Department of Pediatric Research Institute, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders (Chongqing), China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
Chongqing Key Laboratory of Pediatrics, Chongqing, People's Republic of China.
Stem Cell Res Ther. 2021 May 6;12(1):269. doi: 10.1186/s13287-021-02325-6.
Sepsis is a systemic inflammatory response to a local severe infection that may lead to multiple organ failure and death. Previous studies have shown that 40-50% of patients with sepsis have diverse myocardial injuries and 70 to 90% mortality rates compared to 20% mortality in patients with sepsis without myocardial injury. Therefore, uncovering the mechanism of sepsis-induced myocardial injury and finding a target-based treatment are immensely important.
The present study elucidated the mechanism of sepsis-induced myocardial injury and examined the value of human umbilical cord mesenchymal stem cells (huMSCs) for protecting cardiac function in sepsis.
We used cecal ligation and puncture (CLP) to induce sepsis in mice and detect myocardial injury and cardiac function using serological markers and echocardiography. Cardiomyocyte apoptosis and heart tissue ultrastructure were detected using TdT-mediated dUTP Nick-End Labeling (TUNEL) and transmission electron microscopy (TEM), respectively. Fura-2 AM was used to monitor Ca uptake and efflux in mitochondria. FQ-PCR and Western blotting detected expression of mitochondrial Ca distribution regulators and PTEN-induced putative kinase 1 (PINK1). JC-1 was used to detect the mitochondrial membrane potential (Δψm) of cardiomyocytes.
We found that expression of PINK1 decreased in mouse hearts during sepsis, which caused cardiomyocyte mitochondrial Ca efflux disorder, mitochondrial calcium overload, and cardiomyocyte injury. In contrast, we found that exosomes isolated from huMSCs (huMSC-exo) carried Pink1 mRNA, which could be transferred to recipient cardiomyocytes to increase PINK1 expression. The reduction in cardiomyocyte mitochondrial calcium efflux was reversed, and cardiomyocytes recovered from injury. We confirmed the effect of the PINK1-PKA-NCLX axis on mitochondrial calcium homeostasis in cardiomyocytes during sepsis.
The PINK1-PKA-NCLX axis plays an important role in mitochondrial calcium efflux in cardiomyocytes. Therefore, PINK1 may be a therapeutic target to protect cardiomyocyte mitochondria, and the application of huMSC-exo is a promising strategy against sepsis-induced heart dysfunction.
败血症是一种全身性炎症反应，由局部严重感染引起，可能导致多器官衰竭和死亡。先前的研究表明，40-50%的败血症患者存在多种心肌损伤，死亡率为 70-90%，而无心肌损伤的败血症患者死亡率为 20%。因此，揭示败血症引起的心肌损伤的机制并找到基于靶点的治疗方法非常重要。
本研究阐明了败血症引起的心肌损伤的机制，并研究了人脐带间充质干细胞（huMSC）在败血症中保护心脏功能的价值。
我们使用盲肠结扎穿孔（CLP）法在小鼠中诱导败血症，并使用血清标志物和超声心动图检测心肌损伤和心功能。使用 TdT 介导的 dUTP 缺口末端标记法（TUNEL）和透射电子显微镜（TEM）分别检测心肌细胞凋亡和心脏组织超微结构。使用 Fura-2 AM 监测线粒体中的 Ca 摄取和流出。FQ-PCR 和 Western blot 检测线粒体 Ca 分布调节剂和 PTEN 诱导的假定激酶 1（PINK1）的表达。JC-1 用于检测心肌细胞的线粒体膜电位（Δψm）。
我们发现，在败血症期间，小鼠心脏中的 PINK1 表达减少，导致心肌细胞线粒体 Ca 流出紊乱、线粒体钙超载和心肌细胞损伤。相反，我们发现，从 huMSC 分离的外泌体（huMSC-exo）携带 Pink1 mRNA，可转移至受体心肌细胞，增加 PINK1 表达。心肌细胞线粒体钙流出减少得到逆转，心肌细胞从损伤中恢复。我们证实了 PINK1-PKA-NCLX 轴在败血症期间对心肌细胞中线粒体 Ca 稳态的作用。
PINK1-PKA-NCLX 轴在心肌细胞中线粒体 Ca 流出中起重要作用。因此，PINK1 可能是保护心肌细胞线粒体的治疗靶点，huMSC-exo 的应用是对抗败血症引起的心脏功能障碍的有前途的策略。
