Simultaneous transfer of vascular endothelial growth factor and hepatocyte growth factor genes effectively promotes liver regeneration after hepatectomy in cirrhotic rats

BACKGROUND/AIMS: Liver regeneration in a cirrhotic liver is unsatisfactory. In the course of liver regeneration, non-parenchymal cells such as sinusoidal endothelial cells as well as hepatocytes increase in number while the liver structure and physiological functions are maintained. The aim of this study was to examine whether sufficient liver regeneration could be obtained by the simultaneous, preoperative injection of recombinant adenoviral vectors encoding human vascular endothelial growth factor (VEGF), a potent mitogen for sinusoidal endothelial cells, (pAxCAVEGF) and rat hepatocyte growth factor (HGF), a potent mitogen for hepatocytes, (pAxCAHGF) in 70% hepatectomized cirrhotic rats. METHODOLOGY: Forty-eight hours before 70% hepatectomy, dimethylnitrosamine-induced cirrhotic rats were infused intravenously with pAxCAVEGF or with pAxCAVEGF and pAxCAHGF, or with a control virus encoding Escherichia coli beta-galactosidase (pAxCALacZ). RESULTS: Strong VEGF mRNA expressions were shown in the livers of VEGF and VEGF/HGF-treated animals. The plasma HGF concentrations in the VEGF/HGF-treated rats were elevated compared with the other groups. Proliferating cell nuclear antigen immunostaining showed increased labeling indices of hepatocytes in the VEGF/HGF-treated rats at 24 and 48 h after hepatectomy. PCNA labeling indices of SECs were increased in the VEGF and VEGF/HGF-treated rats compared with the control animals at 24 and 48 h after hepatectomy. Moreover, the hepatic regeneration rate after hepatectomy was significantly augmented by the VEGF and VEGF/HGF treatment. CONCLUSIONS: Simultaneous preoperative injection of recombinant adenoviral vectors encoding VEGF and HGF effectively stimulates liver regeneration in cirrhotic rats.     

Hepatocyte growth factor as well as vascular endothelial growth factor gene induction effectively promotes liver regeneration after hepatectomy in Solt-Farber rats

BACKGROUND/AIMS: Hepatic oval cells play an important role in liver regeneration when proliferation of mature hepatocytes is inhibited. The aim of this study was to examine the effect of hepatocyte growth factor (HGF), or vascular endothelial growth factor (VEGF) on proliferation of oval cells in the Solt-Farber rat model. METHODOLOGY: One hour after 70% partial hepatectomy, 2-acetyl-aminofluorene-induced damaged rats were infected intravenously with recombinant adenoviral vectors, encoding rat HGF or human VEGF, or Escherichia coli beta-galactosidase as a control. RESULTS: The plasma HGF concentrations in the HGF-transferred rats were elevated compared with the other groups at 4 and 7 days after hepatectomy. Oval cells were confirmed by positive staining of both cytokeratin-19 and alpha-fetoprotein. Oval cells around the portal tracts in the HGF or VEGF-transferred rats increased in number compared with the control rats at 7 and 9 days after hepatectomy. The proliferating cell nuclear antigen labeling indices of oval cells and the hepatic regeneration rate after hepatectomy were significantly augmented by the HGF or VEGF treatment. Moreover, cyclin E expression was elevated in the HGF-treated rats. CONCLUSIONS: In the Solt-Farber rat model, HGF or VEGF gene injection effectively promoted liver regeneration after hepatectomy mainly with increased proliferation of hepatic oval cells.     

