Implications of the immunoregulatory functions of mesenchymal stem cells in the treatment of human liver diseases. Cell Mol Immunol. 2011;8:19-22. [PMID: 21200380 DOI: 10.1038/cmi.2010.57]

Multiple Dimensions of using Mesenchymal Stem Cells for Treating Liver Diseases: From Bench to Beside

Liver diseases impose a huge burden worldwide. Although hepatocyte transplantation has long been considered as a potential strategy for treating liver diseases, its clinical implementation has created some obvious limitations. As an alternative strategy, cell therapy, particularly mesenchymal stem cell (MSC) transplantation, is widely used in treating different liver diseases, including acute liver disease, acute-on-chronic liver failure, hepatitis B/C virus, autoimmune hepatitis, nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, alcoholic liver disease, liver fibrosis, liver cirrhosis, and hepatocellular carcinoma. Here, we summarize the status of MSC transplantation in treating liver diseases, focusing on the therapeutic mechanisms, including differentiation into hepatocyte-like cells, immunomodulating function with a variety of immune cells, paracrine effects via the secretion of various cytokines and extracellular vesicles, and facilitation of homing and engraftment. Some improved perspectives and current challenges are also addressed. In summary, MSCs have great potential in the treatment of liver diseases based on their multi-faceted characteristics, and more accurate mechanisms and novel therapeutic strategies stemming from MSCs will facilitate clinical practice.

Mesenchymal stromal/stem cells and their extracellular vesicles in liver diseases: insights on their immunomodulatory roles and clinical applications

Liver disease is a leading cause of mortality and morbidity that is rising globally. Liver dysfunctions are classified into acute and chronic diseases. Various insults, including viral infections, alcohol or drug abuse, and metabolic overload, may cause chronic inflammation and fibrosis, leading to irreversible liver dysfunction. Up to now, liver transplantation could be the last resort for patients with end-stage liver disease. However, liver transplantation still faces unavoidable difficulties. Mesenchymal stromal/stem cells (MSCs) with their broad ranging anti-inflammatory and immunomodulatory properties can be effectively used for treating liver diseases but without the limitation that are associated with liver transplantation. In this review, we summarize and discuss recent advances in the characteristics of MSCs and the potential action mechanisms of MSCs-based cell therapies for liver diseases. We also draw attention to strategies to potentiate the therapeutic properties of MSCs through pre-treatments or gene modifications. Finally, we discuss progress toward clinical application of MSCs or their extracellular vesicles in liver diseases.

Establishing an hTERT-driven immortalized umbilical cord-derived mesenchymal stem cell line and its therapeutic application in mice with liver failure

Acute liver failure (ALF) is characterized by rapid liver cell destruction. It is a multi-etiological and fulminant complication with a clinical mortality of over 80%. Therapy using mesenchymal stem cells (MSCs) or MSCs-derived exosomes can alleviate acute liver injury, which has been demonstrated in animal experiments and clinical application. However, similar to other stem cells, different cell sources, poor stability, cell senescence and other factors limit the clinical application of MSCs. To achieve mass production and quality control on stem cells and their exosomes, transfecting umbilical cord mesenchymal stem cell (UCMSC) with lentivirus overexpressing human telomerase reverse transcriptase (hTERT) gene, the hTERT-UCMSC was constructed as an immortalized MSC cell line. Compared with the primary UCMSC (P3) and immortalized cell line hTERT-UCMSC at early passage (P10), the hTERT-UCMSC retained the key morphological and physiological characteristics of UCMSC at the 35th passage (P35), and showed no signs of carcinogenicity and toxic effect in mice. There was no difference in either exosome production or characteristics of exosomes among cultures from P3 primary cells, P10 and P35 immortalized hTERT-UCMSCs. Inoculation of either hTERT-UCMSC (P35) or its exosomes improved the survival rate and liver function of ALF mice induced by thioacetamide (TAA). Our findings suggest that this immortalized cell line can maintain its characteristics in long-term culture. Inoculation of hTERT-UCMSC and its exosomes could potentially be used in clinics for the treatment of liver failure in the future.

Current Therapeutic Options and Potential of Mesenchymal Stem Cell Therapy for Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a globally prevalent chronic liver disease caused by chronic or binge consumption of alcohol. The therapeutic efficiency of current therapies for ALD is limited, and there is no FDA-approved therapy for ALD at present. Various strategies targeting pathogenic events in the progression of ALD are being investigated in preclinical and clinical trials. Recently, mesenchymal stem cells (MSCs) have emerged as a promising candidate for ALD treatment and have been tested in several clinical trials. MSC-released factors have captured attention, as they have the same therapeutic function as MSCs. Herein, we focus on current therapeutic options, recently proposed strategies, and their limitations in ALD treatment. Also, we review the therapeutic effects of MSCs and those of MSC-related secretory factors on ALD. Although accumulating evidence suggests the therapeutic potential of MSCs and related factors in ALD, the mechanisms underlying their actions in ALD have not been well studied. Further investigations of the detailed mechanisms underlying the therapeutic role of MSCs in ALD are required to expand MSC therapies to clinical applications. This review provides information on current or possible treatments for ALD and contributes to our understanding of the development of effective and safe treatments for ALD.

Prednisolone and mesenchymal stem cell preloading protect liver cell migration and mitigate extracellular matrix modification in transplanted decellularized rat liver

INTRODUCTION

Regenerative medicine provides promising approaches for treating chronic liver diseases. Previous studies indicate that decellularized liver architecture is damaged by invading non-hepatic inflammatory cells. This study aimed to use anti-inflammatory and regenerative potency of bone marrow-derived mesenchymal stem cells (BM-MSC) and prednisolone for reducing fibrosis and balancing inflammatory cell migration into the decellularized liver scaffold.

