Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, China.
Acta Biomater. 2012 Jul;8(7):2659-69. doi: 10.1016/j.actbio.2012.03.044. Epub 2012 Apr 3.
Key challenges associated with the outcomes of vascular grafting (for example, to fully vascularize engineered tissues and promptly regenerate blood vessel substitutes) remain unsolved. The local availability of angiogenic growth factors is highly desirable for tissue regeneration, and plasmid loading in scaffolds represents a powerful alternative for local production of tissue-inductive factors. No attempt has been made so far to clarify the efficacy of electrospun fibers with the loading of multiple plasmids to promote tissue regeneration. In the present study, core-sheath electrospun fibers with the encapsulation of polyplexes of basic fibroblast growth factor-encoding plasmid (pbFGF) and vascular endothelial growth factor-encoding plasmid (pVEGF) were evaluated to promote the generation of mature blood vessels. In vitro release indicated a sustained release of pDNA for ∼4 weeks with as low as ∼10% initial burst release, and the release patterns from the single and twofold plasmid-loaded systems coincided. In vitro investigations on human umbilical vein endothelial cells showed that the sustained release of pDNA from fibrous mats promoted cell attachment and viability, cell transfection and protein expression, and extracellular secretion of collagen IV and laminin. The acceleration of angiogenesis was assessed in vivo after subcutaneous implantation of fibrous scaffolds, and the explants were evaluated after 1, 2 and 4 weeks' treatment by histological and immunohistochemical staining. Compared with pDNA polyplex infiltrated fibrous mats, the pDNA polyplex encapsulated fibers alleviated the inflammation reaction and enhanced the generation of microvessels. Although there was no significant difference in the total number of microvessels, the density of mature vessels was significantly enhanced by the combined treatment with both pbFGF and pVEGF compared with those incorporating individual pDNA. The integration of the core-sheath structure, DNA condensation and multiple delivery strategies provided a potential platform for scaffold fabrication to regenerate functional tissues.
血管移植术的结果（例如，使工程组织完全血管化并迅速再生血管替代物）仍然存在诸多挑战，尚未得到解决。组织再生非常需要局部提供血管生成生长因子，而支架中质粒的加载为局部产生组织诱导因子提供了一种强大的替代方法。迄今为止，尚未尝试阐明负载多种质粒的电纺纤维促进组织再生的功效。在本研究中，评估了包封碱性成纤维细胞生长因子（bFGF）编码质粒（pbFGF）和血管内皮生长因子（VEGF）编码质粒（pVEGF）的多聚物的核-鞘电纺纤维，以促进成熟血管的生成。体外释放表明，pDNA 的释放可持续约 4 周，初始突释率低至约 10%，并且单载和双载质粒系统的释放模式一致。体外研究人脐静脉内皮细胞表明，纤维垫中 pDNA 的持续释放可促进细胞附着和活力、细胞转染和蛋白表达以及胶原 IV 和层粘连蛋白的细胞外分泌。皮下植入纤维支架后评估体内血管生成的加速情况，并通过组织学和免疫组织化学染色在治疗 1、2 和 4 周后评估标本。与 DNA 多聚物渗透的纤维垫相比，DNA 多聚物包封的纤维减轻了炎症反应，并增强了微血管的生成。尽管微血管总数没有显著差异，但与单独载 pbFGF 和 pVEGF 相比，两种质粒联合治疗可显著增强成熟血管的密度。核-鞘结构、DNA 凝聚和多种传递策略的整合为支架制造提供了一个再生功能性组织的潜在平台。
