Cellular Mechanisms of Liver Regeneration and Cell-Based Therapies of Liver Diseases. Biomed Res Int. 2017;2017:8910821. [PMID: 28210629 PMCID: PMC5292184 DOI: 10.1155/2017/8910821]

Hepatotoxicity of pristine polyethylene microplastics in neotropical physalaemus cuvieri tadpoles (Fitzinger, 1826)

Plastic waste disposal in the environment is a major issue worldwide, whose effects on different biotas are the object of several investigations. The toxicity caused by microplastics (MPs) in organisms living in freshwater environments remains little explored. Little is known about the consequences of the exposure to these pollutants on the health of amphibians. Thus, we tested the hypothesis that the exposure of Physalaemus cuvieri tadpoles to microplastic polyethylene (PE MP) causes histopathological damage to their liver. Data collected after seven days of exposure to MPs (60 mg/L) have shown that pollutant bioaccumulation in tadpoles' liver was correlated to different histopathological changes (blood vessel dilation, infiltration, congestion, hydropic degeneration, hypertrophy and hyperplasia), which showed the histopathotoxicity of MPs. Furthermore, we observed changes in hepatocyte nuclei size (area and diameter), volume and shape induced by the exposure to PE MPs, a fact that evidenced the cytotoxic effect of these pollutants. To the best of our knowledge, the current study is the first to report the histopathotoxicity of PE MPs in representatives of the amphibian group, and it contributes to improving knowledge about these pollutants and how they may affect the health of these animals.

A pair of cell preservation solutions for therapy with human adipose tissue-derived mesenchymal stromal cells

Introduction

Stem cells for therapy are often suspended in a preservation solution, such as normal saline or lactated Ringer's solution, for a short time before intravenous infusion. However, these solutions are not necessarily ideal for maintaining cell viability and preventing the sedimentation of cells during storage and infusion. In this study, we attempted to optimize the compositions of preservation solutions, which could affect the efficacy and safety of stem cell therapy.

Methods

We determined the characteristics of a preservation solution that would optimize cell viability and the percentage of cells in the supernatant using human adipose-derived mesenchymal stromal cells (hADSCs). We compared solutions that differed by electrolytes (e.g., normal saline and Ringer's solution) and the concentrations of dextran 40 and trehalose. The effects of the solutions on hADSCs were evaluated by assessing cell surface markers, colony-forming capacity, differentiation potential, and cell concentrations in the infusion line.

Results

Optimized preservation solutions consisted of lactated Ringer's solution with 3% trehalose without or with 5% dextran 40 (LR-3T and LR-3T-5D, respectively). The cell viabilities after 24 h of storage at 5 °C in LR-3T and LR-3T-5D were 94.9% ± 2.4% and 97.6% ± 2.4%, respectively. The percentage of cells in the supernatant after 1 h of storage at room temperature in LR-3T-5D was 83.5% ± 7.6%. These solutions preserved the percentage of cell surface marker-positive cells, the colony-forming capacity, and the adipogenic and osteogenic differentiation ability in hADSCs for at least 24 h after preservation at 5 °C and 25 °C.

Discussion

We determined the optimal composition of preservation solutions for hADSCs and confirmed the effects of these solutions on cell viability and the stability of cell characteristics in vitro. Our results suggest that LR-3T and LR-3T-5D can help maintain the quality of stem cells for therapy during preservation and infusion. However, further in vivo research is needed on the efficacy and safety of the solutions in different therapeutic cell lines before clinical use.

Rewiring Host Signaling: Hepatitis C Virus in Liver Pathogenesis

Hepatitis C virus (HCV) is a major cause of liver disease including metabolic disease, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). HCV induces and promotes liver disease progression by perturbing a range of survival, proliferative, and metabolic pathways within the proinflammatory cellular microenvironment. The recent breakthrough in antiviral therapy using direct-acting antivirals (DAAs) can cure >90% of HCV patients. However, viral cure cannot fully eliminate the HCC risk, especially in patients with advanced liver disease or comorbidities. HCV induces an epigenetic viral footprint that promotes a pro-oncogenic hepatic signature, which persists after DAA cure. In this review, we summarize the main signaling pathways deregulated by HCV infection, with potential impact on liver pathogenesis. HCV-induced persistent signaling patterns may serve as biomarkers for the stratification of HCV-cured patients at high risk of developing HCC. Moreover, these signaling pathways are potential targets for novel chemopreventive strategies.