MATERIAL AND METHOD

The liver was decellularized by perfusing Sodium Lauryl Ether Sulfate (SLES), and nuclei depletion and extracellular matrix (ECM) retention were confirmed by DNA quantification, histochemical, and immunohistochemical assessments. Scaffolds were loaded with BM-MSCs, prednisolone, or a combination of both, implanted at the anatomical place in the rat partial hepatectomized and followed up for 2 and 4 weeks.

RESULTS

Labeled-MSCs were traced in the transplanted scaffolds; however, they did not migrate into the intact liver. Immunohistochemistry showed that the hepatoblasts, cholangiocytes, stellate, and oval cells invaded into all the scaffolds. Bile ducts were more abundant in the border of the scaffolds and intact liver. Stereological assessments showed a significant reduction in the number of lymphocytes and neutrophils in prednisolone-loaded scaffolds. The regeneration process and angiogenesis were significantly higher in the group treated with cell/prednisolone-loaded bioscaffolds. Collagen fibers were significantly reduced in the scaffolds pre-treated with cell/prednisolone, prednisolone, or BM-MSCs, compared to the control group.

CONCLUSION

Loading prednisolone into the scaffolds can be a worthy approach to restrict inflammation after transplantation. Although pre-loading of the scaffolds with a combination of cells/prednisolone could not alleviate inflammation, it played an important role in regeneration and angiogenesis.

Role of the Microenvironment in Mesenchymal Stem Cell-Based Strategies for Treating Human Liver Diseases

Liver disease is a severe health problem that endangers human health worldwide. Mesenchymal stem cell (MSC) therapy is a novel treatment for patients with different liver diseases due to its vast expansion potential and distinctive immunomodulatory properties. Despite several preclinical trials having confirmed the considerable efficacy of MSC therapy in liver diseases, the questionable safety and efficacy still limit its application. As a precursor cell, MSCs can adjust their characteristics in response to the surrounding microenvironment. The microenvironment provides physical and chemical factors essential for stem cell survival, proliferation, and differentiation. However, the mechanisms are still not completely understood. We, therefore, summarized the mechanisms underlying the MSC immune response, especially the interaction between MSCs and the liver microenvironment, discussing how to achieve better therapeutic effects.

The impact of recipient age on the effects of umbilical cord mesenchymal stem cells on HBV-related acute-on-chronic liver failure and liver cirrhosis

Background

The results of a previous study verified that umbilical cord mesenchymal stem cells (UCMSCs) have good therapeutic effects for the treatment of HBV-related acute-on-chronic liver failure (ACLF) and liver cirrhosis (LC). Nevertheless, it is still unknown whether the effects of UCMSCs are affected by recipient age.

Methods

Patients treated with UCMSCs who met the criteria of HBV-related ACLF and liver cirrhosis were identified in this retrospective observational study. Patients were divided into subgroups according to the World Health Organization (WHO) age criteria (< 45 vs. ≥ 45 years). Group A included young ACLF patients (< 45 y), and group B included older ACLF patients (≥ 45 y). Young LC patients (< 45 y) were assigned to group C, and group D included older LC patients (≥ 45 y). Patients’ clinical characteristics, demographics, biochemical factors, and model for end-stage liver disease (MELD) scores were compared for 24 weeks.

Results

Sixty-four ACLF patients and 59 LC patients were enrolled in this study. Compared with patients in groups B and C, patients in group A did not show significant superiority in terms of the levels of ALT, AST, TBIL, AFP, and PTA and MELD scores. However, the median decrease and cumulative decrease in the TBIL and ALT levels of patients in group C were larger than those of patients in group D after four weeks of UCMSC transfusions. For older patients (≥ 45 y), the cumulative decrease and the median decrease in the TBIL of ACLF patients were significantly greater than those of LC patients after UCMSC treatment. However, the median decrease in ALT levels of ACLF patients was significantly greater than that of LC patients during UCMSC treatment, and the cumulative decrease in ALT levels of ACLF patients was significantly greater than that of LC patients at all time points.

Conclusion

The therapeutic effects of UCMSCs for HBV-related acute-on-chronic liver failure and liver cirrhosis varied partly by patient age. Assessing patient age is necessary prior to UCMSC clinical use.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02544-x.

Mesenchymal Stem Cell Therapy Using Human Umbilical Cord in a Rat Model of Autoimmune-Induced Premature Ovarian Failure

Premature ovarian failure (POF) is one of the principal causes of female infertility, and although its causes are complex and diverse, autoimmune deficiency may be involved. Human umbilical cord mesenchymal stem cells (UCMSCs) can be used for tissue regeneration and repair. Therefore, the present study was designed to determine the role of UCMSCs in immune factor-induced POF in rats. In this study, different concentrations of UCMSCs were injected into induced POF rats. Ovarian functions were examined by evaluating the estrus cycle, follicular morphology, hormonal secretion, and the proliferation and apoptosis of granulosa cells. Our results showed that the estrus cycle of rats returned to normal and follicular development was significantly improved after transplantation of UCMSCs. In addition, serum concentrations of 17-estradiol (E2), progesterone (P4), and anti-Müllerian hormone (AMH) increased significantly with treatment. Transplantation of UCMSCs also reduced the apoptosis of granulosa cells and promoted the proliferation of granulosa cells. All of these improvements were dose dependent. Furthermore, the results of related gene expression showed that transplanted human UCMSCs upregulated the expression of Bcl-2, AMH, and FSHR in the ovary of POF rats and downregulated the expression of caspase-3. These results further validated the potential mechanisms of promoting the release of cell growth factors and enhancing tissue regeneration and provide a theoretical basis for the clinical application of stem cells in the treatment of premature ovarian failure.

