A good model of hepatic failure after excessive hepatectomy in mice

Coagulation factor XIII is a critical driver of liver regeneration after partial hepatectomy

BACKGROUND

Activation of coagulation and fibrin deposition in the regenerating liver appears to promote adequate liver regeneration in mice. In humans, perioperative hepatic fibrin deposition is reduced in patients who develop liver dysfunction after partial hepatectomy (PHx), but the mechanism underlying reduced fibrin deposition in these patients is unclear.

METHODS AND RESULTS

Hepatic deposition of cross-linked (ie, stabilized) fibrin was evident in livers of mice after two-thirds PHx. Interestingly, hepatic fibrin cross-linking was dramatically reduced in mice after 90% PHx, an experimental setting of failed liver regeneration, despite similar activation of coagulation after two-thirds or 90% PHx. Likewise, intraoperative activation of coagulation was not reduced in patients who developed liver dysfunction after PHx. Preoperative fibrinogen plasma concentration was not connected to liver dysfunction after PHx in patients. Rather, preoperative and postoperative plasma activity of the transglutaminase coagulation factor (F)XIII, which cross-links fibrin, was lower in patients who developed liver dysfunction than in those who did not. PHx-induced hepatic fibrin cross-linking and hepatic platelet accumulation were significantly reduced in mice lacking the catalytic subunit of FXIII (FXIII-/- mice) after two-thirds PHx. This was coupled with a reduction in both hepatocyte proliferation and liver-to-body weight ratio as well as an apparent reduction in survival after two-thirds PHx in FXIII-/- mice.

CONCLUSION

The results indicate that FXIII is a critical driver of liver regeneration after PHx and suggest that perioperative plasma FXIII activity may predict posthepatectomy liver dysfunction. The results may inform strategies to stabilize proregenerative fibrin during liver resection.

The multifaceted role of macrophages during acute liver injury

The liver is situated at the interface of the gut and circulation where it acts as a filter for blood-borne and gut-derived microbes and biological molecules, promoting tolerance of non-invasive antigens while driving immune responses against pathogenic ones. Liver resident immune cells such as Kupffer cells (KCs), a subset of macrophages, maintain homeostasis under physiological conditions. However, upon liver injury, these cells and others recruited from circulation participate in the response to injury and the repair of tissue damage. Such response is thus spatially and temporally regulated and implicates interconnected cells of immune and non-immune nature. This review will describe the hepatic immune environment during acute liver injury and the subsequent wound healing process. In its early stages, the wound healing immune response involves a necroinflammatory process characterized by partial depletion of resident KCs and lymphocytes and a significant infiltration of myeloid cells including monocyte-derived macrophages (MoMFs) complemented by a wave of pro-inflammatory mediators. The subsequent repair stage includes restoring KCs, initiating angiogenesis, renewing extracellular matrix and enhancing proliferation/activation of resident parenchymal and mesenchymal cells. This review will focus on the multifaceted role of hepatic macrophages, including KCs and MoMFs, and their spatial distribution and roles during acute liver injury.

Efficacy of Autologous Skeletal Myoblast Cell Sheet Transplantation for Liver Regeneration in Liver Failure

BACKGROUND

No effective therapies have yet been established for liver regeneration in liver failure. Autologous skeletal myoblast cell sheet transplantation has been proven to improve cardiac function in patients with heart failure, and one of the mechanisms has been reported to be a paracrine effect by various growth factors associated with liver regeneration. Therefore, the present study focused on the effect of myoblast cells on liver regeneration in vitro and in vivo.

METHODS

We assessed the effect of myoblast cells on the cells comprising the liver in vitro in association with liver regeneration. In addition, we examined in vivo effect of skeletal myoblast cell sheet transplantation in C57/BL/6 mouse models of liver failure, such as liver fibrosis induced by thioacetamide and hepatectomy.

RESULTS

In vitro, the myoblast cells exhibited a capacity to promote the proliferation of hepatic epithelial cells and the angiogenesis of liver sinusoidal endothelial cells, and suppress the activation of hepatic stellate cells. In vivo, sheet transplantation significantly suppressed liver fibrosis in the induced liver fibrosis model and accelerated liver regeneration in the hepatectomy model.

CONCLUSIONS

Autologous skeletal myoblast cell sheet transplantation significantly improved the liver failure in the in vitro and in vivo models. Sheet transplantation is expected to have the potential to be a clinically therapeutic option for liver regeneration in liver failure.

Preclinical models of acute liver failure: a comprehensive review

Acute liver failure is marked by the rapid deterioration of liver function in a previously well patient over period of days to weeks. Though relatively rare, it is associated with high morbidity and mortality. This makes it a challenging disease to study clinically, necessitating reliance on preclinical models as means to explore pathophysiology and novel therapies. Preclinical models of acute liver failure are artificial by nature, and generally fall into one of three categories: surgical, pharmacologic or immunogenic. This article reviews preclinical models of acute liver failure and considers their relevance in modeling clinical disease.

Cell Therapy and Bioengineering in Experimental Liver Regenerative Medicine: In Vivo Injury Models and Grafting Strategies

Purpose of Review

To describe experimental liver injury models used in regenerative medicine, cell therapy strategies to repopulate damaged livers and the efficacy of liver bioengineering.

Recent Findings

Several animal models have been developed to study different liver conditions. Multiple strategies and modified protocols of cell delivery have been also reported. Furthermore, using bioengineered liver scaffolds has shown promising results that could help in generating a highly functional cell delivery system and/or a whole transplantable liver.

Summary

To optimize the most effective strategies for liver cell therapy, further studies are required to compare among the performed strategies in the literature and/or innovate a novel modifying technique to overcome the potential limitations. Coating of cells with polymers, decellularized scaffolds, or microbeads could be the most appropriate solution to improve cellular efficacy. Besides, overcoming the problems of liver bioengineering may offer a radical treatment for end-stage liver diseases.

Applications of Nanobiomaterials in the Therapy and Imaging of Acute Liver Failure

This review focuses on the therapeutic mechanisms, targeting strategies of various nanomaterials in acute liver failure, and recent advances of diverse nanomaterials for acute liver failure therapy, diagnosis, and imaging. This review provides an outlook on the applications of nanomaterials, especially on the new horizons in acute liver failure therapy, and inspires broader interests across various disciplines. Acute liver failure (ALF), a fatal clinical disease featured with overwhelming hepatocyte necrosis, is a grand challenge in global health. However, a satisfactory therapeutic option for curing ALF is still absent, other than liver transplantation. Nanobiomaterials are currently being developed for the diagnosis and treatment of ALF. The liver can sequester most of nanoparticles from blood circulation, which becomes an intrinsic superiority for nanobiomaterials targeting hepatic diseases. Nanobiomaterials can enhance the bioavailability of free drugs, thereby significantly improving the therapeutic effects in ALF. Nanobiomaterials can also increase the liver accumulation of therapeutic agents and enable more effective targeting of the liver or specific liver cells. In addition, stimuli-responsive, optical, or magnetic nanomaterials exhibit great potential in the therapeutical, diagnostic, and imaging applications in ALF. Therefore, therapeutic agents in combination with nanobiomaterials increase the specificity of ALF therapy, diminish adverse systemic effects, and offer a multifunctional theranostic platform. Nanobiomaterial holds excellent significance and prospects in ALF theranostics. In this review, we summarize the therapeutic mechanisms and targeting strategies of various nanobiomaterials in ALF. We highlight recent developments of diverse nanomedicines for ALF therapy, diagnosis, and imaging. Furthermore, the challenges and future perspectives in the theranostics of ALF are also discussed.

