Autologous bone marrow-derived mesenchymal stem cell transplantation promotes liver regeneration after portal vein embolization in cirrhotic rats. J Surg Res. 2013;184:1161-1173. [PMID: 23809154 DOI: 10.1016/j.jss.2013.04.054]

Current Perspectives and Progress in Preoperative Portal Vein Embolization with Stem Cell Augmentation (PVESA)

Portal vein embolization with stem cell augmentation (PVESA) is an emerging approach for enhancing the growth of the liver segment that will remain after surgery (i.e., future liver remnant, FLR) in patients with liver cancer. Conventional portal vein embolization (PVE) aims to induce preoperative FLR growth, but it has a risk of failure in patients with underlying liver dysfunction and comorbid illnesses. PVESA combines PVE with stem cell therapy to potentially improve FLR size and function more effectively and efficiently. Various types of stem cells can help improve liver growth by secreting paracrine signals for hepatocyte growth or by transforming into hepatocytes. Mesenchymal stem cells (MSCs), unrestricted somatic stem cells, and small hepatocyte-like progenitor cells have been used to augment liver growth in preclinical animal models, while clinical studies have demonstrated the benefit of CD133 + bone marrow-derived MSCs and hematopoietic stem cells. These investigations have shown that PVESA is generally safe and enhances liver growth after PVE. However, optimizing the selection, collection, and application of stem cells remains crucial to maximize benefits and minimize risks. Additionally, advanced stem cell technologies, such as priming, genetic modification, and extracellular vesicle-based therapy, that could further enhance efficacy outcomes should be evaluated. Despite its potential, PVESA requires more investigations, particularly mechanistic studies that involve orthotopic animal models of liver cancer with concomitant liver injury as well as larger human trials.

Tracking of Stem Cells in Chronic Liver Diseases: Current Trends and Developments

Stem cell therapy holds great promise for future clinical practice for treatment of advanced liver diseases. However, the fate of stem cells after transplantation, including the distribution, viability, and the cell clearance, has not been fully elucidated. Herein, recent advances regarding the imaging tools for stem cells tracking mainly in chronic liver diseases with the advantages and disadvantages of each approach have been described. Magnetic resonance imaging is a promising clinical imaging modality due to non-radioactivity, excellent penetrability, and high spatial resolution. Fluorescence imaging and radionuclide imaging demonstrate relatively increased sensitivity, with the latter excelling in real-time monitoring. Reporter genes specialize in long-term tracing. Nevertheless, the disadvantages of low sensitivity, radiation, exogenous gene risk are inevitably present in each of these means, respectively. In this review, we aim to comprehensively evaluate the current state of methods for tracking of stem cell, highlighting their strengths and weaknesses, and providing insights into their future potential. Multimodality imaging strategies may overcome the inherent limitations of single-modality imaging by combining the strengths of different imaging techniques to provide more comprehensive information in the clinical setting.

Functional Mechanism of Bone Marrow-Derived Mesenchymal Stem Cells in the Treatment of Animal Models with Alzheimer's Disease: Inhibition of Neuroinflammation

The transplantation of bone marrow-derived mesenchymal stem cells (BMMSCs) alleviates neuropathology and improves cognitive deficits in animal models with Alzheimer’s disease. However, the underlying mechanisms remain to be determined. Available data demonstrate transplanted BMMSCs can inhibit neuroinflammation, which may be related to microglial M1/M2 polarization and is regulated by the secretion of autocrine and paracrine cytokines. BMMSCs also mitigate Aβ plaques and Tau tangles in the brain, which may be associated with the recruitment of peripheral blood monocytes and the subsequent comprehensive effects. The therapeutic effects of stem cells involve potential mechanisms such as immunomodulation, apoptosis, and proliferation. BMMSC-mediated functional reconstruction through dynamic remodeling develops a novel balance. Herein, present review recapitulates the molecular basis of BMMSC-assisted biological processes and summarizes the possible mechanisms related to the interaction between BMMSCs and microglia. The transplanted BMMSCs can suppress neuroinflammation that plays a key role in the pathogenesis of Alzheimer’s disease.

Mesenchymal Stromal Cell Therapy in Novel Porcine Model of Diffuse Liver Damage Induced by Repeated Biliary Obstruction

In liver surgery, biliary obstruction can lead to secondary biliary cirrhosis, a life-threatening disease with liver transplantation as the only curative treatment option. Mesenchymal stromal cells (MSC) have been shown to improve liver function in both acute and chronic liver disease models. This study evaluated the effect of allogenic MSC transplantation in a large animal model of repeated biliary obstruction followed by partial hepatectomy. MSC transplantation supported the growth of regenerated liver tissue after 14 days (MSC group, n = 10: from 1087 ± 108 (0 h) to 1243 ± 92 mL (14 days); control group, n = 11: from 1080 ± 95 (0 h) to 1100 ± 105 mL (14 days), p = 0.016), with a lower volume fraction of hepatocytes in regenerated liver tissue compared to resected liver tissue (59.5 ± 10.2% vs. 70.2 ± 5.6%, p < 0.05). Volume fraction of connective tissue, blood vessels and bile vessels in regenerated liver tissue, serum levels of liver enzymes (AST, ALT, ALP and GGT) and liver metabolites (albumin, bilirubin, urea and creatinine), as well as plasma levels of IL-6, IL-8, TNF-α and TGF-β, were not affected by MSC transplantation. In our novel, large animal (pig) model of repeated biliary obstruction followed by partial hepatectomy, MSC transplantation promoted growth of liver tissue without any effect on liver function. This study underscores the importance of translating results between small and large animal models as well as the careful translation of results from animal model into human medicine.