In vitro efficacy of liver microenvironment in bone marrow mesenchymal stem cell differentiation

Bone marrow-derived mesenchymal stem cells (BM-MSCs) represent an interesting alternative to liver or hepatocyte transplantation to treat liver injuries. Many studies have reported that MSCs can treat several diseases, including liver damage, just by injection into the bloodstream, without evidence of differentiation. The improvements were attributed to the organotrophic factors, low immunogenicity, immunomodulatory, and anti-inflammatory effects of MSCs, rather than their differentiation. The aim of the present study was to answer the question of whether the presence of BM-MSCs in the hepatic microenvironment will lead to their differentiation to functional hepatocyte-like cells. The hepatic microenvironment was mimicked in vitro by culture for 21 d with liver extract. The resulted cells expressed marker genes of the hepatic lineage including AFP, CK18, and Hnf4a. Functionally, they were able to detoxify ammonia into urea, to store glycogen as observed by PAS staining, and to synthesize glucose from pyruvate/lactate mixture. Phenotypically, the expression of MSC surface markers CD90 and CD105 decreased by differentiation. This evidenced differentiation into hepatocyte-like cells was accompanied by a downregulation of the stem cell marker genes sox2 and Nanog and the cell cycle regulatory genes ANAPC2, CDC2, Cyclin A1, and ABL1. The present results suggest a clear differentiation of BM-MSCs into functional hepatocyte-like cells by the extracted liver microenvironment. This differentiation is confirmed by a decrease in the stemness and mitotic activities. Tracking transplanted BM-MSCs and proving their in vivo differentiation remains to be elucidated.

Bone Regeneration, Reconstruction and Use of Osteogenic Cells; from Basic Knowledge, Animal Models to Clinical Trials

The deterioration of the human skeleton's capacity for self-renewal occurs naturally with age. Osteoporosis affects millions worldwide, with current treatments including pharmaceutical agents that target bone formation and/or resorption. Nevertheless, these clinical approaches often result in long-term side effects, with better alternatives being constantly researched. Mesenchymal stem cells (MSCs) derived from bone marrow and adipose tissue are known to hold therapeutic value for the treatment of a variety of bone diseases. The following review summarizes the latest studies and clinical trials related to the use of MSCs, both individually and combined with other methods, in the treatment of a variety of conditions related to skeletal health. For example, some of the most recent works noted the advantage of bone grafts based on biomimetic scaffolds combined with MSC and growth factor delivery, with a greatly increased regeneration rate and minimized side effects for patients. This review also highlights the continuing research into the mechanisms underlying bone homeostasis, including the key transcription factors and signalling pathways responsible for regulating the differentiation of osteoblast lineage. Paracrine factors and specific miRNAs are also believed to play a part in MSC differentiation. Furthering the understanding of the specific mechanisms of cellular signalling in skeletal remodelling is key to incorporating new and effective treatment methods for bone disease.

PD-1/PD-L1 Pathway Mediates the Alleviation of Pulmonary Fibrosis by Human Mesenchymal Stem Cells in Humanized Mice

Pulmonary fibrosis is a chronic progressive lung disease with few treatments. Human mesenchymal stem cells (MSCs) have been shown to be beneficial in pulmonary fibrosis because they have immunomodulatory capacity. However, there is no reliable model to test the therapeutic effect of human MSCs in vivo. To mimic pulmonary fibrosis in humans, we established a novel bleomycin-induced pulmonary fibrosis model in humanized mice. With this model, the benefit of human MSCs in pulmonary fibrosis and the underlying mechanisms were investigated. In addition, the relevant parameters in patients with pulmonary fibrosis were examined. We demonstrate that human CD8⁺ T cells were critical for the induction of pulmonary fibrosis in humanized mice. Human MSCs could alleviate pulmonary fibrosis and improve lung function by suppressing bleomycin-induced human T-cell infiltration and proinflammatory cytokine production in the lungs of humanized mice. Importantly, alleviation of pulmonary fibrosis by human MSCs was mediated by the PD-1/programmed death-ligand 1 pathway. Moreover, abnormal PD-1 expression was found in circulating T cells and lung tissues of patients with pulmonary fibrosis. Our study supports the potential benefit of targeting the PD-1/programmed death-ligand 1 pathway in the treatment of pulmonary fibrosis.

Stem Cell-Related Studies and Stem Cell-Based Therapies in Liver Diseases

Owing to the increasing worldwide burden of liver diseases, the crucial need for safe and effective interventions for treating end-stage liver failure has been a very productive line of inquiry in the discipline of hepatology for many years. Liver transplantation is recognized as the most effective treatment for end-stage liver disease; however, the shortage of donor organs, high medical costs, and lifelong use of immunosuppressive agents represent major drawbacks and demand exploration for alternative treatments. Stem cell-based therapies have been widely studied in the field of liver diseases and are considered to be among the most promising therapies. Herein, we review recent advances in the application of stem cell-related therapies in liver disease with the aim of providing readers with relevant knowledge in this field and inspiration to spur further inquiry.

Human Stem Cells Promote Liver Regeneration After Partial Hepatectomy in BALB/C Nude Mice

BACKGROUND

Mesenchymal stem cells (MSCs) have been suggested to augment liver regeneration after surgically and pharmacologically induced liver failure. To further investigate this we processed human bone marrow-derived MSC according to good manufacturing practice (GMP) and tested those cells for their modulatory capacities of metabolic alterations and liver regeneration after partial hepatectomy in BALB/c nude mice.

METHODS

Human MSCs were obtained by bone marrow aspiration of healthy donors as in a previously described GMP process. Transgenic GFP-MSCs were administered i.p. 24 h after 70% hepatectomy in BALB/c nude mice, whereas control mice received phosphate-buffered saline. Mice were sacrificed 2, 3, and 5 d after partial hepatectomy. Blood and organs were harvested and metabolic alterations as well as liver regeneration subsequently assessed by liver function tests, multianalyte profiling immunoassays, histology, and immunostaining.

RESULTS

Hepatocyte and sinusoidal endothelial cell proliferation were significantly increased after partial hepatectomy in mice receiving MSC compared to control mice (Hepatocyte postoperative day 3, P < 0.01; endothelial cell postoperative day 5, P < 0.05). Hepatocyte fat accumulation correlated inversely with hepatocyte proliferation (r² = 0.4064, P < 0.01) 2 d after partial hepatectomy, with mice receiving MSC being protected from severe fat accumulation. No GFP-positive cells could be detected in the samples. Serum levels of IL-6, HGF, and IL-10 were significantly decreased at day 3 in mice receiving MSC when compared to control mice (P < 0.05). Relative body weight loss was significantly attenuated after partial hepatectomy in mice receiving MSC (2 d and 3 d, both P < 0.001) with a trend toward a faster relative restoration of liver weight, when compared to control mice.

