Transplantation of hearts from donation after circulatory death

心脏移植(HTX)是终末期心力衰竭的终极治疗方法，但其使用受到 供体心脏的供应情况。其结果是，大量HTX候选患者在等待移植时死亡。 循环死亡后的捐赠(DCD)为HTX提供了一个有希望的额外来源。然而，它的采用是 因死亡过程中强制性热缺血损伤和随后的再灌注损伤而受阻，AS 以及在运输过程中不适当的保存方式。EVHP提供常温灌流平台 为了令人满意地保存DCD心脏，并提供了提供改善 DCD心脏移植前的复苏。给予干细胞来源的旁分泌保护 心肌缺血，我们的目标是确定缺血后应用干细胞的潜在疗效 使用EVHP的分泌物(条件培养液[CM]、细胞外小泡[EVS]或工程EVS) 在移植前恢复DCD心脏，从而增加可用的供体心脏的数量。我们的 最近的研究报道，在保存液中添加MSC-CM或MSC-EVS可以保护心脏移植物 用体内小鼠HTX模型和MSC-CM恢复冷缺血6h后的性能 心脏转录组图谱受损。这些结果提示骨髓间充质干细胞分泌物对供者的治疗潜力。 心脏保存术。我们已发表的工作和初步数据也表明：1)使用人类MSCs或其 CM改善急性缺血/再灌流(I/R)后EVHP的心功能恢复；2)MSC-CM 防止供体心脏冷缺血造成的线粒体损伤并恢复时钟基因周期2(Per2， 参与线粒体代谢调节)；3)热缺血导致线粒体异常 小鼠和人DCD心脏的结构，PER2降低，4)PER2基因敲除恶化 应激时心肌细胞线粒体损伤，并取消MSC CM介导的线粒体保护作用。 总而言之，我们假设缺血后使用EVHP的MSC分泌物可以改善 热缺血通过PER2诱导线粒体改善导致DCD心脏功能恶化。 我们预计，一种使用工程EVS来运送PER2的新方法将促进线粒体 DCD心脏的恢复和心肌复苏。我们提出了两个目标：1.检验体外实验假说 应用含EVHP的MSC分泌物改善热缺血心肌损伤 DCD心脏中线粒体的保存；2.确定PER2在改善线粒体中的作用 在DCD心脏中的表现，并显示负载PER2的MSC-EVS对心脏复苏的有利作用 DCD红心。MSC衍生疗法和工程化电动汽车的翻译潜力也将得到评估。 在类似人类的猪DCD心脏中。本研究的结果可以为潜在的临床试验提供基础。 因为MSC分泌物可以用来改善DCD的心脏恢复，并帮助我们获得对 限制DCD心脏移植热缺血损伤的治疗靶点。

Heart transplantation (HTx) is the ultimate treatment for end-stage heart failure, but its use is limited by the availability of donor hearts. As a result, a substantial number of HTx candidates die awaiting transplant. Donation after circulatory death (DCD) offers a promising additional source for HTx. However, its adoption is hindered due to obligatory warm ischemic injury during death process and subsequent reperfusion injury, as well as unsuitable preservation modality during transport. The EVHP provides normothermic perfusion platform for satisfactory preservation of DCD hearts and offers the possibility to deliver therapeutic agents that improve resuscitation of DCD hearts prior to transplantation. Given stem cell-derived paracrine protection following myocardial ischemia, our goal is to determine potential efficacy of post-ischemic administration of stem cell secretions (conditioned medium [CM], extracellular vesicles [EVs], or engineered EVs) using the EVHP on recovery of DCD hearts prior to transplantation, thereby increasing the number of available donor hearts. Our recent studies have reported that adding MSC-CM or MSC-EVs to storage solution protected heart graft performance after 6h-cold storage using an in vivo mouse HTx model and MSC-CM restored cold ischemia- impaired cardiac transcriptome profile. These results suggest therapeutic potential of MSC secretions on donor heart preservation. Our published work and preliminary data have also shown: 1) using human MSCs or their CM improved heart functional recovery in the EVHP following acute ischemia/reperfusion (I/R); 2) MSC-CM prevented mitochondrial damage in donor hearts from cold ischemia and restored clock gene period 2 (Per2, with a role in mitochondrial metabolic regulation); 3) warm ischemia resulted in abnormal mitochondrial structure in mouse and human DCD hearts, with decreased Per2, and 4) Per2 knockdown worsened mitochondrial injury and abolished MSC CM-mediated mitochondrial preservation in myocytes during stress. Collectively, we hypothesize that post-ischemic administration of MSC secretions using the EVHP ameliorates warm ischemia-induced functional deterioration of DCD hearts via Per2-elicited mitochondrial improvement. We expect that a novel approach using the engineered EVs to deliver Per2 will promote mitochondrial recovery and myocardial resuscitation in DCD hearts. We propose two aims: 1. test the hypothesis that ex vivo application of MSC secretions using the EVHP ameliorates warm ischemia-induced myocardial damage via mitochondrial preservation in DCD hearts; and 2. determine the role of Per2 in improving mitochondrial performance in DCD hearts and demonstrate beneficial effects of Per2-loaded MSC-EVs on resuscitation of DCD hearts. The translational potential of MSC-derived therapy and the engineered EVs will also be assessed in human-like porcine DCD hearts. The results from this study can provide foundation for potential clinical trials in that MSC secretions can be utilized to improve DCD heart recovery and help us gain mechanistic insights on therapeutic targets to limit warm ischemic injury in DCD hearts for transplantation.