Improving Survival For Small-For-Size Liver Grafts

描述（由申请人提供）： 近年来，部分肝移植技术的使用迅速增加;然而，小尺寸移植物仍然是一个主要问题，因为许多移植物在用作供体器官时失败。因此，需要了解移植物尺寸和移植物失败之间的关系。本研究的目的是阐明小体积肝移植失败的机制，并提出预防小体积肝移植失败的策略。我们将采用减少移植物重量/标准肝重量（GW/SLW）的大鼠减体积肝移植来验证小体积肝移植中自由基增加导致移植失败的独特假设。我们的目标1是研究移植物体积、收获过程中的操作和冷藏对部分肝移植物存活的影响。移植后将在体内观察存活时间、转氨酶释放和肝功能。还将在移植后的移植物隔离灌注中评价肝功能。将测定ATP/ADP/AMP含量和氧摄取以评价线粒体功能。将建立存活和非存活条件，验证其作为机制研究的有用模型。接下来，我们将检验自由基在小尺寸移植物中产生导致损伤的假设。目标2将确定移植物体积、冷藏和收获期间操作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，在小体积肝移植中，自由基的产生将在更大程度上增加，冷藏和操作将进一步增强这种效果。此外，我们将确定细胞来源的自由基使用荧光探针和活体多光子显微镜。在目标3中，将在目标1中确定的非存活条件下评价抗氧化剂治疗（多酚、卡罗莱纳冲洗液和超氧化物歧化酶的基因递送）对小尺寸移植物存活的影响，并将比较对转氨酶、肝功能和自由基产生的影响。我们希望抗氧化剂治疗能防止自由基的产生，减少小移植物的移植失败，并确定最有效的治疗方法。最后，将在目标4中评价抗氧化治疗对肝再生的影响。将评价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。总之，我们期望这些研究将提供明确的证据支持自由基在小尺寸移植物的原发性移植失败中的作用。这项工作将开发基于机制的策略，以增加临床中部分肝脏移植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.