Comparison Study on Four Biodegradable Polymer Coatings for Controlling Magnesium Degradation and Human Endothelial...

Magnesium (Mg)-based bioresorbable cardiovascular scaffold (BCS) is a promising alternative to conventional permanent cardiovascular stents, but it faces the challenges of rapid degradation and poor endothelium recovery after device degradation. To address these challenges, we investigated poly(l-lactic acid) (PLLA), poly(lactic-co-glycolic acid) (PLGA) (90:10), PLGA (50:50), and polycaprolactone (PCL) coatings on Mg, respectively, and evaluated their surface and biological properties. Intact polymer coatings with complete coverage on Mg substrate were achieved. The biological performance of the materials was evaluated by culturing with human umbilical vein endothelial cells (HUVECs) in vitro using the direct culture method. The pH of the culture media and Mg²⁺ and Ca²⁺ ion concentrations in the media were measured after culture to characterize the degradation rate of the materials in vitro. The results showed that the PLGA (50:50) coating improved the adhesion and spreading of HUVECs the most among the four polymer coatings. Moreover, we found three possible factors that promoted HUVECs directly attached on the surface of PLGA (50:50)-coated Mg: (1) the higher concentration of Mg²⁺ ions released into culture media with a concentration range of 9-15 mM; (2) the lower Ca²⁺ ion concentration in culture media at 1.3-1.6 mM; and (3) the favorable surface conditions of PLGA (50:50), when compared with the other sample groups. This in vitro study provided the first evidence that the PLGA (50:50) is a promising coating material for Mg-based biodegradable metals toward potential cardiovascular or neurovascular applications.