The Effect of Fibroblast Growth Factor 15 Signaling in Non-Steatotic and Steatotic Liver Transplantation from Cardiocirculatory Death

We elucidate the relevance of fibroblast growth factor 15 (FGF15) in liver transplantation (LT) using rats with both steatotic and non-steatotic organs from donors after cardiocirculatory death (DCD). Compared to LT from non-DCDs, the induction of cardiocirculatory death (CD) increases hepatic damage, proliferation, and intestinal and circulatory FGF15. This is associated with high levels of FGF15, bilirubin and bile acids (BAs), and overexpression of the enzyme involved in the alternative BA synthesis pathway, CYP27A1, in non-steatotic livers. Furthermore, CD activates the proliferative pathway, Hippo/YAP, in these types of liver. Blocking FGF15 action in LT from DCDs does not affect CYP27A1 but causes an overexpression of CYP7A, an enzyme from the classic BA synthesis pathway, and this is related to further accumulation of BAs and exacerbated damage. FGF15 inhibition also impairs proliferation without changing Hippo/YAP. In spite of worse damage, steatosis prevents a proliferative response in livers from DCDs. In steatotic grafts, CD does not modify CYP7A1, CYP27A1, BA, or the Hippo/YAP pathway, and FGF15 is not involved in damage or proliferation. Thus, endogenous FGF15 protects against BA accumulation and damage and promotes regeneration independently of the Hippo/YAP pathway, in non-steatotic LT from DCDs. Herein we show a minor role of FGF15 in steatotic LT from DCDs.

Within-host mathematical models of hepatitis B virus infection: Past, present, and future

Mathematical modeling has been instrumental in enhancing our understanding of the viral dynamics of hepatitis B virus (HBV) infection. We give a primer on HBV infection in humans and a brief overview of the development of within-host mathematical models of HBV infection. In the last decade, models have advanced from considering chronic HBV infections under therapy to the pathogenesis of infection. We also summarize estimates of key viral dynamic parameters that have varied greatly among studies, and show that they impact model predictions. Future directions for mathematical modeling of HBV infection are proposed to better understand emerging therapies, the HBV life cycle, predicting cure, and the mechanisms involved in the immune response to HBV infection.

The evolving microenvironment of the human hepatocyte: Healthy vs. cirrhotic liver vs. isolated cells

The study of the liver microenvironment and hepatocyte's response to this environment in the setting of healthy liver, cirrhotic liver or cultured primary human hepatocytes (PHHs) addresses key questions for the development of novel liver therapies and predicts relevance of ex vivo PHHs models in liver biology. This study compared quantitative gene and protein expression of the inflammatory profile, oxidative stress response, angiogenesis and homing mechanisms in the biopsies of healthy and cirrhotic human livers and isolated PHHs. These profiles were correlated with the metabolic health of liver and PHHs defined by albumin production. The analysis demonstrated that cirrhotic liver and PHHs exhibited a distinct upregulation of the pro-inflammatory, oxidative stress and homing mechanism markers when compared to normal liver. The upregulation of the oxidative stress markers in PHHs inversely correlated with the albumin production. PHHs had diverse secretion of matrix metalloproteinases and their inhibitors, reflective of the cellular response to non-physiological culture conditions. The current study suggests that ex vivo PHHs manifest adaptive behavior by upregulating stress mechanisms (similar to the cirrhotic liver), downregulating normal metabolic function and upregulating matrix turnover. The ex vivo profile of PHHs may limit their therapeutic functionality and metabolic capacity to serve as in vitro metabolism and toxicology models.

Mesenchymal Stem Cells in the Adult Human Liver: Hype or Hope?

Chronic liver diseases constitute a significant economic, social, and biomedical burden. Among commonly adopted approaches, only organ transplantation can radically help patients with end-stage liver pathologies. Cell therapy with hepatocytes as a treatment for chronic liver disease has demonstrated promising results. However, quality human hepatocytes are in short supply. Stem/progenitor cells capable of differentiating into functionally active hepatocytes provide an attractive alternative approach to cell therapy for liver diseases, as well as to liver-tissue engineering, drug screening, and basic research. The application of methods generally used to isolate mesenchymal stem cells (MSCs) and maintain them in culture to human liver tissue provides cells, designated here as liver MSCs. They have much in common with MSCs from other tissues, but differ in two aspects-expression of a range of hepatocyte-specific genes and, possibly, inherent commitment to hepatogenic differentiation. The aim of this review is to analyze data regarding liver MSCs, probably another type of liver stem/progenitor cells different from hepatic stellate cells or so-called hepatic progenitor cells. The review presents an analysis of the phenotypic characteristics of liver MSCs, their differentiation and therapeutic potential, methods for isolating these cells from human liver, and discusses issues of their origin and heterogeneity. Human liver MSCs are a fascinating object of fundamental research with a potential for important practical applications.

