Regenerative capacities of normal and cirrhotic livers following 70% hepatectomy in rats and the effect of alpha-tocopherol on cirrhotic regeneration

Aberrant regulation of autophagy disturbs fibrotic liver regeneration after partial hepatectomy

Reports indicate that autophagy is essential for maintaining hepatocyte proliferative capacity during liver regeneration. However, the role of autophagy in fibrotic liver regeneration is incompletely elucidated. We investigated the deregulation of autophagic activities in liver regeneration after partial hepatectomy using a CCl4-induced fibrosis mouse model. The baseline autophagic activity was significantly increased in the fibrotic liver. After 50% partial hepatectomy (PHx), liver regeneration was remarkably decreased, accompanied by increased hepatocyte size and binuclearity ratio. Moreover, the expression of autophagy-related proteins was functionally deregulated and resulted in a reduction in the number of autophagosome and autophagosome–lysosome fusions. We further showed upregulation of autophagy activities through verapamil administration, improved hepatocyte proliferation capacity, and restricted cellular hypertrophy and binuclearity ratio. In conclusion, we demonstrated that the impairment of liver regeneration is associated with aberrant autophagy in fibrotic liver and that enhancing autophagy with verapamil may partially restore the impaired liver regeneration following PHx.

ALPPS for Hepatocellular Carcinoma Is Associated with Decreased Liver Remnant Growth

BACKGROUND

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) has been widely described for colorectal liver metastases with insufficient future liver remnant (FLR). However, its role in hepatocellular carcinoma (HCC) remains poorly defined and not widely accepted.

METHODS

A retrospective comparison of clinical data, liver volumetry, histological characteristics, and surgical outcomes between nine HCC and four non-HCC patients who underwent ALPPS was performed.

RESULTS

Patients with HCC were more likely to have histological evidence of hepatic fibrosis (HCC vs. non-HCC, 66.7 vs. 0%, p = 0.049). Baseline demographic and disease characteristics were otherwise comparable between both groups. FLR growth after ALPPS-Stage 1 was significantly less in HCC patients (HCC vs. non-HCC, 154.5 vs. 251.0 ml, p = 0.012). FLR growth was also significantly decreased in patients with hepatic fibrosis (fibrosis vs. non-fibrosis, 157.5 vs. 247.5 ml, p = 0.033). There was no difference in post-hepatectomy liver failure (HCC vs. non-HCC, 28.6 vs. 25%, p = 0.721) or 90-day mortality (HCC vs. non-HCC, 11.1 vs. 0%, p = NS).

DISCUSSION

In our study, HCC patients demonstrated significantly less FLR growth after ALPPS-Stage 1 compared to non-HCC patients. Hepatic fibrosis was also found to negatively impact FLR growth. When considering suitability for ALPPS, patients with HCC may benefit from additional pre-operative assessment of fibrosis.

Microencapsulation of α-tocopherol with zein and β-cyclodextrin using spray drying for colour stability and shelf-life improvement of fruit beverages

Encapsulated forms of α-tocopherol into β-cyclodextrin and zein carriers for colour stability and shelf-life improvement of beverages.

Effect of angiotensin-converting enzyme inhibitor, lisinopril on morphological and biochemical aspects of fibrotic liver regeneration

BACKGROUND/AIMS

Hepatic fibrosis results in defective liver regeneration following partial hepatectomy. Angiotensin converting enzyme (ACE) inhibitors can enhance liver regeneration and are also involved in the reduction of hepatic fibrosis. The present study has been conducted to evaluate the potential effect of an ACE inhibitor, lisinopril, on the morphological and biochemical aspects of fibrotic liver regeneration.

MATERIALS AND METHODS

Eight-week old female Sprague Dawley rats were made fibrotic by intragastric carbon tetrachloride treatment. Rats were given saline or lisinopril (1 mg/kg) orally for 1 week and were subjected to sham surgery or two-third partial hepatectomy. Liver regenerative and functional capacities were determined 48 hours post surgery.

RESULTS

Lisinopril administration did not affect the regeneration rate, proliferation cell nuclear antigen count, and hepatocellular area of fibrotic livers following partial hepatectomy. No statistically significant difference between treated and control rats regarding mitotic count, hepatocyte nuclear area, and binuclear hepatocyte frequency was observed. Serum biochemical analysis showed that lisinopril non-significantly decreased the partial hepatectomy induced elevated levels of alanine aminotransferase, aspartate transaminase, and alkaline phosphatase whereas lactate dehydrogenase and total bilirubin levels were significantly reduced. No marked reduction in hepatic collagen content and alpha smooth actin positive cells was observed by lisinopril treatment.

CONCLUSION

ACE inhibitor lisinopril did not produce major histomorphological alterations in regenerating fibrotic liver following partial hepatectomy, however, it may improve its functional capability.