Therapeutic efficiency of bone marrow-derived mesenchymal stem cells for liver fibrosis: A systematic review of in vivo studies

Although multiple drugs are accessible for recovering liver function in patients, none are considered efficient. Liver transplantation is the mainstay therapy for end-stage liver fibrosis. However, the worldwide shortage of healthy liver donors, organ rejection, complex surgery, and high costs are prompting researchers to develop novel approaches to deal with the overwhelming liver fibrosis cases. Mesenchymal stem cell (MSC) therapy is an emerging alternative method for treating patients with liver fibrosis. However, many aspects of this therapy remain unclear, such as the efficiency compared to conventional treatment, the ideal MSC sources, and the most effective way to use it. Because bone marrow (BM) is the largest source for MSCs, this paper used a systematic review approach to study the therapeutic efficiency of MSCs against liver fibrosis and related factors. We systematically searched multiple published articles to identify studies involving liver fibrosis and BM-MSC-based therapy. Analyzing the selected studies showed that compared with conventional treatment BM-MSC therapy may be more efficient for liver fibrosis in some cases. In contrast, the cotreatment presented a more efficient way. Nevertheless, BM-MSCs are lacking as a therapy for liver fibrosis; thus, this paper also reviews factors that affect BM-MSC efficiency, such as the implementation routes and strategies employed to enhance the potential in alleviating liver fibrosis. Ultimately, our review summarizes the recent advances in the BM-MSC therapy for liver fibrosis. It is grounded in recent developments underlying the efficiency of BM-MSCs as therapy, focusing on the preclinical in vivo experiments, and comparing to other treatments or sources and the strategies used to enhance its potential while mentioning the research gaps.

Mesenchymal stem cell-derived extracellular vesicles suppress the fibroblast proliferation by downregulating FZD6 expression in fibroblasts via micrRNA-29b-3p in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF), a progressive and fatal lung disease, usually leads to an irreversible distortion of the pulmonary structure. The functional roles of bone marrow-derived mesenchymal stem cells (BMSC)-secreted extracellular vesicles (EVs) in fibroblasts have been implicated, yet their actions in the treatment of IPF are not fully understood. This study investigated the roles of BMSC-derived EVs expressing miR-29b-3p in fibroblasts in IPF treatment. EVs derived from BMSCs were successfully isolated and could be internalized by pulmonary fibroblasts, and Cell Counting Kit-8 (CCK-8) and Transwell assay results identified that EVs inhibited the activation of fibroblast in IPF. miR-29b-3p, frizzled 6 (FZD6), α-skeletal muscle actin (α-SMA), and Collagen I expressions were examined, which revealed that miR-29b-3p was poorly expressed and FZD6, α-SMA, and Collagen I were overexpressed in pulmonary tissues. Dual-luciferase reporter assay results demonstrated that miR-29b-3p could inversely target FZD6 expression. The gain- and loss-of-function assays were conducted to determine regulatory effects of FZD6 and miR-29b-3p on IPF. CCK-8 and Transwell assays results displayed that BMSCs-derived EVs overexpressing miR-29b-3p contributed to inhibited pulmonary interstitial fibroblast proliferation, migration, invasion, and differentiation. Furthermore, the effects of BMSCs-derived EVs overexpressing miR-29b-3p on IPF progression were assessed in vivo, which confirmed the repressive effects of BMSCs-derived EVs overexpressing miR-29b-3p on IPF progression. Collectively, BMSCs-derived EVs overexpressing miR-29b-3p relieve IPF through FZD6.

Improving the Safety of Major Resection for Hepatobiliary Malignancy: Portal Vein Embolization and Recent Innovations in Liver Regeneration Strategies

PURPOSE OF REVIEW

For three decades, portal vein embolization (PVE) has been the "gold-standard" strategy to hypertrophy the anticipated future liver remnant (FLR) in advance of major hepatectomy. During this time, CT volumetry was the most common method to preoperatively assess FLR quality and function and used to determine which patients are appropriate surgical candidates. This review provides the most up-to-date methods for preoperatively assessing the anticipated FLR and summarizes data from the currently available strategies used to induce FLR hypertrophy before surgery for hepatobiliary malignancy.

RECENT FINDINGS

Functional and physiological imaging is increasingly replacing standard CT volumetry as the method of choice for preoperative FLR assessment. PVE, associating liver partition and portal vein ligation, radiation lobectomy, and liver venous deprivation are all currently available techniques to hypertrophy the FLR. Each strategy has pros and cons based on tumor type, extent of resection, presence or absence of underlying liver disease, age, performance status, complication rates, and other factors. Numerous strategies can lead to FLR hypertrophy and improve the safety of major hepatectomy. Which is best has yet to be determined.

Adipose-tissue derived porcine mesenchymal stem cells efficiently ameliorate CCl4-induced acute liver failure in mice

Adipose tissue derived mesenchymal stem cells (ADMSCs) may be an attractive therapeutic source for acute liver injury because of their high accessibility and non-invasiveness. Here, we investigated the therapeutic potentials of porcine ADMSCs for acute liver failure (ALF). The morphology, differentiation potential, expression patterns of cell surface markers and liver-specific genes were compared between the ADMSCs derived from the pigs with or without ALF. For therapeutic studies, the expanded porcine ADMSCs from either ALF pig (ALF-ADMSCs) or healthy control pig (Nor-ADMSCs) of passage 3 were transplanted into CCl₄-induced ALF mice, and the liver histology and functional tests were performed at days 1, 7, 14, and 21 after cell transplantation. ALF-ADMSCs expressed higher mRNA level of hepatic growth factor (HGF) than the Nor-ADMSCs. Both ALF-ADMSCs and Nor-ADMSCs improved liver histology, functions, and mouse survival rate. Higher level of porcine hepatocyte-specific genes was seen in the livers of ALF-ADMSCs transplanted mice as compared to the Nor-ADMSCs transplanted mice. In particular, ALF-ADMSCs transplanted mice expressed significantly higher level of albumin and cytokeratin 18 in the liver tissues as compared to the Nor-ADMSCs transplanted mice. ALF-ADMSCs might be superior to Nor-ADMSCs in the treatment of ALF as the former possesses stronger hepatic differentiation potential.

