Autologous EPC lining to improve biocompatibility of circulatory assist devices

描述(由申请人提供)：本申请涉及广泛的挑战领域(15)转化科学和具体的挑战主题，15-HL-101：为植入式接触血液的医疗器械开发改进的生物相容性表面。每年有500多万美国人患有心力衰竭，而且还在不断增加。虽然心脏移植是终末期心力衰竭患者的最佳治疗方法，但可用的供体器官不足。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，血液与其内表面(通常是钛)接触往往会导致凝血障碍，导致出血和血栓形成。大多数MCAD的局部低血流和血瘀区也会增加血栓形成的风险，特别是在部分循环支持设备中，这些设备可能会使100多万患有较不严重心力衰竭的患者受益。我们假设患者自身内皮祖细胞(EPC)的融合衬里将提供更具抗血栓形成和生物相容性的表面，并提出以下特定目标：特定目标1：通过在细胞种植于钛(Ti)管内之前过度表达抗凝和抗炎蛋白血栓调节蛋白(TM)，从基因上增强从猪外周血中分离的内皮祖细胞。具体目标2：通过外科手术将内衬有基因增强型(TM-EPC)或非增强型内皮祖细胞的钛管植入来源为内皮祖细胞的猪的下腔静脉，并将其与一组植入无涂层、裸露钛管的猪进行比较。第四组将是只接受假手术的对照组。将在四个时间点从所有猪身上采集外周血液样本，并使用成熟的生物检测方法对血栓形成和炎症的已知标记物进行量化。我们假设，已知的血栓形成和炎症标志物，从这些猪的外周血液样本中量化，将证明EPC衬里的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型细胞(TM-EPC)将使钛的血栓形成能力更低。具体目标3：对所有外周血液样本进行基于分析微阵列的蛋白质组分析，并比较每种动物体内四个不同的组和时间点，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子集将反映EPC种子的影响，并揭示基因增强的TM-EPC和裸钛植入物之间的差异。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的生物标志物。根据美国心脏协会的数据，美国有500多万人患有心力衰竭。此外，心力衰竭的患病率正在稳步上升，部分原因是我们人口的老龄化。尽管药物治疗有所改进，但这些患者的死亡率仍然非常高，男性和女性的5年中位存活率仅为25%和38%。仅在2004年，美国就有100多万人在出院时被诊断为心力衰竭。据估计，超过25万名患者处于这种疾病的晚期，并患有严重的症状，即使进行最大限度的药物治疗也无法缓解。我们的提议的结果可能会带来一种技术，通过为部分和完全支持衰竭的心脏的机械循环辅助设备提供生物兼容的血液接触表面，可以缓解100多万美国人的症状。此外，该技术还可应用于其他钛/钛合金血液接触表面，如镍钛合金血管支架。这些支架可能会对支架内再狭窄产生抵抗力，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。 与公共健康相关：根据美国心脏协会的数据，美国有500多万人患有心力衰竭。此外，心力衰竭的患病率正在稳步上升，部分原因是我们人口的老龄化。尽管药物治疗有所改进，但这些患者的死亡率仍然非常高，男性和女性的5年中位存活率仅为25%和38%。仅在2004年，美国就有100多万人在出院时被诊断为心力衰竭。据估计，超过25万名患者处于这种疾病的晚期，并患有严重的症状，即使进行最大限度的药物治疗也无法缓解。我们的提议的结果可能会带来一种技术，通过为部分和完全支持衰竭的心脏的机械循环辅助设备提供生物兼容的血液接触表面，可以缓解100多万美国人的症状。此外，该技术还可应用于其他钛/钛合金血液接触表面，如镍钛合金血管支架。这些支架可能会对支架内再狭窄产生抵抗力，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.