[Liver regeneration after resection in clinical and experimental conditions]

The researches devoted to postoperative liver regeneration and influence in this process were analyzed. Liver injury is followed by hypertrophy of residual liver parenchyma. The use of various cytokines is perspective for activation, acceleration and inhibition of liver recovery. Cellular technologies in the treatment of liver diseases can affect its repair. Moreover, these methods could make unnecessary resection and transplantation of liver in certain cases. It is generally accepted that the main effect of multipotent stromal cells (MSC) in liver failure is associated with their differentiation to the cellular elements of this organ. At the same time, recent reports revealed that MSC injection to the liver is followed by their quick death, dissemination to other organs and tissues or even elimination from the organism. Regeneration of non-parenchymal structures (vascular network and bile ducts) should be considered in addition to functional recovery of liver parenchyma after resection. Clarification of indications and contraindications for MSC therapy, as well as prevention of possible complications associated with cellular technologies are required.

Assessment of the protective and therapeutic effect of melatonin against thioacetamide-induced acute liver damage

Acute or chronic damage to the liver may occur through alcohol, drugs, viruses, genetic disorders, and toxicity. In this study, we planned to investigate the protective and therapeutic effects of melatonin (Mel) by causing damage to the liver with thioacetamide (TAA). Thirty-five rats were used. Group I: control group (seven pieces), group II: Mel group (seven pieces) the single dose on the first day of the experiment was 10 mg/kg, group III: TAA (seven pieces) 300 mg/kg with 24-hour intervals, two doses, group IV: Mel + TAA group (seven pieces) 10 mg/kg single dose Mel was applied 24  hours before TAA application, group V: TAA + Mel group (seven pieces) single dose (24th hour) of 10 mg/kg Mel was administered after TAA (300 mg/kg) two doses. The liver histology was evaluated. Apoptosis, autophagy, and necrosis markers in tissue were determined by immunohistochemistry. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) levels in blood serum samples and transforming growth factor-β (TGF-β) and tumor necrosis factor-α (TNF-α) levels were determined in liver tissue. TAA affected histologically the classical lobule structure both in cell cords and sinusoids. Caspase-3, RIP3, and LC3 levels were increased in group III compared with the control group. TAA did not cause a statistically significant change in TNF-α level but decreased the TGF-β level significantly. AST and ALT levels were statistically significant in group II and V compared with group I, the ALP level was significant in group IV compared with group II. The results of this study showed that TAA caused significant damage to tissues and increased cell death, Mel was found to have more therapeutic than the protective effect on tissues.

Role of interleukin 6 in liver cell regeneration after hemi-hepatectomy, correlation with liver enzymes and flow cytometric study

Aim of the study

Liver regeneration after hemi-hepatectomy may be affected by several growth factors and cytokines. The aim is to evaluate the importance of interleukin 6 (IL-6) in the induction of liver cell regeneration and find correlations with other parameters such as liver enzymes, and DNA analysis by flow cytometric studies.

Material and methods

80 adult male Sprague-Dawley rats were obtained and divided into two equal groups (n = 40 rats) to undergo 70% partial hepatectomy: group 1 - untreated (control) group; 40 rats not treated; and group 2 - treated group, 40 rats treated with IL-6 35 μg/100 gm body weight according to a lethality study for a period of 4 days, then hepatic resection was carried out according to the steps of Higgins and Anderson. Assessment of liver enzymes and bilirubin level was done. Flow cytometric study was done using a flow cytometer (FACSCalibur; Becton Dickinson) and DNA content was estimated with CellQuest software (Becton Dickinson).

Results

The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were significantly higher in the untreated group of rats with liver resection. A higher value of bilirubin was observed in the treated group. Rat weight at sacrification was significantly lower in the group of rats treated with IL-6 than those without treatment, p < 0.001. Liver weight at sacrification was significantly higher in the group of rats treated with IL-6 (p < 0.001). The percentage of apoptotic cells with hypodiploid DNA content was determined from DNA histograms. Untreated rat resected liver showed a peak pattern that represented liver damage with high damage of 73.4%.

Conclusions

Interleukin 6 is of value in induction of liver cell regeneration after seventy percent hemi-hepatectomy as evident by increased liver cell mass, liver enzymes and flow cytometric analysis.

A Simple and Easily Reproducible Model of Reversible Obstructive Jaundice in Rats

BACKGROUND/AIM

Cholangiocarcinoma and pancreatic carcinoma are major malignancies that cause obstructive jaundice (OJ). This study aimed to develop a simple and easily reproducible rat model of reversible OJ (ROJ).

MATERIALS AND METHODS

OJ was induced by clamping the common bile duct (CBD) using a U-shaped titanium hemoclip and its base was attached by ligation using 2-cm long 4-0 polypropylene suture. An anti-adhesive sheet was placed around the CBD. OJ was mitigated by pulling the suture to remove the clip under laparotomy 3 days later. Serum chemistry and liver histopathology were compared between the ROJ group and sham surgery (SH) groups.

RESULTS

Three days after inducing OJ, serum total bilirubin, aspartate aminotransferase, and alanine aminotransferase were remarkably elevated in the ROJ group and thereafter reduced significantly after mitigating OJ. Similar findings were confirmed by histopathology.

CONCLUSION

Our rat model of reversible OJ was considered simple and easily reproducible.

CAR-mediated repression of Cdkn1a(p21) is accompanied by the Akt activation

It was shown that CAR participates in the regulation of many cell processes. Thus, the activation of CAR causes a proliferating effect in the liver, which provides grounds to consider CAR as a therapeutic target when having a partial resection of this organ. Even though a lot of work has been done on the function of CAR in regulating hepatocyte proliferation, very little has been done on its complex mediating mechanism. This study, therefore, showed that the liver growth resulting from CAR activation leads to the decline in the level of PTEN protein and subsequent Akt activation in mouse liver. The increase of Akt activation produced by CAR agonist was accompanied by a decrease in the level of Foxo1, which was correlated with decreased expression of Foxo1 target genes, including Cdkn1a(p21). Moreover, the study also demonstrated that there exists a negative regulatory impact of CAR on the relationship between Foxo1 and targeted Cdkn1a(p21) promoter. Therefore, the study results revealed an essential function of CAR-Akt-Foxo1 signalling pathway in controlling hepatocyte proliferation by repressing the cell cycle regulator Cdkn1a (p21).

Effects of splanchnic vasoconstrictors on liver regeneration and survival after 90% rat hepatectomy

Purpose

Posthepatectomy liver failure is a serious complication and considered to be caused by increased portal pressure and flow. Splanchnic vasoactive agents and propranolol are known to decrease portal pressure. The aim of this study was to identify optimal candidates with potential for clinical use among somatostatin, terlipressin, and propranolol using rats with 90% hepatectomy.

