Use of hepatocyte and stem cells for treatment of post-resectional liver failure: are we there yet?

Post-hepatectomy liver failure: A timeline centered review

BACKGROUND

Post-hepatectomy liver failure (PHLF) is a leading cause of postoperative mortality after liver surgery. Due to its significant impact, it is imperative to understand the risk stratification and preventative strategies for PHLF. The main objective of this review is to highlight the role of these strategies in a timeline centered way around curative resection.

DATA SOURCES

This review includes studies on both humans and animals, where they addressed PHLF. A literature search was conducted across the Cochrane Library, Embase, MEDLINE/PubMed, and Web of Knowledge electronic databases for English language studies published between July 1997 and June 2020. Studies presented in other languages were equally considered. The quality of included publications was assessed using Downs and Black's checklist. The results were presented in qualitative summaries owing to the lack of studies qualifying for quantitative analysis.

RESULTS

This systematic review with 245 studies, provides insight into the current prediction, prevention, diagnosis, and management options for PHLF. This review highlighted that liver volume manipulation is the most frequently studied preventive measure against PHLF in clinical practice, with modest improvement in the treatment strategies over the past decade.

CONCLUSIONS

Remnant liver volume manipulation is the most consistent preventive measure against PHLF.

Multilineage Differentiating Stress Enduring (Muse) Cells: A New Era of Stem Cell-Based Therapy

Stem cell transplantation has recently demonstrated a significant therapeutic efficacy in various diseases. Multilineage-differentiating stress-enduring (Muse) cells are stress-tolerant endogenous pluripotent stem cells that were first reported in 2010. Muse cells can be found in the peripheral blood, bone marrow and connective tissue of nearly all body organs. Under basal conditions, they constantly move from the bone marrow to peripheral blood to supply various body organs. However, this rate greatly changes even within the same individual based on physical status and the presence of injury or illness. Muse cells can differentiate into all three-germ-layers, producing tissue-compatible cells with few errors, minimal immune rejection and without forming teratomas. They can also endure hostile environments, supporting their survival in damaged/injured tissues. Additionally, Muse cells express receptors for sphingosine-1-phosphate (S1P), which is a protein produced by damaged/injured tissues. Through the S1P-S1PR2 axis, circulating Muse cells can preferentially migrate to damaged sites following transplantation. In addition, Muse cells possess a unique immune privilege system, facilitating their use without the need for long-term immunosuppressant treatment or human leucocyte antigen matching. Moreover, they exhibit anti-inflammatory, anti-apoptotic and tissue-protective effects. These characteristics circumvent all challenges experienced with mesenchymal stem cells and induced pluripotent stem cells and encourage the wide application of Muse cells in clinical practice. Indeed, Muse cells have the potential to break through the limitations of current cell-based therapies, and many clinical trials have been conducted, applying intravenously administered Muse cells in stroke, myocardial infarction, neurological disorders and acute respiratory distress syndrome (ARDS) related to novel coronavirus (SARS-CoV-2) infection. Herein, we aim to highlight the unique biological properties of Muse cells and to elucidate the advantageous difference between Muse cells and other types of stem cells. Finally, we shed light on their current therapeutic applications and the major obstacles to their clinical implementation from laboratory to clinic.

Characterization and role of collagen gene expressing hepatic cells following partial hepatectomy in mice

BACKGROUND AND AIMS

The mechanism underlying liver regeneration following partial hepatectomy (PH) is not fully elucidated. We aimed to characterize collagen gene expressing hepatic cells following PH and examine their contribution to liver regeneration.

