Monday, May 15, 2017

PLGA from PolySciTech used as rapamycin eluting coating on magnesium alloy stents for restenosis prevention as part of heart-disease research


A popular treatment for cardiac blockage is angioplasty. Under this treatment, a thin catheter is run up to the affection portion of the heart and then a balloon is expanded near the tip to remove the blockage. A drawback to this technique is that, over time, the affected blood vessel re-narrows unless something is left in place, such as a stent. Over a longer period of time, the tissues of the blood vessel will regrow over the stent and re-block the vessel by a process called restenosis. A wide variety of technologies have been applied to dealing with this issue so as to provide a long-term and effective angioplasty treatment for treating coronary artery diseases which can lead to heart-attacks if the vessel.  Recently, Researchers working jointly at Purdue University, Shanghai Jiao Tong University (China), and Microport Endovascular Co. utilized PLGA from PolySciTech (www.polyscitech.com) (PolyVivo AP122) to generate a drug-loaded coating on the stent which released anti-proliferative rapamycin to prevent restenosis. They tested this coating both on conventional stainless steel surfaces as well as novel magnesium alloys. They analyzed these samples for drug release, polymer degradation, cellular response, and other parameters. They found drug release was accelerated by the magnesium alloy underlayment and that these materials showed superior anti-proliferative capacity relative to stainless steel. This research holds promise to effectively treat coronary artery disease and prevent heart-attacks by maintaining good blood flow through the blood vessels of the heart. Read more:  Shi, Yongjuan, Jia Pei, Lei Zhang, Byung Kook Lee, Yeonhee Yun, Jian Zhang, Zhonghua Li, Song Gu, Kinam Park, and Guangyin Yuan. "Understanding the effect of magnesium degradation on drug release and anti-proliferation on smooth muscle cells for magnesium-based drug eluting stents." Corrosion Science (2017). http://www.sciencedirect.com/science/article/pii/S0010938X16314433

“Abstract: 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. Highlights: We firstly reported that the degradation of magnesium substrate would improve the in vitro rapamycin release from drug-loading PLGA/RAPA system on a Mg-Nd-Zn-Zr alloy. We quantitatively analyzed the factors enhancing the in vitro drug release kinetics from Mg-based drug-eluting system, distinguishing that it was mainly caused by H2 evolution, while pH only played a trivial role. We reported for the first time that the Mg-based PLGA/RAPA drug-loading system exhibited more pronounced long-term inhibition for the proliferation of smooth muscle cells, under conditions that PLGA with low degradation rate was used as the drug carrier. Keywords Magnesium; Organic coatings; Polymer; Erosion; Interfaces; Kinetic parameters.”
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