Assessment of animal experimental models of toxic liver injury in the context of their potential application as preclinical models for cell therapy

Preclinical animal models allow to study development and progression of several diseases, including liver disorders. These studies, for ethical reasons and medical limits, are impossible to carry out in human patients. At the same time, such experimental models constitute an important source of knowledge on pathomechanisms for drug- and virus-induced hepatotoxicity, both acute and chronic. Carbon tetrachloride, D-Galactosamine, and retrorsine are xenobiotics that can be used in immunocompetent animal models of hepatotoxicity, where chemical-intoxicated livers present histological features representative of human viruses-related infection. A prolonged derangement into liver architecture and functions commonly lead to cirrhosis, eventually resulting in hepatocellular carcinoma. In human, orthotopic liver transplantation commonly resolve most the problems related to cirrhosis. However, the shortage of donors does not allow all the patients in the waiting list to receive an organ on time. A promising alternative treatment for acute and chronic liver disease has been advised in liver cell transplantation, but the limited availability of hepatocytes for clinical approaches, in addition to the immunosuppressant regiment required to sustain cellular long-term engraftment have been encouraging the use of alternative cell sources. A recent effective source of stem cells have been recently identified in the human amnion membrane. Human amnion epithelial cells (hAEC) have been preclinically tested and proven sufficient to rescue immunocompetent rodents lethally intoxicated with drugs. The adoption of therapeutic procedures based on hAEC transplant in immunocompetent recipients affected by liver diseases, as well as patients with immune-related disorders, may constitute a successful new alternative therapy in regenerative medicine.

Strategies to improve the efficiency of mesenchymal stem cell transplantation for reversal of liver fibrosis

End‐stage liver fibrosis frequently progresses to portal vein thrombosis, formation of oesophageal varices, hepatic encephalopathy, ascites, hepatocellular carcinoma and liver failure. Mesenchymal stem cells (MSCs), when transplanted in vivo, migrate into fibrogenic livers and then differentiate into hepatocyte‐like cells or fuse with hepatocytes to protect liver function. Moreover, they can produce various growth factors and cytokines with anti‐inflammatory effects to reverse the fibrotic state of the liver. In addition, only a small number of MSCs migrate to the injured tissue after cell transplantation; consequently, multiple studies have investigated effective strategies to improve the survival rate and activity of MSCs for the treatment of liver fibrosis. In this review, we intend to arrange and analyse the current evidence related to MSC transplantation in liver fibrosis, to summarize the detailed mechanisms of MSC transplantation for the reversal of liver fibrosis and to discuss new strategies for this treatment. Finally, and most importantly, we will identify the current problems with MSC‐based therapies to repair liver fibrosis that must be addressed in order to develop safer and more effective routes for MSC transplantation. In this way, it will soon be possible to significantly improve the therapeutic effects of MSC transplantation for liver regeneration, as well as enhance the quality of life and prolong the survival time of patients with liver fibrosis.

The potential theragnostic (diagnostic+therapeutic) application of exosomes in diverse biomedical fields

Exosomes are membranous vesicles of 30-150 nm in diameter that are derived from the exocytosis of the intraluminal vesicles of many cell types including immune cells, stem cells, cardiovascular cells and tumor cells. Exosomes participate in intercellular communication by delivering their contents to recipient cells, with or without direct contact between cells, and thereby influence physiological and pathological processes. They are present in various body fluids and contain proteins, nucleic acids, lipids, and microRNAs that can be transported to surrounding cells. Theragnosis is a concept in next-generation medicine that simultaneously combines accurate diagnostics with therapeutic effects. Molecular components in exosomes have been found to be related to certain diseases and treatment responses, indicating that they may have applications in diagnosis via molecular imaging and biomarker detection. In addition, recent studies have reported that exosomes have immunotherapeutic applications or can act as a drug delivery system for targeted therapies with drugs and biomolecules. In this review, we describe the formation, structure, and physiological roles of exosomes. We also discuss their roles in the pathogenesis and progression of diseases including neurodegenerative diseases, cardiovascular diseases, and cancer. The potential applications of exosomes for theragnostic purposes in various diseases are also discussed. This review summarizes the current knowledge about the physiological and pathological roles of exosomes as well as their diagnostic and therapeutic uses, including emerging exosome-based therapies that could not be applied until now.

High regenerative capacity of the liver and irreversible injury of male reproductive system in carbon tetrachloride-induced liver fibrosis rat model

BACKGROUND

Liver fibrosis (LF) is a chronic disease, associated with many collateral diseases including reproductive dysfunction. Although the normal liver has a large regenerative capacity the complications of LF could be severe and irreversible. Hormone and sex-related issues of LF development and interactions with male reproductive have not been finally studied. The aim was to study the reproductive function of male rats in experimental CCl4-induced liver fibrosis rat model, and the capability for restoration of both the liver and male reproduction system.

MATERIALS

Studies were conducted on 20 3-month old Wistar male rats. The experimental animals were injected with freshly prepared 50% olive oil solution of carbohydrate tetrachloride (CCl4). On the 8th week after injection we noted the manifestations of liver fibrosis. The rats were left to self-healing of the liver for 8 weeks. All male rats underwent ultrasound and biopsy of the liver and testes on the 8th and 16th weeks. The male rats were mated with healthy females before CCl4 injection, after modeling LF on the 8th week, and after self-healing of the liver. Pregnancy was monitored on ultrasound.

RESULTS

On the 8th week of experiment we observed ultrasound manifestation of advanced liver fibrosis, including hepatosplenomegaly, portal hypertension. Ultrasound exam of the rat testes showed testicular degeneration, hydrocele, fibrosis, scarring, petrifications, size reduction, and restriction of testicular descent; testes size decreased from 1.24 ± 0.62 ml to 0.61 ± 0.13, p < 0.01. Liver histology showed granular dystrophy of hepatocytes, necrotic areas, lipid inclusions in parenchyma. Rats with liver fibrosis demonstrated severe injury of the reproductive system and altering of fertility: the offspring of male rats with advanced LF was 4.71 ± 0.53 born alive vs 9.55 ± 0.47 born from mating with healthy males, p < 0.001. Eight weeks after last CCl4 injection, we revealed signs of liver regeneration, significant recovery of its structure. The ALT and AST levels significantly decreased and reached background measurements. As a result of the second interbreeding after liver self-healing no significant difference was found vs previous mating.