CONCLUSIONS

Human bone marrow-derived MSC attenuate metabolic alterations and improve liver regeneration after partial hepatectomy in BALB/c nude mice. Obtained results using GMP-processed human MSC suggest functional links between fat accumulation and hepatocyte proliferation, without any evidence for cellular homing. This study using GMP-proceeded MSC has important regulatory implications for an urgently needed translation into a clinical trial.

The assessment of multipotent cell transplantation in acute-on-chronic liver failure: a systematic review and meta-analysis

Acute-on-chronic liver failure (ACLF) is a serious life-threatening disease with high prevalence. Liver transplantation is the only efficient clinical treatment for ACLF. Because of the rapid progression and lack of liver donors, it is urgent to find an effective and safe therapeutic approach to ACLF. Recent studies showed that multipotent cell transplantation could improve the patients' liver function and enhance their preoperative condition. Cells such as mesenchymal stem cells, bone marrow mononuclear cells and autologous peripheral blood stem cells, which addressed in this study have all been used in multipotent cell transplantation for liver diseases. However, its clinical efficiency is still debatable. This systematic review and meta-analysis explored the clinical efficiency of multipotent cell transplantation as a therapeutic approach for patients with ACLF. A detailed search of the Cochrane Library, MEDLINE, and Embase databases was conducted from inception to November 2017. The outcome measures were serum albumin, prothrombin time, alanine aminotransferase, total bilirubin, platelets, hemoglobin, white blood cells, and survival time. The quality of evidence was assessed using GRADEpro and Jaded scores. A literature search resulted in 537 citations. Of these, 9 articles met the inclusion criteria. It was found that multipotent cell transplantation was able to alleviate liver damage and improve liver function. Multipotent cell transplantation can also enhance the short-term and medium-term survival rates of ACLF. All 9 research articles included in this analysis reported no statistically significant adverse events, side effects, or complications. In conclusions, this study suggested that multipotent cell transplantation could be recommended as a potential therapeutic supplementary tool in clinical practice. However, clinical trials in large-volume centers still needed.

Three-dimensional hepatocyte culture system for the study of Echinococcus multilocularis larval development

Background

Hepatocyte-based metacestode culture is an attractive method to study alveolar echinococcosis (AE), but it is limited by the relatively short lifespan of cultured hepatocytes in maintaining their normal function.

Methodology/principal findings

We describe a three-dimensional (3D) hepatic culture system developed from co-cultured hepatocytes and mesenchymal stem cells using a collagen scaffold to study the development of Echinococcus multilocularis larvae. This 3D culture system preserved the function of hepatocytes for a longer period of time than their monolayer counterparts, with albumin secretion, 7-ethoxyresorufin O-deethylation activity, urea synthesis, CYP3A4 and CYP2D6 activity being highly preserved for 21–28 days. The expression levels of hepatocyte-specific genes including CLDN-3, Bsep, AFP, G6P, A1AT, CYP3A4 and NR1I3 were significantly higher in the 3D cultured system compared with their monolayer counterparts after 14-days in culture. Additionally, in the presence of 3D cultured hepatocytes, 81.2% of E. multilocularis protoscoleces rapidly de-differentiated into infective vesicles within eight weeks. Transcriptomic analyses revealed 807 differentially expressed genes between cultured vesicles and protoscoleces, including 119 genes uniquely expressed in protoscoleces, and 242 genes uniquely expressed in vesicles. These differentially expressed genes were mainly involved in parasite growth relating to the G-protein coupled receptor activity pathway, substrate-specific transmembrane transporter activity, cell-cell adhesion process, and potentially with neuroactive ligand-receptor interaction.

Conclusions/significance

This culture system provides a valuable advance in prolonging hepatocyte functionality, a foundation for future in-depth analysis of the host-parasite interaction in AE, and a useful model to evaluate potential therapeutic strategies to treat AE.

Alveolar echinococcosis (AE) is one of the world’s most dangerous zoonoses. Although there have been recent advances in some aspects of the molecular biology of E. multilocularis, larval development is far from understood. An in vitro hepatocyte based cultivation system for the metacestode stage of E. multilocularis has been developed to improve our understanding of AE. However, in two-dimensional conventional cultures, hepatocytes rapidly lose key phenotypic and functional characteristics after only approximately seven days. This hinders long-term in vitro studies of E. multilocularis larvae, which require several months for development. Thus, in this paper, a three-dimensional (3D) hepatic model was developed for simulating the organotropism of E. multilocularis toward the liver of its intermediate host. This 3D model can preserve the functions of hepatocytes and results in rapidly developed E. multilocularis larva. Genes uniquely expressed in protoscoleces and vesicles provided key information for the further study of AE. The 3D hepatic model provides a new foundation for E. multilocularis developmental studies and in-depth analysis of the host-parasite interaction in AE.

The combination of miR-122 overexpression and Let-7f silencing induces hepatic differentiation of adipose tissue-derived stem cells

Human adipose tissue-derived stem cells (hADSCs) have been considered as a promising source for cell therapy of liver diseases due to their accessibility, abundance, and expression of hepatocyte markers. Currently, the important role of certain microRNAs (miRNAs) has been reported during hepatic differentiation of stem cells. However, the combination effect of miRNAs on hepatic differentiation of these cells needs to be more investigated. The present study seeks to determine whether the combination of miRNAs can enhance hepatic differentiation of hADSCs in the absence of any other stimulation. First, lentiviral transduction was used to overexpress miR-122 and silence d let-7f in hADSCs for up to 21 days. Then, hepatic functionality was evaluated by analyzing specific hepatocyte genes and biochemical markers at different time points of differentiation induction. Stable miR-122 overexpression and let-7f silencing together in hADSCs resulted in increased expression of hepatocyte markers including ALB, AFP, CK18, CK19, and HNF4a. In addition, urea and albumin production, immunocytochemistry, and glycogen staining confirmed that the treated cells differentiated toward hepatocyte-like cells. Therefore, our findings demonstrate the possibility of using microRNAs to induce hADSCs into functional hepatocyte-like cells.

