トランスジェニックマウスを用いた肝臓切除におけるエネルギー代謝の研究-遺伝子治療の肝臓外科への導入

肌酸激酶对肌酸/磷酸肌酸系统的催化作用在肝脏中不表达。1994年和1995年分别用表达肌酸激酶的转基因小鼠肝脏研究了肝切除术后肝再生的促进作用和内毒素耐受的诱导。在存在磷酸肌酸的情况下，通过喂食肌酸，抑制了伴随肝再生的ATP减少，并将线粒体内ATP维持在高水平。因此，线粒体氧化磷酸化增强，导致肝脏重量的快速恢复和DNA合成的加速。在内毒素给药的第二项研究中，磷酸肌酸的存在导致炎性细胞因子反应减弱，抑制肝脏中活性氧的产生，下调ICAM-1，导致内毒素的致死作用降低。这些结果表明，将肌酸激酶基因转染到肝脏中对手术应激诱导的肝衰竭具有预防作用。在使用从转基因小鼠肝脏分离的肝细胞的第三项研究中，将肌酸添加到培养基中防止了通过用铵负荷激发的肝细胞ATP水平的降低。在使用半乳糖胺和内毒素组合的暴发性肝炎模型的第四项研究中，磷酸肌酸的存在抑制了伴有细胞凋亡的出血性坏死。总之，肝内转染肌酸激酶基因为肝衰竭的治疗提供了一种可能。

The catalysis of creatine/phsophocreatine system by creatine kinase is not expressed in the liver. Promoting effect of liver regeneration after hepatectomy and induction of endotoxin tolerance were studied using transgenic mouse liver expressing creatine kinase in 1994 and 1995, respectively. In the presence of phosphocreatine in the liver by feeding creatine, decrease in ATP accompanied with liver regeneration was inhibited, and intramitochondrial ATP was maintained at high level. Consequently, mitochondrial oxidative phosphorylation was enhanced, resulting in rapid recovery of liver weight and acceleration of DNA synthesis. In the second study of endotoxin administration, the presence of phosphocreatine caused attenuation of inflamatory cytokine response, inhibition of generation of reactive oxygen species in the liver, down-regulation of ICAM-1, resulting in decrease in lethal effect of endotoxin. These results indicate that transfection of creatine kinase gene into the liver has a prophylactic effect for liver failure induced by surgical stresses. In the third study using isolated hepatocyte from the transgenic mouse liver, addition of creatine into the culture medium prevented decrease in hepatocellular ATP level by challenge with ammonium load. In the fourth study of fulminant hepatitis model using combination of galactosamine and endotoxin, the presence of phosphocreatine inhibited hemorrhagic necrosis with apoptosis. In summary, transfection of creatine kinase gene into the liver provides a possible treatment for liver failure.