CONCLUSION

Carbohydrate tetrachloride induces injury of liver parenchyma evoking fast and severe liver fibrosis, and is associated with irreversible structural and functional changes in testes, reducing fertility, decreasing potential pregnancy rate, and affecting its development. Liver showed high potential to regenerate, however the self-restoring after liver fibrosis was not accompanied with recovery of the reproductive system.

Membrane complement regulatory protein reduces the damage of transplanting autologous bone marrow mesenchymal stem cells by suppressing the activation of complement

There are few studies on the interaction of transplanting autologous bone marrow mesenchymal stem cells (BMSCs) and complement. In order to further explore the effect of complement on BMSCs, BMSCs were obtained from bone marrow of 20 cases clinical patients, and then experimented in vitro. The cytotoxicity of complement on the mesenchymal stem cells in autologous human serum (AHS) was measured by Europium cytotoxicity assay. The complement membrane attack complex (MAC) deposited on the membrane surface was detected by flow cytometry. Finally, the cytotoxicity on BMSCs was measured after mCRPs overexpression or knockdown. We found that more than 90% of cells derived from bone marrow were identified to be mesenchymal stem cells through detection of cell membrane surface markers by flow cytometry. BMSCs harvested from the 20 patients all had cytotoxicity after incubated with AHS, and the cytotoxicity was significant higher than that incubated with complement inactivated autologous human serum (iAHS). Complement attack complex (MAC) could be detected on the BMSCs incubated with AHS, which implied the complement activation. We also found that mCRPs CD55 and CD59 overexpressions can resist the cytotoxicity induced by complement activation, while mCRPs CD55 and CD59 knockdown can enhance the cytotoxicity. Thus, the results indicated that mCRPs could effectively protect BMSCs from attacking by complement by suppressing the activation of complement.

Portal vein ligation alters coding and noncoding gene expression in rat livers

Portal vein occlusion increases the resectability of initially unresectable liver cancer by inducing hypertrophy in non-occluded liver lobes. However, the mechanisms of how portal vein occlusion induces hepatic hypertrophy remain unclear. A cDNA microarray was used to identify the gene expression signatures of ligated (LLLs) and nonligated liver lobes (NLLLs) at different time points after portal vein ligation (PVL). The results of a bioinformatics analysis revealed that LLLs and NLLLs displayed different gene expression profiles. Moreover, the expression levels of both coding and noncoding RNA were different between LLLs and NLLLs at different time points after PVL. A series test of cluster analysis revealed that the No. 22 and No. 5 expression patterns, which showed altered expression at 24 h and maintained this altered expression over the following 14 days, had the lowest P values and the highest number of differentially expressed genes in both the LLLs and NLLLs. The results of a GO analysis showed the activation of hypoxia pathways in LLLs and the activation of cell proliferation and cell-cycle pathways in NLLLs, suggesting the involvement of these pathways in PVL-induced hepatic hypertrophy and regeneration. These results provide insight into the molecular mechanisms underlying hepatic hypertrophy and regeneration induced by portal vein occlusion, and they identify potential targeting pathways that can promote the clinical application of PVL in liver cancer therapy.

Biological effects of bone marrow mesenchymal stem cells on hepatitis B virus in vitro

The aim of the present study was to explore the effects of co‑culturing bone marrow‑derived mesenchymal stem cells (BM-MSCs) cultured with hepatitis B virus (HBV)‑infected lymphocytes in vitro. BM‑MSCs and lymphocytes from Brown Norway rats were obtained from the bone marrow and spleen, respectively. Rats were divided into the following five experimental groups: Group 1, splenic lymphocytes (SLCs); group 2, HepG2.2.15 cells; group 3, BM‑MSCs + HepG2.2.15 cells; group 4, SLCs + HepG2.2.15 cells; and group 5, SLCs + BM‑MSCs + HepG2.2.15 cells. The viability of lymphocytes and HepG2.2.15 cells was assessed using the MTT assay at 24, 48 and 72 h, respectively. Levels of supernatant HBV DNA and intracellular HBV covalently closed circular DNA (cccDNA) were measured using quantitative polymerase chain reaction. Supernatant cytokine levels were measured by enzyme‑linked immunosorbent assay (ELISA). T cell subsets were quantified by flow cytometry using fluorescence‑labeled antibodies. In addition, the HBV genome sequence was analyzed by direct gene sequencing. Levels of HBV DNA and cccDNA in group 5 were lower when compared with those in group 3 or group 4, with a significant difference observed at 48 h. The secretion of interferon‑γ was negatively correlated with the level of HBV DNA, whereas secretion of interleukin (IL)‑10 and IL‑22 were positively correlated with the level of HBV DNA. Flow cytometry demonstrated that the percentage of CD3+CD8+ T cells was positively correlated with the levels of HBV DNA, and the CD3+CD4+/CD3+CD8+ ratio was negatively correlated with the level of HBV DNA. Almost no mutations in the HBV DNA sequence were detected in HepG2.2.15 cells co‑cultured with BM‑MSCs, SLCs, or in the two types of cells combined. BM‑MSCs inhibited the expression of HBV DNA and enhanced the clearance of HBV, which may have been mediated by the regulation of the Tc1/Tc2 cell balance and the mode of cytokine secretion to modulate cytokine expression.

Nanofiber-expanded stem cells mitigate liver fibrosis: Experimental study

OBJECTIVES

This study examines a pretreatment strategy to strengthen the hepatic lineage divergence of mesenchymal stem cells (MSCs).

DESIGN AND METHODS

BMSCs were expanded in the presence or absence of nanofiber (NF) and treated with growth factors (GF) prior to transplantation. Thioacetamide (TA) was used for liver fibrosis induction and transplantation of NF-expanded BMSCs was compared biochemically and histologically to the cells expanded without NF scaffold.