The peculiar aging of human liver: A geroscience perspective within transplant context

An appraisal of recent data highlighting aspects inspired by the new Geroscience perspective are here discussed. The main findings are summarized as follows: i) liver has to be considered an immunological organ, and new studies suggest a role for the recently described cells named telocytes; ii) the liver-gut axis represents a crucial connection with environment and life style habits and may influence liver diseases onset; iii) the physiological aging of liver shows relatively modest alterations. Nevertheless, several molecular changes appear to be relevant: a) an increase of microRNA-31-5p; -141-3p; -200c-3p expressions after 60 years of age; b) a remodeling of genome-wide DNA methylation profile evident until 60 years of age and then plateauing; c) changes in transcriptome including the metabolic zones of hepatocyte lobules; d) liver undergoes an accelerated aging in presence of chronic inflammation/liver diseases in a sort of continuum, largely as a consequence of unhealthy life styles and exposure to environmental noxious agents. We argue that chronic liver inflammation has all the major characteristics of "inflammaging" and likely sustains the onset and progression of liver diseases. Finally, we propose to use a combination of parameters, mostly obtained by omics such as transcriptomics and epigenomics, to evaluate in deep both the biological age of liver (in comparison with the chronological age) and the effects of donor-recipient age-mismatches in the context of liver transplant.

Understanding the marvels behind liver regeneration

Tissue regeneration is a process by which the remaining cells of an injured organ regrow to offset the missed cells. This field is relatively a new discipline that has been a focus of intense research by clinicians, surgeons, and scientists for decades. It constitutes the cornerstone of tissue engineering, creation of artificial organs, and generation and utilization of therapeutic stem cells to undergo transformation to different types of mature cells. Many medical experts, scientists, biologists, and bioengineers have dedicated their efforts to deeply comprehend the process of liver regeneration, striving for harnessing it to invent new therapies for liver failure. Liver regeneration after partial hepatectomy in rodents has been extensively studied by researchers for many years. It is divided into three important distinctive phases including (a) Initiation or priming phase which includes an overexpression of specific genes to prepare the liver cells for replication, (b) Proliferation phase in which the liver cells undergo a series of cycles of cell division and expansion and finally, (c) termination phase which acts as brake to stop the regenerative process and prevent the liver tissue overgrowth. These events are well controlled by cytokines, growth factors, and signaling pathways. In this review, we describe the function, embryology, and anatomy of human liver, discuss the molecular basis of liver regeneration, elucidate the hepatocyte and cholangiocyte lineages mediating this process, explain the role of hepatic progenitor cells and elaborate the developmental signaling pathways and regulatory molecules required to procure a complete restoration of hepatic lobule. This article is categorized under: Adult Stem Cells, Tissue Renewal, and Regeneration > Regeneration Signaling Pathways > Global Signaling Mechanisms Gene Expression and Transcriptional Hierarchies > Cellular Differentiation.

Genetic Lineage Tracing of Biliary Epithelial Cells

Lineage tracing of liver cells is a powerful tool to understand liver embryonic development, healthy liver cell homeostasis, tissue repair, and regeneration. Lineage tracing of biliary epithelial cells (BECs) in the adult liver has been used to assess the contribution of the biliary epithelium to liver injury, regeneration, and disease. These studies have shown the contribution of BECs to the expansion of ductular reaction (DR) and liver progenitor cells (LPCs) and eventually the generation of new hepatocytes. Few genetic lineage-tracing mouse models have been proved to trace BECs. This chapter is focused on lineage tracing of BECs in mouse models of liver injury and regeneration. First, we mention different existing approaches to trace the biliary epithelium based on proteins specifically expressed by BECs such as sex-determining region Y-box 9 (SOX9), osteopontin (OPN), and cytokeratin-19 (KRT19). Second, we describe mouse models that can be used to evaluate cell fate during liver injury and regeneration (i.e., partial hepatectomy (PHx), acute liver injury models, and chronic liver damage models such as 3,5-diethoxycarbonyl-1,4-dihydro-collidin (DDC) diet, choline-deficient ethionine-supplemented (CDE) diet, or chronic carbon tetrachloride (CCl₄) administration). Third, we suggest possible readouts to assess BECs fate based on immunofluorescence analysis.