Methods

Rats were divided into 5 groups: sham operation (n = 6), control (n = 20), propranolol (n = 20), somatostatin (n = 20), and terlipressin group (n = 20). Seven-day survival rates and portal pressure change were measured, and biochemical, histologic, and molecular analyses were performed.

Results

Portal pressure was significantly decreased in all 3 treatment groups compared to control. All treatment groups showed a tendency of decreased liver injury markers, and somatostatin showed the most prominent effect at 24 hours postoperatively. Histologic liver injury at 24 hours was significantly decreased in propranolol and terlipressin groups (P = 0.016, respectively) and somatostatin group showed borderline significance (P = 0.056). Hepatocyte proliferation was significantly increased after 24 hours in all treatment groups. Median survival was significantly increased in terlipressin group compared to control group (P < 0.01).

Conclusion

Terlipressin is considered as the best candidate, while somatostatin has good potential for clinical use, considering their effects on portal pressure and subsequent decrease in liver injury and increase in liver regeneration.

Adult-Derived Human Liver Stem/Progenitor Cells Infused 3 Days Postsurgery Improve Liver Regeneration in a Mouse Model of Extended Hepatectomy

There is growing evidence that cell therapy constitutes a promising strategy for liver regenerative medicine. In the setting of hepatic cancer treatments, cell therapy could prove a useful therapeutic approach for managing the acute liver failure that occurs following extended hepatectomy. In this study, we examined the influence of delivering adult-derived human liver stem/progenitor cells (ADHLSCs) at two different early time points in an immunodeficient mouse model (Rag2-/-IL2Rγ-/-) that had undergone a 70% hepatectomy procedure. The hepatic mesenchymal cells were intrasplenically infused either immediately after surgery (n = 26) or following a critical 3-day period (n = 26). We evaluated the cells' capacity to engraft at day 1 and day 7 following transplantation by means of human Alu qPCR quantification, along with histological assessment of human albumin and α-smooth muscle actin. In addition, cell proliferation (anti-mouse and human Ki-67 staining) and murine liver weight were measured in order to evaluate liver regeneration. At day 1 posttransplantation, the ratio of human to mouse cells was similar in both groups, whereas 1 week posttransplantation this ratio was significantly improved (p < 0.016) in mice receiving ADHLSC injection at day 3 posthepatectomy (1.7%), compared to those injected at the time of surgery (1%). On the basis of liver weight, mouse liver regeneration was more extensive 1 week posttransplantation in mice transplanted with ADHLSCs (+65.3%) compared to that of mice from the sham vehicle group (+42.7%). In conclusion, infusing ADHLSCs 3 days after extensive hepatectomy improves the cell engraftment and murine hepatic tissue regeneration, thereby confirming that ADHLSCs could be a promising cell source for liver cell therapy and hepatic tissue repair.

Constitutive androstane receptor (Car)-driven regeneration protects liver from failure following tissue loss

BACKGROUND & AIMS

Liver can recover following resection. If tissue loss is too excessive, however, liver failure will develop as is known from the small-for-size-syndrome (SFSS). The molecular processes underlying liver failure are ill-understood. Here, we explored the role and the clinical potential of Nr1i3 (constitutive androstane receptor, Car) in liver failure following hepatectomy.

METHODS

Activators of Car, various hepatectomies, Car(-/-) mice, humanized CAR mice, human tissue and ex vivo liver slice cultures were used to study Car in the SFSS. Pathways downstream of Car were investigated by in vivo siRNA knockdown.

RESULTS

Excessive tissue loss causing liver failure is associated with deficient induction of Car. Reactivation of Car by an agonist normalizes all features associated with experimental SFSS. The beneficial effects of Car activation are relayed through Foxm1, an essential promoter of the hepatocyte cell cycle. Deficiency in the CAR-FOXM1 axis likewise is evident in human SFSS. Activation of human CAR mitigates SFSS in humanized CAR mice and improves the culture of human liver slices.

CONCLUSIONS

Impaired hepatic Car-Foxm1 signaling provides a first molecular characterization of liver that fails to recover after tissue loss. Our findings place deficient regeneration as a principal cause behind the SFSS and suggest CAR agonists may bear clinical potential against liver failure.

LAY SUMMARY

The unique regenerative capacity of liver has its natural limits. Following tissue loss that is too excessive, such as through extended resection in the clinic, liver failure may develop. This is known as small-for-size-syndrome (SFSS) and represents the most frequent cause of death due to liver surgery. Here we show that deficient induction of the protein Car, a central regulator of liver function and growth, is a cause of liver failure following extended resection; reactivation of Car through pharmacological means is sufficient to prevent or rescue the SFSS.

Peritoneal Albumin Dialysis as a Novel Approach for Liver Support: Study in a Porcine Model of Acute Hepatic Failure

Artificial liver support gained considerable interest in recent years due to the development of various albumin dialysis systems, which prolong survival of some patients with acute liver failure (ALF). Τhis study aims to examine the role of peritoneal albumin dialysis in a postoperative ALF model. ALF was induced in 14 female Landrace pigs by a combination of major liver resection (70-75% of total parenchyma) and ischemic-reperfusion injury on the liver remnant. Animals were randomly divided in two groups (n = 7 each). Both were monitored for 12 h of reperfusion and received peritoneal dialysis for 6 h, beginning 6 h after reperfusion. The albumin group received an albumin-rich solution and the control group received albumin-free solution. The control group gradually developed intracranial hypertension, whereas, in the albumin group, rise in the intracranial pressure was substantially attenuated (P < 0.01, t = 12 h). Albumin-treated animals had significantly lower levels of ammonia (P < 0.01), total bile acids (P < 0.01), free fatty acids (P < 0.05), lactate (P < 0.01), and total bilirubin (P < 0.05). Liver malondialdehyde and protein carbonyl were significantly reduced (P = 0.007 and P = 0.001 at t = 12 h) after albumin dialysis. Results suggest that this method may become a useful adjunct in the management of ALF, thus, justifying further study.

A reliable scoring system after major liver resection in mice

BACKGROUND

Posthepatectomy liver failure and its transplant counterpart, small-for-size syndrome, remain significant limitations for liver resections and segmental liver transplantation. Partial hepatectomy in mice is one of the most commonly used models to study liver regeneration, but blood and tissue sampling necessary to collect data can affect outcomes or even require euthanasia. We therefore developed a quantitative observational system to predict death from hepatectomy during the first 24 postoperative hours.

MATERIALS AND METHODS

A total of 100 female, 10 to 12-week-old C57BL/6 mice underwent two-thirds hepatectomy and were monitored for up to 7 d. Our scoring system was based on five categories, each assigned 0-2 points: activity level, body posture, fur condition, respiratory status, and eye appearance. Seventy-five mice were scored 6 h, 12 h, 24 h, 2 d, 3 d, 5 d, and 7 d after surgery. The remaining 25 mice were scored similarly, but underwent, in addition, blood sampling for serum alanine aminotransferase, total bilirubin, interleukin-6, tumor necrosis factor-alpha, or euthanasia with liver sampling for conventional hematoxylin-eosin and Ki-67 staining.

