Rat Model Of Liver Regeneration Research Articles

Inherent control of hepatocyte proliferation after subtotal liver resection.

At the normal physiological conditions, hepatocytes predominantly reside in G0 phase of cell cycle; they actively proceed to G1 phase upon damage to the organ. As it was shown in experiments with restoration of liver mass in rats after subtotal hepatectomy (resection of 80% of the organ mass may be considered as a model of the 'small for size' liver syndrome), the growth inhibition is due to prolonged arrest of hepatocyte proliferation, molecular mechanisms of which remain understudied. In a rat model of liver regeneration after surgical removal of 80% of its mass, we observe a delayed onset of hepatocyte proliferation: Ki67+ hepatocytes begin to appear as late as at 30 h after liver subtotal resection. Their appearance coincides with the beginning of transcription of genes for cyclins A2, B1, D 1 , and E 1 at 24-30 h after surgery. The corresponding increase in concentrations of cyclin D 1 and E proteins is further delayed till 48 h after liver resection. We have also observed a prolonged decrease in the expression of proto-oncogene c-met (the hepatocyte growth factor receptor-encoding gene Met), an increase in expression of the transforming growth factor β1 (TGFβ 1 ) receptor-encoding gene Tgfbr2. At the same time, irreversible block of hepatocyte proliferation is prevented by expression of certain factors, notably of the TWEAK/Fn14 signaling pathway: concentrations of the corresponding proteins in remnant livers have peaked from 24 to 48 h after liver subtotal resection.

Omega-3 fatty acids inhibit oxidative stress in a rat model of liver regeneration.

PurposeLipid peroxidation and consequent reactive oxygen species in the setting of oxidative stress have crucial roles in liver regeneration, which may adversely affect the regeneration itself and lead to liver failure. The aim of the current study is to investigate whether omega-3 fatty acid supplementation inhibits oxidative stress in an experimental model of liver regeneration.MethodsForty rats were allocated to four groups. Rats in group A received a sham operation. Rats in group B were subjected to right portal vein ligation (RPVL) and saline infusion. Rats in groups C and D were subjected to RPVL and total parenteral nutrition (TPN) with an all-in-one admixture containing a soybean oil based lipid emulsion. Rats in group D were additionally supplemented with omega-3 fatty acid infusion. Oxidative stresses in the blood and liver were measured by glutathione, superoxide dismutase, catalase, glutathione peroxidase, malondialdehyde, and nitric oxide.ResultsOmega-3 supplementation to the TPN solution significantly corrected alterations in the blood and tissue concentrations of oxidants and anti-oxidants during regeneration (P < 0.05).ConclusionOmega-3 fatty acid supplementation to the TPN solution revealed promising results in removal of oxidative stress that emerges during liver regeneration.

Expression of Cytokine Genes and Growth Factors in Rat Lungs and Kidneys after Subtotal Hepatectomy.

Expression of il1b, il6, il10, tnfa, hgf, tgfb, vegf, and fgf2 genes in the lungs and kidneys was examined on rat model of liver regeneration after subtotal hepatectomy. Enhanced expression of il6, il10, tnfa, hgf, and fgf2 genes was detected at the early terms after 80% liver resection.

A novel rat model of liver regeneration: possible role of cytokine induced neutrophil chemoattractant-1 in augmented liver regeneration.

BackgroundLiver resection is the mainstay of treatment for most of the liver tumors. Liver has a unique capability to restore the lost volume following resection, however, most of the primary tumors grow in a liver with preexisting parenchymal diseases and secondary tumors often present in multiple liver lobes precluding a safe curative resection. Two-stage hepatectomy and portal vein ligation (PVL) are used to achieve a safer future remnant liver volume (FRLV), however, these procedures take several weeks to achieve adequate FRLV. A recently introduced faster alternative two-stage hepatectomy, also know as associated liver partitioning and portal vein ligation for staged hepatectomy (ALPPS), produces a desirable FRLV in days.MethodsTo have an insight into the mechanism of ALPPS associated liver regeneration, we reproduced a rat model of ALPPS and compared the results with the PVL group.ResultsOur results convincingly showed an advantage of the ALPPS procedure over PVL group in terms of early regeneration, however, in 1-week time the amount of regeneration was comparable. An early regeneration in the ALPPS group coincided with an early entry of hepatocytes into the cell proliferation phase, a significant increase in portal pressure and increase in hepatic enzymes in the ALPPS group compared with the PVL group. According to the protein array evaluation of 29 cytokines/chemokines, cytokine induced neutrophil chemoattractant-1 had the highest expression whereas IL-6 had the highest fold (>6 vs PVL group) expression at the early phase of regeneration in the ALPPS group.ConclusionsThis unique rat model of ALPPS would help to improve our understanding about the liver generation process and also will help in further refinement of the ALPPS procedure for the clinical benefit.Electronic supplementary materialThe online version of this article (doi:10.1186/s13022-015-0020-3) contains supplementary material, which is available to authorized users.