Therapeutic Potential of Autologous Adipose-Derived Stem Cells for the Treatment of Liver Disease

Currently, the most effective therapy for liver diseases is liver transplantation, but its use is limited by organ donor shortage, economic reasons, and the requirement for lifelong immunosuppression. Mesenchymal stem cell (MSC) transplantation represents a promising alternative for treating liver pathologies in both human and veterinary medicine. Interestingly, these pathologies appear with a common clinical and pathological profile in the human and canine species; as a consequence, dogs may be a spontaneous model for clinical investigations in humans. The aim of this work was to characterize canine adipose-derived MSCs (cADSCs) and compare them to their human counterpart (hADSCs) in order to support the application of the canine model in cell-based therapy of liver diseases. Both cADSCs and hADSCs were successfully isolated from adipose tissue samples. The two cell populations shared a common fibroblast-like morphology, expression of stemness surface markers, and proliferation rate. When examining multilineage differentiation abilities, cADSCs showed lower adipogenic potential and higher osteogenic differentiation than human cells. Both cell populations retained high viability when kept in PBS at controlled temperature and up to 72 h, indicating the possibility of short-term storage and transportation. In addition, we evaluated the efficacy of autologous ADSCs transplantation in dogs with liver diseases. All animals exhibited significantly improved liver function, as evidenced by lower liver biomarkers levels measured after cells transplantation and evaluation of cytological specimens. These beneficial effects seem to be related to the immunomodulatory properties of stem cells. We therefore believe that such an approach could be a starting point for translating the results to the human clinical practice in future.

The Role of Adipokines in Surgical Procedures Requiring Both Liver Regeneration and Vascular Occlusion

Liver regeneration is a perfectly calibrated mechanism crucial to increase mass recovery of small size grafts from living donor liver transplantation, as well as in other surgical procedures including hepatic resections and liver transplantation from cadaveric donors. Regeneration involves multiple events and pathways in which several adipokines contribute to their orchestration and drive hepatocytes to proliferate. In addition, ischemia-reperfusion injury is a critical factor in hepatic resection and liver transplantation associated with liver failure or graft dysfunction post-surgery. This review aims to summarize the existing knowledge in the role of adipokines in surgical procedures requiring both liver regeneration and vascular occlusion, which increases ischemia-reperfusion injury and regenerative failure. We expose and discuss results in small-for-size liver transplantation and hepatic resections from animal studies focused on the modulation of the main adipokines associated with liver diseases and/or regeneration published in the last five years and analyze future perspectives and their applicability as potential targets to decrease ischemia-reperfusion injury and improve regeneration highlighting marginal states such as steatosis. In our view, adipokines means a promising approach to translate to the bedside to improve the recovery of patients subjected to partial hepatectomy and to increase the availability of organs for transplantation.

Efficacy and safety of autologous stem cell transplantation for decompensated liver cirrhosis: A retrospective cohort study

AIM

To evaluate the long-term efficacy and safety of autologous stem cell transplantation (SCT) for decompensated liver cirrhosis.

METHODS

Consecutive patients with decompensated liver cirrhosis were included and assigned into the SCT group and non-transplantation (non-SCT) group according to whether they received SCT treatment. Patients were followed up for ten years. The long-term survival rate and incidence of hepatocellular carcinoma (HCC) were compared between groups.

RESULTS

A total of 159 patients were enrolled, including 27 cases in the SCT group and 132 cases in the non-SCT group. The baseline characteristics were significantly different between the two groups. Propensity score matching (PSM) was used to match SCT and non-SCT patients. After PSM, 92 subjects were enrolled in the final analysis, including 23 cases in the SCT group and 69 cases in the non-SCT group. The overall mortality was 73.9% and 55.1%, and the median survival period was 48 and 64 mo, respectively. However, no significant difference was found in the long-term survival rate between the two groups (P > 0.05). In addition, the incidence of HCC was higher in the SCT group than in the non-SCT group (47.8% vs 21.7%, P < 0.05). After adjusting for other covariates, SCT (OR = 3.065, 95%CI: 1.378-6.814) and age (OR = 1.061, 95%CI: 1.021-1.102) were independently correlated with the development of HCC in this decompensated liver cirrhosis cohort.