Parenteral solution of nutritional hepatotrophic factors improves regeneration in thioacetamide-induced cirrhotic livers after partial hepatectomy

Liver resection is a suitable option for the treatment of certain hepatic conditions, particularly hepatocarcinomas, in patients with cirrhosis. However, this disease impairs liver regeneration, which increases the risk of liver failure and postoperative death. Supportive treatments for regeneration of the remaining liver may be useful for the recovery of these patients. We demonstrated that nutritional hepatotrophic factors (NHF) is an effective regenerative stimulus for cirrhotic livers in rats subjected to partial hepatectomy (PH). The rats with thioacetamide-induced cirrhosis were subjected to PH, and they were divided into 2 groups. One group received intraperitoneal administration of NHF, and the other group received saline solution. After 12 days, biometric data, collagen content, hepatocyte regeneration (proliferation cell nuclear antigen immunochemistry), and profibrotic gene expression (Collagen-α1, matrix metalloproteinase 2, tissue inhibitor of metalloproteinase 1, and transforming growth factor beta 1) were assessed. The results indicated that the rats treated with NHF after PH had an increased liver size, a reduced amount of collagen, and a higher hepatocyte proliferation index compared with the rats that underwent PH alone. In addition, collagen-α1 gene expression was decreased in the NHF-treated rats. Thus, postoperative improvement in the liver morphology following NHF treatment may cause a significant decrease in the risk of liver failure and mortality after hepatic resection.

Antioxidative, antiapoptotic, and proliferative effect of curcumin on liver regeneration after partial hepatectomy in rats

The aim of the present study was to assess the influence of curcumin on liver regeneration after partial hepatectomy (PH) in rats. A total of 24 male Sprague Dawley rats were divided into three groups: sham-operated (SH), PH, and PH + curcumin; each group contains eight animals. The rats in curcumin-treated groups were given curcumin (in a dose of 100 mg/kg body weight) once a day orally for 7 days, starting 3 days prior to hepatectomy operation. At 7 days after resection, liver samples were collected. The malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) levels were estimated in liver homogenates. Moreover, histopathological examination, mitotic index (MI), proliferating cell nuclear antigen labeling, proliferation index (PI), transferase-mediated 2'-deoxyuridine, 5'-triphosphate nick end-labeling assay, and apoptotic index (AI) were evaluated at 7 days after hepatectomy. As a result, curcumin significantly increased MI and PI and significantly decreased AI in PH rats. Additionally, curcumin remarkably inhibited MDA elevation, restored impaired antioxidant SOD activity and GSH level and also attenuated hepatic vacuolar degeneration and sinusoidal congestion. These results suggested that curcumin treatment had a beneficial effect on liver regenerative capacity of the remnant liver tissue after hepatectomy, probably due to its antioxidative, antiapoptotic, and proliferative properties.

Co-administration of prostaglandin E1 with somatostatin attenuates acute liver damage after massive hepatectomy in rats via inhibition of inflammatory responses, apoptosis and endoplasmic reticulum stress

Acute liver damage is considered to be the major cause of mortality after massive hepatectomy. Prostaglandin E1 (PGE1) and somatostatin (SST) have been shown to protect against hepatic injury of rats after partial hepatectomy. However, the precise mechanisms remain largely unknown. In this study, we examined the effects of PGE1, SST and the combination of these two drugs on acute liver damage of rats after 90% hepatectomy. We found that animal survival was improved when pretreated with PGE1 and SST. Portal venous pressure (PVP), serum alanine aminotransferase (ALT) and aspartate aminotransaminase (AST), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were all reduced after administration of PGE1 and SST. In addition, apoptosis was inhibited via upregulation of Bcl-2 and downregulation of Bax and caspase-3 in drug treatment groups. Furthermore, pretreatment with PGE1 and SST alleviated endoplasmic reticulum (ER) stress by induction of heat shock protein 70 (HSP70) and glucose-regulated protein 78 (GRP78), but suppression of transcription factor C/EBP homologous protein (CHOP). Our data suggest that administration of PGE1 and SST, particularly in combination, may prevent acute liver damage of rats after massive hepatectomy by inhibiting inflammatory responses, apoptosis and ER stress.

Ursolic acid enhances mouse liver regeneration after partial hepatectomy

CONTEXT

Ursolic acid is a pentacyclic triterpenoid which has hepatoprotective and antihepatotoxic activities.

OBJECTIVE

This study investigated whether ursolic acid is able to stimulate liver regeneration in partially hepatectomized mice.

MATERIALS AND METHODS

Ursolic acid or the vehicle solution was orally administered to the experimental, sham-operated and vehicle-treated group mice for 7 days, positive control animal (mice) was treated with recombinant human hepatocyte growth factor (rhHGF), and then the 70% liver partial hepatectomy was performed. The liver mass recovery rate was estimated by measuring the ratios of mice liver weight to body weight. The liver cells undergoing DNA synthesis were identified by immunohistochemistry analysis using monoclonal anti-BrdU antibodies. The expression levels of cyclin D1, cyclin E and C/EBP proteins (C/EBPα and C/EBPβ) were detected by the Western blotting technique.

RESULTS

Our results showed administration of ursolic acid significantly increased the ratio of the liver to body weight and BrdU labeling index at 36 and 48 h after partial hepatectomy, and the potency of UA is similar to rhHGF treated positive control mice. In addition, ursolic acid treatment significantly increased cyclin D1, cyclin E and C/EBPβ protein expression levels at 36 h after liver PHx compared with the vehicle-treated control mice.

