Metabolic Engineering for Improved Liver Function

描述（由申请人提供）：原位肝移植（奥尔特）是一种非常成功的治疗急性和慢性肝功能衰竭的治疗方式，这种治疗方式受到供体肝脏稀缺的严重限制。在脑死亡后捐献的肝脏中，术后肝功能衰竭最常见的单一诱发风险因素是脂肪变性;因此，脂肪肝通常被认为是移植“不可接受”或“勉强可接受”的。根据尸检研究和供体肝活检，肝脂肪变性的发生率为10 - 25%。很明显，挽救因严重脂肪变性而被丢弃的供体的方法可以显著减少患者死亡人数，并有助于缩小肝移植供需之间的差距。总的假设是，丢弃的供体肝脏，更具体地说，脂肪肝（以及在心脏死亡后的长期供体），可以通过在良好控制的条件下和在生理温度下用人工溶液灌注来挽救，以促进脱脂和细胞修复，结果使其能够经受外科手术并将术后肝功能障碍的风险降低到与正常肝脏中观察到的水平相似的水平。在本文提出的研究中，我们的目标是将这种方法应用于脂肪肝，并最终应用于更复杂的缺血性肝脏病例（即心脏死亡后的供体）。我们的具体目标是：（1）优化常温或亚低温灌注脱脂脂肪肝的代谢;（2）研究热休克和热灌注对脂肪肝微血管功能和可移植性的联合作用;（3）建立一种常温灌注方案，恢复热缺血肝脏线粒体功能和ATP储存。在短期内，拟议的研究可以（a）为增加供体库规模提供合理依据;（B）改善接受边缘供体肝脏的患者的结局;（c）延长脂肪变性、脱脂以及热缺血肝脏的有效保存时间。从长远来看，这些研究将导致（a）增加供体库的规模和（B）增加器官储存时间，超过目前冷藏技术的限制。这些结果将显著缓解供体短缺，并为供体银行开辟道路，有可能彻底改变供体肝脏分配。公共卫生相关性：拟议的研究将提供基本的科学信息和新技术，使供体肝脏能够从供体库中回收。从长远来看，这些研究将导致（a）增加供体库的规模和（B）增加器官储存时间，超过目前冷藏技术的限制。这些结果将显著缓解供体短缺，并为供体银行开辟道路，有可能彻底改变供体肝脏分配。

DESCRIPTION (provided by applicant): Orthotopic liver transplantation (OLT) is a highly successful therapeutic modality for the treatment of both acute and chronic liver failure which is severely limited by the scarcity of donor livers. Among the livers donated after brain death, the most common single predisposing risk factor for postoperative liver failure is steatosis; thus, fatty livers are often considered to be "unacceptable" or "marginally acceptable" for transplantation. The incidence of hepatic steatosis is 10 to 25% based on autopsy studies and donor liver biopsies. It is clear that methods that would salvage discarded donors because of severe steatosis could significantly reduce the number of patient deaths, and help close the gap between supply and demand in liver transplantation. The overall hypothesis is that discarded donor livers, and more specifically steatotic livers (and in the long run donors after cardiac death), can be salvaged by perfusion with artificial solutions under well-controlled conditions and at physiological temperatures in order to promote defatting and cellular repair, and as a result made capable to withstand surgical procedures and reduce the risk of postoperative liver dysfunction to a level similar to that observed in normal livers. In the studies proposed herein, our objective is to apply this approach to fatty livers, and eventually to the more complex case of ischemic livers (i.e. from donors after cardiac death). Our specific aims are: (1) To optimize metabolism for defatting steatotic livers during normothermic or mild hypothermic perfusion; (2) To investigate the combined effects of heat shock and warm perfusion on microvascular function and transplantability in steatotic livers; (3) To develop a normothermic perfusion protocol that restores mitochondrial function and ATP stores in warm ischemic livers. In the short-term, the proposed studies could (a) provide the rationale basis for increasing the donor pool size; (b) improve the outcome of patients which receive marginal donor livers; (c) prolong the useful preservation time of steatotic, defatted, as well as warm ischemic livers. In the long-term, these studies will lead to (a) increased donor pool size and (b) increased organ storage time beyond the limits of current cold storage techniques. These outcomes will significantly alleviate donor shortage and lead the way to donor banking, with the potential to revolutionize donor liver allocation. PUBLIC HEALTH RELEVANCE: The proposed studies will provide basic scientific information and new technologies that will enable the recovery of donor livers that are otherwise rejected from the donor pool. In the long-term, these studies will lead to (a) increased donor pool size and (b) increased organ storage time beyond the limits of current cold storage techniques. These outcomes will significantly alleviate donor shortage and lead the way to donor banking, with the potential to revolutionize donor liver allocation.