Induction of Ischemic Tolerance by Augmentation of Hepatic Stem Cells in the Rat

[引言]已知干细胞对缺氧条件具有耐受性。我们在此报告，增强肝干细胞（HSC）可以诱导对肝脏缺血再灌注损伤的耐受。[方法]（1）S-D大鼠脾移位3周后结扎门静脉主干，证实HSC增强。然后，使大鼠经受60分钟的全肝缺血; 5只大鼠在缺血前3天具有PVO（PVO组）和5只大鼠无PVO（对照组）。(2)采用免疫印迹法和免疫组化法研究热休克蛋白（HSP）72和血红素氧合酶（HO）-1在诱导缺血耐受中的作用。[结果]（1）再灌注3 h后，对照组血清AST和ALT分别为3，854 ± 767 IU/L和5，345 ±1，722 IU/L，PVO组分别为1，813 ± 169 IU/L和1，149 ± 459 IU/L（P<0.01）。对照组再灌注后3小时的组织学检查显示大量凝固性坏死，而PVO组的肝结构和肝细胞活力保存良好。(2)PVO后HSP 72在肝脏中几乎未检测到。另一方面，HO-1的检测在肝组织中的Western印迹和免疫组化显示，HO-1的存在下，而不是在肝实质细胞，但在许多窦衬里细胞。[结论]门静脉阻断后3天，大鼠肝脏对缺血再灌注损伤表现出耐受性，HSC的增强可能是这种耐受性的原因。HSC的诱导可能成为抗缺血再灌注损伤的新策略。应激蛋白在肝缺血耐受中可能不起重要作用，肝窦衬里细胞中出现完整的HO-1可能减轻肝损伤。

【Introduction】 A stem cell is known to have tolerance against hypoxic condition. We herein report that augmentation of hepatic stem cell (HSC) can induce tolerance against ischemia-reperfusion injury to the liver. 【IMethods】 (1) The portal trunk of S-D rat was ligated 3 weeks after splenic transposition and augmentation of HSC was verified. Then, rats were subjected to total liver ischemia of 60 minutes; 5 rats with PVO 3 days before ischemia (PVO group) and 5 rats without PVO (control group). (2) The role of heat shock protein (HSP) 72 and heme oxygenase (HO)-1 in the induction of the ischemic tolerance was investigated using Western blotting and immunohistochemistry.【IResults】 (1) Serum AST and Alt levels 3 hours after reperfusion in the control group were 3,854±767IU/ and 5,345±1,722IU/L、while those in the PVO group were 1,813±169IU/ and 1,149±459IU/L, respectively(P<0.01). Histological examination 3 hours after reperfusion in the control group revealed massive coagulation necrosis, whereas hepatic architecture and the viability of hepatocytes were well preserved in the PVO group. (2) HSP72 was hardly detected in the liver after PVO. On the other hand, HO-1 was detected in the liver tissue by Western blotting and immunohistochemistry revealed the presence of HO-1 not in liver parenchymal cells but in many of sinusoidal lining cells.【IConclusion】 The tolerance against ischemia-reperfusion injury was shown in rat liver 3 days after portal vein occlusion and augmentation of HSC might play a causative role in this tolerance. Induction of HSC can be a new strategy against ischemia-reperfusion injury. Stress proteins seemed not to play an important role in this ischemic tolerance, whole HO-1 appearing in the sinusoidal lining cells might relieve the liver damage.