RESULTS

Retrospective analysis indicated that body condition scores ≤5 on two consecutive time points within the first 24 postoperative hours accurately predicted eventual death. Animals in the low scoring group also had significantly higher serum alanine aminotransferase, total bilirubin, interleukin-6, tumor necrosis factor-alpha, more hepatocyte necrosis in hematoxylin-eosin, and fewer Ki-67 positive hepatocytes.

CONCLUSIONS

Our scoring system accurately predicts survival, hepatocyte damage, liver regeneration, and systemic inflammation in a mouse hepatectomy model, within the first 24 hours of surgery. This could be useful in evaluating posthepatectomy interventions for their effect on survival and liver regeneration.

The role of bile salts in liver regeneration

A growing body of evidence has demonstrated that bile salts are important for liver regeneration following partial hepatectomy. The relative bile salt overload after partial liver resection causes activation of bile salt receptors in non-parenchymal (viz. the plasma membrane receptor TGR5) and parenchymal (viz. the intracellular receptor FXR) cells in the liver, thus, providing signals to the regenerative process. Impaired bile salt signaling in mice with genetic deficiency of Tgr5 or Fxr results in delayed liver regeneration after partial hepatectomy, and is accompanied by mortality in case of Fxr knock-out mice. Conversely, compensatory liver re-growth in hepatectomized mice can be stimulated by feeding of bile salts or alisol B 23-acetate, a natural triterpenoid agonist of Fxr. A large number of animal studies underscore the importance of strict maintenance of bile salt homeostasis for proper progression of liver regeneration. Both ileal and hepatic Fxr play a key role in regulation of bile salt homeostasis and, thus, preventing hepatotoxicity caused by excessive levels of bile salts. They further contribute to liver regeneration by induction of mitogenic factors. Agents that target bile salt receptors hold promise as drugs to stimulate liver regeneration in selected patients.

Hepatocytes in liver injury: Victim, bystander, or accomplice in progressive fibrosis?

Chronic liver disease causes significant morbidity and mortality through progressive fibrosis, cirrhosis, and liver cancer. The classical theory of fibrogenesis has hepatic stellate cells (HSCs) as the principal and only significant source of abnormal extracellular matrix (ECM). Further, HSCs have the major role in abnormal ECM turnover. It is the death of hepatocytes, as the initial target of injury, that initiates a sequence of events including the recruitment of inflammatory cells and activation of HSCs. Following this initial response, the ongoing insult to hepatocytes is regarded as perpetuating injury, but otherwise, hepatocytes are regarded as "victims" and "bystanders" in progressive fibrosis. Recent developments, however, challenge this view and suggest the concept of the hepatocyte being an active participant in liver injury. It is clear now that hepatocytes undergo phenotypic changes, adapt to injury, and react to the altered microenvironment. In this review, we describe studies showing that hepatocytes contribute to progressive fibrosis by direct manipulation of the surrounding ECM and through signaling to effector cells, particularly HSCs and intrahepatic immune cells. Together, these findings suggest an active "accomplice" role for the hepatocyte in progressive liver fibrosis and highlight novel pathways that could be targeted for development of future anti-fibrotic therapies.

mTOR-Dependent Suppression of Remnant Liver Regeneration in Liver Failure After Massive Liver Resection in Rats

BACKGROUND AND AIMS

Massive hepatectomy often leads to fatal liver failure because of a small remnant liver volume. The aim of this study was to investigate the potential mechanisms leading to liver failure.

METHODS

Sprague-Dawley rats had performed a sham operation, 85 % partial hepatectomy (PH) or 90 % PH, and all had free access to water with or without supplemented glucose. Liver function and survival were evaluated. Liver parenchymal injury was assessed by evaluating hepatic pathology, blood biochemistry, and apoptotic and necrotic alterations. The regeneration response was assessed by the weight gain of the remnant liver, hepatocyte proliferation markers, and regeneration-related molecules.

RESULTS

The 90 % hepatectomy resulted in a significantly lower survival rate and impaired liver function; however, no significant more serious liver parenchymal injuries were detected. TNF-α, HGF, myc and IL-6 were either similarly expressed or overexpressed; however, the increase in remnant liver weight, mitotic index, and the presence of Ki-67 and PCNA were significantly lower in the 90 %-hepatectomized rats. mTOR, p70S6K and 4EBP1 were not activated in the remnant liver after a 90 % hepatectomy as obviously as those after an 85 % hepatectomy, which was concomitant with the higher expression of phospho-AMPK and a lower intrahepatic ATP level. Glucose treatment significantly improved the survival rate of 90 %-hepatectomized rats.

CONCLUSIONS

Suppression of remnant liver regeneration was observed in the 90 % PH and contributed to fatal liver failure. This suppressed liver regenerative capacity was related to the inhibited activation of mTOR signaling.

Effect of LSKL peptide on thrombospondin 1-mediated transforming growth factor β signal activation and liver regeneration after hepatectomy in an experimental model

Background

A strategy for accelerating liver regeneration after hepatectomy would offer great benefits in preventing postoperative liver failure and improving surgical outcomes. Transforming growth factor (TGF) β is a potent inhibitor of hepatocyte proliferation. Recently, thrombospondin (TSP) 1 has been identified as a negative regulator of liver regeneration by activation of local TGF-β signals. This study aimed to clarify whether the LSKL (leucine–serine–lysine–leucine) peptide, which inhibits TSP-1-mediated TGF-β activation, promotes liver regeneration after hepatectomy in mice.

Methods

Mice were operated on with a 70 per cent hepatectomy or sham procedure. Operated mice received either LSKL peptide or normal saline intraperitoneally at abdominal closure and 6 h after hepatectomy. Perioperative plasma TSP-1 levels were measured by enzyme-linked immunosorbent assay in patients undergoing hepatectomy.

Results

Administration of LSKL peptide attenuated Smad2 phosphorylation at 6 h. S-phase entry of hepatocytes was accelerated at 24 and 48 h by LSKL peptide, which resulted in faster recovery of the residual liver and bodyweight. Haematoxylin and eosin tissue staining and blood biochemical examinations revealed no significant adverse effects following the two LSKL peptide administrations. In the clinical setting, plasma TSP-1 levels were lowest on the first day after hepatectomy. However, plasma TSP-1 levels at this stage were significantly higher in patients with subsequent liver dysfunction compared with levels in those without liver dysfunction following hepatectomy.

Conclusion

Only two doses of LSKL peptide during the early period after hepatectomy can promote liver regeneration. The transient inhibition of TSP-1/TGF-β signal activation using LSKL peptide soon after hepatectomy may be a promising strategy to promote subsequent liver regeneration.

