Vergleichende in vivo Untersuchung verschiedener Konservierungsverfahren von allogenen Herzklappen

同种异体心脏瓣膜不同保存方法的体内比较研究

• 批准号: 51176423
• 负责人: Professor Dr. Ulrich A. Stock
• 金额: --
• 依托单位: Universitätsklinik für Thorax-, Herz- und Gefäßchirurgie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/51176423?language=en
• 关键词: Vergleichende; vivo; Untersuchung; verschiedener; Konservierungsverfahren

Human heart valves or allografts represent nearly perfect heart valve substitutes. They have optimal hemodynamic characteristics and are resistant to infections. Disadvantages particularly in pediatric patients are limited availability, an inability to grow, degeneration and long-term failure. Potential culprits for the latter include immunological responses and an increased calcium metabolism. The first clinical use of allograft heart valves was as homovitals that were transplanted after antibiotic incubation without any preservation. Since 1968 standard frozen cryopreservation (SFC) has been employed including storage in vapour phase liquid nitrogen. Application of multiphoton imaging analysis (MIA) enables three dimensional visualization of elastin and collagen by induction of autofluorescence without fixation, embedding and staining in fresh tissue. MIA allowed for the first time detection of partial destruction of elastic and collagenous matrix in SFC porcine valves ex situ. As the overall amount of collagen and elastin remains unchanged the etiology of the above described destruction is postulated as freezing induced extracellular matrix (ECM) damage due to ice crystals. Disruptive interstitial ice damage that occurs during cryopreservation can be avoided by promoting vitrification, glass formation, instead of ice formation below the cryopreservation solutions glass transition temperature. As the preservation and warming is accomplished without any tissue destruction, vitrification enabled for the first time complete preservation of extracellular matrix in heart valves. In order to simplify the required infrastructure, we have further developed ice free cryopreservation (IFC), which permits storage above the solutions glass transition temperature in a 80C freezer. We applied IFC in a recent sheep study and were able to demonstrate that maintaining ECM results in better valve function and diminished degeneration. Furthermore, IFC is antiinflammatory preventing CD3 positive T cell mediated responses. The exact mechanism of this attenuated adaptive immune response remains unknown. Recent studies in a porcine tissue to human responder peripheral blood leukocyte combination have shown that treatment of valve tissue with IFC preservation medium reduces leaflet immunogenicity and induces responder monocyte differentiation towards endothelial like cells. Accordingly application of IFC for xenogeneic heart valves might overcome organ scarcity. Simplification by omitting controlled rate freezing and liquid nitrogen storage will improve cost effectiveness and allow application in third world and developing countries with limited financial resources.

人类心脏瓣膜或同种异体移植物几乎代表完美的心脏瓣膜替代品。它们具有最佳的血液动力学特征，并且对感染具有抵抗力。尤其是在儿科患者中的缺点是有限的可用性，无法生长，退化和长期失败。后者的潜在罪魁祸首包括免疫反应和钙代谢增加。同种异体移植心脏瓣膜的首次临床用途是同型抗生素孵育后移植而没有任何保存。自1968年以来，已经采用了标准冷冻保存（SFC），包括在蒸气相液氮中存储。多光子成像分析（MIA）的应用可以通过诱导自动荧光而无需固定，嵌入和染色的新鲜组织中的自动荧光来实现三维可视化和胶原蛋白。 MIA允许首次检测到SFC猪瓣阀中的弹性和胶原基质的部分破坏。由于胶原蛋白和弹性蛋白的总体数量保持不变，因此上述破坏的病因被认为是由于冰晶引起的冻结诱导的细胞外基质（ECM）损伤。可以通过促进玻璃化，玻璃形成，而不是冷冻保存溶液玻璃过渡温度下的冰层形成，而不是冰层形成，可以避免在冷冻保存过程中发生的破坏性间质冰损伤。由于保存和变暖是在没有任何组织破坏的情况下完成的，因此首次启用了心脏瓣膜外基质的玻璃化。为了简化所需的基础架构，我们进一步开发了无冰冷冻保存（IFC），这允许在80c冰箱中以上的溶液玻璃过渡温度的存储空间。我们在最近的一项绵羊研究中应用了IFC，并能够证明维持ECM会导致瓣膜功能更好和变性减少。此外，IFC是防止CD3阳性T细胞介导的反应的抗炎。这种减弱的适应性免疫反应的确切机制仍然未知。在人类响应者外周血白细胞组合中，在猪组织中的最新研究表明，用IFC保存培养基对瓣膜组织进行处理可降低小叶免疫原性，并诱导响应者单核细胞分化，从而向内皮类似细胞。因此，将IFC应用于异类心脏瓣膜可能会克服器官稀缺。通过省略控制率冷冻和液体氮的储存来简化，将提高成本效益，并允许在财务资源有限的第三世界和发展中国家中应用。