APPROACH AND RESULTS

Col-GFP mice, which express GFP under the control of the collagen gene promoter, were used to detect collagen gene expressing cells following PH. The GFP-expressing cells were analyzed via single-cell RNA sequencing (scRNA-seq). Additionally, Col-ER Cre/RFP and Col-ER Cre/DTA mice were utilized to examine the cell fates and functional roles of collagen gene expressing cells in liver regeneration, respectively. The number of collagen gene expressing cells was found to be increased on day 3 and subsequently decreased on day 7 following PH. ScRNA-seq analysis of sorted collagen gene expressing cells showed that the regenerating liver was characterized by three distinct hepatic stellate cell (HSC) clusters, including one representing classic myofibroblasts. The other HSC clusters included an intermediately activated HSC cluster and a proliferating HSC cluster. Of these, the latter cluster was absent in the CCl 4 -induced liver fibrosis model. Cell fate tracing analysis using Col-ER Cre/RFP mice demonstrated that the collagen gene expressing cells escaped death during regeneration and remained in an inactivated state in the liver. Further, depletion of these cells using Col-ER Cre/DTA mice resulted in impaired liver regeneration.

CONCLUSIONS

Heterogeneous HSC clusters, one of which was a unique proliferating cluster, were found to appear in the liver following PH. Collagen gene expressing cells, including HSCs, were found to promote liver regeneration.

The evaluation of the safety and efficacy of intravenously administered allogeneic multilineage-differentiating stress-enduring cells in a swine hepatectomy model

INTRODUCTION

Multilineage-differentiating stress-enduring (Muse) cells are non-tumorigenic endogenous pluripotent-like cells residing in the bone marrow that exert a tissue reparative effect by replacing damaged/apoptotic cells through spontaneous differentiation into tissue-constituent cells. Post-hepatectomy liver failure (PHLF) is a potentially fatal complication. The main purpose of this study was to evaluate the safety and efficiency of allogeneic Muse cell administration via the portal vein in a swine model of PHLF.

METHODS

Swine Muse cells, collected from swine bone marrow-mesenchymal stem cells (MSCs) as SSEA-3(+) cells, were examined for their characteristics. Then, 1 × 10⁷ allogeneic-Muse cells and allogeneic-MSCs and vehicle were injected via the portal vein in a 70% hepatectomy swine model.

RESULTS

Swine Muse cells exhibited characteristics comparable to previously reported human Muse cells. Compared to the MSC and vehicle groups, the Muse group showed specific homing of the administered cells into the liver, resulting in improvements in the control of hyperbilirubinemia (P = 0.04), prothrombin international normalized ratio (P = 0.05), and suppression of focal necrosis (P = 0.04). Integrated Muse cells differentiated spontaneously into hepatocyte marker-positive cells.

CONCLUSIONS

Allogeneic Muse cell administration may provide a reparative effect and functional recovery in a 70% hepatectomy swine model and thus may contribute to the treatment of PHLF.

Mesenchymal Stem Cells Transplantation following Partial Hepatectomy: A New Concept to Promote Liver Regeneration-Systematic Review of the Literature Focused on Experimental Studies in Rodent Models

Mesenchymal stem cells (MSCs) are an attractive source for regenerative medicine because they are easily accessible through minimally invasive methods and have the potential to enhance liver regeneration (LG) and improve liver function, following partial hepatectomy (PH) and acute or chronic liver injury. A systematic review of the literature was conducted for articles published up to September 1st, 2016, using the MEDLINE database. The keywords that were used in various combinations were as follows: “Mesenchymal stem cells”, “transplantation”, “stem cells”, “adipose tissue derived stem cells”, “bone marrow-derived stem cells”, “partial hepatectomy”, “acute liver failure”, “chronic liver failure”, “liver fibrosis”, “liver cirrhosis”, “rats”, “mice”, and “liver regeneration”. All introduced keywords were searched for separately in MeSH Database to control relevance and terminological accuracy and validity. A total of 41 articles were identified for potential inclusion and reviewed in detail. After a strict selection process, a total of 28 articles were excluded, leaving 13 articles to form the basis of this systematic review. MSCs transplantation promoted LG and improved liver function. Furthermore, MSCs had the ability to differentiate in hepatocyte-like cells, increase survival, and protect hepatocytes by paracrine mechanisms. MSCs transplantation may provide beneficial effects in the process of LG after PH and acute or chronic liver injury. They may represent a new therapeutic option to treat posthepatectomy acute liver failure.