RESULTS

The ultraweb NF caused better proliferation and characterization of MSCs. MSCs transplantation significantly improved liver functions, increased hepatic HGF and Bcl-2 levels, whereas decreased serum fibronectin, hepatic TNF-α and TGF-β1 levels. Hepatic HNF4α, FOXa2, CYP7a1 genes expression were enhanced while β-5-Tub and AFP genes expression were depressed. Histological study documented these results. Differentiated NF-MSCs showed pronounced enhancement of the aforementioned parameters as compared to differentiated MSCs in the absence of NF.

CONCLUSION

pretreatment with growth factors in the presence of NF augment homing, repopulation and hepatic differentiation abilities of MSCs and proves to be a promising approach for the treatment of liver fibrosis.

Mesenchymal Stem/Stromal Cells in Liver Fibrosis: Recent Findings, Old/New Caveats and Future Perspectives

Mesenchymal stem/stromal cells (MSCs) are progenitors which share plastic-adherence capacity and cell surface markers but have different properties according to their cell and tissue sources and to culture conditions applied. Many recent publications suggest that MSCs can differentiate into hepatic-like cells, which can be a consequence of either a positive selection of rare in vivo pluripotent cells or of the original plasticity of some cells contributing to MSC cultures. A possible role of MSCs in hereditary transmission of obesity and/or diabetes as well as properties of MSCs regarding immunomodulation, cell fusion and exosome release capacities are discussed according to recent literature. Limitations in methods used to track MSCs in vivo especially in the context of liver cirrhosis are addressed as well as strategies explored to enhance their migratory, survival and proliferation properties, which are known to be relevant for their future clinical use. Current knowledge regarding mechanisms involved in liver cirrhosis amelioration mediated by naïve and genetically modified MSCs as well as the effects of applying preconditioning and combined strategies to improve their therapeutic effects are evaluated. Finally, first reports of GMP guidelines and biosafety issues in MSCs applications are discussed.

Enhanced renoprotective effect of IGF-1 modified human umbilical cord-derived mesenchymal stem cells on gentamicin-induced acute kidney injury

The therapeutic action of umbilical cord-derived mesenchymal stem cells (UC-MSCs) against acute kidney injury (AKI) has been demonstrated by several groups. However, how to further enhance the renoprotective effect of UC-MSCs and improve the therapy effect, are still unclear. In this study, we mainly investigated whether insulin-like growth factor-1 (IGF-1)-modified UC-MSCs hold an enhanced protective effect on gentamicin-induced AKI in vivo. Our results indicated that the IGF-1 overexpression could enhance the therapeutic action of human UC-MSCs, and the AKI rats treated with IGF-1-overexpressed UC-MSCs (UC-MSCs-IGF-1) showed better recovery of biochemical variables in serum or urine associated with renal function, histological injury and renal apoptosis, compared with AKI rats treated with normal UC-MSCs. RNA microarray analysis indicated that some key genes in the signal pathways associated with anti-oxidation, anti-inflammatory, and cell migratory capacity were up-regulated in UC-MSCs-IGF-1, and the results were further confirmed with qPCR. Furthermore, a series of detection in vitro and in vivo indicated that the UC-MSCs-IGF-1 hold better anti-oxidation, anti-inflammatory, and cell migratory capacity for IGF-1 overexpression. Thus, our study indicated that enhancement of UC-MSCs bioactivities with IGF-1 overexpression could increase the UC-MSCs therapeutic potential and further developed a new therapeutic strategy for the treatment of AKI.

Superior performance of co-cultured mesenchymal stem cells and hepatocytes in poly(lactic acid-glycolic acid) scaffolds for the treatment of acute liver failure

Recently, cell-based therapies have attracted attention as promising treatments for acute liver failure (ALF). Bone marrow-derived mesenchymal stem cells (MSCs) are potential candidates for co-culture with hepatocytes in poly(lactic acid-glycolic acid) (PLGA) scaffolds to support hepatocellular function. However, the mechanism of culturing protocol using PLGA scaffolds for MSC differentiation into hepatocyte-like cells as well as the therapeutic effect of cell seeded PLGA scaffolds on ALF remain unsatisfactory in clinical application. Here, MSCs and hepatocytes were co-cultured at ratios of 1:2.5 (MSCs: Hep), 1:5 and 1:10, respectively. The proliferation abilities of these co-cultured cells were detected by CCK8, MTT, EdU and by scanning electron microscopy (SEM), and the ability of MSCs to differentiate into hepatocytes was detected by PCR, western blot and immunofluorescence staining. Therapeutic trials of cell seeded PLGA scaffolds were conducted through mouse abdominal cavity transplantation. Results showed that the 1:5 group showed significantly higher cellular proliferation than the 1:2.5 and 1:10 groups, supernatant albumin and urea nitrogen levels were also significantly higher in the 1:5 group than in other two groups. Similarly, the 1:5 group demonstrated better DNA transcription and liver-specific protein (albumin, CK18 and P450) production. Meanwhile, the GalN-stimulated levels of ALT, AST and TBil in mouse serum were down-regulated significantly more by (MSC  +  Hep)-PLGA scaffold treatment than MSC-PLGA or Hep-PLGA scaffold treatments. Furthermore, the (MSC  +  Hep)-PLGA scaffold-treated ALF mice showed a lower immunogenic response level than the other two groups. These data suggested that the ratio of 1:5 (MSC:Hep) co-cultures was the optimal ratio for MSCs to support hepatocellular metabolism and function in PLGA scaffolds in vitro, the (MSC  +  Hep)-PLGA scaffold treatment could perform better restoration for damaged liver function and could give ALF mice a greater survival rate than the monocell seeded PLGA scaffold treatment.