CONCLUSION

Autologous SCT may fail to improve the long-term efficacy and increase the incidence of HCC for decompensated liver cirrhosis. Close monitoring of HCC is strongly recommended in patients undergoing autologous SCT.

Regenerative medicine and war: a front-line focus for UK defence

The recent prolonged conflicts in Iraq and Afghanistan saw the advancement of deployed trauma care to a point never before seen in war. The rapid translation of lessons from combat casualty care research, facilitated by an appetite for risk, contributed to year-on-year improvements in care of the injured. These paradigms, however, can only ever halt the progression of damage. Regenerative medicine approaches, in contrast, hold a truly disruptive potential to go beyond the cessation of damage from blast or ballistic trauma, to stimulate its reversal, and to do so from a very early point following injury. The internationally distributed and, in parts austere environments in which operational medical care is delivered provide an almost unique challenge to the development and translation of regenerative medicine technologies. In parallel, however, an inherent appetite for risk means that Defence will always be an early adopter. In focusing our operational priorities for regenerative medicine, the authors conducted a review of the current research landscape in the UK and abroad and sought wide clinical opinion. Our priorities are all applicable very far forward in the patient care pathway, and are focused on three broad and currently under-researched areas, namely: (a) blood, as an engineered tissue; (b) the mechanobiology of deep tissue loss and mechanobiological approaches to regeneration, and; (c) modification of the endogenous response. In focusing on these areas, we hope to engender the development of regenerative solutions for improved functional recovery from injuries sustained in conflict.

Cell Therapy as a Tool for Induction of Immunological Tolerance after Liver Transplantation

Transplantation of solid organs, including liver, induces a number of serious complications related to immune incompatibility and requiring long-term use of immunosuppressive drugs. Finding the ways to inducing recipient immunological tolerance to the grafts is a top priority in organ transplantation and immunology. Along with the search for immunosupressive therapy, the development of alternative approaches to induction of immunological tolerance based on cell technologies is now in progress. In this regard, studies of the so-called spontaneous operational tolerance observed in ~20% patients after orthotopic liver transplantation is a promising trend. Understanding of this phenomenon can shed light on the mechanisms of immunological tolerance to allografts and will help to identify specific tolerance biomarkers and cell types with the aptitude for the induction of tolerance to liver allografts.

Partial Hepatectomy-Induced Upregulation of miR-1907 Accelerates Liver Regeneration by Activation Autophagy

Liver regeneration after partial hepatectomy (PH) is a highly orchestrated biological process in which synchronized hepatocyte proliferation is induced after massive liver mass loss. Hepatocyte proliferation could be regulated by multiple signals, such as miRNAs and autophagy, but underlying mechanism remains unclear. Here a functional miRNA during liver regeneration was identified and its underlying mechanism was delineated in vitro and in vivo. We found that miR-1907 was highly upregulated during liver regeneration after 2/3 PH at various timepoints. The level of miR-1907 was also increased in normal liver cell line treated with HGF at different concentrations. Functionally, miR-1907 enhanced hepatocyte proliferation in vitro and in vivo, and the liver/body weight ratio in miR-1907-overexpressed mice was significantly higher in comparison to the control mice after 2/3 PH. Forced expression of miR-1907 promoted autophagy activation of hepatocyte. Importantly, autophagy inhibition significantly attenuated miR-1907-induced hepatocyte proliferation and the liver/body weight ratio. Finally, GSK3β, a suppressor of autophagy signaling, was identified as the direct target gene of miR-1907. Taken together, miR-1907 accelerates hepatocyte proliferation during liver regeneration by activating autophagy; thus pharmacological intervention regulating miR-1907/autophagy axis may be therapeutically beneficial in liver transplantation and liver failure by inducing liver regeneration.