Prospects for Adult Stem Cells in the Treatment of Liver Diseases

Hepatocytes constitute the main bulk of the liver and perform several essential functions. After injury, the hepatocytes have a remarkable capacity to regenerate and restore functionality. However, in some cases, the endogenous hepatocytes cannot replicate or restore the function, and liver transplantation, which is not exempt of complications, is required. Stem cells offer in theory the possibility of generating unlimited supply of hepatocytes in vitro due to their capacity to self-renew and differentiate when given the right cues. Stem cells isolated from an array of tissues have been investigated for their capacity to differentiate into hepatocyte-like cells in vitro and are employed in rescue experiments in vivo. Adult stem cells have gained in attractiveness over embryonic stem cells for liver cell therapy due to their origin, multipotentiality, and the possibility of autologous transplantation. This review deals with the promise and limitations of adult stem cells in clinically restoring liver functionality.

Attenuation of Postoperative Acute Liver Failure by Mesenchymal Stem Cell Treatment Due to Metabolic Implications

OBJECTIVE

To prevent posthepatectomy acute liver failure after extended resection by treatment with mesenchymal stem cells (MSCs).

BACKGROUND

Liver tumors often require extended liver resection, overburdening metabolic and regenerative capacities of the remnant organ. Resulting dysfunction and failure may be improved by the proregenerative characteristics of MSCs.

METHODS

Extended liver resection was performed in (DPPIV)-deficient F344-Fischer rats. Wild-type animals served as donors of peritoneal adipose-derived MSCs. These were predifferentiated in vitro into hepatocytic cells and delivered to the liver by splenic application. Liver-related blood parameters (international normalized ratio, bilirubin, aspartate aminotransferase, alanine aminotransferase) and liver histology (hematoxylin-eosin, Sudan III) were determined to monitor liver function. Metabolic changes were assessed by metabolomic analyses in the remnant liver and the serum. Liver damage and regeneration were quantified by determination of the apoptotic and proliferation rates.

RESULTS

MSCs supported survival after partial hepatectomy. They decreased liver-related blood parameters indicative for the improvement of liver function. The extensive lipid accumulation in hepatocytes illustrating the metabolic overload after resection was attenuated. Treatment with MSCs normalized imbalance of amino acids, acylcarnitines, sphingolipids, and glycerophospholipids in the liver and blood. Furthermore, MSCs decreased the apoptotic rate and increased the proliferation rate. The experimental time period (48 hours) was too short to allow for integration of MSCs into the host liver. Thus, the mode of action was probably indirect.

CONCLUSIONS

MSCs ameliorated hepatic dysfunction and improved liver regeneration after extended resection by paracrine mechanisms. They may represent a new therapeutic option to treat posthepatectomy acute liver failure.

Immunological aspects of liver cell transplantation

Within the field of regenerative medicine, the liver is of major interest for adoption of regenerative strategies due to its well-known and unique regenerative capacity. Whereas therapeutic strategies such as liver resection and orthotopic liver transplantation (OLT) can be considered standards of care for the treatment of a variety of liver diseases, the concept of liver cell transplantation (LCTx) still awaits clinical breakthrough. Success of LCTx is hampered by insufficient engraftment/long-term acceptance of cellular allografts mainly due to rejection of transplanted cells. This is in contrast to the results achieved for OLT where long-term graft survival is observed on a regular basis and, hence, the liver has been deemed an immune-privileged organ. Immune responses induced by isolated hepatocytes apparently differ considerably from those observed following transplantation of solid organs and, thus, LCTx requires refined immunological strategies to improve its clinical outcome. In addition, clinical usage of LCTx but also related basic research efforts are hindered by the limited availability of high quality liver cells, strongly emphasizing the need for alternative cell sources. This review focuses on the various immunological aspects of LCTx summarizing data available not only for hepatocyte transplantation but also for transplantation of non-parenchymal liver cells and liver stem cells.