Inhibition of 5-lipoxygenase promotes the regeneration of the liver after partial hepatectomy in normal and icteric rats

The role of leukotriene (LT) on liver regeneration after hepatectomy is still unknown. LTB4 stagnates in the liver with obstructive jaundice, because LTB4 is excreted in the bile; therefore, LTB4 may have an effect on liver regeneration after hepatectomy with obstructive jaundice. Release of obstructive jaundice and simultaneous 70% hepatectomy was performed in rats to study the effect of 5-lipoxygenase inhibitor (AA-861) on liver regeneration. Group 1 underwent hepatectomy with administration of 0.1 mL dimethyl sulfoxide (DMSO), group 2 underwent hepatectomy with administration of AA-861 (20 mg/kg/d) dissolved in 0.1 mL DMSO, group 3 underwent hepatectomy with administration of AA-861 (40 mg/kg/d) dissolved in 0.1 mL DMSO, group 4 underwent release of obstructive jaundice and hepatectomy with administration of 0.1 mL DMSO, and group 5 underwent relief of obstructive jaundice and hepatectomy with administration of AA-861 (20 mg/kg/d). DMSO or AA-861 was administered 24 hours before, during, and 24 hours after hepatectomy in each group. Whole blood LTB4 and serum alanine aminotransferase (ALT), total bilirubin, and bromodeoxyuridine labeling index (LI) were measured before and after hepatectomy. The LTB4 level increased during obstructive jaundice and after hepatectomy. LTB4 and serum ALT levels were significantly lower after hepatectomy in the rats that were administered AA-861, and a significantly higher LI was observed at 24 hours after hepatectomy in rats receiving AA-861. Inhibition of 5-lipoxygenase promotes liver regeneration and decreases hepatocyte injury after hepatectomy associated with obstructive jaundice. (Hepatology 1996 Mar;23(3):544-8)     

Expressions of molecules associated with hepatocyte growth factor activation after hepatectomy in liver cirrhosis

BACKGROUND/AIMS: The activation pathway of hepatocyte growth factor (HGF), including HGF activator (HGFA) and HGFA inhibitor-1, 2 (HAI-1, 2), has recently been clarified. The present study examined mRNA expressions of HGF, HGFA and HAI-1 following partial hepatectomy in normal and cirrhotic rats. METHODOLOGY: Liver cirrhosis was induced by intraperitoneal injections of dimethylnitrosamine. Two weeks after, the cirrhotic and normal rats underwent 70% hepatectomy and the liver regeneration rate, DNA synthesis of hepatocytes, plasma HGF level, and mRNA expressions of HGF, HGFA, and HAI-1 in the liver, spleen, and lung were examined at different times. RESULTS: Liver regeneration in the cirrhotic rats was deteriorated with a later peak of hepatocellular DNA synthesis. Hepatic HGF mRNA and splenic HAI-1 mRNA were upregulated and liver HGFA mRNA was downregulated in the cirrhotic rats. CONCLUSIONS: Insufficient HGF activation both by a reduced expression of hepatic HGFA and an increased expression of splenic HAI-1 may be one of the reasons for the impaired liver regeneration in cirrhosis.     

Growth hormone promotes early initiation of hepatocyte growth factor gene expression in the liver of hypophysectomized rats after partial hepatectomy.

GH accelerates hepatic regeneration in the rat. Hepatocyte growth factor (HGF), a potent hepatocyte mitogen in vitro, is considered to be a major regulator of hepatic regeneration. In the present study, the effects of GH and insulin-like growth factor-I (IGF-I) on HGF gene expression in regenerating rat liver was investigated. In hypophysectomized rats treated with GH, hepatic HGF mRNA levels were increased 3 h after partial hepatectomy and reached peak levels after 5 h. In rats with intact pituitaries and in hypophysectomized rats not given GH treatment, HGF mRNA levels in liver were unchanged during the first 5 h following hepatectomy and reached peak levels after 10-18 h. DNA synthesis in the liver of GH-treated rats increased from low levels 10 h after hepatectomy to peak levels after 18 h. In rats without GH treatment the synthesis of DNA was still low 18 h after hepatectomy and was increased after 26 h. Treatment of hypophysectomized rats with IGF-I promoted increases in hepatic HGF mRNA levels and DNA synthesis 3.5 h and 15 h after hepatectomy respectively. HGF mRNA levels were constantly lower after sham-hepatectomy than after partial hepatectomy. In summary, in hypophysectomized rats the responses of hepatic HGF gene expression and DNA synthesis to partial hepatectomy were both accelerated by treatment with GH or IGF-I.     