Immune-protected xenogeneic bioartificial livers with liver-specific microarchitecture and hydrogel-encapsulated cells

Development of a xenogeneic biological liver support is important in providing a bridge to transplantation or liver regeneration, thus helping to overcome the chronic shortage of liver donors. Among the critical factors in developing biological liver support are the creation of in vivo mimetic micro liver tissue (mLT), especially mLTs containing liver-specific ultrastructure, and an encapsulation method that can package massive numbers of cells while providing immune-protection from the host immune system. We describe here the development of mLTs that include liver microarchitecture and their in situ encapsulation in hydrogel composites. Concave microwells and the tri-culture of three types of primary liver cells were applied for the construction of mLTs showing excellent liver functions and long-term (>1 month) viability in vitro. Large quantities of rat mLTs were encapsulated in collagen-alginate composites, implanted into hepatic failure mice and sustained their survival during regeneration of the remaining liver. The proposed liver support system offers xenogeneic hepatic assistance by mimicking native liver microarchitecture and providing immune-protection without the need for complicated devices or processes, and as such represents a promising system for recovery of organ function.

Effects of splenectomy on hepatic gene expression profiles after massive hepatectomy in rats

BACKGROUND AND AIM

Possible spleno-hepatic relationships affected by hepatectomy still remained unclear. We have previously reported that splenectomy may ameliorate liver injuries and promote appropriate liver regeneration after massive hepatectomy. Therefore, we investigated the effects of splenectomy on the DNA expression profile in the liver after massive hepatectomy in rats.

METHODS

Rats were divided into the following two groups: 90% hepatectomy (Hx group) and 90% hepatectomy with splenectomy (Hx + Sp group). Rats were sacrificed 3 and 6 h after surgery, and mRNA from liver tissue was isolated and hybridized to Affymetrix GeneChip Rat Genome 230 2.0 Array (Affymetrix, Santa Clara, CA, USA) and a pathway analysis was done with Ingenuity Pathway Analysis (Ingenuity Systems, Mountain View, CA, USA).

RESULTS

We determined the Hx + Sp/Hx ratio to assess the influence of splenectomy, and cut-off values were set at more than 2.0-fold or less than 1/2 (0.5)-fold. Immediate early response gene including early growth response-1 and FBJ murine osteosarcoma-related pathways were markedly downregulated by splenectomy. In contrast, heme oxygenase-1 gene-related pathway was upregulated by splenectomy.

CONCLUSIONS

Splenectomy provided the protective effects for liver failure and promoted liver regeneration, possibly owing to the downregulation of immediate early response genes and upregulation of the heat shock protein, heme oxygenase-1.

Proteomic analysis of immediate-early response plasma proteins after 70% and 90% partial hepatectomy

AIM

Partial hepatectomy (PH) induces robust hepatic regenerative and metabolic responses that are considered to be triggered by humoral factors. The aim of the study was to identify plasma protein factors that potentially trigger or reflect the body's immediate-early responses to liver mass reduction.

METHODS

Male C57BL/6 mice were subjected to sham operation, 70% PH or 90% PH. Blood was collected from the inferior vena cava at 20, 60 and 180 min after surgery.

RESULTS

Using a label-free quantitative mass spectrometry-based proteomics approach, we identified 399 proteins exhibiting significant changes in plasma expression between any two groups. Of the 399 proteins, 167 proteins had multiple unique sequences and high peptide ID confidence (>90%) and were defined as priority 1 proteins. A group of plasma proteins largely associated with metabolism is enriched after 70% PH. Among the plasma proteins that respond to 90% PH are a dominant group of proteins that are also associated with metabolism and one known cytokine (platelet factor 4). Ninety percent PH and 70% PH induces similar changes in plasma protein profile.

CONCLUSION

Our findings enable us to gain insight into the immediate-early response of plasma proteins to liver mass loss. Our data support the notion that increased metabolic demands of the body after massive liver mass loss may function as a sensor that calibrates hepatic regenerative response.

Hypothermia predicts hepatic failure after extensive hepatectomy in mice

AIM

To investigate the effect of hypothermia on the function of the liver remnant (LR) after extended hepatectomy.

METHODS

We performed a 75% partial hepatectomy (PH) in male C57BL/6J mice. Body temperature was measured with a rectal probe. The study mice were prospectively grouped as hypothermic (HT) or normothermic (NT) if their body temperature was < 34 °C vs ≥ 34 °C, respectively. Blood and liver samples were obtained at 24 and 48 h after 75% PH. Various factors during and after 75% PH were compared at each time point and the most important factor for a good outcome after 75% PH was determined.

RESULTS

At 24 and 48 h after 75% PH, LR weight was decreased in HT mice compared with that in NT mice and the assay results in the HT mice were consistent with liver failure. NT mice had normal liver regeneration. Each intra- and post-operative factor which showed statistical significance in univariate analysis was evaluated by multivariate analysis. The most important factor for a good outcome after 75% PH was body temperature at both 24 and 48 h after surgery.

CONCLUSION

Hypothermia after an extensive hepatectomy predicts impending liver failure and may be a useful clinical marker for early detection of liver failure after extended hepatectomy.

Effect of different liver resection methods on liver damage and regeneration factors VEGF and FGF-2 in mice

BACKGROUND

Different approaches to study liver regeneration in murine models have been proposed. We investigated the effect of different liver resection models on liver damage and regeneration parameters in mice.

METHODS

We compared the technical aspect of the 2 most commonly used techniques of 50% and 70% liver resection. Liver damage, as determined by the change in serum alanine aminotransferase and aspartate aminotransferase, as well as the regeneration parameters VEGF and FGF-2 were analyzed at 6 time points. A postoperative vitality score was introduced.

RESULTS

Cholestasis was not observed for either technique. Both resection techniques resulted in full weight recovery of the liver after 240 hours, with no significant difference between sham and resection groups. Postoperative animal morbidity and total protein levels did not differ significantly for either method, indicating early and full functional recovery. However, comparing the mitogenic growth factors FGF-2 and VEGF, a significant increase in serum levels and, therefore, increased growth stimulus, was shown in the extended resection group.

CONCLUSION

Extended resection led to a greater response in growth factor expression. This finding is important since it shows that growth factor response differs acdording to the extent of resection. We have demonstrated the need to standardize murine hepatic resection models to adequately compare the resulting liver damage.

Intrasplenic transplantation of bioencapsulated mesenchymal stem cells improves the recovery rates of 90% partial hepatectomized rats

Mesenchymal stem cells (MSCs) derived from bone marrow can secrete cytokines and growth factors and can transdifferentiate into liver cells. We transplanted polymeric membrane bioencapsulated MSCs into the spleens of 90% partial hepatectomized rats. This resulted in 91.6% recovery rates. This is compared to a recovery rate of 21.4% in the 90% hepatectomized rats and 25% in the 90% hepatectomized rats receiving intrasplenic transplantation of free MSCs. After 14 days, the remnant livers in the bioencapsulated MSCs group are not significantly different in weight when compared to the sham control group. From day 1 to day 3 after surgery, in the bioencapsulated MSCs group, the plasma HGF and IL-6 were significantly higher than those in the free MSCs group and control group (P < 0.01); plasma TNF-α was significantly lower (P < 0.001). We concluded that the intrasplenic transplantation of bioencapsulated MSCs significantly increases the recovery rates of 90% hepatectomized rats. It is likely that the initial effect is from proliver regeneration factors followed later by the transdifferentiated hepatocyte-like cells. However, histopathological analysis and hepatocyte proliferation study will be needed to better understand the regenerative mechanisms of this result. This study has implications in improving the survival and recovery of patients with very severe liver failure due to hepatitis, trauma, or extensive surgical resection.

