BIOACTIVE SCAFFOLDS FOR VASCULAR SURGERY

描述（由申请人提供）：管状移植物和贴片形式的人工和天然生物材料经常用于成人和儿童血管疾病的手术治疗。虽然这些生物材料恢复了所需的基本机械功能，但它们不能完全融入它们所处的生物环境，并因动脉粥样硬化、血栓形成、感染、变性和钙化而失效。此外，当植入儿科患者体内时，它们无法生长。总的来说，临床现实是传统的人工假体装置不能完全替代器官，自体移植组织不常见，同种异体移植组织需求量大但供应不足。由于心血管疾病是一个严重的健康问题，我们认为这项研究与公众健康高度相关。因此，我们的长期目标是为血管手术开发“现成的、功能性的组织工程血管移植物和贴片”，从而最终影响成千上万的患者。我们的方法是基于血管衍生的非细胞支架的发展，这种支架可以促进宿主细胞的再生，促进植入后的重塑，同时保持足够的机械功能。由于基质非常致密，脱细胞血管不完全有利于细胞再生，除非支架稳定，否则植入后可能发生变性和钙化。我们的纯弹性蛋白支架通过去除胶原成分（除了细胞去除）获得，比去细胞动脉更多孔，与去细胞动脉相比，更容易在体内重新填充和重塑。在具体目标1。我们将制备并充分表征从猪动脉中获得的纯弹性蛋白支架，并用五没食子酰葡萄糖（PGG）处理，一种稳定弹性蛋白的酚类单宁，用于管理酶介导的生物降解和抑制钙化。作为稳定的标准，我们将使用重量法，ELISA和超微结构分析来测试对金属蛋白酶（MMPs）的抗性。稳定弹性蛋白的力学性能包括应力应变、顺应性、破裂压力和残余应变（后坐力）也将进行评估。然后用碱性成纤维细胞生长因子（bFGF）处理稳定的弹性蛋白支架，以增强再生和新生血管，并通过体外浸出研究来检测bFGF结合的稳定性。在具体目标2。将稳定的、具有生物活性的弹性蛋白支架植入大鼠皮下，初步评估其生物相容性和宿主反应，并选择最佳的PGG浓度。用PGG和bFGF处理的管状弹性蛋白构建体将植入自体内皮细胞以抵抗血栓形成，并在循环兔模型中用作介入血管移植物，并评估其特性，包括通畅、重塑、炎症、免疫反应性和血栓形成性。工程弹性蛋白支架的性能将与去细胞化动脉对照进行一致的比较。

DESCRIPTION (provided by applicant): Artificial and natural biomaterials in the form of tubular grafts and patches are frequently used for surgical treatment of vascular diseases in adults and children. While these biomaterials restore the required basic mechanical functions, they fail to fully integrate into the biological milieu to which they are subjected and fail due to atherosclerosis, thrombosis, infections, degeneration and calcification. Moreover, they fail to grow when implanted in a pediatric patient. Overall, the clinical reality is that traditional artificial prosthetic devices cannot fully replace organs, autograft tissue is not typically available, and allograft tissue is in high demand but short supply. Since cardiovascular diseases are a serious health concern we believe that this study is highly relevant to public health. Therefore, our long-term objective is to develop "off the shelf, functional tissue-engineered vascular grafts and patches for vascular surgery, thus ultimately impacting thousands of patients. Our approach is based on development of acellular scaffolds derived from blood vessels that encourage repopulation by host cells and facilitate remodeling after implantation, while maintaining adequate mechanical functions. Due to their very dense matrix, decellularized blood vessels are not fully conducive to cell repopulation and unless scaffolds are stabilized, degeneration and calcification may occur upon implantation. Our pure elastin scaffolds obtained by removal of the collagen component (in addition to cell removal), are more porous than decellularized arteries and are more readily repopulated and remodeled in vivo, as compared to decellularized arteries. In Specific Aim 1. We will prepare and fully characterize pure elastin scaffolds obtained from porcine arteries and treat with penta-galloyl glucose (PGG), an elastin- stabilizing phenolic tannin, for management of enzyme-mediated biodegradation and inhibition of calcification. As criteria for stabilization we will test resistance to metalloproteinases (MMPs) using gravimetry, ELISA and ultrastructural analysis. Mechanical properties of stabilized elastin including stress- strain, compliance, burst pressure and residual strain (recoil) will also be evaluated. Stabilized elastin scaffolds will be then treated with basic fibroblast growth factor (bFGF) for enhanced repopulation and neovascularization, and bFGF-binding stability will be assayed by in vitro leaching studies. In Specific Aim 2. stabilized, bioactive elastin scaffolds will be implanted subdermally in rats for initial evaluation of biocompatibility and host reactions and selection of optimal PGG concentration. Tubular elastin constructs, treated with PGG and bFGF, will be seeded with autologous endothelial cells for thrombosis resistance and used as interposition vascular grafts in a circulatory rabbit model and their properties, including patency, remodeling, inflammation, immunological reactivity and thrombogenicity, will be evaluated. Properties of engineered elastin scaffolds will be consistently compared to those of decellularized artery controls.