DISCUSSION AND CONCLUSION

All these results suggest that ursolic acid stimulates liver proliferation after partial hepatectomy, and this effect may be associated with the stimulation of C/EBPβ expression.

[Hepatocellular carcinoma and cholangiocarcinoma]

Hepatocellular carcinoma and cholangiocarcinoma are relatively rare tumors of the gastrointestinal tract in western Europe but their incidence has been increased in recent years. Newly diagnosed intrahepatic lesions or intrahepatic cholestasis require extensive laboratory tests and imaging studies in order to confirm the diagnosis of hepatocellular carcinoma, intrahepatic or extrahepatic cholangiocarcinoma. The treatment options range from liver resection or liver transplantation to conservative measures (in cases of non-resectable lesions). This review article aims to provide an overview on the diagnostic options and the subsequent treatment.

Hepatotrophic factors reduce hepatic fibrosis in rats

CONTEXT: Hepatic fibrosis occurs in response to several aggressive agents and is a predisposing factor in cirrhosis. Hepatotrophic factors were shown to stimulate liver growth and to restore the histological architecture of the liver. They also cause an improvement in liver function and accelerate the reversion of fibrosis before it progresses to cirrhosis. OBJECTIVE: To test the effects of hepatic fibrosis solution composed by amino acids, vitamins, glucose, insulin, glucagon and triiodothyronine on hepatic fibrosis in rats. METHODS: Fibrosis was induced in rats by gastric administration of dimethylnitrosamine (10 mg/kg) for 5 weeks. After liver biopsy, the rats received either hepatotrophic factors solution (40 mg/kg/day) or saline solution for 10 days by intraperitoneal injection. Blood samples and liver fragments were collected for hepatic function analysis, standard histopathology evaluation, and morphometric collagen quantification. RESULTS: Rats in the hepatotrophic factors group showed a decrease of the histopathological components of fibrosis and an increase of their hepatic mass (12.2%). There was no development of neoplasic lesions in both groups. Compared with the saline group, the hepatotrophic factors group also had a decrease of blood levels of hepatic-lesion markers (AST, ALT) and a decrease of collagen content in the portal spaces (31.6%) and perisinusoidal spaces (42.3%), as well as around the hepatic terminal vein (57.7%). Thus, hepatotrophic factors administration in the portal blood promoted a regenerative hepatic response, with an overall reduction of the volumetric density of collagen, improved hepatic function, and a general improvement in the histopathological aspects of fibrosis. CONCLUSION: Taken together, these results suggest the potential therapeutic use of this hepatotrophic factors solution to treat chronic liver diseases.

alpha-Methylspermidine protects against carbon tetrachloride-induced hepatic and pancreatic damage

The role of polyamines in carbon tetrachloride (CCl(4))-induced organ injury was studied in syngenic rats and transgenic rats with activated polyamine catabolism. In syngenic rats, administration of CCl(4) resulted in the induction of hepatic spermidine/spermine N(1)-acetyltransferase (SSAT), accumulation of putrescine, reduction in spermine level and appearance of moderate hepatic injury within 24 h. Upon treatment with CCl(4), transgenic rats overexpressing SSAT displayed induction of both hepatic and pancreatic SSAT, with subsequent accumulation of putrescine and decrease of both spermidine and spermine pools. Administration of CCl(4) in SSAT transgenic rats induced not only massive hepatic injury, but also severe acute necrotizing pancreatitis. Pretreatment of the animals with catabolically stable functional polyamine mimetic, alpha-methylspermidine (MeSpd) prevented pancreatic and hepatic injury in SSAT rats and markedly reduced liver damage in syngenic animals. As assessed by immunostaining of proliferating cell nuclear antigen, MeSpd increased the amount of regenerating hepatocytes in both genotypes. These results show that CCl(4) induces hepatic and pancreatic polyamine catabolism, and the extent of organ damage correlates with the degree of polyamine depletion. Furthermore, MeSpd protects against CCl(4)-induced hepatic and pancreatic damage and promotes tissue regeneration.

Effects of bicyclol on liver regeneration after partial hepatectomy in rats

Bicyclol is a synthetic antihepatitis drug with antioxidative property. The present study was performed to investigate the effect of bicyclol on liver regeneration after partial hepatectomy in rats. Bicyclol (300 mg/kg) was given to rats subjected to 70% hepatectomy three times before operation. At 6, 24, and 48 h after resection, samples were collected for the measurement of serum alanine aminotransferase (ALT), total bilirubin (TBil), hepatic glycogen, malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH). Moreover, liver regeneration rate, proliferating cell nuclear antigen (PCNA) labeling, proliferation index, and histopathological examination were evaluated at 48 h after hepatectomy. As a result, bicyclol significantly increased regeneration rate, mitotic index (MI), PCNA labeling index, and proliferation index in PH rats. Additionally, bicyclol remarkably inhibited the elevation of serum ALT and TBil levels, alleviated the formation of liver MDA, restored impaired antioxidant SOD and GSH, increased hepatic glycogen content, and also attenuated hepatic vacuolar degeneration. These results suggested that bicyclol had a beneficial effect on liver regenerative capacity of the remnant liver tissue after hepatectomy, probably due to its antioxidative property.