Omega-3 polyunsaturated fatty acids promote liver regeneration after 90% hepatectomy in rats

AIM: To evaluate the effectiveness of omega-3 polyunsaturated fatty acid (ω-3 PUFA) administration on liver regeneration after 90% partial hepatectomy (PH) in rats.

METHODS: ω-3 PUFAs were intravenously injected in the ω-3 PUFA group before PH surgery. PH, sparing only the caudate lobe, was performed in both the control and the ω-3 PUFA group. Survival rates, liver weight/body weight ratios, liver weights, HE staining, transmission electron microscope imaging, nuclear-associated antigen Ki-67, enzyme-linked immunosorbent assay and signal transduction were evaluated to analyze liver regeneration.

RESULTS: All rats in the control group died within 30 h after hepatectomy. Survival rates in the ω-3 PUFA group were 20/20 at 30 h and 4/20 1 wk after PH. Liver weight/body weight ratios and liver weights increased significantly in the ω-3 PUFA group. The structure of sinusoidal endothelial cells and space of Disse was greatly restored in the ω-3 PUFA group compared to the control group after PH. In the ω-3 PUFA group, interleukin (IL)-4 and IL-10 levels were significantly increased whereas IL-6 and tumor necrosis factor-α levels were dramatically decreased. In addition, activation of protein kinase B (Akt) and of signal transducer and activator of transcription 3 signaling pathway were identified at an earlier time after PH in the ω-3 PUFA group.

CONCLUSION: Omega-3 polyunsaturated fatty acids may prevent acute liver failure and promote liver regeneration after 90% hepatectomy in rats.

Simple and reproducible hepatectomy in the mouse using the clip technique

AIM: To investigate the reliability of massive hepatectomy models by using clip techniques.

METHODS: We analyzed anatomical findings in 100 mice following massive hepatectomy induced by liver reduction > 70%. The impact of various factors in the different models was also analyzed, including learning curves, operative time, survival curves, and histopathological findings.

RESULTS: According to anatomical results, models with 75%, 80%, and 90% hepatectomy produced massive hepatectomy. Learning curves and operative times were most optimal with the clip technique. Each hepatectomy performed using the clip technique produced a reasonable survival curve, and there were no differences in histopathological findings between the suture and clip techniques.

CONCLUSION: Massive hepatectomy by the clip technique is simple and can provide reliable and relevant data.

Matrix metalloproteinase-9 contributes to parenchymal hemorrhage and necrosis in the remnant liver after extended hepatectomy in mice

AIM: To investigate the effect of matrix metalloproteinase-9 (MMP-9) on the remnant liver after massive hepatectomy in the mouse.

METHODS: Age-matched, C57BL/6 wild-type (WT), MMP-9(-/-), and tissue inhibitors of metalloproteinases (TIMP)-1(-/-) mice were used. The mice received 80%-partial hepatectomy (PH). Samples were obtained at 6 h after 80%-PH, and we used histology, immunohistochemical staining, western blotting analysis and zymography to investigate the effect of PH on MMP-9. The role of MMP-9 after PH was investigated using a monoclonal antibody and MMP inhibitor.

RESULTS: We examined the remnant liver 6 h after 80%-PH and found that MMP-9 deficiency attenuated the formation of hemorrhage and necrosis. There were significantly fewer and smaller hemorrhagic and necrotic lesions in MMP-9(-/-) remnant livers compared with WT and TIMP-1(-/-) livers (P < 0.01), with no difference between WT and TIMP-1(-/-) mice. Serum alanine aminotransaminase levels were significantly lower in MMP-9(-/-) mice compared with those in TIMP-1(-/-) mice (WT: 476 ± 83 IU/L, MMP-9(-/-): 392 ± 30 IU/L, TIMP-1(-/-): 673 ± 73 IU/L, P < 0.01). Western blotting and gelatin zymography demonstrated a lack of MMP-9 expression and activity in MMP-9(-/-) mice, which was in contrast to WT and TIMP-1(-/-) mice. No change in MMP-2 expression was observed in any of the study groups. Similar to MMP-9(-/-) mice, when WT mice were treated with MMP-9 monoclonal antibody or the synthetic inhibitor GM6001, hemorrhagic and necrotic lesions were significantly smaller and fewer than in control mice (P < 0.05). These results suggest that MMP-9 plays an important role in the development of parenchymal hemorrhage and necrosis in the small remnant liver.

CONCLUSION: Successful MMP-9 inhibition attenuates the formation of hemorrhage and necrosis and might be a potential therapy to ameliorate liver injury after massive hepatectomy.

Analysis of gene expression profiles in fatal hepatic failure after hepatectomy in mice

BACKGROUND

We developed 90%-hepatectomized mice that were the fatal model, and analyzed the gene expression profiles using a complementary DNA (cDNA) microarray to clarify the mechanisms of hepatic failure after excessive hepatectomy.

MATERIALS AND METHODS

Ribonucleic acid (RNA)s from the remnant hepatic tissue of 70%- and 90%-hepatectomized mice were labeled with fluorescent dyes, and hybridized to the Riken set of 39,168 full-length enriched mouse cDNA arrays. The gene expression profiles in 90%- and 70%-hepatectomized mice were analyzed by scanning date for fluorescent dye signals.

RESULTS

The down-regulated genes in 90%-hepatectomized mice were genes activating extracellular matrix (ECM) remodeling (matrix metalloproteinases, laminins, and integrins), genes related to cytokines (tumor necrosis factor α converting enzyme, and Janus kinase 3) that were related to the priming, genes related to growth factor (heparin-binding epidermal growth factor-like growth factor and others), and genes promoting cell cycle progression (cyclin D1, D2, and E2) that were related to the progression of hepatocytes. The up-regulated genes were genes inhibiting ECM remodeling [plasminogen activator inhibitors (PAIs)].

CONCLUSIONS

Hepatic failure after hepatectomy was characterized by the inhibition of hepatic cell cycle priming and progression both induced by ECM remodeling in liver regeneration. Particularly, the overexpression of PAIs was thought to play the major role in the first step of inhibition of ECM remodeling.

Liver regeneration after partial hepatectomy: critical analysis of mechanistic dilemmas

Liver regeneration after partial hepatectomy is one of the most studied models of cell, organ, and tissue regeneration. The complexity of the signaling pathways initiating and terminating this process have provided paradigms for regenerative medicine. Many aspects of the signaling mechanisms involved in hepatic regeneration are under active investigation. The purpose of this review is to focus on the areas still not well understood. The review also aims to provide insights into the ways by which current concepts of liver regeneration can provide understanding regarding malfunction of the regenerative process in liver diseases, such as acute liver failure.