Autologous adipose tissue‑derived mesenchymal stem cells are involved in rat liver regeneration following repeat partial hepatectomy

Adipose tissue-derived mesenchymal stem cells (ADSCs) have been considered to be attractive and readily available adult mesenchymal stem cells, and they are becoming increasingly popular for use in regenerative cell therapy, as they are readily accessible through minimally invasive techniques. The present study investigated whether autologous ADSC transplantation promoted liver regeneration following a repeat partial hepatectomy in rats. The rats were divided into three groups as follows: 70% partial hepatectomy (PH) group; repeat PH (R-PH) group and R-PH/ADSC group, subjected to R-PH and treated with autologous ADSCs via portal vein injection. In each group, the rats were sacrificed at different time points postoperatively in order to evaluate the changes in liver function and to estimate the liver regenerative response. The expression of proliferating cell nuclear antigen (PCNA) labeling index in the liver was measured using immunohistochemistry. The expression levels of hepatocyte growth factor (HGF) mRNA were measured using reverse transcription polymerase chain reaction. The results showed that regeneration of the remaining liver following R-PH was significantly promoted by ADSC transplantation, as shown by a significant increase in liver to body weight ratio and the PCNA labeling index at 24 h post-hepatectomy. Additionally, ADSC transplantation markedly inhibited the elevation of serum levels of alanine aminotransferase, aspartate aminotransferase and total bilirubin, increased HGF content and also attenuated hepatic vacuolar degeneration 24 h postoperatively. Furthermore, the liver was found to almost fully recover from hepatocellular damage due to hepatectomy among the three groups at 168 h postoperatively. These results indicated that autologous ADSC transplantation enhanced the regenerative capacity of the remnant liver tissues in the early phase following R-PH.

HGF gene modified bone marrow mesenchymal stem cells for treatment of hepatic fibrosis

Hepatic fibrosis is a reversible pathological change caused by liver cell inflammation, necrosis, or abnormal hyperplasia of connective tissue. It has been proved that hepatocyte growth factor (HGF) gene modified bone marrow mesenchymal stem cells can reduce or inhibit liver fibrosis, with better effects than those of unmodified bone marrow mesenchymal stem cells. Thus, HGF gene modified bone marrow mesenchymal stem cells represent a promising method for anti-hepatic fibrosis.

Stem cell-based regenerative opportunities for the liver: State of the art and beyond

The existing mismatch between the great demand for liver transplants and the number of available donor organs highlights the urgent need for alternative therapeutic strategies in patients with acute or chronic liver failure. The rapidly growing knowledge on stem cell biology and the intrinsic repair processes of the liver has opened new avenues for using stem cells as a cell therapy platform in regenerative medicine for hepatic diseases. An impressive number of cell types have been investigated as sources of liver regeneration: adult and fetal liver hepatocytes, intrahepatic stem cell populations, annex stem cells, adult bone marrow-derived hematopoietic stem cells, endothelial progenitor cells, mesenchymal stromal cells, embryonic stem cells, and induced pluripotent stem cells. All these highly different cell types, used either as cell suspensions or, in combination with biomaterials as implantable liver tissue constructs, have generated great promise for liver regeneration. However, fundamental questions still need to be addressed and critical hurdles to be overcome before liver cell therapy emerges. In this review, we summarize the state-of-the-art in the field of stem cell-based therapies for the liver along with existing challenges and future perspectives towards a successful liver cell therapy that will ultimately deliver its demanding goals.

Autologous bone marrow stem cell transplantation in patients with liver failure: a meta-analytic review

Autologous bone marrow stem cell (ABMSC) transplantation has been utilized in clinical practice to treat patients with liver failure, but the therapeutic effect remains to be defined. A meta-analysis is essential to assess clinical advantages of ABMSC transplantation in patients with liver failure. A systematic search of published works [eg, PubMed, Medline, Embase, Chin J Clinicians (Electronic edition), and Science Citation Index] was conducted to compare clinical outcomes of ABMSC transplantation in patients with liver failure. Meta-analytic results were tested by fixed-effects model or random-effects model, dependent on the characteristics of variables. A total of 534 patients from seven studies were included in final meta-analysis. Subsequent to ABMSC transplantation, there was no significant improvement in general symptom and signs such as loss of appetite, fatigue, and ascites. Activities of serum ALT were not significantly decreased with weighted mean difference (WMD) of -19.36 and 95% confidence interval (CI) -57.53 to 18.80 (P=0.32). Postoperative level of albumin (ALB) was expectedly enhanced by stem cell transplantation (WMD 2.97, 95% CI 0.52 to 5.43, P<0.05, I(2)=84%). Coagulation function was improved as demonstrated by a short prothrombin time (PT) (WMD -1.18, 95% CI -2.32 to -0.03, P<0.05, I(2)=6%), but was not reflected by prothrombin activity (PTA) (P=0.39). Total bilirubin (TBIL) was drastically diminished after ABMSC therapy (WMD -14.85, 95% CI -20.39 to -9.32, P<0.01, I(2)=73%). Model for end-stage liver disease (MELD) scores were dramatically reduced (WMD -2.27, 95% CI -3.53 to -1.02, P<0.01, I(2)=0%). The advantage of ABMSC transplantation could be maintained more than 24 weeks as displayed by time-courses of ALB, TBIL, and MELD score. ABMSC transplantation does provide beneficial effects for patients with liver failure. Therapeutic effects can last for 6 months. However, long-term effects need to be determined.

Predicting early intrahepatic recurrence after curative resection of colorectal liver metastases with molecular markers

BACKGROUND

The aim of this case-control study was to identify clinicopathological factors and test three relevant biomarkers for their ability to predict early intrahepatic recurrence after curative liver resection for colorectal liver metastases (CLM).

METHODS

Of the 184 patients with CLM undergoing hepatectomy between January 2007 and December 2009, thirty patients had intrahepatic disease recurrence within 6 months. The control group was randomly selected from a cohort of patients between April 1997 and December 2005 who have survived without disease recurrence after CLM resection for over 5 years. Both groups were matched for size of metastasis greater than 5.0 cm, the presence of multiple metastases, and synchronous versus metachronous CLM. The final study population consisted of 60 patients with CLM undergoing R0 hepatectomy, 30 of whom had early intrahepatic-only recurrences (study group) and 30 patients without recurrence for more than 5 years (control group). Both groups were analyzed and compared for the presence of clinical factors and expression levels of CD133, survivin, and Bcl-2 within tumor tissue.