Geranylgeranylacetone prevents acute liver damage after massive hepatectomy in rats through suppression of a CXC chemokine GRO1 and induction of heat shock proteins

BACKGROUND AND METHODS

Acute liver failure after massive hepatectomy remains a challenging problem. In this study, using a microarray designed to monitor the side effects of drugs, we examined changes in gene expression in the remnant liver during the 24 h after hepatectomy and the effects of a nontoxic heat shock protein (HSP) 70 inducer, geranylgeranylacetone (GGA), after 90% hepatectomy in rats.

RESULTS

A single oral administration of 100 mg/kg GGA significantly suppressed the release of aminotransferases and improved survival compared with vehicle administration. The hepatectomy upregulated 74 genes and downregulated 95. Interestingly, ten cytokine genes were upregulated, while no cytokine-related gene was downregulated. Among the ten cytokine genes, a potent chemoattractant for neutrophils, GRO1, was most rapidly and markedly upregulated after 90% hepatectomy. GGA effectively suppressed the up-regulation of GRO1 messenger ribonucleic acid, and this was validated by Northern hybridization. Microarray and immunoblot analyses showed that, in addition to HSP70 and HSP27, GGA preferentially induced an endoplasmic reticulum chaperone, BIP.

CONCLUSION

Considering hemodynamic and metabolic overloading as a primary cause of acute lever failure, the ER stress response enhanced by GGA may also play an important role in the prevention of overload-induced liver damage.

Restrictive model of compensated carbon tetrachloride-induced cirrhosis in rats

AIM: To develop a simplified and quick protocol to induce cirrhosis and standardize models of partial liver resection in rats.

METHODS: In Fischer F344 rats two modified protocols of phenobarbital-carbon tetrachloride (CCl₄) (dilution 50%) gavage to induce cirrhosis (frequency adjusted according to weight, but each subsequent dose was systematically administered) were tested, i.e. the rapid and slow protocols. Prothrombin time (PT) and total bilirubin (TB) were also evaluated. Animals from the rapid group underwent 15% hepatectomy and animals from the slow group underwent 70% hepatectomy.

RESULTS: Rapid protocol: This corresponded to 1 gavage/4 d over 6 wk (mortality 30%). Mean PT was 35.2 ± 2.8 s (normal: 14.5 s), and mean TB was 1.8 ± 0.2 mg/dL (normal: 0.1 mg/dL). Slow protocol: This corresponded to 1 gavage/6 d over 9 wk (mortality 10%). Mean PT was 11.8 ± 0.2 s (normal: 14.5 s), and mean TB was 0.4 ± 0.04 mg/dL (normal: 0.1 mg/dL). Pathological analyses were performed in both protocols which showed persistent cirrhosis at 3 mo. Rat mortality in the rapid gavage group who underwent 15% hepatectomy and in the slow gavage group who underwent 70% hepatectomy was 50% and 70%, respectively.

CONCLUSION: Our modified model is a simplified method to induce cirrhosis which is rapid (6 to 9 wk), efficient and stable up to 3 mo. Using this method, “Child Pugh A” or “Child Pugh BC” cirrhotic rats were obtained. Our models of cirrhosis and hepatectomy can be used in various situations focusing on postoperative survival.

Beneficial effects of Kampo medicine Inchin-ko-to on liver function and regeneration after hepatectomy in rats

AIM

Inchin-ko-to (ICKT), Kampo medicine, is known to inhibit hepatocyte apoptosis as well as promote the secretion and excretion of bile. The aim of this study is to clarify the effects of ICKT on liver function and hepatic regeneration after massive hepatectomy in rats.

METHODS

Male Wistar rats received 2 g/kg ICKT from 3 days preoperatively and underwent 90% hepatectomy. Liver sections were stained using immunohistochemistry (hemeoxygenase-1 [HO-1], alpha-smooth muscle actin [SMA], and proliferating cell nuclear antigen [PCNA]).

RESULTS

The survival period was significantly prolonged, and the remnant liver/body weight ratio was significantly increased postoperatively in the ICKT group. The values of transaminase, total bile acid, and total bilirubin were significantly improved in the ICKT group. In the ICKT group, PCNA and HO-1 were strongly expressed early postoperatively, but the expression of alpha-SMA was weak.

CONCLUSION

The preoperative administration of ICKT has been suggested to provide beneficial effects in promoting hepatic regeneration and preventing postoperative hepatic failure. The reduced activation of stellate cells may be involved in their mechanisms.

IL-6 Promotes compensatory liver regeneration in cirrhotic rat after partial hepatectomy

Major hepatic resection in cirrhotic patients is associated with impaired liver regeneration and failure, leading to high peri-operative mortality. In this work, the causes of defective regeneration in cirrhotic liver and the utility of IL-6 treatment were investigated in an experimental model combining cirrhosis and partial hepatectomy in the rat. Relative to normal controls, decompensated cirrhotic animals showed decreased survival, while compensated cirrhotic animals showed similar survival but reduced hepatic DNA synthesis and newly regenerated liver mass amount. Defective liver regeneration was associated with a decrease in STAT3 and NF-kB activation, consistent with an increased accumulation of their respective inhibitors PIAS3 and IkBalpha, and with a decreased induction of Bcl-xL. Treatment with recombinant IL-6 enhanced survival of decompensated cirrhotic animals, while it did not affect survival of compensated cirrhotic animals but sustained liver regeneration, by restoring STAT3 and NF-kB activation and Bcl-xL induction to the levels found in normal controls. The pro-growth effects exerted by IL-6 treatment in cirrhotic liver were attained also at low, pharmacologically acceptable doses. In conclusion, our results suggest that IL-6 treatment may be therapeutic in major resection of cirrhotic liver.