Influence of portosystemic shunt on liver regeneration after hepatic resection in pigs

Objective. The minimal amount of liver mass necessary for regeneration is still a matter of debate. The aim of the study was to analyze liver regeneration factors after extended resection with or without portosystemic shunt. Methods. An extended left hemihepatectomy was performed in 25 domestic pigs, in 15 cases after a portosystemic H-shunt. The expression of Ki-67, VEGF, TGF-α, FGF, and CK-7 was analyzed in paraffin-embedded tissue sections. Results. The volume of the remnant liver increased about 2.5-fold at the end of the first week after resection. With 19 cells/10 Glisson fields versus 4/10, Ki-67-expression was significantly higher in the H-shunt group. VEGF- and CK-7-expressions were significantly higher in the control group. No significant change was found in FGF-expression. The expression of TGF-α was higher, but not significantly, in the control group. Conclusions. The expression of Ki-67, and therefore hepatocyte regeneration, was increased in the shunt group. The expression of CK-7 on biliary epithelium and the expression of VEGF, however, were stronger in the control group.

Improved survival of fulminant liver failure by transplantation of microencapsulated cryopreserved porcine hepatocytes in mice

The aim of this study was to establish hepatocyte isolation in pigs, and to evaluate function of isolated hepatocytes after encapsulation, cryopreservation, and transplantation (Tx) in a mouse model of fulminant liver failure (FLF). After isolation, porcine hepatocytes were microencapsulated with alginate-poly-L-Lysine-alginate membranes and cryopreserved. In vitro, albumin production of free and encapsulated hepatocytes were measured by enzyme linked-immunoadsorbent assay. In vivo, encapsulated hepatocytes were transplanted into different groups of mice with FLF and the following experimental groups were performed: group 1, Tx of empty capsules; group 2, Tx of free primary porcine hepatocytes; group 3, Tx of fresh encapsulated porcine hepatocytes; group 4, Tx of cryopreserved encapsulated porcine hepatocytes. In vitro, fresh or cryopreserved encapsulated porcine hepatocytes showed a continuous decreasing metabolic function over 1 week (albumin and urea synthesis, drug catabolism). In vivo, groups 1 and 2 showed similar survival (18% and 25%, respectively, p > 0.05). In groups 3 and 4, Tx of fresh or cryopreserved encapsulated porcine hepatocytes significantly increased survival rate to 75% and 68%, respectively (p < 0.05). Primary porcine hepatocytes maintained metabolic functions after encapsulation and cryopreservation. In mice with FLF, Tx of encapsulated xenogeneic hepatocytes significantly improved survival. These results indicate that porcine hepatocytes can successfully be isolated, encapsulated, stored using cryopreservation, and transplanted into xenogeneic recipients with liver failure and sustain liver metabolic functions.

Focal liver necrosis appears early after partial hepatectomy and is dependent on T cells and antigen delivery from the gut

INTRODUCTION

Progressive liver failure may develop following removal of a large part of the liver or transplantation of a small for size liver graft. The pathophysiology of this clinical syndrome is only partially understood.

METHODS

We assessed liver damage and hepatocyte 5-bromo-2'-deoxyuridine (BrdU) incorporation following partial hepatectomy (PH) in C57BL/6, BALB/C and immune-deficient mice. Hepatic lymphocyte subpopulations were characterized. Lipopolysaccharide (LPS) treatment and bowel decontamination determined the role of gut antigens.

RESULTS

Discrete, round necrotic lesions were observed as early as 2 h following 70%, but not 30% PH. In immune competent mice the extent of hepatocyte necrosis inversely correlated with BrdU incorporation. T, natural killer and natural killer T cells were recruited to the liver early after PH; however, only T-cell depletion abrogated hepatic necrosis. Hepatic injury was significantly reduced in non-obese diabetic/severe combined immunodeficient mice undergoing PH, while BrdU incorporation was not affected. Liver injury was augmented by LPS injection and reduced by gut decontamination.

CONCLUSIONS

A distinct pattern of early focal hepatic necrosis is observed following extensive PH in mice. T cells infiltrating the liver immediately after PH and gut-derived antigens are indispensable for the observed liver necrosis and may thus provide therapeutic targets to ameliorate liver damage following PH.

Aberrant cell cycle progression and endoreplication in regenerating livers of mice that lack a single E-type cyclin

BACKGROUND & AIMS

E-cyclins control the transition of quiescent cells into the cell cycle. Two E-cyclins, CcnE1 and CcnE2, have been described, but their specific contributions to cell cycle reentry in vivo are poorly understood. Liver regeneration following partial hepatectomy is an excellent in vivo model for the study of cell cycle reentry of quiescent cells. We investigated the relevance of E-cyclins in directing resting hepatocytes into the cell cycle after partial hepatectomy using CcnE1 and CcnE2 knockout mice.

METHODS

Partial hepatectomy (70%) was performed in CcnE1 (E1(-/-)) and CcnE2 (E2(-/-)) knockout and wild-type mice. Liver regeneration was monitored by cell cycle markers for G(1)/S phase, S phase, and M phase as well as by determining the liver/body weight ratio after partial hepatectomy. Ploidy of hepatocytes was determined by fluorescence-activated cell sorting and fluorescent in situ hybridization.

RESULTS

CcnE1 deletion resulted in normal liver regeneration with a slight delay of the G(1)/S-phase transition and a defect in endoreplication of otherwise polyploid hepatocytes. Surprisingly, E2(-/-) mice displayed accelerated and sustained DNA synthesis after partial hepatectomy, excessive endoreplication in hepatocytes, and a liver mass that was 45% greater than that of wild-type mice after termination of the regeneration process. CcnE2 depletion induced overexpression of CcnE1 and prolonged cdk2 kinase activity after partial hepatectomy.

CONCLUSIONS

CcnE2 has an unexpected role in repressing CcnE1; the phenotype of E2(-/-) mice appears to result from CcnE1 overexpression and cdk2 hyperactivation. CcnE1 and CcnE2 therefore have nonredundant functions for S-phase entry and endoreplication during liver regeneration.

An overview of animal models for investigating the pathogenesis and therapeutic strategies in acute hepatic failure

Acute hepatic failure (AHF) is a severe liver injury accompanied by hepatic encephalopathy which causes multiorgan failure with an extremely high mortality rate, even if intensive care is provided. Management of severe AHF continues to be one of the most challenging problems in clinical medicine. Liver transplantation has been shown to be the most effective therapy, but the procedure is limited by shortage of donor organs. Although a number of clinical trials testing different liver assist devices are under way, these systems alone have no significant effect on patient survival and are only regarded as a useful approach to bridge patients with AHF to liver transplantation. As a result, reproducible experimental animal models resembling the clinical conditions are still needed. The three main approaches used to create an animal model for AHF are: surgical procedures, toxic liver injury and infective procedures. Most common models are based on surgical techniques (total/partial hepatectomy, complete/transient devascularization) or the use of hepatotoxic drugs (acetaminophen, galactosamine, thioacetamide, and others), and very few satisfactory viral models are available. We have recently developed a viral model of AHF by means of the inoculation of rabbits with the virus of rabbit hemorrhagic disease. This model displays biochemical and histological characteristics, and clinical features that resemble those in human AHF. In the present article an overview is given of the most widely used animal models of AHF, and their main advantages and disadvantages are reviewed.

Role of platelets on liver regeneration after 90% hepatectomy in mice

BACKGROUND/AIMS

Mortality after 90% partial hepatectomy in mice was associated with severe acute liver failure. Recently, we revealed that platelets have a strong promotional effect on hepatic regeneration. In the present study, we investigated the effect of thrombocytosis on liver regeneration after 90% hepatectomy in mice.

