通过形状优化方法设计的可生物降解镁合金血管支架的体内与体外评估

In vivo and in vitro evaluation of a biodegradable magnesium vascular stent designed by shape optimization strategy

发表状态：

Biomaterials. Volume 221, November 2019, 119414

研究团队：

Chenxin Chen,a,b※Jiahui Chen,c※Wei Wu,b,d※Yongjuan Shi,a Liang Jin,a Lorenza Petrini,eLi Shen,c Guangyin Yuan,a,* Wenjiang Ding,a Junbo Ge,c Elazer R. Edelmanf,g and Francesco

Migliavaccab,*

Kristopher W. Kolewe,§,† Kerianne M. Dobosz,§,† Katrina A. Rieger,† Chia-Chih Chang,‡ Todd Emrick,‡
and Jessica D. Schiffman*,†
†Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
‡Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303,
United States

研究内容：

可降解镁合金支架（BMgS）需要特别注意残余应力不均匀分布和应力集中的性能，这可能会加速植入后的局部降解。现在我们报道一种使用有限元法（FEM）软件包进行支架结构优化的新理念。具有均匀降解行为的Mg-Nd-Zn-Zr合金是BMgS的基材。支架优化综合体外评估进行，同时基于观察到的卷曲和球囊膨胀行为，径向强度测量以及通过微区XRD验证应力条件。此外，将雷帕霉素洗脱聚合物涂层喷涂在原型BMgS上来改善耐腐蚀性并释放抗增生药物。经过涂层改进后，在新西兰白兔的髂动脉中进行BMgS的体内评价，未观察到血栓或早期再狭窄，并且涂覆后的BMgS在降解之前可以有效地支撑血管及之后的动脉愈合。

提出的基于FEM的形状优化框架为支架设计提供了一种新理念，并深入了解了变形历史对BMgS生物力学性能的影响。计算分析工具确实可以促进可生物降解的镁支架的发展。

Abstract：

The performance of biodegradable magnesium alloy stents (BMgS) requires special attention to non-uniform residual stress distribution and stress concentration, which can accelerate localized degradation after implantation. We now report on a novel concept in stent shape optimization using a finite element method (FEM) toolkit. A Mg-Nd-Zn-Zr alloy with uniform degradation behavior served as the basis of our BMgS. Comprehensive in vitro evaluations drove stent optimization, based on observed crimping and balloon inflation performance, measurement of radial strength, and stress condition validation via microarea-XRD. Moreover, a Rapamycin-eluting polymer coating was sprayed on the prototypical BMgS to improve the corrosion resistance and release anti-hyperplasia drugs. In vivoevaluation of the optimized coated BMgS was conducted in the iliac artery of New Zealand white rabbit with quantitative coronary angiography (QCA), optical coherence tomography (OCT) and micro-CT observation at 1, 3, 5-month follow-ups. Neither thrombus or early restenosis was observed, and the coated BMgS supported the vessel effectively prior to degradation and allowed for arterial healing thereafter.

The proposed shape optimization framework based on FEM provides an novel concept in stent design and in-depth understanding of how deformation history affects the biomechanical performance of BMgS. Computational analysis tools can indeed promote the development of biodegradable magnesium stents.

（来源： 仿生医用材料课题组）