The Therapeutic Promise of Mesenchymal Stem Cells for Liver Restoration

Hepatocyte transplantation aims to provide a functional substitution of liver tissue lost due to trauma or toxins. Chronic liver diseases are associated with inflammation, deterioration of tissue homeostasis, and deprivation of metabolic capacity. Recent advances in liver biology have focused on the pro-regenerative features of mesenchymal stem cells (MSCs). We argue that MSCs represent an attractive therapeutic option to treat liver disease. Indeed, their pleiotropic actions include the modulation of immune reactions, the stimulation of cell proliferation, and the attenuation of cell death responses. These characteristics are highly warranted add-ons to their capacity for hepatocyte differentiation. Undoubtedly, the elucidation of the regenerative mechanisms of MSCs in different liver diseases will promote their versatile and disease-specific therapeutic use.

Preoperative hepatocyte transplantation improves the survival of rats with nonalcoholic steatohepatitis-related cirrhosis after partial hepatectomy

Liver failure after liver resection for cirrhosis is a critical problem, and no effective therapy except liver transplantation is currently available. The objective of this study was to examine whether hepatocyte transplantation (HT) reduces the poststandard liver resection mortality rate of rats with nonalcoholic steatohepatitis (NASH)-related cirrhosis. Liver resection for hepatocellular carcinoma (HCC) combined with NASH-related cirrhosis has become increasingly common. We developed a rat model of acute liver failure after two-thirds partial hepatectomy (PH) for NASH-related cirrhosis. The mechanism by which HT improved the survival of the model rats was examined in short- and long-term investigations. Female DPPIV(-) recipient F344 rats were fed the choline-deficient l-amino acid (CDAA)-defined diet for 12 weeks. Some of the rats were transplanted with male F344 DPPIV(+) rat hepatocytes 24 h before undergoing PH. The overall post-PH survival of each group was evaluated, and short- and long-term pathological and molecular biological evaluations were also performed. Overall survival was significantly longer in the HT group than the non-HT group (7-day survival rates: 46.7% and 7.7%, respectively). Compared with the recipient livers of the non-HT group, numerous Ki-67(+) hepatocytes and few TUNEL(+) hepatocytes were observed in the livers of the HT group. At 6 months after the HT, the DPPIV(+) hepatocytes had partially replaced the recipient liver and formed hepatocyte clusters in the spleen. Preoperative HT might improve the survival of rats with NASH-related cirrhosis after PH by preventing the host hepatocytes from accelerating their growth and falling into apoptosis.

Therapeutic potential of umbilical cord mesenchymal stem cells in mice with acute hepatic failure

BACKROUND/OBJECTIVE

Mesenchymal stem cells are probably one of the most promising alternatives for liver regeneration and repair. We present data supporting the ability of human umbilical cord mesenchymal stem cells (hUCMSCs) to generate hepatic elements and discuss the best transplantation pathway.

METHODS

AHF mice were given hUCMSCs through tail-vein injection or into the liver lobes. Blood serum and liver tissues were collected to analyze the improvement of liver function and histological repair 24 h after hUCMSC administration. Real-time polymerase chain reaction and immunohistochemistry were used to detect the expression of human hepatocyte-specific markers in liver tissues.

RESULTS

The results showed significant statistical differences in liver function after transplantation (P<.05). Real-time PCR and immunochemistry results demonstrated that the expression of hepatocyte-specific markers such as CK18 and AFP were obviously increased in the treatment groups through both transplantation pathways. Our data indicate that hUCMSCs are one of the stem cell candidates for liver repair because hUCMSCs can be easily and readily isolated and differentiated into hepatocytes both in vitro and in vivo. Additionally, tail-vein injection of hUCMSCs has a similar therapeutic efficacy but is more convenient compared to liver lobe injection.

CONCLUSIONS

Our findings highlight the potential therapeutic value of hUCMSCs and show that cell transplantation through a peripheral vein is a safe and effective way to treat AHF mice. Furthermore, this method might mediate repair in patients with liver damage or disease in future clinical therapy.