大鼠结缔组织生长因子部分cDNA序列的克隆及其mRNA在实验性 …

目的 克隆出大鼠结缔组织生长因子（ｃｏｎｎｅｃｔｉｖｅ ｔｉｓｓｕｅ ｇｒｏｗｔｈ ＣＴＧＦ）的部分ｃＤＮＡ序列,并观察在实验性肝经大鼠肝脏中ＣＴＧＦ ｍＲＮＡ的表达改变。方法 根据小鼠ＣＴＧＦ ｍＲＮＡ序列设计引物,用ＲＴ－ＰＣＲ从大鼠肝脏总ＲＮＡ中扩增出一段４３０ｂｐ的产物,并测定其序列,将１６只雌性Ｗｉｓｔａｒ大鼠随机为胆管堵塞组（ｎ＝８）及假手术组（ｎ＝８）,６周后取大鼠提取总ＲＮＡ,利用     

Hyperbaric oxygenation promotes regeneration of biliary cells and improves cholestasis in rats

AIM:To investigate the effects of hyperbaric oxygenation(HBO) on regeneration of the biliary ductal system and postoperative cholestasis in hepatectomized rats.METHODS:HBO was performed in Wistar rats daily starting 12 h after a 70% partial hepatectomy.Regenerated liver weight,serum parameters and the proliferating cell nuclear antigen labeling index of hepatocytes and biliary ductal cells were measured.Hepatocyte growth factor(HGF),c-Met and transforming growth factor(TGF) β-1 mRNA expression levels were a...     

FK506 promotes liver regeneration by suppressing natural killer cell activity

We examined the mechanism of promotion of liver regeneration by tacrolimus hydrate (FK506), a potent immunosuppressant, after partial hepatectomy. The administration of FK506 significantly increased the bromodeoxyuridine (BrdU) labelling index at 36 and 48 h after 70% hepatectomy compared with the placebo group. Using the same model, we examined the effect of FK506 on the expression of hepatocyte growth factor (HGF) and transforming growth factor-β1 (TGF-β1) and found no changes in HGF and TGF-β1 mRNA expression in the liver or in the HGF protein concentration in plasma. We found that pretreatment with FK506 markedly reduced the activity and number of liver-resident natural killer (NK) cells at the time of partial hepatectomy. Our observations suggest that the promotion of liver regeneration by FK506 may be attributable to a reduction in the number of liver-resident NK cells and to inhibition of their activity.     

熊脱氧胆酸促进肝脏部分切除后肝细胞再生

目的 探讨熊脱氧胆酸（ｕｒｓｏｄｅｏｘｙｃｈｏｌｉｃ ａｃｉｄ，ＵＤＣＡ）对胆道梗阻肝脏部分切除（ＰＨ）后肝细胞再生的影响。方法Ｗｉｓｔａｒ大鼠随机分为正常７０％肝部分切除组（Ｎ－ＰＨ）、胆道梗阻２周７０％ＰＨ组（ＢＤＯ－ＰＨ）、ＢＤＯ—ＰＨ ＵＤＣＡ治疗组及ＢＤＯ—ＰＨ生理盐水治疗组。观察肝组织学改变，检测７０％ＰＨ后肝细胞ＢｒｄＵ标记、肝内肝细胞生长因子（ＨＧＦ）及其受体Ｍｅｔ ｍＲＮＡ表达。结果 ＵＤＣＡ治疗能促进胆道梗阻后肝功能好转并减轻肝组织学病变；ＵＤＣＡ治疗组大鼠７０％ＰＨ后肝内ＨＧＦ／Ｍｅｔ ｍＲＮＡ高峰表达值均高于ＢＤＯ—ＰＨ组（Ｐ ＜ ０．０５），肝细胞 ＢｒｄＵ高峰标记指数（５９．３９±１０．８２）％高于 ＢＤＯ—ＰＨ组肝细胞 ＢｒｄＵ高峰标记指数（３６．２２±８．３７％（ｔ＝４．１４９，Ｐ＜０．０１），而与Ｎ－ＰＮ组肝细胞ＢｒｄＵ高峰标记指数（６８．６４±１１．２６％）％相比差异无显著性（ｔ＝１．４５１，Ｐ＞０．０５）。结论 ＵＤＣＡ通过缓解胆道梗阻后肝组织损害并上调７０％ＰＨ后肝内ＨＧＦ／Ｍｅｔ ｍＲＮＡ表达，从而促进胆道梗阻肝脏部分切除后肝细胞再生。     

