Tuesday, May 23, 2017

Biodegradable polyesters (PLGA, PLA, PCL) from PolySciTech investigated for controlling Mg-based cardiovascular stent degradation



One treatment for cardiovascular disease is balloon angioplasty, in which a stent is emplaced at the site of arterial blockage in the heart. Initial work with bare-metal stents had reasonably successful results in keeping the artery open by providing structural support but, over time, the tissue of the vessel would grow back over the stent and into the interior portion of it reclosing the artery by a process known as restenosis. A variety of strategies have been applied to solving this issue. One strategy is to utilize a temporary, biodegradable stent comprised primarily of magnesium, which slowly corrodes back into biocompatible magnesium ions leaving no foreign surface for the arterial cells to grow over. However, the speed of Mg breakdown, on its own, is too rapid for stent application. Recently, researchers working at University of California at Riverside and Norco College utilized PLGA, PLLA, and PCL from PolySciTech (www.polyscitech.com) PLLA (No. AP007), PLGA (90:10) (No. AP049), PLGA (50:50) (No. AP089), and PCL (No. AP009) to develop a series of biodegradable coatings to cover over magnesium-type stents. These coatings were used to delay Mg degradation and to improve the stent-surface interaction with arterial cells. This research holds promise for improved cardiovascular treatment by using biodegradable stents which do not suffer from late-stage restenosis. Read more: Jiang, Wensen, Qiaomu Tian, Tiffany Vuong, Matthew Shashaty, Chris Gopez, Tian Sanders, and Huinan Liu. "Comparison Study on Four Biodegradable Polymer Coatings for Controlling Magnesium Degradation and Human Endothelial Cell Adhesion and Spreading." ACS Biomaterials Science & Engineering (2017). http://pubs.acs.org/doi/abs/10.1021/acsbiomaterials.7b00215

“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. Keywords: bioresorbable cardiovascular scaffold; bioresorbable magnesium implants; human umbilical vein endothelial cells; in vitro direct culture method; polymer coatings”
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