Effect of thalidomide on the expression of vascular endothelial growth factor in a rat model of liver regeneration

Liver regeneration is an angiogenesis-associated phenomenon. The present study investigated the influence of thalidomide, an antiangiogenic agent, on vascular endothelial growth factor (VEGF) expression and liver regeneration after 70% partial hepatectomy (PH) in rats. PH was performed on 50 rats dosed with either thalidomide (100 mg/kg) or a vehicle (controls) by intragastric administration. Serial changes in hepatic microcirculation were evaluated by laser Doppler flowmetry. The VEGF expression in liver tissue was assessed by immunohistochemical study and western blot analysis. Following hepatectomy, the liver regeneration rate increased markedly and reached a peak at 96 h in the two groups. Thalidomide did not affect the overall restoration of liver mass, although a delay in cell proliferation was observed. Prior to PH, the liver microcirculation in rats treated with thalidomide for 2 days was comparatively less than that in their corresponding controls; however, no significant difference between the groups was detected at any time-point following PH. Western blotting showed that the expression of VEGF was upregulated by hepatectomy and the expression levels in the two groups were equal at all studied time-points. The immunohistochemical staining revealed a waved pattern of VEGF expression which advanced from the periportal to pericentral area in both groups, but a slower advancement was detected in thalidomide-treated rats. In conclusion, thalidomide exerted no significant effects on the expression of VEGF and did not impair the overall restoration of liver mass in a rat model of PH-induced liver regeneration, providing supportive evidence for its use as an adjunct treatment modality for liver cancers.

Transplantation of allogeneic hepatocyte‐like cells differentiated from adipose tissue mesenchymal stem cells (MSC) in rat models of liver regeneration and cirrhosis

It has been demonstrated that MSC may differentiate to hepatocyte‐like cells, which after syngeneic transplantation into a host liver persist in the parenchyma. Evidence emerges that MSC display tolerogenic attributes. Therefore, we investigated acceptance of allogeneic MSC transplants in rat models of liver regeneration and cirrhosis.MSC were isolated from adipose tissue of CD26 wildtype DA rats and cells either undifferentiated or after hepatocyte differentiation transplanted into the livers of CD26‐deficient Fischer rats via portal vein. After 10 weeks, small clusters of allogeneic donor cells were visible in the host parenchyma. Compared with undifferentiated cells, clusters were seemingly larger when differentiated cells were used but were by far smaller as compared to the transplantation of syngeneic MSC. When cells were applied systemically via tail vein injection, small clusters of allogeneic donor‐derived cells were visible in the host liver parenchyma after 5 days in animals challenged with partial hepatectomy and with CCl4‐induced liver cirrhosis. This demonstrates that allogeneic MSC home to the liver after acute and chronic liver injury. They integrate into the host liver indicating their acceptance by the host immune system at least in the short term range. This offers the opportunity to use allogeneic MSC for the therapy of liver diseases avoiding immune suppression.

Integrative and comparative genomics analysis of early hepatocellular carcinoma differentiated from liver regeneration in young and old

BackgroundHepatocellular carcinoma (HCC) is the third-leading cause of cancer-related deaths worldwide. It is often diagnosed at an advanced stage, and hence typically has a poor prognosis. To identify distinct molecular mechanisms for early HCC we developed a rat model of liver regeneration post-hepatectomy, as well as liver cells undergoing malignant transformation and compared them to normal liver using a microarray approach. Subsequently, we performed cross-species comparative analysis coupled with copy number alterations (CNA) of independent early human HCC microarray studies to facilitate the identification of critical regulatory modules conserved across species.ResultsWe identified 35 signature genes conserved across species, and shared among different types of early human HCCs. Over 70% of signature genes were cancer-related, and more than 50% of the conserved genes were mapped to human genomic CNA regions. Functional annotation revealed genes already implicated in HCC, as well as novel genes which were not previously reported in liver tumors. A subset of differentially expressed genes was validated using quantitative RT-PCR. Concordance was also confirmed for a significant number of genes and pathways in five independent validation microarray datasets. Our results indicated alterations in a number of cancer related pathways, including p53, p38 MAPK, ERK/MAPK, PI3K/AKT, and TGF-β signaling pathways, and potential critical regulatory role of MYC, ERBB2, HNF4A, and SMAD3 for early HCC transformation.ConclusionsThe integrative analysis of transcriptional deregulation, genomic CNA and comparative cross species analysis brings new insights into the molecular profile of early hepatoma formation. This approach may lead to robust biomarkers for the detection of early human HCC.