Obstructive jaundice increases sensitivity to lipopolysaccharide via TLR4 upregulation: possible involvement in gut-derived hepatocyte growth factor-protection of hepatocytes

BACKGROUND: Patients with obstructive jaundice are prone to sepsis after biliary tract surgery. The present study was designed to determine the effect of biliary obstruction on cytokine responses to lipopolysaccharide (LPS). METHODS: Wister rats were allocated into two groups; the BDL group underwent bile duct ligation, followed 2 weeks later by administration of LPS into the duodenum. The control group underwent sham operation, and similarly received enteral LPS. Specimens were collected serially, and applied for the assays. RESULTS: Serum aspartate aminotransferase and alanine aminotransferase levels were significantly increased in BDL rats. High tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-6 levels in peripheral blood were observed 2 h after LPS administration in BDL rats. In contrast, no increases in both cytokines were noted in peripheral and portal blood in control rats. Baseline HGF levels in portal and peripheral blood in BDL rats were significantly higher than in control rats. LPS significantly increased hepatocyte growth factor (HGF) levels in portal blood and decreased in peripheral blood in BDL rats, but not in control rats. Immunohistochemical analysis revealed that BDL increased expressions of Toll-like receptor (TLR)4, CD14 and CD68 both in the small intestine and liver. Both TLR4 and CD14 mRNAs were upregulated in the small intestine and liver after LPS administration in BDL rats. CONCLUSION: Obstructive jaundice and LPS stimulation induced TLR4 upregulation both in the liver and small intestine, which led to increased TNF-alpha and IL-6 production in liver and HGF production in the small intestine. The upregulation of TLR4 may lead to pathological and host defense reactions in obstructive jaundice complicated with Gram-negative bacterial infection.     

HGF及其受体c-met在肝衰竭与部分肝切除模型中表达差异性研究

目的研究HGF及其受体c-met在肝衰竭和部分肝切除两种动物模型肝组织的表达差异。方法分别采用D-GalN/LPS腹腔注射和70%肝脏外科切除术建立肝衰竭和部分肝切除模型,同时以健康大鼠作为对照组。采用ELISA法检测血清HGF水平,采用Real-time PCR和Western-blot法分别检测肝组织c-met基因和蛋白的表达水平。结果与对照组比,部分肝切除模型大鼠血清HGF及其受体c-met表达水平均有明显升高（P〈0.01）,而在肝衰竭模型大鼠血清HGF水平虽有升高,但c-met蛋白表达水平却明显降低（P〈0.01）。结论肝细胞c-met表达水平的降低是D-GalN/LPS诱导肝衰竭大鼠肝细胞再生障碍的主要原因。     

