Improving Survival For Small-For-Size Liver Grafts

描述(由申请人提供)： 近年来，部分肝移植技术的应用迅速增加；然而，小体积肝移植仍然是一个主要问题，因为许多移植肝在用作供体器官时失败。因此，需要了解移植物大小和移植物失败之间的关系。该项目的目标是阐明小体积移植物失败的机制，并制定预防策略。我们将使用降低移植物重量/标准肝重量的减体积肝移植(GW/SLW)来验证小体积移植物中自由基增加导致移植物失败的独特假设。我们在目标1中的目标是调查移植物体积、收获时的操作和冷藏对部分肝移植物存活率的影响。移植后的存活、转氨酶释放和肝功能的时间进程将在体内观察。在移植后的移植物隔离灌流中也将评估肝功能。测定线粒体ATP/ADP/AMP含量和氧摄取量以评价线粒体功能。生存条件和非生存条件将被建立，验证它是一个有用的机械研究模型。接下来，我们将检验这样一种假设，即在小尺寸移植物中产生自由基会导致损伤。在目标2中，将确定移植物体积、冷藏和收获期间的处理对部分移植物移植后自由基产生、4-羟基壬烯醛和GSH的影响。我们预计在小体积肝移植物中自由基的产生将得到更大程度的增加，而冷藏和处理将进一步增强这种影响。此外，我们将使用荧光探针和活体内多光子显微镜来识别细胞内的自由基来源。在目标3中，将在目标1确定的非存活条件下评估抗氧化剂治疗(多酚、Carolina Rinse溶液和超氧化物歧化酶基因传递)对小尺寸移植物存活的影响，并将对转氨酶、肝功能和自由基产生的影响进行比较。我们期望抗氧化剂治疗将防止自由基的产生，减少小体积移植物的移植物失败，并确定最有效的治疗方法。最后，在目标4中将评估抗氧化剂治疗对肝脏再生的影响。将评估5-溴-2‘-脱氧尿苷和调节再生的因子(细胞因子、转录因子、生长因子和能量供应)的掺入。综上所述，我们预计这些研究将提供明确的证据，支持自由基在小体积移植物初次移植物失败中的作用。这项工作将开发基于机制的策略，以增加部分肝脏在临床上的使用并改善其结果。

DESCRIPTION (provided by applicant): Use of partial liver grafting techniques has increased rapidly in recent years; however, small-for-size grafts remain a major problem since many fail when used as donor organs. Therefore, the relationship between graft size and graft failure needs to be understood. The goals of this project are to elucidate mechanisms involved in the failure of small-for-size grafts and to develop strategies to prevent it. We will use reduced-size liver transplantation of decreasing graft weight/standard liver weight (GW/SLW) in rats to test the unique hypothesis that free radicals increase in small-for-size grafts leading to graft failure. Our goal in Aim 1 will be to investigate the effects of graft volume, manipulation during harvest, and cold storage on survival of partial liver grafts. The time course of survival, transaminase release, and liver function will be observed in vivo after transplantation. Liver function will also be evaluated in isolated-perfusion of grafts after transplantation. ATP/ADP/AMP contents and oxygen uptake will be determined to evaluate mitochondrial function. Survival and non-survival conditions will be established, validating it as a useful model for mechanistic studies. Next, we will test the hypothesis that free radicals are produced in small-for-size grafts leading to injury. Effects of graft volume, cold storage, and manipulation during harvest on free radical production, 4-hydroxynonenal, and GSH after transplantation of partial grafts will be determined in Aim 2. We expect free radical production will be increased to a greater extent in small-for-size liver grafts, and cold storage and manipulation will further enhance this effect. In addition, we will identify cellular sources of free radicals using fluorescent probes and intravital multiphoton microscopy. In Aim 3, the effects of antioxidant therapies (polyphenols, Carolina Rinse solution, and gene delivery of superoxide dismutase) on survival of small-for-size grafts will be evaluated under non-survival conditions determined in Aim 1, and effects on transaminase, liver function and free radical production will be compared. We expect that antioxidant therapies will prevent free radical production and reduce graft failure of small-for-size grafts and to identify the most effective therapy. Finally, the effects of antioxidant therapies on liver regeneration will be evaluated in Aim 4. Incorporation of 5-bromo-2'-deoxyuridine and factors regulating regeneration (cytokines, transcription factors, growth factors, and energy supply) will be evaluated. Taken together, we expect that these studies will provide unequivocal evidence supporting a role for free radicals in primary graft failure of small-for-size grafts. This work will develop mechanism-based strategies to increase the use and improve the outcome of partial livers for transplantation in the clinic.