Mitochondrial metabolic modulation to minimize ischemic damage in donor heart

终末期心力衰竭患者需要机械循环支持，如果符合条件，还需要心脏支持。 移植(HT)以挽救他们的生命。高达20%的患者在登记进行心脏移植时死亡。这个 由于目前捐献心脏的唯一来源是病人，供体心脏的供应已经达到了一个平台期 有不可逆的严重脑损伤(脑死亡后捐赠，DBD)。因此，迫切需要 扩大心脏捐赠者储备。这种供体心脏的一个潜在来源是DCD(循环后捐赠 死亡)捐赠者。DCD捐赠者提高了实体器官的移植比率，包括肝、肺和 肾脏。不幸的是，DCD方案会导致持续的热缺血时间，从而损害心肌 排除了它用于临床移植的可能性。因此，缺血(ISC)形成的DCD方案， 储存引起的心肌损伤和再灌流(REP)相关的损伤相结合代表着额外的风险 以加重DCD心脏的损伤，使其不能用于临床移植。 虽然DCD心脏热缺血是不可避免的，但通过适当的干预可以减少心脏的损伤。 在REP开始时应用干预措施。我们建议制定新的战略来预防重复性肺炎 损伤将减少对DCD心脏的损害。线粒体是心脏损伤的关键靶点和介体 在代表期间。我们先前的研究发现，线粒体呼吸的暂时性和可逆性抑制在 ISC后心脏复跳时间可减少心脏损伤。保护包括减少ROS 线粒体通透性转换孔开放的产生和抑制。我们建议 呼吸快速起效和可逆性抑制剂的使用将在早期呼吸发作之前和期间立即进行 减少DCD心脏的心脏损伤。体外DCD人体心脏代表着一个独特的机会 将这种来自强大的临床前数据的强大的心脏保护转化为人类疾病。 在ISC-rep过程中损伤的心肌细胞激活了基于细胞的内部炎症机制，包括 点样受体蛋白3(NLRP3)炎症体。来自受损线粒体的ROS被激活 NLRP3炎症小体并使组织损伤进一步持久。这个项目采取了独特的方法来 结合免费干预措施以钝化急性线粒体驱动的损伤并减轻长期代表 由于抑制炎症体信号而造成的损害。损伤的潜在力学关系 在DCD心脏模型中，研究了线粒体和炎症体信号的激活。 我们假设，线粒体最初的保护之后是线粒体的衰减- 激活的炎症信号将保护DCD的心脏功能，使其能够用于心脏 移植。我们的新策略是使用异巴比妥治疗，快速、可逆和瞬时 调节线粒体呼吸减轻急性ISC-rep损伤继而抑制炎症 居间伤害。该项目的目标是在复活期间保护DCD心脏，维持 保存功能性线粒体以达到类似于DBD的可移植心脏的质量。 使用DCD大鼠心脏模型，目标1将评估电子可逆性抑制的保护作用 使用体外灌流的心脏在REP开始时的转运。这之后将是目标2，其中 这些有丝分裂保护的DCD心脏的同种异位羟色胺将受到 炎性小体介导的延迟再灌注损伤。然后将对异位移植的心脏进行评估 用于移植物存活、功能和病理评估，包括炎性浸润物和 MRI、超声心动图和组织学检查显示肝纤维化。我们计划的实验和预期的 研究结果将为DCD心脏的保护策略提供初步的见解。使用集成的 治疗方法我们的目标是将DCD心脏用于临床移植。

Patients with end stage heart failure (HF) require mechanical circulatory support, and if eligible, heart transplantation (HT) to save their life. Up to 20% of patients die while listed for heart transplantation. The supply of donor hearts has reached a plateau since the only current source of donor hearts consists of patients with irreversible severe brain damage (donation after brain death, DBD). Thus, there is an urgent need to expand the heart donor pool. A potential source of such donor hearts is from DCD (donation after circulatory death) donors. DCD donors have increased the transplantation rates of solid organs including liver, lungs and kidney. Unfortunately, DCD protocol induces a sustained warm ischemic time that damages myocardium precluding its use for clinical transplantation. Thus, the ischemia (ISC) form DCD protocol, the potential myocardial injury from storage, and reperfusion (REP) associated injury combine to represent additional risks to exacerbate injury in the DCD heart precluding their use in clinical transplantation. Although the warm ischemia is inevitable in DCD hearts, REP injury can be decreased through proper interventions applied at the onset of REP. We propose that development of new strategies to prevent REP injury will reduce damage to the DCD heart. Mitochondria are critical targets and mediators of cardiac injury during REP. Our previous studies found that temporary and reversible inhibition of mitochondrial respiration at the time of REP in hearts following ISC decreases cardiac injury. Protection involved the reduction of the ROS generation and inhibition of the opening of the mitochondrial permeability transition pores. We propose that the use of rapid onset and reversible inhibitors of respiration immediately before and during early REP will decrease cardiac injury in DCD hearts. The ex vivo DCD human heart represents a unique opportunity to translate this robust cardiac protection derived from strong pre-clinical data to human disease. Myocytes injured during ISC-REP activate internal cell-based mechanisms of inflammation including the NOD like receptor protein 3 (NLRP3) inflammasome. ROS derived from damaged mitochondria activates the NLRP3 inflammasome and perpetuates tissue injury further. This project takes the unique approach to combine complimentary interventions to blunt acute mitochondrial-driven injury and attenuate longer-term REP damage from inhibition of inflammasome signaling. The potential mechanistic relationship of damaged mitochondria and the activation of inflammasome signaling are studied in the DCD heart model. We hypothesize that the initial protection of mitochondria followed by attenuation of mitochondria- activated inflammatory signaling will protect the DCD heart function, enabling it to be used for heart transplantation. Our novel strategy is to use amobarbital treatment to rapidly, reversibly and transiently modulate mitochondrial respiration to decrease acute ISC-REP injury followed by inhibition of inflammation mediated injury. The goal of this project is to protect the DCD heart during reanimation, sustain the preservation of functional mitochondria in order to reach the quality of a transplantable heart similar to DBD. Using a rat model of DCD heart, Aim 1 will evaluate the protection from reversible inhibition of electron transport at the onset of REP using the perfused heart ex vivo. This will be followed by Aim 2 where the syngeneic heterotopic HT of these mito-protected DCD hearts will be subjected to protection from inflammasome mediated delayed reperfusion injury. The heterotopic transplanted hearts will then be evaluated for graft survival, function and pathological assessment including the presence of inflammatory infiltrates and fibrosis on MRI, ECHO cardiogram and histological examination. Our planned experiments and the anticipated results will provide the initial insight into the protective strategies for DCD hearts. Using an integrated treatment approach as proposed we aim to move toward use of DCD hearts for clinical transplantation.