Hepatocyte growth factor gene therapy prevents radiation-induced liver damage

AIM: To transfer human HGF gene into the liver of rats by direct electroporation as a means to prevent radiation-induced liver damage. METHODS: Rat whole liver irradiation model was accomplished by intra-operative approach. HGF plasmid was injected into liver and transferred by electroporation using a pulse generator. Control rats (n =8) received electrogene therapy (EGT) vehicle plasmid and another 8 rats received HGF-EGT 100 μg 48 h before WLIR. Expression of HGF in liver was examined by RT-PCR and ELISA methods. Apoptosis was determined by TUNEL assay. Histopathology was evaluated 10 wk after whole liver irradiation. RESULTS: Marked decrease of apoptotic cells and down-regulation of transforming growth factor-beta 1 (TGF-β1) mRNA were observed in the HGF-EGT group 2 d after liver irradiation compared to control animals. Less evidence of radiation-induced liver damage was observed morphologically in liver specimen 10 wk after liver irradiation and longer median survival time was observed from HGF-EGT group (14 wk) compared to control rats (5wk).(P=0.031). CONCLUSION: For the first time it has been demonstrated that HGF-EGT would prevent liver from radiation-induced liver damage by preventing apoptosis and down-regulation of TGF-β1.     

Cell cycle effects resulting from inhibition of hepatocyte growth factor and its receptor c-Met in regenerating rat livers by RNA interference

Hepatocyte growth factor (HGF) and its receptor c-Met are involved in liver regeneration. The role of HGF and c-Met in liver regeneration in rat following two-thirds partial hepatectomy (PHx) was investigated using RNA interference to silence HGF and c-Met in separate experiments. A mixture of 2 c-Met-specific short hairpin RNA (ShRNA) sequences, ShM1 and ShM2, and 3 HGF-specific ShRNA, ShH1, ShH3, and ShH4, were complexed with linear polyethylenimine. Rats were injected with the ShRNA/PEI complex 24 hours before and at the time of PHx. A mismatch and a scrambled ShRNA served as negative controls. ShRNA treatment resulted in suppression of c-Met and HGF mRNA and protein compared with that in controls. The regenerative response was assessed by PCNA, mitotic index, and BrdU labeling. Treatment with the ShHGF mixture resulted in moderate suppression of hepatocyte proliferation. Immunohistochemical analysis revealed severe suppression of incorporation of BrdU and complete absence of mitosis in rats treated with ShMet 24 hours after PHx compared with that in controls. Gene array analyses indicated abnormal expression patterns in many cell-cycle- and apoptosis-related genes. The active form of caspase 3 was seen to increase in ShMet-treated rats. The TUNEL assay indicated a slight increase in apoptosis in ShMet-treated rats compared with that in controls. CONCLUSION: The data indicated that in vivo silencing of c-Met and HGF mRNA by RNA interference in normal rats results in suppression of mRNA and protein, which had a measurable effect on proliferation kinetics associated with liver regeneration.     

Transforming growth factor beta mRNA increases during liver regeneration: a possible paracrine mechanism of growth regulation.

Transforming growth factor beta (TGF-beta) is a growth factor with multiple biological properties including stimulation and inhibition of cell proliferation. To determine whether TGF-beta is involved in hepatocyte growth responses in vivo, we measured the levels of TGF-beta mRNA in normal liver and during liver regeneration after partial hepatectomy in rats. TGF-beta mRNA increases in the regenerating liver and reaches a peak (about 8 times higher than basal levels) after the major wave of hepatocyte cell division and mitosis have taken place and after the peak expression of the ras protooncogenes. Although hepatocytes from normal and regenerating liver respond to TGF-beta, they do not synthesize TGF-beta mRNA. Instead, the message is present in liver nonparenchymal cells and is particularly abundant in cell fractions enriched for endothelial cells. TGF-beta inhibits epidermal growth factor-induced DNA synthesis in vitro in hepatocytes from normal or regenerating liver, although the dose-response curves vary according to the culture medium used. We conclude that TGF-beta may function as the effector of an inhibitory paracrine loop that is activated during liver regeneration, perhaps to prevent uncontrolled hepatocyte proliferation.     