Effects of carvacrol upon the liver of rats undergoing partial hepatectomy

The present study aims to investigate the possible effects of carvacrol obtained from origanum oil upon the regenerative feature of the liver subsequent to partial hepatectomy in rats. Male Wistar Albino rats, weighing 230+/-30g, were divided into three experiment groups. Group I (n=8) were used as sham operation group. Group II (n=8) were applied saline solution and hepatectomy. Carvacrol and hepatectomy (73mg/kg) were applied to Group III (n=8). One dose of test material was injected 1h before 68% partial hepatectomy. At the end of the experiments, blood and organs were removed. The liver regeneration rate of the rats was calculated measuring the weights of their liver before and after the hepatectomy. Hematoxylin and eosin, interleukin-6 (IL-6) and proliferating cell nuclear antigen (PCNA) treatments were applied to liver sections. Aspartate transaminase (AST), alanine transaminase (ALT), tumor necrosis factor-alpha (TNF-alpha) and IL-6 levels were determined in serum samples. The liver regeneration, mitotic index and PCNA index increased significantly in rats of Group III over the Group II at the 72nd hour after partial hepatectomy. Histological evaluations were also similar with these results of PCNA and mitotic indexes. In AST, ALT, TNF-alpha and IL-6 levels, there was no statistically significant difference. According to these results, it is concluded that carvacrol increases the liver regeneration rate.

Addressing liver fibrosis with liposomes targeted to hepatic stellate cells

Liver fibrosis is a chronic disease that results from hepatitis B and C infections, alcohol abuse or metabolic and genetic disorders. Ultimately, progression of fibrosis leads to cirrhosis, a stage of the disease characterized by failure of the normal liver functions. Currently, the treatment of liver fibrosis is mainly based on the removal of the underlying cause of the disease and liver transplantation, which is the only treatment for patients with advanced fibrosis. Hepatic stellate cells (HSC) are considered to be key players in the development of liver fibrosis. Chronically activated HSC produces large amounts of extracellular matrix and enhance fibrosis by secreting a broad spectrum of cytokines that exert pro-fibrotic actions in other cells, and in an autocrine manner perpetuate their own activation. Therefore, therapeutic interventions that inhibit activation of HSC and its pro-fibrotic activities are currently under investigation worldwide. In the present study we applied targeted liposomes as drug carriers to HSC in the fibrotic liver and explored the potential of these liposomes in antifibrotic therapies. Moreover, we investigated effects of bioactive compounds delivered by these liposomes on the progression of liver fibrosis. To our knowledge, this is the first study demonstrating that lipid-based drug carriers can be selectively delivered to HSC in the fibrotic liver. By incorporating the bioactive lipid DLPC, these liposomes can modulate different processes such as inflammation and fibrogenesis in the fibrotic liver. This dual functionality of liposomes as a drug carrier system with intrinsic biological effects may be exploited in new approaches to treat liver fibrosis.

Serum Endostatin Levels and Regenerative Capacities of Normal and Cirrhotic Livers Following Partial Hepatectomy in Mice: The Response to Different Resection Sizes

BACKGROUND

Angiogenesis has an important role in liver regeneration. Antiangiogenic response in remnant liver following resection and its relationship to regeneration is not well known. The aim of this study was to investigate the effect of hepatectomy size on serum endostatin levels, and the effect of endostatin levels to liver regeneration after partial hepatectomy in normal and cirrhotic mice.

MATERIALS AND METHODS

Sixty noncirrhotic and 36 carbon tetrachloride-induced cirrhotic mice were included in the study. Noncirrhotic mice were randomly divided into four main groups: sham, 20%, 40%, and 70% hepatectomy groups. Similarly, cirrhotic mice were randomly divided into three main groups: sham, 20%, and 40% hepatectomy groups. The mice in each group were further divided into two subgroups to compare serum endostatin levels and liver regeneration indexes on days 1 and 14. Liver regeneration was evaluated by the proliferating cell nuclear antigen-labeling index. Serum endostatin level was measured to evaluate antiangiogenic response.

RESULTS

Serum endostatin levels on the first day and 14th day increased significantly in correlation with the hepatectomy size, both in normal mice and cirrhotic mice (P < 0.05). In normal mice with high regeneration indexes that underwent 40% and 70% hepatectomies, there was a significant increase in serum endostatin levels on the 14th day compared with the first day (P < 0.05). However, the increase in mice that underwent 20% hepatectomies was not significant. After 20% and 40% hepatectomies, first day serum endostatin levels were significantly higher in cirrhotic mice compared with normal mice (P < 0.05), which was independent of regeneration. Nevertheless, after 40% hepatectomies, 14th day serum endostatin levels were significantly lower in cirrhotic mice compared with normal mice, attributable to the limited regeneration capacity of cirrhotic liver (P < 0.05). Regeneration capacity of cirrhotic liver was low at all times.