Current status and future prospects of mesenchymal stem cell therapy for liver fibrosis

Liver fibrosis is the end-stage of many chronic liver diseases and is a significant health threat. The only effective therapy is liver transplantation, which still has many problems, including the lack of donor sources, immunological rejection, and high surgery costs, among others. However, the use of cell therapy is becoming more prevalent, and mesenchymal stem cells (MSCs) seem to be a promising cell type for the treatment of liver fibrosis. MSCs have multiple differentiation abilities, allowing them to migrate directly into injured tissue and differentiate into hepatocyte-like cells. Additionally, MSCs can release various growth factors and cytokines to increase hepatocyte regeneration, regress liver fibrosis, and regulate inflammation and immune responses. In this review, we summarize the current uses of MSC therapies for liver fibrosis and suggest potential future applications.

Anti-fibrotic potential of human umbilical cord mononuclear cells and mouse bone marrow cells in CCl4- induced liver fibrosis in mice

Liver fibrosis is the consequence of hepatocyte injury that leads to the activation of hepatic stellate cells (HSC). The treatment of choice is Liver transplantation; however, it has many problems such as surgery-related complications, immunological rejection and high costs associated with the procedure. Stem cell-based therapy would be a potential alternative, so the aim of this study is to investigate the therapeutic potential of human umbilical cord mononuclear cells (MNC) and mouse bone marrow cells (BMC) against carbon tetrachloride (CCl₄) induced liver fibrosis in mice and compare it with that of silymarin. In the present study, male albino mice (N=60) were divided into six groups (10 mice each), the first group served as the normal control group while the remaining five groups were rendered fibrotic by intraperitoneal injections of CCl₄ and being left for 6 weeks to develop hepatic fibrosis. Thereafter, the mice were divided into CCl₄ group, CCl₄ group receiving MNC or BMC or silymarin or MNC and silymarin combination. After the specified treatment period, animals were then euthanized, blood and tissue samples were collected for measurement of alanine aminotransferase(ALT), aspartate aminotransferase(AST), malondialdehyde(MDA), reduced glutathione(GSH), collagen, Laminin, transforming growth factor β1(TGFβ1), tumor necrosis factor alpha(TNFα). MNC, BMC, and the combination therapy showed a significant decrease in ALT, AST, MDA, collagen, Laminin, TGFβ1, and TNFα and a significant increase in GSH. The data displayed a similar regression of fibrosis with the histological and immunohistological parameters. In conclusion, MNC, BMC and the combination therapy showed a potential therapeutic effect against liver fibrosis via reducing oxidative stress, inflammatory mediators, and fibrogenic markers.

Immunomodulatory oligonucleotide IMT504: Effects on mesenchymal stem cells as a first-in-class immunoprotective/immunoregenerative therapy

The immune responses of humans and animals to insults (i.e., infections, traumas, tumoral transformation and radiation) are based on an intricate network of cells and chemical messengers. Abnormally high inflammation immediately after insult or abnormally prolonged pro-inflammatory stimuli bringing about chronic inflammation can lead to life-threatening or severely debilitating diseases. Mesenchymal stem cell (MSC) transplant has proved to be an effective therapy in preclinical studies which evaluated a vast diversity of inflammatory conditions. MSCs lead to resolution of inflammation, preparation for regeneration and actual regeneration, and then ultimate return to normal baseline or homeostasis. However, in clinical trials of transplanted MSCs, the expectations of great medical benefit have not yet been fulfilled. As a practical alternative to MSC transplant, a synthetic drug with the capacity to boost endogenous MSC expansion and/or activation may also be effective. Regarding this, IMT504, the prototype of a major class of immunomodulatory oligonucleotides, induces in vivo expansion of MSCs, resulting in a marked improvement in preclinical models of neuropathic pain, osteoporosis, diabetes and sepsis. IMT504 is easily manufactured and has an excellent preclinical safety record. In the small number of patients studied thus far, IMT504 has been well-tolerated, even at very high dosage. Further clinical investigation is necessary to demonstrate the utility of IMT504 for resolution of inflammation and regeneration in a broad array of human diseases that would likely benefit from an immunoprotective/immunoregenerative therapy.

Simultaneous Administration of ADSCs-Based Therapy and Gene Therapy Using Ad-huPA Reduces Experimental Liver Fibrosis

Background and Aims

hADSCs transplantation in cirrhosis models improves liver function and reduces fibrosis. In addition, Ad-huPA gene therapy diminished fibrosis and increased hepatocyte regeneration. In this study, we evaluate the combination of these therapies in an advanced liver fibrosis experimental model.

Methods

hADSCs were expanded and characterized before transplantation. Ad-huPA was simultaneously administrated via the ileac vein. Animals were immunosuppressed by CsA 24 h before treatment and until sacrifice at 10 days post-treatment. huPA liver expression and hADSCs biodistribution were evaluated, as well as the percentage of fibrotic tissue, hepatic mRNA levels of Col-αI, TGF-β1, CTGF, α-SMA, PAI-I, MMP2 and serum levels of ALT, AST and albumin.

Results

hADSCs homed mainly in liver, whereas huPA expression was similar in Ad-huPA and hADSCs/Ad-huPA groups. hADSCs, Ad-huPA and hADSCs/Ad-huPA treatment improves albumin levels, reduces liver fibrosis and diminishes Collagen α1, CTGF and α-SMA mRNA liver levels. ALT and AST serum levels showed a significant decrease exclusively in the hADSCs group.