Activated hepatic stellate cells overexpress p75NTR after partial hepatectomy and undergo apoptosis on nerve growth factor stimulation.

BACKGROUND: Expression of neurotrophins (NTs) and their receptors is increased during hepatic regeneration, but their role is not well understood. METHODS: NTs and their receptors were investigated by RT-PCR and immunostaining in regenerating livers after two-thirds hepatectomy (PH) and in hepatocytes and hepatic stellate cells (HSCs) isolated from regenerating livers in mice. Induction of apoptosis after treatment with NGF and the expression of alpha-smooth muscle actin (SMA), interleukin 6 (IL-6) and hepatocyte growth factor (HGF) were also investigated in regenerating HSCs. RESULTS: Nerve growth factor (NGF) and p75 NT receptor (p75NTR) mRNA were elevated after PH, while other NTs and NT receptors showed no remarkable change. NGF was detected in regenerating hepatocytes, but not in normal hepatocytes. Regenerating HSCs expressed increased p75NTR and SMA in vivo and showed an activated phenotype and the high expression of HGF and IL-6 in vitro. Enhanced cell death was seen in HSCs, both from normal and regenerating liver, after treatment with NGF. CONCLUSIONS: Although activated HSCs may produce the factors that regulate liver regeneration, the de novo NGF production by regenerating hepatocytes may induce the death of activated HSCs via p75NTR, leading to termination of hepatic regeneration.     

Effect of IL-10 on the expression of HSC growth factors in hepatic fibrosis rat

AIM: To study the effect of IL-10 on the expression of growth factors - transforming growth factor-β1(TGF-β1), epidermal growth factor (EGF), hepatocyte growth factor (HGF)and platelet-derived growth factor (PDGF) of hepatic stellate cells (HSCs) of hepatic fibrosis rat and the anti-fibrogenic role of exogenous IL-10. METHODS: Hepatic fibrosis was induced by CCl4 administration intra-peritoneally. Sixty clean male Sprague-Dawley (SD) rats were randomly divided into three groups: normal control group (GN, 8 rats), hepatic fibrosis model group (GC, 28 rats) and IL-10 treated group (GI, 24 rats). At the beginning of the 7th and 11th wk, rats in each group were routinely perfused with pronase E and type IV collag-enase through a portal vein catheter and the suspension obtained from the liver was spun by centrifugation with 11% Nycodenz density gradient to isolate HSCs. Histological examination was used to determine the degree of hepatic fibrosis. RT-PCR was employed to analyze mRNA expression from freshly isolated cells. Immunocytochemistry was performed to detect protein expression in primary cultured HSCs. RESULTS: Rat hepatic fibrosis was developed with the increase of injection frequency of CCl4, and HSCs were successfully isolated. At the 7th and 11th wk, TGF-β1, EGF, and HGF mRNA in GC increased obviously compared with GN (P= 0.001/0.042, 0.001/0.001, 0.001/0.001) and GI (P=0.001/0.007, 0.002/0.001, 0.001/0.001). For TGF-β1, no difference was observed between GI and GN. For EGF, mRNA level in GI increased compared with GN during the 7th wk (P=0.005) and 11th wk (P=0.049). For HGF, mRNA level in GI decreased compared with GN at the 7th wk (P=0.001) and 11th wk (P=0.021). Between these two time points, TGF-β1 expression at the 7th wk was higher than that of the 11th wk (P=0.049), but for EGF, the former was lower than the latter (P=0.022). As for PDGF mRNA, there was no significant difference between these groups, but difference seemed to exist in protein levels. Results by immunocytochemistry of TGF-β1 and EGF were paralleled with the above findings. CONCLUSION: The expression of TGF-β1, EGF and HGF increased in HSC of hepatic fibrosis rat and decreased after treatment with IL-10. IL-10 plays an anti-fibrogenic role by suppressing growth factors expression.