CONCLUSIONS

The current study suggests that there is a significant relationship between serum endostatin levels and regeneration capacity after hepatectomy in normal mice. On the other hand, following resection of cirrhotic liver, regeneration capacity is depressed and high endostatin levels are independent of hepatic regeneration.

Both plasma lysophosphatidic acid and serum autotaxin levels are increased in chronic hepatitis C

OBJECTIVES

Recent accumulating evidence indicates that lysophosphatidic acid (LPA) is a lipid mediator, abundantly present in blood, with a wide range of biologic actions including the regulation of proliferation and contraction in liver cells. Although it is speculated that LPA might play a role in pathophysiologic processes in vivo, not only its role but also even a possible alteration in its blood concentration under specific diseases is essentially unknown. Autotaxin (ATX), originally purified as an autocrine motility factor for melanoma cells, was revealed to be a key enzyme in LPA synthesis. We determined LPA and ATX levels in the blood of patients with liver disease.

METHODS

ATX activity was measured by determining choline with the substrate of lysophosphatidylcholine, and the LPA level by an enzymatic cycling method in 41 patients with chronic hepatitis C.

RESULTS

The serum ATX activity and plasma LPA level were significantly increased in patients, and were correlated positively with serum hyaluronic acid, and negatively with platelets, albumin, and prothrombin time. The plasma LPA level was strongly correlated with serum ATX activity. There were significant correlations between the histologic stage of fibrosis and both the serum ATX activity and plasma LPA level.

CONCLUSIONS

The serum ATX activity and plasma LPA level are increased in chronic hepatitis C in association with liver fibrosis. Our study may provide the first evidence showing a significant increase of both ATX and LPA in the blood under a specific disease.

Mechanisms of liver fibrosis

Liver fibrosis represents a significant health problem worldwide of which no acceptable therapy exists. The most characteristic feature of liver fibrosis is excess deposition of type I collagen. A great deal of research has been performed to understand the molecular mechanisms responsible for the development of liver fibrosis. The activated hepatic stellate cell (HSC) is the primary cell type responsible for the excess production of collagen. Following a fibrogenic stimulus, HSCs change from a quiescent to an activated, collagen-producing cell. Numerous changes in gene expression are associated with HSC activation including the induction of several intracellular signaling cascades, which help maintain the activated phenotype and control the fibrogenic and proliferative state of the cell. Detailed analyses in understanding the molecular basis of collagen gene regulation have revealed a complex process offering the opportunity for multiple potential therapeutic strategies. However, further research is still needed to gain a better understanding of HSC activation and how this cell maintains its fibrogenic nature. In this review we describe many of the molecular events that occur following HSC activation and collagen gene regulation that contribute to the fibrogenic nature of these cells and provide a review of therapeutic strategies to treat this disease.

Persistence of liver cirrhosis in association with proliferation of nonparenchymal cells and altered location of alpha-smooth muscle actin-positive cells

This study was carried out to achieve pathological understanding for the persistence of cirrhosis induced by thioacetamide (TAA). Forty-five, male,21-day-old, F344 rats were randomly allocated to group I and received drinking water as a control, and groups 2 and 3 given 0.015% or 0.03%TAA, respectively for 12 weeks. Two-third of animals per group were sacrificed, and remainder were maintained for a further 4 weeks without TAA treatment. Liver cirrhosis was induced in all animals in group 3 at week 12, with obvious increase of collagen content, and this persisted after cessation of TAA. Proliferating cell nuclear antigen (PCNA) positive labeling indices of nonparenchymal cells were increased significantly after cessation in groups 2 and 3 (p < 0.01). RT-RCR analysis of a-smooth muscle actin (alpha-SMA) showed significant increase in group 3 compared to that of control at both time points (p < 0.05). Immunohistochemical staining of it demonstrated positive cells to mainly be located around regenerating hepatic nodules at week 12, however, they were focused into enlarged portal areas consisting of fibrous tissues and pseudo-bile ductular cells after the cessation. Taken together, we conclude persistence of liver cirrhosis could be associated with the proliferation of nonparenchymal cells and altered location of alpha-SMA positive cells.

Geranylgeranylacetone suppresses inflammatory responses and improves survival after massive hepatectomy in rats

Overproduction of heat shock protein 70 (HSP70) in the liver protects hepatocytes under various pathologic conditions. In this study we examined the effects of a nontoxic HSP70 inducer, geranylgeranylacetone (GGA), on acute hepatic failure after 95% hepatectomy in rats. When GGA (100 mg/kg) or vehicle was intragastrically administered to rats 4 hours before 95% hepatectomy, all 25 rats pretreated with vehicle died within 60 hours after the operation, whereas 10 of 25 rats pretreated with GGA survived. During the 24-hour postoperative period, GGA significantly suppressed the release of aspartate or alanine aminotransferase and elevation of the serum interleukin-6 level, and completely inhibited an increase in the serum level of tumor necrosis factor-alpha. Histologic examinations showed that GGA prevented hemorrhagic necrosis, which was observed in vehicle-treated livers more than 12 hours after the operation. During the 24-hour postoperative period, HSP70 induction was absent in remnant livers of vehicle-treated rats. In contrast, GGA stimulated the HSP70 mRNA expression and HSP70 accumulation within 4 hours, and viable hepatocytes contained abundant HSP70 in their nuclei. Our results suggest that GGA may prevent acute liver failure after massive hepatectomy, at least in part, by enhancing HSP70 induction in the remnant liver.

