Radcliffe Department of Medicine, Wellcome Trust Centre for Human Genetics, Department of Cardiovascular Medicine , University of Oxford , Roosevelt Drive, Old Road Campus , Headington, Oxford OX3 7BN , U.K.
Applied Biotechnology Research Group, Faculty of Science and Technology , University of Westminster , 115 New Cavendish Street , London W1W 6UW , U.K.
ACS Appl Mater Interfaces. 2018 Aug 1;10(30):25056-25068. doi: 10.1021/acsami.8b06096. Epub 2018 Jul 18.
Medium-chain length polyhydroxyalkanoates (MCL-PHAs) have demonstrated exceptional properties for cardiac tissue engineering (CTE) applications. Despite prior work on MCL-PHA/polycaprolactone (PCL) blends, optimal scaffold production and use as an alternative delivery route for controlled release of seeded cardiac progenitor cells (CPCs) in CTE applications in vivo has been lacking. We present herein applicability of MCL-PHA/PCL (95/5 wt %) blends fabricated as thin films with an improved performance compared to the neat MCL-PHA. Polymer characterization confirmed the chemical structure and composition of the synthesized scaffolds, while thermal, wettability, and mechanical properties were also investigated and compared in neat and porous counterparts. In vitro cytocompatibility studies were performed using perfluorocrown-ether-nanoparticle-labeled murine CPCs and studied using confocal microscopy and F magnetic resonance spectroscopy and magnetic resonance imaging (MRI). Seeded scaffolds were implanted and studied in the postmortem murine heart in situ and in two additional C57BL/6 mice in vivo (using single-layered and double-layered scaffolds) and imaged immediately after and at 7 days postimplantation. Superior MCL-PHA/PCL scaffold performance has been demonstrated compared to MCL-PHA through experimental comparisons of (a) morphological data using scanning electron microscopy and (b) contact angle measurements attesting to improved CPC adhesion, (c) in vitro confocal microscopy showing increased SC proliferative capacity, and (d) mechanical testing that elicited good overall responses. In vitro MRI results justify the increased seeding density, increased in vitro MRI signal, and improved MRI visibility in vivo, in the double-layered compared to the single-layered scaffolds. Histological evaluations [bright-field, cytoplasmic (Atto647) and nuclear (4',6-diamidino-2-phenylindole) stains] performed in conjunction with confocal microscopy imaging attest to CPC binding within the scaffold, subsequent release and migration to the neighboring myocardium, and increased retention in the murine myocardium in the case of the double-layered scaffold. Thus, MCL-PHA/PCL blends possess tremendous potential for controlled delivery of CPCs and for maximizing possible regeneration in myocardial infarction.
中链长度聚羟基烷酸酯（MCL-PHAs）在心脏组织工程（CTE）应用中表现出了卓越的性能。尽管之前已经有关于 MCL-PHA/聚己内酯（PCL）共混物的研究，但在 CTE 应用中，作为种子心脏祖细胞（CPCs）控释的替代输送途径，最优支架的生产和使用仍有待完善。本文介绍了 MCL-PHA/PCL（95/5wt%）共混物作为薄膜的应用适用性，与纯 MCL-PHA 相比，其性能得到了改善。聚合物特性分析证实了合成支架的化学结构和组成，同时还研究并比较了纯支架和多孔支架的热性能、润湿性和机械性能。使用全氟冠醚纳米粒子标记的鼠 CPCs 进行了体外细胞相容性研究，并使用共聚焦显微镜和 F 磁共振光谱和磁共振成像（MRI）进行了研究。植入种子支架后，在原位和另外两只 C57BL/6 小鼠体内（使用单层和双层支架）进行了研究，并在植入后立即和 7 天后进行了成像。通过对（a）扫描电子显微镜的形态数据和（b）接触角测量结果的比较，证明了 MCL-PHA/PCL 支架的性能优于 MCL-PHA，接触角测量结果证明了 CPC 黏附性的提高，（c）共聚焦显微镜显示出增强的 SC 增殖能力，以及（d）力学测试得到了良好的整体响应。体外 MRI 结果证明，与单层支架相比，双层支架具有更高的种子密度、更高的体外 MRI 信号和更好的体内 MRI 可见度。与共聚焦显微镜成像相结合的组织学评估（明场、细胞质（Atto647）和核（4'，6-二脒基-2-苯基吲哚）染色）证明了 CPC 在支架内的结合，随后释放和迁移到邻近的心肌，并在双层支架的情况下在鼠心肌中的保留增加。因此，MCL-PHA/PCL 共混物具有控制 CPC 释放和最大限度促进心肌梗死再生的巨大潜力。