RESULTS

Characteristics of patients were similar between the two groups except primary tumor location and administration of postoperative chemotherapy. Expression level of CD133 and survivin were significantly increased in tumors of patients with recurrence compared to patients without recurrence. On multivariate analysis high tumor expression levels of CD133 (odds ratio [OR] 14.7, confidence interval [CI] 1.8-121.3, p = 0.012) and survivin (OR 9.5, CI 2.1-44.3, p = 0.004) and postoperative chemotherapy (OR 4.8, CI 1.01-22.9, p = 0.049) were independent factors associated with early intrahepatic recurrence.

CONCLUSIONS

Tumor expression levels of CD133 and survivin may be a useful predictor of early intrahepatic recurrence after hepatectomy for CLM. Administration of postoperative chemotherapy may prevent early intrahepatic recurrence.

In Vitro and In Vivo Hepatic Differentiation of Adult Somatic Stem Cells and Extraembryonic Stem Cells for Treating End Stage Liver Diseases

The shortage of liver donors is a major handicap that prevents most patients from receiving liver transplantation and places them on a waiting list for donated liver tissue. Then, primary hepatocyte transplantation and bioartificial livers have emerged as two alternative treatments for these often fatal diseases. However, another problem has emerged. Functional hepatocytes for liver regeneration are in short supply, and they will dedifferentiate immediately in vitro after they are isolated from liver tissue. Alternative stem-cell-based therapeutic strategies, including hepatic stem cells (HSCs), embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and mesenchymal stem cells (MSCs), are more promising, and more attention has been devoted to these approaches because of the high potency and proliferation ability of the cells. This review will focus on the general characteristics and the progress in hepatic differentiation of adult somatic stem cells and extraembryonic stem cells in vitro and in vivo for the treatment of end stage liver diseases. The hepatic differentiation of stem cells would offer an ideal and promising source for cell therapy and tissue engineering for treating liver diseases.

Therapeutic effect of human umbilical cord mesenchymal stem cell transplantation via peripheral vein on decompensated cirrhosis

AIM: To assess the efficacy and safety of human umbilical cord mesenchymal stem cell transplantation via peripheral vein in the treatment of different degrees of decompensated cirrhosis.

METHODS: Twenty patients with different degrees of hepatitis B virus related cirrhosis were enrolled, including 6 with Child-Pugh A disease, 8 with Child-Pugh B and 6 with Child-Pugh C. On the basis of routine treatment, these patients were given intravenous infusion of human umbilical cord mesenchymal stem cells via peripheral vein (stem cell group). Another 20 patients with hepatitis B virus related cirrhosis comprised a control group and were given routine treatment, including 5 with Child-Pugh A disease, 9 with Child-Pugh B and 6 with Child-Pugh C. The changes of liver function and coagulation function were detected before transplantation and 2, 4, 12 and 24 wk after transplantation. Clinical symptoms and side effects were also observed after stem cell treatment.

RESULTS: For patients with Child-Pugh A or B disease, the levels of albumin (ALB) and cholinesterase (CHE) in the stem cell group at 12 and 24 wk were significantly increased compared with those before treatment or in the control group after treatment (P < 0.05); the value of prothrombin activity (PTA) was increased from 62% ± 15% pre-therapy to 80% ± 17% at 24 wk post-therapy in the stem cell group; the levels of PTA in the stem cell group were significantly increased compared with the control group at 4, 12, and 24 wk after treatment (P < 0.01); the levels of PTA in the stem cell group at 4, 12, and 24 wk after treatment were significantly increased than that before treatment (P < 0.01); there were no significant differences in levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), or total bilirubin (TBIL) between the stem cell group and control group (P > 0.05). For patients with Child-Pugh C disease, there were no significant differences in levels of ALT, AST, TBIL, ALB, CHE or PTA between two groups or pre-therapy and post-therapy with stem cells. The clinical symptoms in the stem cell group were improved obviously compared with those in the control group in patients with Child-Pugh A or B disease (P < 0.05), although there were no significant differences between the stem cell group and control group in patients with Child-Pugh C disease (P > 0.05). No related complications or adverse effects were observed in these patients.

CONCLUSION: Human umbilical cord mesenchymal stem cell transplantation via peripheral vein in the treatment of decompensated cirrhosis is safe and effective, and the curative effect in patients with Child-Pugh A or B disease is much remarkable than those with Child-Pugh C.

Expression of cancer stem cell biomarkers as a tool for a correct therapeutic approach to hepatocellular carcinoma

Liver cancer is the fifth most commonly diagnosed malignancy and the second most frequent cause of cancer death in men worldwide. Amongst liver cancers, hepatocellular carcinoma (HCC) represents the major histological subtype and it is one of the most common malignant human tumors worldwide. Research into the molecular biology of hepatocarcinogenesis has identified several biomarkers, which could provide additional informations in order to better understand the biology of HCC. A large number of biomarkers have been shown to have potential predictive significance and a wide variety of molecular markers have been proven to be excellent diagnostic tools for HCC but it is difficult to characterize HCC with a single biomarker. Thus, signatures of a combination of biomarkers may be more valuable for the diagnosis, staging and prognosis of HCC. Specifically, a correlation of HCC-CSCs phenotype to specific hepatic cancer subtypes and to specific clinical and pathological features has not yet been reported in human liver tumors. In this view we will first discuss the possible sources of liver stem cells and their relation with liver cancer development and we will secondly focus on the prognostic significance of clinical and pathological features of HCC.

New Tools in Experimental Cellular Therapy for the Treatment of Liver Diseases

The current standard of care for end stage liver disease is orthotopic liver transplantation (OLT). Through improvement in surgical techniques, immunosuppression, and general medical care, liver transplantation has become an effective treatment over the course of the last half-century. Unfortunately, due to the limited availability of donor organs, there is a finite limit to the number of patients who will benefit from this therapy. This review will discuss current research in experimental cellular therapies for acute, chronic, and metabolic liver failure that may be appropriate when liver transplantation is not an immediate option.