Conclusions

These results showed that combinatorial effect of cell and gene-therapy does not improve the antifibrogenic effects of individual treatments, whereas hADSCs transplantation seems to reduce liver fibrosis in a greater proportion.

Identification of Pathways in Liver Repair Potentially Targeted by Secretory Proteins from Human Mesenchymal Stem Cells

BACKGROUND

The beneficial impact of mesenchymal stem cells (MSC) on both acute and chronic liver diseases has been confirmed, although the molecular mechanisms behind it remain elusive. We aim to identify factors secreted by undifferentiated and hepatocytic differentiated MSC in vitro in order to delineate liver repair pathways potentially targeted by MSC.

METHODS

Secreted factors were determined by protein arrays and related pathways identified by biomathematical analyses.

RESULTS

MSC from adipose tissue and bone marrow expressed a similar pattern of surface markers. After hepatocytic differentiation, CD54 (intercellular adhesion molecule 1, ICAM-1) increased and CD166 (activated leukocyte cell adhesion molecule, ALCAM) decreased. MSC secreted different factors before and after differentiation. These comprised cytokines involved in innate immunity and growth factors regulating liver regeneration. Pathway analysis revealed cytokine-cytokine receptor interactions, chemokine signalling pathways, the complement and coagulation cascades as well as the Januskinase-signal transducers and activators of transcription (JAK-STAT) and nucleotide-binding oligomerization domain-like receptor (NOD-like receptor) signalling pathways as relevant networks. Relationships to transforming growth factor β (TGF-β) and hypoxia-inducible factor 1-α (HIF1-α) signalling seemed also relevant.

CONCLUSION

MSC secreted proteins, which differed depending on cell source and degree of differentiation. The factors might address inflammatory and growth factor pathways as well as chemo-attraction and innate immunity. Since these are prone to dysregulation in most liver diseases, MSC release hepatotropic factors, potentially supporting liver regeneration.

Mitochondria dysfunction: A novel therapeutic target in pathological lung remodeling or bystander?

The renascence in mitochondrial research has fueled breakthroughs in our understanding of mitochondrial biology identifying major roles in biological processes ranging from cellular oxygen sensing and regulation of intracellular calcium levels through to initiation of apoptosis or a shift in cell phenotype. Chronic respiratory diseases are no exception to the resurgent interest in mitochondrial biology. Microscopic observations of lungs from patients with chronic respiratory diseases such as pulmonary arterial hypertension, asthma and COPD show accumulation of dysmorphic mitochondria and provide the first evidence of mitochondrial dysfunction in diseased lungs. Recent mechanistic insights have established links between mitochondrial dysfunction or aberrant biogenesis and the pathogenesis of chronic respiratory diseases through playing a causative role in structural remodeling of the lung. The aim here is to discuss the case for a mitochondrial basis of lung remodeling in patients with chronic respiratory diseases. The present article will focus on the question of whether currently available data supports mitochondrial mechanisms as a viable point of therapeutic intervention in respiratory diseases and suggestions for future avenues of research in this rapidly evolving field.

Intra-Arterially Delivered Mesenchymal Stem Cells Are Not Detected in the Brain Parenchyma in an Alzheimer's Disease Mouse Model

Mesenchymal stem cells (MSCs) have a promising role as a therapeutic agent for neurodegenerative diseases such as Alzheimer’s disease (AD). Prior studies suggested that intra-arterially administered MSCs are engrafted into the brain in stroke or traumatic brain injury (TBI) animal models. However, a controversial standpoint exists in terms of the integrity of the blood brain barrier (BBB) in transgenic AD mice. The primary goal of this study was to explore the feasibility of delivering human umbilical cord-blood derived mesenchymal stem cells (hUCB-MSCs) into the brains of non-transgenic WT (C3H/C57) and transgenic AD (APP/PS1) mice through the intra-arterial (IA) route. Through two experiments, mice were infused with hUCB-MSCs via the right internal carotid artery and were sacrificed at two different time points: 6 hours (experiment 1) or 5 minutes (experiment 2) after infusion. In both experiments, no cells were detected in the brain parenchyma while MSCs were detected in the cerebrovasculature in experiment 2. The results from this study highlight that intra-arterial delivery of MSCs is not the most favorable route to be implemented as a potential therapeutic approach for AD.

Human umbilical cord blood-mesenchymal stem cells transplantation renovates the ovarian surface epithelium in a rat model of premature ovarian failure: Possible direct and indirect effects

This study aimed to isolate mesenchymal stem cells (MSC) from human umbilical cord blood (HCB) and to explore their influence on the ovarian epithelium after paclitaxel-induced ovarian failure. Ninety-five rats were divided into 6 groups: control, paclitaxel, paclitaxel and saline, HCB-MSC-treated for 2 weeks, HCB-MSC-treated for 4 weeks, and HCB-MSC-treated for 6 weeks. HCB cells were studied for CD34, CD44, and Oct ¾ using flow cytometry. Serum levels of FSH and E2 were measured using ELISA, RT-PCR analysis for human gene; beta-actin (ACTB), immunohistochemical analysis for CK 8/18, TGF-ß, PCNA and CASP-3 were performed. We found that ACTB gene was expressed in all rats' ovaries received HCB-MSC. After 4 weeks of transplantation, there was significant reduction in FSH, elevation in E2 levels, stabilization of the surface epithelium morphostasis, an increase in the antral follicle count and increase in integrated densities (ID) of CK 8/18, TGF-ß, and PCNA expressions and decrease in ID of CASP-3 expression. We concluded that HCB-MSC can restore the ovarian function after paclitaxel injection through a direct triggering effect on the ovarian epithelium and/or indirect enrichment of ovarian niche through regulating tissue expression of CK 8/18, TGF-ß and PCNA. These molecules are crucial in regulating folliculogenesis and suppressing CASP-3-induced apoptosis.