Polyamines are required for the initiation of rat liver regeneration

A large number of studies applying inhibitors of polyamine biosynthesis have indicated that these compounds are required for animal cell proliferation. Here we show, using a transgenic rat model with activated polyamine catabolism, that a certain critical concentration of the higher polyamines spermidine and spermine is required for liver regeneration. Partial hepatectomy of transgenic rats expressing spermidine/spermine N(1)-acetyltransferase (SSAT) under the control of mouse metallothionein promoter strikingly induced the enzyme at 24 h and reduced hepatic spermidine by 80%. At that time, the weight of the liver remnant was significantly increased in syngenic rats and proliferating cell nuclear antigen (PCNA) labelling index was 20%, whereas the transgenic rats showed no liver weight gain and their PCNA-positive cells accounted for 0.5% of hepatocytes. Similarly, hepatic thymidine incorporation was markedly enhanced at this time point in syngenic, but not in transgenic, animals, whereas the rate of leucine incorporation was only marginally affected in the transgenic animals. At 3 days after operation, the spermidine pool in transgenic livers had increased to the pre-operative level, the remnant weight was significantly elevated and hepatic PCNA labelling index increased to 5%. N(1),N(11)-Diethylnorspermine, a powerful inducer of SSAT, inhibited liver weight gain and proliferative activity in both syngenic and transgenic rats. We found an extremely close correlation between hepatic spermidine, and less close between spermine, concentrations and PCNA labelling index during early liver regeneration. These results indicate that spermidine and/or spermine, but apparently not putrescine, are required for liver regeneration, yet at concentrations smaller than those normally found after partial hepatectomy.

Hepatocyte growth factor and c-Met inhibition by hepatic cell hypoxia: a potential mechanism for liver regeneration failure in experimental cirrhosis

Hepatic resection in cirrhotic patients is associated with impaired liver regeneration and poor clinical outcome. Because experimental cirrhosis is associated with hepatic cell hypoxia, we herein investigated whether hypoxia might alter the mechanisms of liver regeneration in the cirrhotic liver. Cirrhosis was induced by diethylnitrosamine in rats. Immunohistochemistry was performed to assess hepatocellular hypoxia and proliferation 24 hours after a two-thirds partial hepatectomy (PH) in cirrhotic and control rats. Cultured hepatocytes and myofibroblastic hepatic stellate cells were submitted to hypoxia using anaerobic jars. Hepatocyte growth factor (HGF) and c-Met expressions were determined by reverse transcriptase-polymerase chain reaction, Northern blot, and Western blot. In control rats, hypoxia was restricted to perivenular hepatocytes, and PH induced a marked increase in hepatocyte proliferation and in liver HGF expression, whereas c-Met expression remained unchanged. In cirrhotic rats, hypoxia was detected virtually in all of the hepatocytes, and PH induced no significant change in hepatocyte proliferation and in liver HGF expression, whereas c-Met expression was decreased as compared to normal livers. In vitro, the expression of HGF in myofibroblastic hepatic stellate cells and of c-Met in hepatocytes underwent a dramatic decrease under hypoxia. Our results suggest that hepatocellular hypoxia causes inhibition of HGF (and of c-Met)-mediated proliferation and thereby might contribute to liver regeneration failure in cirrhotic liver.

A growth-constrained environment drives tumor progression invivo

We recently have shown that selective growth of transplanted normal hepatocytes can be achieved in a setting of cell cycle block of endogenous parenchymal cells. Thus, massive proliferation of donor-derived normal hepatocytes was observed in the liver of rats previously given retrorsine (RS), a naturally occurring alkaloid that blocks proliferation of resident liver cells. In the present study, the fate of nodular hepatocytes transplanted into RS-treated or normal syngeneic recipients was followed. The dipeptidyl peptidase type IV-deficient (DPPIV(-)) rat model for hepatocyte transplantation was used to distinguish donor-derived cells from recipient cells. Hepatocyte nodules were chemically induced in Fischer 344, DPPIV(+) rats; livers were then perfused and larger (>5 mm) nodules were separated from surrounding tissue. Cells isolated from either tissue were then injected into normal or RS-treated DPPIV(-) recipients. One month after transplantation, grossly visible nodules (2--3 mm) were seen in RS-treated recipients transplanted with nodular cells. They grew rapidly, occupying 80--90% of the host liver at 2 months, and progressed to hepatocellular carcinoma within 4 months. By contrast, no liver nodules developed within 6 months when nodular hepatocytes were injected into the liver of recipients not exposed to RS, although small clusters of donor-derived cells were present in these animals. Taken together, these results directly point to a fundamental role played by the host environment in modulating the growth and the progression rate of altered cells during carcinogenesis. In particular, they indicate that conditions associated with growth constraint of the host tissue can drive tumor progression in vivo.

