Pathophysiology and prevention of degeneration of heterograft biomaterials due to advanced glycation end products and serum protein infiltration

生物人工心脏瓣膜(BHV)，由戊二醛固定的牛等异种生物材料制成 心包(BP)被广泛用于患有严重心脏瓣膜疾病(HVD)的患者的替代品， 这影响了全球数百万人。尽管有效，但由英国石油公司制造的BHV的局限性是 它们会经历结构瓣膜退化(SVD)，这限制了耐久性。尽管最常见的是 归因于钙化，最近的研究表明，晚期糖基化终产物(AGE)和血清 蛋白质渗透也是导致SVD的原因之一。AGE机制损害内皮细胞生长，并可能 BHV内皮化不足的机制在实验和临床上都有一定的作用。许多研究都是为了 已经进行了抑制BP钙化的研究；然而，减轻AGE-血清蛋白积聚的策略 才刚刚开始探索。通过我们最近的研究，我们发现了一种年龄抑制因子 吡哆胺(PYR)，一种维生素B6维生素，是一种领先的模型化合物，对 降低BP在大鼠皮下埋植剂体内和体外的AGE蓄积和血清蛋白摄取 学习。此外，我们还建立了一种创新的聚2-甲基-2-羟基丁二酸二异氰酸酯修饰BP。 恶唑啉(POZ)，它显著降低了体外和大鼠皮下组织对血清蛋白质的摄取。 本论文和本方案的中心假设是：用PYR和POZ对BP进行预处理可以 减轻导致非钙化性SVD机制的年龄和血清蛋白病理生理学。乙醇 BP的(无水乙醇)预处理是FDA批准的抗钙化方法，将是一种基于机械的 在我的研究设计中进行实验干预，这将有助于探索钙化和非钙化之间的相互作用 钙化的SVD机制。目的1：体外研究AGE和AGE的抑制作用机制及疗效 通过研究内皮细胞与BP的相互作用来提高异种移植生物相容性的血清蛋白渗透。 Subaim 1a：评估PYR预处理BP以延缓年龄和血清蛋白机制的效果： 血液生长内皮细胞(BOEC)培养的高剪切流模拟研究。苏巴伊姆1b：至 确定POZ介导的血清蛋白排斥对促进BOEC黏附和还原的作用 血管内皮细胞的激活。目的2：探讨AGE和血清抑制作用的机制和疗效 使用大鼠皮下BP植入物的蛋白质SVD病理以及与钙化的相互作用：PYR和POZ 学习。Subaim 2a：研究PYR处理的BP在有或没有乙醇预处理的情况下的疗效 使用大鼠皮下植入模型减轻年龄-血清蛋白病理生理学和钙化。苏巴伊姆 2B：研究POZ单独以及BP与PYR、POZ和乙醇联合预处理的疗效。 减轻大鼠皮下植入模型的年龄、血清蛋白摄取和钙化。调查结果来自 这项建议将推进我的研究培训，并有助于提高我们对BHV SVD的了解。

Bioprosthetic heart valves (BHV), fabricated from heterograft biomaterials such as glutaraldehyde-fixed bovine pericardium (BP), are widely used as a replacement for patients who have severe heart valve disease (HVD), which affects millions of people worldwide. Despite being effective, a limitation of BHV fabricated from BP is that they undergo structural valve degeneration (SVD) which limits durability. Although most commonly attributed to calcification, recent research has shown that advanced glycation end products (AGE) and serum protein infiltration also contributes to SVD. AGE mechanisms impair endothelial cell growth and may mechanistically contribute to lack of endothelialization of BHV experimentally and clinically. Many studies to inhibit calcification of BP have been done; however, strategies to mitigate AGE-serum protein accumulation have just begun to be explored. Through our studies we have recently identified, the AGE-inhibitor pyridoxamine (PYR), a vitamin B6 vitamer, to be a leading model compound that is effective in significantly reducing AGE accumulation and serum protein uptake of BP both in vitro and in vivo in rat subdermal implant studies. Furthermore, we have also established an innovative modification of BP with Poly-2-methyl-2- oxazoline (POZ), which significantly reduced serum protein uptake both in vitro and in rat subdermal explants. The central hypothesis of both my dissertation and this proposal is: Pretreatment of BP with PYR and POZ can mitigate AGE and serum protein pathophysiology that contributes to noncalcific SVD mechanisms. Ethanol (EtOH) pretreatment of BP, an FDA approved anti-calcification methodology, will be a mechanistically based experimental intervention in my study design, that will help explore the interactions between calcific and non- calcific SVD mechanisms. Aim 1: Investigate in vitro the mechanism and efficacy of inhibition of AGE and serum protein infiltration to enhance heterograft biocompatibility by studying endothelial cell-BP interactions. Subaim 1a: Evaluate the effects of PYR pretreatment of BP to mitigate AGE and serum protein mechanisms: blood outgrowth endothelial cell (BOEC) culture studies with high shear flow simulation. Subaim 1b: To determine the effect of POZ mediated serum protein exclusion on promotion of BOEC adhesion and reduction of endothelial activation. Aim 2: To investigate the mechanism and efficacy of inhibition of AGE and serum protein SVD pathology, and interactions with calcification using rat subdermal BP implants: PYR and POZ studies. Subaim 2a: To study the efficacy of PYR pretreated BP, with or without ethanol pretreatment, on mitigating AGE-serum protein pathophysiology and calcification using a rat subdermal implant model. Subaim 2b: To study the efficacy of POZ alone, and the combined BP pretreatment with PYR, POZ, and ethanol for mitigating AGE, serum protein uptake and calcification in the rat subdermal implant model. The findings from this proposal will advance my research training and contribute to advances in our knowledge of SVD of BHV.