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

肝细胞外基质重塑被认为参与了肝再生。我们研究了肝脏中胶原酶活性的增加是否可以在体内诱导肝细胞的增殖。用重组腺病毒Ad5MMP1转导胶原酶后，肝细胞BrdU标记指数和有丝分裂指数显著增加，肝干重增加，而腺病毒Ad5LacZ的作用最小。肝细胞在感染Ad5MMP1后48h左右开始增殖，2周时基本停止。感染Ad5MMP1后，以AST、ALT和LDH升高为标志的一过性肝损伤也出现，峰值在1周左右，并伴有肝细胞凋亡。作为胶原酶诱导的肝细胞增殖过程中的重要现象，糖原合成酶-3β丝氨酸残基的磷酸化、β-连环蛋白在肝细胞胞浆内的积聚和E-钙粘蛋白表达…的一过性降低是胶原酶诱导肝细胞增殖的重要现象观察到更多的SSION。因此，我们报道了胶原酶对肝细胞外基质的修饰在体内诱导了短暂的肝细胞增殖，提示肝细胞外基质本身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的未能消除是由于太少的间质胶原酶(MMP1或MMP13)和过多的ECM和TIMPs之间的失衡所致。在持续性肝纤维化的大鼠模型中，我们通过使用基因疗法传递基质金属蛋白酶-1来短暂改变平衡来检验这一假设。感染Ad5MMP1而未感染Ad5LacZ的大鼠肝纤维化在感染后2周明显减轻。有趣的是，感染Ad5MMP1的大鼠激活的肝星状细胞数量也减少了。此外，只有Ad5MMP1组大鼠肝小梁结构紊乱，肝细胞大小不均，干重增加，提示MMP1促进了肝细胞的增殖，BrdU染色证实了这一点。我们的研究结果表明，在肝脏中瞬时过表达的基质金属蛋白酶-1有效地减轻了已形成的纤维化，并诱导了肝细胞的增殖。较少

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