METHODS

For thrombocytosis induction PEG-rHuMGDF was injected 5 days before operation. Hepatectomy, sparing only the caudate lobe, was performed in normal and thrombocytotic BALB/c mice. Survival rate, platelet number, liver weight/body weight ratio, proliferating cell nuclear antigen, serum parameters, signal transduction and overexpressed genes were examined.

RESULTS

Platelet number was significantly higher in thrombocytotic group. All mice in normal group died within 30 h after hepatectomy. Survival rate in thrombocytotic group was 6/11 at 30 h and 3/11 one week after hepatectomy. Activation of Akt and STAT3 signaling pathways in thrombocytotic group was observed earlier and recognized to be stronger compared to normal group. Cell cycle, signaling pathways, metabolism and transport genes were significantly overexpressed in thrombocytotic group up to 24h after hepatectomy.

CONCLUSIONS

Under the thrombocytotic condition, liver regeneration occurred even in 90% hepatectomized mice. Platelets contribute to cell cycle progression and metabolic pathways in addition to preventing acute liver failure.

Transfection of NF-kappaB decoy oligodeoxynucleotides into macrophages reduces murine fatal liver failure after excessive hepatectomy

BACKGROUND

Macrophages play an important role in the initiation of hypercytokinemia, which is involved in the development of liver failure after excessive hepatectomy. This study was aimed at evaluating whether the selective suppression of nuclear factor kappa B (NF-kappaB) in macrophages by decoy oligodeoxynucleotides (ODN) could prevent liver failure after excessive hepatectomy.

MATERIALS AND METHODS

Ninety percent hepatectomy was performed in 8-wk-old mice. NF-kappaB/decoy/ODN was transfected into the liver by the hemagglutinating virus of Japan-liposome method. The survival rate, serum levels of interleukin (IL)-1beta IL-6, and tumor necrosis factor-alpha, and the histological findings in the remnant liver were compared between the 90%-hepatectomized mice transfected with the decoy ODN (decoy group) and the 90%-hepatectomized mice injected with saline (control group).

RESULT

The control group mice died within 48 h of the operation, while the survival rate in the decoy group at 48 h after the operation was 35%, and at 2 wk, 15%. The serum levels of all cytokines were significantly lower in the decoy group than in the control group. The number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling-positive cells in the remnant liver was smaller in the decoy group.

CONCLUSION

Transfection of NF-kappaB/decoy/ODN reduces fatal liver failure in mice after excessive hepatectomy by suppressing hypercytokinemia, but offers only a low rate of survival.

Rodent models of partial hepatectomies

Small rodents are the most used experimental models in liver surgical research. Hepatic resections in rodents are commonly performed to study liver regeneration, acute liver failure, hepatic metastasis, hepatic function, 'small-for-size' transplantation and metabolic response to injury. Most resections require only basic skills, are fast, reliable and highly reproducible. The partial hepatectomy technique in rodents can be improved by microsurgical techniques, which permit individualized dissection and ligature of the vascular and biliary branches with minimal operative morbidity and mortality. This is particularly relevant for murine models of liver resection. However, it requires advanced microsurgical skills. Here, we review the models, surgical techniques, results and limitations of partial liver resections in rodent models. We also reported for the first time segmentectomies of the median lobe in rodent models.

Intraabdominal bacterial infections significantly alter regeneration and function of the liver in a rat model of major hepatectomy

BACKGROUND

No systematic investigations of interactions of postoperative infections and liver regeneration after resection are available.

MATERIALS AND METHODS

Male Sprague-Dawley rats underwent sham operation, 70% partial hepatectomy (PH), cecal ligation and puncture (CLP), or synchronous PH + CLP and were killed at regular intervals. Liver regeneration and function were measured by the mitotic index, Bromo-deoxy-uridine labeling, and Ki-67 as well as bilirubin, albumin, and indocyanine green plasma disappearance rate. The inflammatory response was evaluated by determination of IL-1beta and myeloperoxidase (MPO) activity. Bacterial concentrations in different organs were quantified.

RESULTS

Simultaneous CLP + PH resulted in a significantly delayed regeneration kinetic, which was most pronounced at 24 h. This was preceded by hyperinflammation with increased liberation of pro-inflammatory cytokines in the PH + CLP group at 6 h. After 48 h, the pro-inflammatory response declined, and regeneration proceeded also in the PH + CLP group. Liver function was found impaired in both groups; however, it was significantly worse in the PH + CLP group. Especially after 48 h, when regeneration peaked in this group, liver function significantly declined. At 96 h, only minor differences were seen, but the persistently elevated proliferative activity indicated the delay of regeneration after PH + CLP.

CONCLUSION

The present analysis shows that infectious conditions delay liver regeneration. Our data suggest a cross-linkage of both conditions via the functional liver capacity. A direct role of microorganisms seems unlikely; however, the inhibitory effect of the pro-inflammatory cytokines may be involved.

A new mouse model for intraportal islet transplantation with limited hepatic lobe as a graft site

Intraportal site is the standard for grafting in clinical islet transplantation. In the mouse model, the whole liver has been used as the grafting site to mimic clinical islet transplantation. However, this model lacks the potency to directly assess the contribution of the islet graft to diabetes control. Only demonstrating the immediate recurrence of diabetes in a surviving recipient after the removal of the islet graft can validate this assessment. In this study, we develop a mouse model of intraportal islet transplantation equipped with the potency of this assessment by injecting islets selectively into the right hepatic lobe under temporal clamp of the left portal vein. The mouse of this model survives after the right hepatectomy by which the islet graft is removed. This model can be applied to investigate both the specific graft-recipient interaction in the liver and the islet graft contribution to the control of diabetes.

A rat model of a repeat 70% major hepatectomy

BACKGROUND

This study investigated the effects of a repeat 70% major hepatectomy in a rat model.

MATERIALS AND METHODS

The left lateral and median lobes of the livers of 80 seven-week-old male Wistar rats were excised during primary hepatectomy, removing a total of 70% of the liver. In 40 of the rats, the regenerated right lateral lobe, comprising 70% of the remnant liver, was excised during secondary hepatectomy 7 days after the initial procedure. The survival rate, posthepatectomized regeneration ratio, and laboratory blood data were compared between the groups that had undergone initial only and repeat hepatectomies.

RESULTS

All of the rats survived for at least 7 days after each procedure. The remaining liver returned to up to about 90% of its original wet weight by 5 days in both groups. The serum glutamic-pyruvic transaminase levels peaked 12 h after hepatectomy, remained at a similar level at 36 h, and had normalized by 2 days. Serum total bilirubin levels were similar in both groups. The total cell numbers after 5 days were significantly higher in the initial hepatectomy group than in the repeat hepatectomy group.

CONCLUSIONS

We established a rat model in which an initial 70% major hepatectomy was followed by a repeat 70% major hepatectomy of the regenerated liver. The time taken to restore the integrity of the liver was longer in the rats that underwent repeat hepatectomy. We believe that this model will be useful for investigating the regenerative ability of the liver after a second major hepatectomy.