Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
Cell Transplant. 2014 Feb;23(2):207-20. doi: 10.3727/096368912X659862. Epub 2012 Dec 4.
Tissue damage by ischemia/reperfusion (I/R) results from a temporary cessation of blood flow followed by the restoration of circulation. The injury depresses mitochondrial respiration, increases the production of reactive oxygen species (ROS), decreases the mitochondrial transmembrane potential, and stimulates invasion by inflammatory cells. The primary objective of this work was to address the potential use of bone marrow stem cells (BMSCs) to preserve and restore mitochondrial function in the kidney after I/R. Mitochondria from renal proximal tubule cells were isolated by differential centrifugation from rat kidneys subjected to I/R (clamping of renal arteries followed by release of circulation after 30 min), without or with subcapsular administration of BMSCs. Respiration starting from mitochondrial complex II was strongly affected following I/R. However, when BMSCs were injected before ischemia or together with reperfusion, normal electron fluxes, electrochemical gradient for protons, and ATP synthesis were almost completely preserved, and mitochondrial ROS formation occurred at a low rate. In homogenates from cultured renal cells transiently treated with antimycin A, the coculture with BMSCs induced a remarkable increase in protein S-nitrosylation that was similar to that found in mitochondria isolated from I/R rats, evidence that BMSCs protected against both superoxide anion and peroxynitrite. Labeled BMSCs migrated to damaged tubules, suggesting that the injury functions as a signal to attract and host the injected BMSCs. Structural correlates of BMSC injection in kidney tissue included stimulus of tubule cell proliferation, inhibition of apoptosis, and decreased inflammatory response. Histopathological analysis demonstrated a score of complete preservation of tubular structures by BMSCs, associated with normal plasma creatinine and urinary osmolality. These key findings shed light on the mechanisms that explain, at the mitochondrial level, how stem cells prevent damage by I/R. The action of BMSCs on mitochondrial functions raises the possibility that autologous BMSCs may help prevent I/R injuries associated with transplantation and acute renal diseases.
缺血/再灌注（I/R）导致的组织损伤是由于血流暂时停止，然后循环恢复引起的。损伤会抑制线粒体呼吸，增加活性氧物种（ROS）的产生，降低线粒体跨膜电位，并刺激炎症细胞的侵袭。这项工作的主要目的是探讨骨髓干细胞（BMSCs）在 I/R 后保护和恢复肾脏线粒体功能的潜力。通过从大鼠肾脏中分离出的差异离心法，从经历 I/R（肾动脉夹闭 30 分钟后释放循环）的肾脏中分离出肾近端小管细胞的线粒体，没有或有 BMSCs 被皮下注射。I/R 后，从线粒体复合物 II 开始的呼吸受到强烈影响。然而，当 BMSCs 在缺血前或与再灌注同时注射时，几乎完全保留了正常的电子通量、质子电化学梯度和 ATP 合成，并且线粒体 ROS 的形成以低速率发生。在短暂用安密妥 A 处理的培养肾细胞的匀浆中，与 BMSCs 的共培养诱导了蛋白质 S-亚硝化为高水平，这与从 I/R 大鼠中分离出的线粒体相似，这表明 BMSCs 可防止超氧阴离子和过氧亚硝酸盐。标记的 BMSCs 迁移到受损的小管，表明损伤作为信号吸引和容纳注射的 BMSCs。BMSC 注射到肾组织中的结构相关性包括刺激小管细胞增殖、抑制细胞凋亡和减少炎症反应。组织病理学分析表明，BMSC 完全保留了管状结构，与正常的血浆肌酐和尿渗透压相关。这些关键发现阐明了在线粒体水平上解释干细胞如何防止 I/R 损伤的机制。BMSCs 对线粒体功能的作用提出了这样一种可能性，即自体 BMSCs 可能有助于预防与移植和急性肾脏疾病相关的 I/R 损伤。