Management of post-hepatectomy complications

Hepatic resection had an impressive growth over time. It has been widely performed for the treatment of various liver diseases, such as malignant tumors, benign tumors, calculi in the intrahepatic ducts, hydatid disease, and abscesses. Management of hepatic resection is challenging. Despite technical advances and high experience of liver resection of specialized centers, it is still burdened by relatively high rates of postoperative morbidity and mortality. Especially, complex resections are being increasingly performed in high risk and older patient population. Operation on the liver is especially challenging because of its unique anatomic architecture and because of its vital functions. Common post-hepatectomy complications include venous catheter-related infection, pleural effusion, incisional infection, pulmonary atelectasis or infection, ascites, subphrenic infection, urinary tract infection, intraperitoneal hemorrhage, gastrointestinal tract bleeding, biliary tract hemorrhage, coagulation disorders, bile leakage, and liver failure. These problems are closely related to surgical manipulations, anesthesia, preoperative evaluation and preparation, and postoperative observation and management. The safety profile of hepatectomy probably can be improved if the surgeons and medical staff involved have comprehensive knowledge of the expected complications and expertise in their management. This review article focuses on the major postoperative issues after hepatic resection and presents the current management.

Transcriptome temporal and functional analysis of liver regeneration termination

Decades of liver regeneration studies still left the termination phase least elucidated. However regeneration ending mechanisms are clinicaly relevant. We aimed to analyse the timing and transcriptional control of the latest phase of liver regeneration, both controversial. Male Wistar rats were subjected to 2/3 partial hepatectomy with recovery lasting from 1 to 14 days. Time-series microarray data were assessed by innovative combination of hierarchical clustering and principal component analysis and validated by real-time RT-PCR. Hierarchical clustering and principal component analysis in agreement distinguished three temporal phases of liver regeneration. We found 359 genes specifically altered during late phase regeneration. Gene enrichment analysis and manual review of microarray data suggested five pathways worth further study: PPAR signalling pathway; lipid metabolism; complement, coagulation and fibrinolytic cascades; ECM remodelling and xenobiotic biotransformation. Microarray findings pertinent for termination phase were substantiated by real-time RT-PCR. In conclusion, transcriptional profiling mapped late phase of liver regeneration beyond 5(th) day of recovery and revealed 5 pathways specifically acting at this time. Inclusion of longer post-surgery intervals brought improved coverage of regeneration time dynamics and is advisable for further works. Investigation into the workings of suggested pathways might prove helpful in preventing and managing liver tumours.

A pilot study of autologous CD34-depleted bone marrow mononuclear cell transplantation via the hepatic artery in five patients with liver failure

BACKGROUND AIMS

Many rodent experiments and human studies on stem cell therapy have shown promising therapeutic approaches to liver diseases. We investigated the clinical outcomes of five patients with liver failure of various causes who received autologous CD34-depleted bone marrow-derived mononuclear cell (BM-MNC) transplantation, including mesenchymal stromal cells, through the hepatic artery.

METHODS

CD34-depleted BM-MNCs were obtained from five patients waiting for liver transplantation by bone marrow aspiration and using the CliniMACS CD34 Reagent System (Miltenyi Biotech, Bergisch Gladbach, Germany), and autologous hepatic artery infusion was performed. The causes of hepatic decompensation were hepatitis B virus (HBV), hepatitis C virus (HCV), propylthiouracil-induced toxic hepatitis and Wilson disease.

RESULTS

Serum albumin levels improved 1 week after transplantation from 2.8 g/dL, 2.4 g/dL, 2.7 g/dL and 1.9 g/dL to 3.3 g/dL, 3.1 g/dL, 2.8 g/dL and 2.6 g/dL. Transient liver elastography data showed some change from 65 kPa, 33 kPa, 34.8 kPa and undetectable to 46.4 kPa, 19.8 kPa, 29.1 kPa and 67.8 kPa at 4 weeks after transplantation in a patient with Wilson disease, a patient with HCV, and two patients with HBV. Ascites decreased in two patients. One of the patients with HBV underwent liver transplantation 4 months after the infusion, and the hepatic progenitor markers (cytokeratin [CD]-7, CD-8, CD-9, CD-18, CD-19, c-Kit and epithelial cell adhesion molecule [EpCAM]) were highly expressed in the explanted liver.

