Autologous EPC lining to improve biocompatibility of circulatory assist devices

描述（由申请人提供）：该申请涉及广泛的挑战领域（15）转化科学和特定的挑战主题，15- HL-101：为植入式血液接触医疗设备开发改进的生物相容性表面。每年有超过500万美国人患有心力衰竭，而且人数还在不断增加。虽然心脏移植是终末期心力衰竭患者的最佳治疗方法，但供体器官不足。机械循环辅助装置（mcad）可以降低死亡风险，提高这些患者的生活质量；然而，血液与它们的内表面（通常是钛）接触往往会引起凝血功能障碍，导致出血和血栓形成。在大多数mcad中，局部低流量和血瘀也会增加血栓形成的风险，特别是在部分循环支持装置中，这可能使100多万不太严重的心力衰竭患者受益。我们假设患者自身内皮祖细胞（EPCs）的融合内衬将提供更抗血栓形成和生物相容性的表面，并提出以下具体目标：具体目标1：在将细胞植入钛（Ti）管内部之前，通过过度表达抗凝血和抗炎蛋白血栓调节蛋白（TM），从猪外周血中分离出内皮祖细胞。具体目标2：通过手术将内衬有基因增强（TM-EPC）或未增强EPCs的Ti管植入EPCs来源的猪下腔静脉，并将其与一组接受未涂层裸Ti管植入的猪进行比较。第四组将作为对照组，只进行假手术。将在4个时间点采集所有猪的外周血样本，并使用成熟的生物测定法对已知的血栓和炎症标志物进行量化。我们假设，从这些猪的外周血样本中量化的已知血栓和炎症标志物将证明epc衬里血液接触表面的生物相容性得到改善。此外，我们预计我们的基因增强细胞（TM-EPC）将使钛更少的血栓形成。具体目标3：对所有外周血样本进行基于微阵列的分析性蛋白质组学分析，并比较每只动物的四个不同组和时间点，以确定与凝血、纤溶、炎症和补体激活相关的大量已知蛋白质的差异表达水平。我们假设这些特定蛋白质的一个子集将反映EPC播种的影响，以及揭示基因增强的TM-EPCs与裸Ti植入物之间的差异。所获得的知识将扩展我们对血液接触表面生物相容性的理解，并可能产生一组新的血液接触表面生物相容性生物标志物。根据美国心脏协会的数据，在美国有超过500万人患有心力衰竭。此外，心力衰竭的发病率正在稳步上升，部分原因是人口老龄化。尽管医学治疗有所改善，但这些患者的死亡率仍然非常高，男性的5年中位生存率仅为25%，女性为38%。仅在2004年，美国就有超过100万人因心力衰竭出院。据估计，有25万以上的患者处于该病的晚期，症状严重，即使进行最大限度的药物治疗也无法缓解。我们建议的结果可能会导致一种技术，通过为机械循环辅助装置提供生物相容的血液接触面来减轻100多万美国人的症状，以部分或完全支持衰竭的心脏。此外，该技术还可以应用于其他钛/钛合金血液接触面，如镍钛诺血管支架。它们可以抵抗支架内再狭窄，并使数百万正在接受冠状动脉或血管支架治疗的美国人受益。

DESCRIPTION (provided by applicant): This application addresses broad Challenge Area (15) Translational Science and specific Challenge Topic, 15- HL-101: Develop improved biocompatible surfaces for implantable blood-contacting medical devices. More than five million Americans, and increasingly more, suffer from heart failure yearly. Although cardiac transplantation is the best treatment for end-stage heart failure patients, not enough donor organs are available. Mechanical circulatory assist devices (MCADs) can reduce the risk of death and increase the quality of life for these patients; however, the contact of blood with their inner surface (usually titanium) often causes a coagulopathy resulting in bleeding and thrombosis. Local areas of low flow and blood stasis in most MCADs also contribute to the risk for thrombosis, especially in partial circulatory support devices that could benefit more than a million patients with less advanced heart failure. We hypothesize that a confluent lining of the patients' own endothelial progenitor cells (EPCs) will provide a more antithrombogenic and biocompatible surface and propose the following specific aims: Specific Aim 1: to genetically enhance endothelial progenitor cells, isolated from swine peripheral blood, by over-expressing the anticoagulant and anti-inflammatory protein thrombomodulin (TM) before the cells are seeded on the inside of titanium (Ti) tubes. Specific Aim 2: to surgically implant Ti tubes lined with either genetically enhanced (TM-EPC) or un-enhanced EPCs into the inferior vena cava of those pigs from which the EPCs were derived, and compare them to a group of pigs that undergoes implantation of uncoated, bare Ti tubes. A fourth group will be a control group undergoing sham operations only. Peripheral blood samples will be obtained at four time points from all pigs, and known markers of thrombosis and inflammation will be quantified with well-established bioassays. We hypothesize that known markers of thrombosis and inflammation, quantified from peripheral blood samples in these pigs, will demonstrate an improved biocompatibility of EPC-lined blood contacting surfaces. Furthermore, we anticipate that our genetically enhanced cells (TM-EPC) will