Kerkweg Uta, Jacob Monika, De Groot Herbert, Mannherz Hans-Georg, Rauen Ursula
Institut für Physiologische Chemie, Universitätsklinikum, Essen, Germany.
Transplantation. 2003 Aug 15;76(3):501-8. doi: 10.1097/01.TP.0000069830.78758.1C.
Maintenance of the integrity of the vascular endothelium is a critical issue in liver preservation, but hypothermia, applied for cellular protection, induces apoptotic cell death in liver endothelial cells. This cold-induced apoptosis is mediated by an iron-dependent formation of reactive oxygen species. Here, we study the involvement of mitochondria in this process.
Cultured rat liver endothelial cells were incubated in cold University of Wisconsin solution for 18 hr and subsequently rewarmed in cell culture medium. Mitochondrial morphology and membrane potential were evaluated using laser scanning microscopy.
During cold incubation in University of Wisconsin solution, a marked, progressive mitochondrial shortening and a reduction in mitochondrial membrane potential occurred. Rewarming of the cells led to mitochondrial ultracondensation, complete loss of the mitochondrial membrane potential, and subsequent apoptotic cell death. The inhibitors of mitochondrial permeability transition, trifluoperazine and fructose, or iron chelation with deferoxamine did not affect mitochondrial shortening during cold incubation but inhibited ultracondensation, loss of mitochondrial membrane potential, and loss of viability during rewarming. Moreover, in these protected cells, an almost complete reestablishment of the mitochondrial membrane potential and morphology could be observed; the few mitochondria that were irreversibly damaged were incorporated into autophagosomes during cellular recovery.
Two apparently independent mitochondrial alterations take place during cold incubation and subsequent rewarming of liver endothelial cells. Cold-induced mitochondrial shortening represents a reversible process, whereas iron-mediated mitochondrial permeability transition and ultracondensation during rewarming are irreversible and constitute an important mediator of cold-induced apoptosis.
维持血管内皮的完整性是肝脏保存中的关键问题，但用于细胞保护的低温会诱导肝内皮细胞发生凋亡性细胞死亡。这种冷诱导的凋亡是由铁依赖性活性氧的形成介导的。在此，我们研究线粒体在这一过程中的作用。
将培养的大鼠肝内皮细胞在冷的威斯康星大学溶液中孵育18小时，随后在细胞培养基中复温。使用激光扫描显微镜评估线粒体形态和膜电位。
在威斯康星大学溶液中冷孵育期间，线粒体明显逐渐缩短，线粒体膜电位降低。细胞复温导致线粒体超浓缩、线粒体膜电位完全丧失，随后发生凋亡性细胞死亡。线粒体通透性转换抑制剂三氟拉嗪和果糖，或与去铁胺进行铁螯合，在冷孵育期间不影响线粒体缩短，但在复温期间抑制超浓缩、线粒体膜电位丧失和活力丧失。此外，在这些受保护的细胞中，可以观察到线粒体膜电位和形态几乎完全恢复；在细胞恢复过程中，少数不可逆受损的线粒体被纳入自噬体。
在肝内皮细胞冷孵育及随后复温过程中发生了两个明显独立的线粒体改变。冷诱导的线粒体缩短是一个可逆过程，而复温期间铁介导的线粒体通透性转换和超浓缩是不可逆的，并且是冷诱导凋亡的重要介质。
