REGULATION OF HEPATOCYTE GROWTH

肝细胞再生的调节被认为是抑制细胞因子如TGF-β和促进细胞因子如HGF之间的平衡。据报道，主要产生TGF-b的细胞是在肝脏纤维化中起重要作用的星状细胞。在慢性炎症状态下，再生肝细胞或星状细胞主要产生的细胞外基质替代坏死组织。NK细胞也可能参与肝细胞再生的调控。本研究的结果如下：(1)每周2次猪血清处理诱导肝纤维化，TGF-β表达增加，70%的肝切除术后TGF-β诱导的肝与正常肝相比再生迟缓。(2)胆碱缺乏饮食诱导肝硬化伴癌前病变和肝细胞癌，活化的星状细胞TGF-b表达升高，瘤前病变周围被活化的星状细胞包围，产生TGF-β，这些肝细胞在瘤前病变中生长（再生）速度的程度大于正常肝细胞。因此，肿瘤前病变已经摆脱了TGF-β的调控。(3) NK细胞可攻击未成熟再生肝细胞，阻碍肝再生。

The reguration of hepatocyte regeneration has been thought the balane betwen inhibitory cytokines i. e. TGF-β and accelerating cytokines i. e. HGF.It has been reported that main TGF-b producing cell is the stellate cell which palys an important role of fibrosis in the liver. Under chronic inflamatory condition, either regenerated hepatocyte or extarcellular matrix, which stellate cell mainly produces, will replace the necrotic tissue. Also NK cell may be involved in the regulation of hepatocyte regeneration. The results of this study are followings ;(1) Pig serum treatment twice a week induced hepatic fibrosis with increased TGF-β expression and 70% hepatectomy of this TGF-β induced liver showed retarded regeneration compared with normal liver.(2) Choline deficient diet induced liver cirrhosis with preneoplastic lesions and hepatocellular carcinoma with incerased TGF-b expression by activated stellate cell and preneoplastic lesions are surrounded with activated stellate cell, producing TGF-β The extent of growth (regeneration) rate of these hepatocytes in the preneoplastic lesions is more than that of normal hepatocytes. Thus preneoplastic lesions are already escaped from the regulation of TGF-β.(3) NK cell may attack inmature regenerated hepatocytes and retard hepatic regeneration.