Transplantation of autologous mesenchymal stem cells for end-stage liver cirrhosis: a meta-analysis based on seven controlled trials

Background. The bone marrow-derived mesenchymal stem cells (BM-MSCs) have demonstrated great potential as regenerative medicine in different therapeutic applications. This study aims to pool previous controlled clinical trials to make an update assessment of the effectiveness of BM-MSC transplantation on end-stage liver cirrhosis. Methods. Relevant studies published between January 1990 and June 2014 were searched among Pubmed, Embase, and ClinicalTrial.gov. A meta-analysis was performed to assess the effect of BM-MSCs on liver function indicators, including Models of End-Stage Liver Disease (MELD) score, serum albumin (g/L), total bilirubin (mg/dl), Prothrombin concentration (%), and alanine aminotransferase (ALT) (U/L). Results. BM-MSCs therapy could significantly improve liver function in patients with end-stage liver cirrhosis, in terms of MELD score, serum albumin, total bilirubin, and prothrombin concentration, at least during the half year after transplantation. Conclusions. Due to BM-MSCs' immunomodulatory functions and the potential to differentiate into hepatocytes, they are a promising therapeutic agent to liver cirrhosis. Considering currently available evidence, this therapy is relatively safe and effective in improving liver function. However, how different variables should be controlled to optimize the therapeutic effect is still not clear. Thus, future mechanism studies and clinical trials are required for this optimization.

Effects of bone marrow-derived mesenchymal stem cells transplanted via the portal vein or tail vein on liver injury in rats with liver cirrhosis

The aim of the present study was to compare the effects of bone marrow-derived mesenchymal stem cells (BMSCs) transplanted via the portal vein or tail vein on liver injury in rats with liver cirrhosis. BMSCs were isolated from rat bone marrow and labeled with green fluorescent protein (GFP). Then, the labeled BMSCs were injected into rats with liver injury via the portal vein or tail vein. Two weeks after transplantation, three rats in each group were sacrificed to test the distribution of GFP in the liver and the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and albumin. Six weeks later, the remaining rats were sacrificed, and serum ALT, AST, albumin, hyaluronic acid (HA), laminin (LN) and procollagen type III (PC-III) levels were measured. The expression of albumin in the liver was analyzed by immunohistochemistry. Two weeks after BMSC transplantation, GFP-positive cells were detected in the livers of rats with BMSCs transplanted via the portal vein and tail vein. Compared with pre-transplantation levels, the ALT levels of the groups with BMSC transplantation via the portal vein and tail vein were significantly decreased after two and six weeks of BMSC transplantation (P<0.05), whereas the AST and albumin levels were not significantly different at two weeks after BMSC transplantation in the two groups (all P>0.05). However, the AST and albumin levels were significantly reduced at six weeks after BMSC transplantation (all P<0.05). At six weeks after BMSC transplantation, the serum HA, LN and PC-III levels in rats transplanted with BMSCs via the portal vein or tail vein had decreased significantly (all P<0.05), as compared with the levels prior to BMSC transplantation. BMSCs transplanted via the portal vein and tail vein achieved similar improvements in liver function in rats with liver cirrhosis, which suggests that peripheral venous administration is a convenient and effective route for BMSC transplantation.

Therapeutic action of bone marrow-derived stem cells against acute kidney injury

Acute kidney injury (AKI) is a frequent clinical disease with a high morbidity rate and mortality rate, while the treatment options for this intractable disease are limited currently. In recent years, bone marrow-derived mesenchymal stem cells (BMSCs) have been demonstrated to hold an effect therapeutic action against AKI by scientists gradually, and the cells are capable to localize to renal compartments and contribute to kidney regeneration though differentiation or paracrine action. Especially, the advantages of BMSCs, such as low toxicity and side effect as well as autologous transplantation, endue the cell with a promising potential in clinical therapy against AKI. In this review, we mainly provide a concise overview of the application of BMSCs in the treatment of AKI, and summarize a series of published data regarding the mechanisms and optimizations of the BMSC-based therapy in renal repair after AKI. Even though some critical points about the BMSC-based therapy model still need clarification, we hope to develop more reliable pharmacological or biotechnical strategies utilizing the stem cell for the eventual treatment of humans with AKI, based on these studies and the understanding of mechanism of renal protection by BMSCs.

Administration of BMSCs with muscone in rats with gentamicin-induced AKI improves their therapeutic efficacy

The therapeutic action of bone marrow-derived mesenchymal stem cells (BMSCs) in acute kidney injury (AKI) has been reported by several groups. However, recent studies indicated that BMSCs homed to kidney tissues at very low levels after transplantation. The lack of specific homing of exogenously infused cells limited the effective implementation of BMSC-based therapies. In this study, we provided evidence that the administration of BMSCs combined with muscone in rats with gentamicin-induced AKI intravenously, was a feasible strategy to drive BMSCs to damaged tissues and improve the BMSC-based therapeutic effect. The effect of muscone on BMSC bioactivity was analyzed in vitro and in vivo. The results indicated that muscone could promote BMSC migration and proliferation. Some secretory capacity of BMSC still could be improved in some degree. The BMSC-based therapeutic action was ameliorated by promoting the recovery of biochemical variables in urine or blood, as well as the inhibition of cell apoptosis and inflammation. In addition, the up-regulation of CXCR4 and CXCR7 expression in BMSCs could be the possible mechanism of muscone amelioration. Thus, our study indicated that enhancement of BMSCs bioactivities with muscone could increase the BMSC therapeutic potential and further developed a new therapeutic strategy for the treatment of AKI.

Mechanisms of liver repair following injury

Liver injury caused by a variety of physical or chemical factors is a common disease, and severe or persistent liver injury can ultimately lead to acute liver failure. Its treatment is still a formidable challenge to clinicians. Elucidation of mechanisms underlying liver repair following injury is the cornerstone of treatment of hepatic diseases. Despite many research efforts over the past decades, the mechanisms behind liver repair following injury are still not clear. Recent studies have demonstrated that oval cells and bone marrow stem cells are involved in this complex process. A variety of cells and factors may play a role in different stages of this process. In this paper, we will review mechanisms of liver repair following injury.