Acceleration of liver regeneration by gene transfer with matrix metalloproteinase (MMP)-1

肝细胞外基质的重塑被认为参与了肝脏再生。我们研究了肝内胶原酶活性的增加是否能诱导肝细胞增殖。重组腺病毒Ad5MMP-1介导的胶原酶基因转移诱导肝细胞BrdU标记指数和有丝分裂指数显著增加，导致干肝重量增加，而对照腺病毒Ad5LacZ的影响很小。Ad5MMP-1感染后48小时左右开始肝细胞增殖，2周后几乎停止增殖。Ad5MMP-1感染后，肝细胞也出现短暂性肝损伤，表现为AST、ALT和LDH升高，并在1周左右达到峰值，同时伴有肝细胞凋亡。作为胶原酶诱导肝细胞增殖过程中的重要现象，糖原合成酶激酶(GSK)-3β丝氨酸残基磷酸化，β-catenin在肝细胞细胞质中积累，E-cadherin表达短暂性降低。因此，我们报道了胶原酶修饰肝细胞外基质在体内诱导肝细胞短暂增殖，这表明肝细胞外基质本身的状况在调节肝细胞增殖中起着关键作用。在另一项实验中，我们假设肝纤维瘢痕无法愈合的原因是间质胶原酶（MMP-1或MMP-13）过少与ECM和timp过多之间的不平衡。我们通过在持续肝纤维化大鼠模型中使用基因疗法传递MMP-1来短暂改变平衡，从而验证了这一假设。感染Ad5MMP-1而非Ad5LacZ的大鼠在感染后2周纤维化明显减轻。有趣的是，Ad5MMP-1感染的大鼠活化的肝星状细胞数量也减少。此外，仅在Ad5MMP-1处理的大鼠中，观察到肝小梁的紊乱、肝细胞大小的异质性和干肝重量的增加，表明MMP-1刺激了肝细胞的增殖，BrdU染色证实了这一点。我们的研究结果表明，肝脏中短暂的MMP-1过表达可有效减轻已建立的纤维化并诱导肝细胞增殖。少

Remodeling of hepatic extracellular matrix has been supposed to participate in liver regeneration. We investigated whether increased activity of collagenase in the liver could induce hepatocyte proliferation in vivo. Gene transfer of collagenase with a recombinant adenovirus Ad5MMP-1 induced significant increase in BrdU labeling index and mitotic index in hepatocytes, leading to an increased dried liver weight, while a control adenovirus, Ad5LacZ, had a minimal effect. Hepatocyte proliferation started around 48hr after the infection with Ad5MMP-1 and almost ended at 2weeks. Transient liver injury indicated by increased AST, ALT, and LDH with peaks around 1 week was also detected after Ad5MMP-1 infection, accompanied by apoptosis in hepatocytes. As important phenomena during collagenase-induced hepatocyte proliferation, phosphorylation of glycogen synthase kinase (GSK)-3β at serine residue, accumulation of β-catenin in cytoplasm of hepatocytes, and transient decrease in E-cadherin expre … More ssion were observed. Thus, we report that modification of hepatic extracellular matrix by collagenase induces transient hepatocyte proliferation in vivo, suggesting that the condition of hepatic extracellular matrix per se plays a pivotal role in regulating hepatocyte proliferation.In another experiment, we hypothesized that failure to resolve the hepatic fibrous scar results from the imbalance between too little interstitial collagenases (MMP-1 or MMP-13) and too much ECM and TIMPs. We tested this hypothesis by transiently changing the balance by using gene therapy to deliver MMP-1 in a rat model of persistent liver fibrosis. In Ad5MMP-1 infected, but not in Ad5LacZ infected, rats the fibrosis was dramatically attenuated at 2 weeks after the infection. Interestingly, the number of activated hepatic stellate cells was also decreased in Ad5MMP-1 infected rats. Moreover, disorganization of hepatic trabecule, heterogeneity in size of hepatocytes, and increased dried liver weight were observed only in Ad5MMP-1 treated rats, suggesting that MMP-1 stimulated hepatocyte proliferation, which was confirmed by BrdU staining. Our findings demonstrate that transient MMP-1 overexpression in the liver effectively attenuates established fibrosis and induces hepatocyte proliferation. Less