Human Umbilical Cord Mesenchymal Stem Cells Therapy in Cyclophosphamide-Induced Premature Ovarian Failure Rat Model

Premature ovarian failure (POF) is one of the most common causes of infertility in women. In our present study, we established cyclophosphamide- (CTX-) induced POF rat model and elucidated its effect on ovarian function. We detected the serum estrogen, follicle stimulating hormone, and anti-Müllerian hormone of mice models by ELISA and evaluated their folliculogenesis by histopathology examination. Our study revealed that CTX administration could severely disturb hormone secretion and influence folliculogenesis in rat. This study also detected ovarian cells apoptosis by deoxy-UTP-digoxigenin nick end labeling (TUNEL) and demonstrated marked ovarian cells apoptosis in rat models following CTX administration. In order to explore the potential of human umbilical cord mesenchymal stem cells (UCMSCs) in POF treatment, the above indexes were used to evaluate ovarian function. We found that human UCMSCs transplantation recovered disturbed hormone secretion and folliculogenesis in POF rat, in addition to reduced ovarian cell apoptosis. We also tracked transplanted UCMSCs in ovaries by fluorescence in situ hybridization (FISH). The results manifested that the transplanted human UCMSCs could reside in ovarian tissues and could survive for a comparatively long time without obvious proliferation. Our present study provides new insights into the great clinical potential of human UCMSCs in POF treatment.

Promising Therapy Candidates for Liver Fibrosis

Liver fibrosis is a wound-healing process in response to repeated and chronic injury to hepatocytes and/or cholangiocytes. Ongoing hepatocyte apoptosis or necrosis lead to increase in ROS production and decrease in antioxidant activity, which recruits inflammatory cells from the blood and activate hepatic stellate cells (HSCs) changing to myofibroblasts. Injury to cholangiocytes also recruits inflammatory cells to the liver and activates portal fibroblasts in the portal area, which release molecules to activate and amplify cholangiocytes. No matter what origin of myofibroblasts, either HSCs or portal fibroblasts, they share similar characteristics, including being positive for α-smooth muscle actin and producing extracellular matrix. Based on the extensive pathogenesis knowledge of liver fibrosis, therapeutic strategies have been designed to target each step of this process, including hepatocyte apoptosis, cholangiocyte proliferation, inflammation, and activation of myofibroblasts to deposit extracellular matrix, yet the current therapies are still in early-phase clinical development. There is an urgent need to translate the molecular mechanism of liver fibrosis to effective and potent reagents or therapies in human.

Transplantation of umbilical cord mesenchymal stem cells via different routes in rats with acute liver failure

OBJECTIVE

This study aimed to compare the therapeutic efficacy of transplantation of human umbilical cord mesenchymal stem cells (hUCMSC) in different routes in acute hepatic failure (ALF) in rats.

METHODS

hUCMSCs were isolated and identified by detection of surface antigens via flow cytometry. In T group and H group, ALF rats received hUCMSC transplantation through the tail vein and intrahepatic injection, respectively. In hUCMSC group, healthy rats received hUCMSCs transplantation via the tail vein. In ALF group, rats received injection of normal saline through the tail vein.

RESULTS

The TBil and ALT in ALF rats with and without transplantation were significantly higher than in healthy rats (P<0.05). HE staining of the liver showed obvious hepatocyte regeneration and reduced infiltration of inflammatory cells, and liver pathology was improved in T group and H group as compared to ALF group. At 3 d after transplantation, CK18 expression was detectable in both H group and T group. At 1 w and 2 w, the mRNA expressions of CK8, CK18 and AFP in H group and T group were significantly different from those in ALF group (P<0.05). The liver function and differentiation of stem cells were comparable between H group and T group (P>0.05).

CONCLUSION

hUCMSCs transplantation can improve the liver function and promote the liver repair following ALF. hUCMSCs transplantation via tail vein has similar therapeutic efficacy to that through intrahepatic injection.

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.

Inhibition of hepatic stellate cells by bone marrow-derived mesenchymal stem cells in hepatic fibrosis

BACKGROUND/AIMS

Therapies involving bone-marrow-derived mesenchymal stem cells (BM-MSCs) have considerable potential in the management of hepatic disease. BM-MSCs have been investigated in regenerative medicine due to their ability to secrete various growth factors and cytokines that regress hepatic fibrosis and enhance hepatocyte functionality. The aim of this study was to determine the antifibrosis effect of BM-MSCs on activated hepatic stellate cells (HSCs) and the mechanism underlying how BM-MSCs modulate the function of activated HSCs.

METHODS

We used HSCs in both direct and indirect co-culture systems with BM-MSCs to evaluate the antifibrosis effect of BM-MSCs. The cell viability and apoptosis were evaluated by a direct co-culture system of activated HSCs with BM-MSCs. The activations of both HSCs alone and HSCs with BM-MSCs in the direct co-culture system were observed by immunocytochemistry for alpha-smooth muscle actin (α-SMA). The levels of growth factors and cytokines were evaluated by an indirect co-culture system of activated HSCs with BM-MSCs.

RESULTS

The BM-MSCs in the direct co-culture system significantly decreased the production of α-SMA and the viability of activated HSCs, whereas they induced the apoptosis of activated HSCs. The BM-MSCs in the indirect co-culture system decreased the production of transforming growth factor-β1 and interleukin (IL)-6, whereas they increased the production of hepatocyte growth factor and IL-10. These results confirmed that the juxtacrine and paracrine effects of BM-MSCs can inhibit the proliferative, fibrogenic function of activated HSCs and have the potential to reverse the fibrotic process by inhibiting the production of α-SMA and inducing the apoptosis of HSCs.

CONCLUSIONS

These results have demonstrated that BM-MSCs may exert an antifibrosis effect by modulating the function of activated HSCs.