Reduction of carbon tetrachloride-induced rat liver injury by IRFI 042, a novel dual vitamin E-like antioxidant

Carbon tetrachloride (CCl4 )-induced hepatotoxicity is likely the result of a CCl4 -induced free radical production which causes membrane lipid peroxidation and activation of transcription factors regulating both the TNF-alpha gene and the early-immediate genes involved in tissue regeneration. IRFI 042 is a novel vitamin E-like compound having a masked sulphydryl group in the aliphatic side chain. We studied the effect of IRFI 042 on CCl4 -induced liver injury. Liver damage was induced in male rats by an intraperitoneal injection of CCl4 (1 ml/kg in vegetal oil). Serum alanine aminotransferase (ALT) activity, liver malondialdehyde (MAL), hydroxyl radical formation (OH*), calculated indirectly by a trapping agent, hepatic reduced glutathione (GSH) concentration, plasma TNF-alpha, liver histology and hepatic mRNA levels for TNF-alpha were evaluated 48 h after CCl4 administration. Hepatic vitamin E (VE) levels were evaluated, in a separate group of animals, 2 h after CCl4 injection. A control group with vitamin E (100 mg/kg) was also treated in order to evaluate the differences versus the analogue treated groups. Intraperitoneal injection of carbon tetrachloride produced a marked increase in serum ALT activity (CCl4 = 404.61 +/- 10.33 U/L; Controls= 28.54 +/- 4.25 U/L), liver MAL (CCl4 = 0.67 +/- 0.16 nmol/mg protein; Controls= 0.13 +/- 0.06 nmol/mg protein), OH(7) levels assayed as 2,3-DHBA (CCl4 = 8.73 +/- 1.46 microM; Controls= 0.45 +/- 0.15 microM) and 2,5-DHBA (CCl4 = 24.61 +/- 3.32 microM; Controls= 2.75 +/- 0.93 microM), induced a severe depletion of GSH (CCl4 = 3.26 +/- 1.85 micromol/g protein; Controls= 17.82 +/- 3.13 micromol/g protein) and a marked decrease in VE levels (CCl4 = 5.67 +/- 1.22 nmol/g tissue; Controls= 13.47 +/- 3.21 nmol/g tissue), caused liver necrosis, increased plasma TNF-alpha levels (CCl4 = 57.36 +/- 13.24 IU/ml; Controls= 7.26 +/- 2.31 IU/ml) and enhanced hepatic mRNA for TNF-alpha (CCl4 = 19.22 +/- 4.38 a.u.; Controls= 0.76 +/- 0.36 a.u.). IRFI 042 (100 mg/kg, 30 min after CCl4 injection) blunted liver MAL (0.32 +/- 0.17 nmol/mg protein), decreased the serum levels of ALT (128.71 +/- 13.23 U/L), and restored the hepatic concentrations of VE (9.52 +/- 3.21 nmol/g tissue), inhibited OH* production (2,3-DHBA= 3.54 +/- 1.31 microM; 2,5-DHBA= 7.37 +/- 2.46 microM), restored the endogenous antioxidant GSH (12.77 +/- 3.73 mmol/g protein) and improved histology. Furthermore IRFI 042 treatment suppressed plasma TNF-alpha concentrations (31.47 +/- 18.25 IU/ml) and hepatic TNF-alpha mRNA levels (11.65 +/- 3.21 a.u.). The acute treatment with vitamin E failed to exert any protective effect against CCl4 -induced hepatotoxicity. These investigations suggest that IRFI 042 treatment may be of benefit during free radical-mediated liver injury.

Cardiac-specific overexpression of cyclin-dependent kinase 2 increases smaller mononuclear cardiomyocytes

Cyclin-dependent kinase 2 (cdk2) plays a critical role in the G1- to S-phase checkpoint of the cell cycle. Adult cardiomyocytes are believed to withdraw from the cell cycle. To determine whether forced overexpression of cdk2 results in altered cell-cycle regulation in the adult heart, we generated transgenic mice specifically overexpressing cdk2 in hearts. Transgenic hearts expressed high levels of both cdk2 mRNA and catalytically active cdk2 proteins. Cdk2 overexpression significantly increased the levels of cdk4 and cyclins A, D3, and E. There was an increase in both DNA synthesis and proliferating cell nuclear antigen levels in the adult transgenic hearts. The ratio of heart weight to body weight in cdk2 transgenic mice was significantly increased in neonatal day 2 but not in adults compared with that of wild-type mice. Analysis of dispersed individual adult cardiomyocytes showed a 5.6-fold increase in the proportion of smaller mononuclear cardiomyocytes in the transgenic mice. Echocardiography revealed that transgenic heart was functionally normal. However, adult transgenic ventricles expressed beta-myosin heavy chain and atrial natriuretic factor. Surgically induced pressure overload caused an exaggerated maladaptive hypertrophic response in transgenic mice but did not change the proportion of mononuclear cardiomyocytes. The data suggest that overexpression of cdk2 promotes smaller, less-differentiated mononuclear cardiomyocytes in adult hearts that respond in an exaggerated manner to pressure overload.