CONCLUSIONS

Serum albumin levels, liver stiffness, liver volume, subjective healthiness and quality of life improved in the study patients. Although these findings were observed in a small population, the results may suggest a promising future for autologous CD34-depleted BM-MNC transplantation as a bridge to liver transplantation in patients with liver failure.

Liposomes as drug deposits in multilayered polymer films

The ex vivo growth of implantable hepatic or cardiac tissue remains a challenge and novel approaches are highly sought after. We report an approach to use liposomes embedded within multilayered films as drug deposits to deliver active cargo to adherent cells. We verify and characterize the assembly of poly(l-lysine) (PLL)/alginate, PLL/poly(l-glutamic acid), PLL/poly(methacrylic acid) (PMA), and PLL/cholesterol-modified PMA (PMAc) films, and assess the myoblast and hepatocyte adhesion to these coatings using different numbers of polyelectrolyte layers. The assembly of liposome-containing multilayered coatings is monitored by QCM-D, and the films are visualized using microscopy. The myoblast and hepatocyte adhesion to these films using PLL/PMAc or poly(styrenesulfonate) (PSS)/poly(allyl amine hydrochloride) (PAH) as capping layers is evaluated. Finally, the uptake of fluorescent lipids from the surface by these cells is demonstrated and compared. The activity of this liposome-containing coating is confirmed for both cell lines by trapping the small cytotoxic compound thiocoraline within the liposomes. It is shown that the biological response depends on the number of capping layers, and is different for the two cell lines when the compound is delivered from the surface, while it is similar when administered from solution. Taken together, we demonstrate the potential of liposomes as drug deposits in multilayered films for surface-mediated drug delivery.

Effect of bone marrow mesenchymal stem cells on hepatocellular carcinoma in microcirculation

This study aims t explore the effect and application of bone marrow mesenchymal stem cells (BMSCs) on hepatocellular carcinoma in microcirculation by observing the angiogenesis of hepatocellular carcinoma in transplanted area. BMSCs were isolated and cultured primarily using the method of whole bone marrow culture and identifying surface antigens of third-generation bone marrow-derived mesenchymal stem cells using flow cytometry. Hepatoma cells cultured with BMSCs-conditioned medium (BMSCs-CM) were assayed using the cell proliferation rate of the MTT method. Nude mice were divided into control group (group A), BMSCs cell transplantation group (group B), HepG-2 cell group (group C), and combined BMSCs and HepG-2 cell cotransplanted group (group D). The result showed that the microvascular density was not significantly different in groups A and B. However, the microvascular density at 14 days was higher than 0 day in group C (P < 0.05). In group D, the microvascular density at 14 days was higher than that of 7 and 0 days (P < 0.05) and 7 days was higher than 0 days (P < 0.05). It was showed that the microvascular density did not get significant difference at 0 and 7 days in the four groups (P > 0.05). But the microvascular density of group C was higher than groups A and B at 14 days (P < 0.05), group D was higher than groups A and B at 14 days (P < 0.05) and group D was higher than group C at 14 days (P < 0.05). BMSCs could promote the growth of microvascular in hepatoma cells in a transplanted area.

Safety evaluation of stem cells used for clinical cell therapy in chronic liver diseases; with emphasize on biochemical markers

There are several issues to be considered to reduce the risk of rejection and minimize side effects associated with liver cell transplantation in chronic liver diseases. The source and the condition of stem cell proliferation and differentiation ex vivo and the transplantation protocols are important safety considerations for cell based therapy. The biochemical and molecular markers are important tools for safety evaluation of different processes of cell expansion and transplantation. Studies show that hepatocytes differentiated from adult and embryonic stem cells exhibit biochemical and metabolic properties resembling mature hepatocytes. Therefore these assays can help to assess the biological and metabolic performance of hepatocytes and progenitor stem cells. The assays also help in testing the contribution of transplanted hepatocytes in improving the repair and function of damaged liver in the recipient. Here we review the biochemical and metabolic markers, which are implicated in evaluation of safety issues of stem cells used for therapeutic purposes in chronic liver diseases and regeneration of damaged liver. We also highlight application of biochemical tests for assessment of liver cell transplantation.