render the titanium even less thrombogenic. Specific Aim 3: to perform analytical microarray-based proteomic analysis on all peripheral blood samples and to compare the four different groups and time points within each animal in order to determine the differential expression levels of a large number of known proteins associated with coagulation, fibrinolysis, inflammation and complement activation. We hypothesize that a subset of these specific proteins will reflect the effects of EPC seeding, as well as reveal differences between genetically enhanced TM-EPCs and bare Ti implants. The knowledge gained will extend our understanding of the biocompatibility of blood-contacting surfaces, and may give rise to a panel of novel biomarkers of biocompatibility of blood-contacting surfaces. According to the American Heart Association, that there are more than 5 million people living in the United States who are suffering from heart failure. Moreover, the prevalence of heart failure is steadily increasing, in part because of the aging of our population. Despite improvements in medical therapy, the mortality rate in these patients has remained extremely high, with a 5-year median survival rate of only 25% in men and 38% in women. In 2004 alone, there were over one million hospitalizations in the US with a first listed discharge diagnosis of heart failure. It is estimated that more than 250,000 of patients are in the terminal phases of this disease and suffering from severe symptoms, which cannot be alleviated even with maximal medical therapy. The results of our proposal may lead to a technology, which could alleviate the symptoms of more than one million of Americans by providing a biocompatible blood-contacting surface for mechanical circulatory assist devices for partial as well as full support of the failing heart. Furthermore, this technology could be applicable to other titanium /titanium-alloy blood-contacting surfaces, such as nitinol vascular stents. These could become resistant to in-stent restenosis and benefit millions of Americans who are being treated with coronary or vascular stents. PUBLIC HEALTH RELEVANCE: According to the American Heart Association, that there are more than 5 million people living in the United States who are suffering from heart failure. Moreover, the prevalence of heart failure is steadily increasing, in part because of the aging of our population. Despite improvements in medical therapy, the mortality rate in these patients has remained extremely high, with a 5-year median survival rate of only 25% in men and 38% in women. In 2004 alone, there were over one million hospitalizations in the US with a first listed discharge diagnosis of heart failure. It is estimated that more than 250,000 of patients are in the terminal phases of this disease and suffering from severe symptoms, which cannot be alleviated even with maximal medical therapy. The results of our proposal may lead to a technology, which could alleviate the symptoms of more than one million of Americans by providing a biocompatible blood-contacting surface for mechanical circulatory assist devices for partial as well as full support of the failing heart. Furthermore, this technology could be applicable to other titanium /titanium-alloy blood-contacting surfaces, such as nitinol vascular stents. These could become resistant to in-stent restenosis and benefit millions of Americans who are being treated with coronary or vascular stents.