was partially deteriorated by magnesium degradation, the drug-loading system on magnesium substrates exhibited a more potent long-term inhibition on smooth muscle cell proliferation in vitro as compared to drug-loaded stainless steel.