The Mitogenic Activity of Hepatocyte Growth Factor on Rat Hepatocytes Is Dependent upon Endogenous Transforming Growth Factor-α

Both transforming growth factor-alpha (TGF-alpha) and hepatocyte growth factor (HGF) induce DNA synthesis in hepatocytes in vitro and in vivo. Hepatic and circulating levels of HGF have been reported to increase before an increase in TGF-alpha levels in several rat models of liver regeneration. In addition, serum TGF-alpha levels increase after an increase in serum HGF levels in patients with either partial hepatectomy or acute hepatitis. In this study, we investigate the significance of TGF-alpha in hepatocyte proliferation. TGF-alpha contents and DNA synthesis in cultured rat hepatocytes increased in response to HGF addition to the culture medium in a dose-related manner. These increases were suppressed by the addition of anti-sense TGF-alpha mRNA oligonucleotide. Furthermore, the addition of anti-TGF-alpha rabbit IgG suppressed the increase in DNA synthesis. When the anti-TGF-alpha antibody was administered to rats after partial hepatectomy, the number of mitotic hepatocytes was reduced in comparison to rats treated with normal rabbit IgG. These results were observed even though hepatic HGF levels were increased equally in rats given either anti-TGF-alpha antibody or normal rabbit IgG. Our results suggest that HGF stimulates TGF-alpha production in rat hepatocytes, and that the mitogenic activity of HGF depends on endogenous TGF-alpha activity.

Transforming Growth Factor α Levels in Liver and Blood Correlate Better than Hepatocyte Growth Factor with Hepatocyte Proliferation during Liver Regeneration

Transforming growth factor alpha (TGFalpha) and hepatocyte growth factor (HGF) are mitogens for hepatocytes in vitro and in vivo, produced by hepatocytes or nonparenchymal cells such as stellate cells in the liver. It is still uncertain whether TGFalpha and HGF are essential for liver regeneration. To assess the role of these growth factors in liver regeneration, their circulating and hepatic levels were studied in various rat models of liver regeneration. Hepatic and plasma HGF levels were increased with increased number of mitotic hepatocytes in rats after partial hepatectomy or carbon tetrachloride intoxication. However, hepatic HGF levels were decreased despite an increased number of mitotic hepatocytes and increased or unchanged plasma HGF levels in rats given phenobarbital and in rats after dimethylnitrosamine intoxication, which can induce hepatic necrosis after apoptosis of hepatic stellate cells. In contrast, hepatic and serum TGFalpha levels were increased in all of the models. In sham-operated rats with no increased number of mitotic hepatocytes, hepatic and circulating levels of HGF were increased, whereas those levels of TGFalpha were unchanged. The results indicate that TGFalpha levels in liver and blood more closely correlate with hepatocyte mitogenesis than HGF levels.

Ethanol interferes with regeneration-associated changes in biotransforming enzymes: A potential mechanism underlying ethanol's carcinogenicity?

The effects of chronic ethanol consumption on enzyme systems involved in carcinogen activation and detoxification were studied in a rat model of liver regeneration. In control rats, steady-state messenger RNAs of cytochrome P450j decreased 12 to 24 hr after partial hepatectomy but were fully recovered by 48 to 72 hr. In contrast, messenger RNA levels of cytochrome P450b and P450d did not vary significantly during that period. Steady-state messenger RNA levels for the placental form of glutathione S-transferase decreased within 30 min after partial hepatectomy but fluctuated until levels returned to normal by 48 hr. Preliminary nuclear run-on analyses suggest that the regulation of cytochrome P450j and the placental form of glutathione S-transferase messenger RNA levels involves posttranscriptional control in these animals. In ethanol-fed rats, as in controls, expression of cytochrome P450j and the placental form of glutathione S-transferase decreased transiently after partial hepatectomy. However, compared with control values, messenger RNA levels for cytochrome P450j were greater in ethanol-fed rats at each time point. Similar results were noted for placental glutathione S-transferase levels from 12 to 48 hr after partial hepatectomy. Ethanol feeding had no apparent effect on steady-state messenger RNA levels of cytochrome P450d, P450b or the multidrug-resistant gene. In both ethanol and control rats, only prehepatectomy levels of cytochrome P450 transcripts correlated with levels of the respective P450 isoenzymes. These data indicate that liver regeneration selectively decreases the steady-state messenger RNA expression of certain isoenzymes of cytochrome P450 and glutathione S-transferase.(ABSTRACT TRUNCATED AT 250 WORDS)