Thermo-rheological responsive microcapsules for time-dependent controlled release of human mesenchymal stromal cells

Human mesenchymal stromal cells (hMSCs) are adult-source cells that have been extensively evaluated for cell-based therapies. hMSCs delivered by intravascular injection have been reported to accumulate at the sites of injury to promote tissue repair and can also be employed as vectors for the delivery of therapeutic genes. However, the full potential of hMSCs remains limited as the cells are lost after injection due to anoikis and the adverse pathologic environment. Encapsulation of cells has been proposed as a means of increasing cell viability. However, controlling the release of therapeutic cells over time to target tissue still remains a challenge today. Here, we report the design and development of thermo-rheological responsive hydrogels that allow for precise, time dependent controlled-release of hMSCs. The encapsulated hMSCs retained good viability from 76% to 87% dependent upon the hydrogel compositions. We demonstrated the design of different blended hydrogel composites with modulated strength (S parameter) and looseness of hydrogel networks (N parameter) to control the release of hMSCs from thermo-responsive hydrogel capsules. We further showed the feasibility for controlled-release of encapsulated hMSCs within 3D matrix scaffolds. We reported for the first time by a systematic analysis that there is a direct correlation between the thermo-rheological properties associated with the degradation of the hydrogel composite and the cell release kinetics. This work therefore provides new insights into the further development of smart carrier systems for stem cell therapy.

Bone marrow or adipose tissue mesenchymal stem cells: Comparison of the therapeutic potentials in mice model of acute liver failure

Acute liver failure (ALF) is a lethal disease with limited life-saving therapy. Because lack of whole organ donors for liver transplantation, a substitute treatment strategy is needed for these patients. Preclinical and clinical findings have proved that treatment with mesenchymal stem cells (MSCs) is beneficial for recovery from ALF. In this approach, however, the appropriate sources of these cells are unclear. In the present study, we investigated and compared the therapeutic potentials of bone marrow-mesenchymal stem cells (BM-MSC) with those of adipose tissue (AT-MSC) in carbon tetrachloride (CCL4)-induced acute liver failure in mice. Murine BM- and AT-MSCs obtained from normal mice were cultured and labelled. The cells were transplanted to CCL4-induced ALF mice models intravenously. After cell transplantation, blood samples and liver tissues were collected daily for 72 h to analyze liver enzymes and liver histopathology, respectively. We found that survival rate of AT-MSC transplanted (AT-TR) mice was significantly higher than that of control (ALF) group. Liver histopathology was superior in the AT-TR mice, but not significantly, compared to that in BM-MSC transplanted (BM-TR) ones. Furthermore, in the AT-TR mice the level of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), in some time points were significantly less than those of BM-TR. Taken together, these data suggest that in comparison to BM-MSC, AT-MSCs is an appropriate choice for cell therapy in the case of acute liver failure.

Autogenous hepatic tissue transplantation into the omentum in a novel ectopic liver regeneration murine model

BACKGROUND

Liver regeneration involves hyperplasia and hypertrophy of hepatic cells. The capacity of macroscopic liver tissue to regenerate in ectopic sites is unknown. We aim to develop a novel in vivo model of ectopic liver survivability and regeneration and assess its functionality.

METHODS

Adult male Sprague-Dawley rats (n = 23) were divided into four groups: (1) single-stage (SS) group, wedge liver resection was performed, and the parenchyma was directly implanted into the omentum; (2) double-stage (DS) group, omentum pedicle was transposed over the left hepatic lobe followed by wedge liver resection along with omental flap; (3) Biogel + DS group, rats received intraperitoneal injection of inert polymer particles prior to DS; (4) Biogel + DS + portal vein ligation (PVL) group, Biogel + DS rats underwent subsequent PVL. Hepatobiliary iminodiacetic acid scintigraphy assessed bile excretion from ectopic hepatic implants.

RESULTS

Histologically, the scores of necrosis (P < 0.001) and fibrosis (P = 0.004) were significantly improved in rats undergoing DS procedure (groups 2, 3, and 4) compared with the SS group. Biogel rats (Biogel + DS and Biogel + DS + PVL) demonstrated statistically increased scores of bile duct neoformation (P = 0.002) compared to those without the particles (SS and DS). Scintigraphy demonstrated similar uptake of radiotracer by ectopic hepatic implants in groups 2, 3, and 4.

CONCLUSIONS

Omental transposition provided adequate microcirculation for proliferation of ectopic hepatic cells after liver resection. Inert polymers enhanced the regeneration by promoting differentiation of new bile ducts. The ectopic hepatic implants showed preserved function on scintigraphy. This model provides insights into the capacity of liver parenchyma to regenerate in ectopic sites and the potential as therapeutic target for cell therapy in end-stage liver disease.