Cell therapy for liver diseases: current medicine and future promises

Liver diseases are a major health problem worldwide since they usually represent the main causes of death in most countries, causing excessive costs to public health systems. Nowadays, there are no efficient current therapies for most hepatic diseases and liver transplant is infrequent due to the availability of organs, cost and risk of transplant rejection. Therefore, alternative therapies for liver diseases have been developed, including cell-based therapies. Stem cells (SCs) are characterized by their self-renewing capacity, unlimited proliferation and differentiation under certain conditions into tissue- or organ-specific cells with special functions. Cell-based therapies for liver diseases have been successful in experimental models, showing anti-inflammatory, antifibrogenic and regenerative effects. Nowadays, clinical trials using SCs for liver pathologies are increasing in number, and those that have reached publication have achieved favorable effects, encouraging us to think that SCs will have a potential clinical use in a short time.

Progress in research of hepatic stem cells

Liver disease is a rising cause of mortality and morbidity, and treatment options remain limited. Liver transplantation is curative but limited by donor organ availability, operative risk and long-term complications. There is currently a clear need for new therapies for liver disease, and it is possible that hepatic stem cell (HSC) therapy represents an exciting new therapeutic option. HSCs are undifferentiated cells with the unique ability to self-renew and potentially provide a source of human hepatocytes for regeneration of the injured liver. Evidence from pre-clinical studies is encouraging, but conclusive evidence that this translates into humans remains lacking. Further studies of the mechanisms responsible for the beneficial effects of HSC therapy are needed.

Human mesenchymal stromal cells enhance the immunomodulatory function of CD8(+)CD28(-) regulatory T cells

One important aspect of mesenchymal stromal cells (MSCs)-mediated immunomodulation is the recruitment and induction of regulatory T (Treg) cells. However, we do not yet know whether MSCs have similar effects on the other subsets of Treg cells. Herein, we studied the effects of MSCs on CD8(+)CD28(-) Treg cells and found that the MSCs could not only increase the proportion of CD8(+)CD28(-) T cells, but also enhance CD8(+)CD28(-)T cells' ability of hampering naive CD4(+) T-cell proliferation and activation, decreasing the production of IFN-γ by activated CD4(+) T cells and inducing the apoptosis of activated CD4(+) T cells. Mechanistically, the MSCs affected the functions of the CD8(+)CD28(-) T cells partially through moderate upregulating the expression of IL-10 and FasL. The MSCs had no distinct effect on the shift from CD8(+)CD28(+) T cells to CD8(+)CD28(-) T cells, but did increase the proportion of CD8(+)CD28(-) T cells by reducing their rate of apoptosis. In summary, this study shows that MSCs can enhance the regulatory function of CD8(+)CD28(-) Treg cells, shedding new light on MSCs-mediated immune regulation.

Mesenchymal stromal cells engineered to produce IGF-I by recombinant adenovirus ameliorate liver fibrosis in mice

Liver cirrhosis involves chronic wound healing and fibrotic processes. Mesenchymal stromal cells (MSCs) are multipotent adult progenitor cells that are used as vehicles of therapeutic genes. Insulin growth factor like-I (IGF-I) was shown to counteract liver fibrosis. We aimed at analyzing the effect of applying IGF-I overexpressing mouse bone marrow-derived MSCs on hepatic fibrosis. Fibrosis was induced by chronic thioacetamide application or bile duct ligation. MSCs engineered to produce green fluorescent protein (GFP) (AdGFP-MSCs) or IGF-I (AdIGF-I-MSCs) were applied systemically, and changes in collagen deposition and in the expression of key pro-fibrogenic and pro-regenerative genes/proteins were assessed. In addition, immunogenicity of transduced cells was analyzed. Liver fibrosis was further ameliorated after a single-dose application of AdIGF-I-MSCs when compared with AdGFP-MSCs and/or recombinant IGF-I treatments. Interestingly, an early and transitory upregulation in IGF-I and hepatocyte growth factor (HGF) mRNA expression was found in the liver of MSC-treated animals, which was more pronounced in AdIGF-I-MSCs condition. A reduction in hepatic stellate cell activation status was found after incubation with MSCs conditioned media. In addition, the AdIGF-I-MSCs cell-free supernatant induced the expression of IGF-I and HGF in primary cultured hepatocytes. From day 1 after transplantation, the proliferation marker proliferating cell nuclear antigen was upregulated in the liver of AdIGF-I-MSCs group, mainly in hepatocytes. MSCs were in vivo traced till day 14 after injection. In addition, multiple doses of Ad-IGF-I-MSCs likely suppressed antiviral immune response and it further reduced collagen deposition. Our results uncover early events that are likely involved in the anti-fibrogenic effect of genetically modified MSCs and overall would support the use of AdIGF-I-MSCs in treatment of liver fibrosis.

Non-enzymatic dissociation of human mesenchymal stromal cells improves chemokine-dependent migration and maintains immunosuppressive function

BACKGROUND AIMS

Human bone marrow-derived mesenchymal stromal cells (MSC) can suppress inflammation; therefore their therapeutic potential is being explored in clinical trials. Poor engraftment of infused MSC limits their therapeutic utility; this may be caused by MSC processing before infusion, in particular the method of their detachment from culture.

METHODS

Enzymatic methods of detaching MSC (Accutase and TrypLE) were compared with non-enzymatic methods (Cell Dissociation Buffer [CDB], ethylenediamine tetra-acetic acid and scraping) for their effect on MSC viability, chemokine receptor expression, multi-potency, immunomodulation and chemokine-dependent migration.

RESULTS

TrypLE detachment preserved MSC viability and tri-lineage potential compared with non-enzymatic methods; however, this resulted in near complete loss of surface chemokine receptor expression. Of the non-enzymatic methods, CDB detachment preserved the highest viability while retaining significant tri-lineage differentiation potential. Once re-plated, CDB-detached MSC regained their original morphology and reached confluence, unlike with the use of other non-enzymatic methods. Viability was significantly reduced with the use of ethylenediamine tetra-acetic acid and further reduced with the use of cell scraping. Addition of 1% serum during CDB detachment led to higher MSC numbers entering autophagy and increased MSC recovery after re-plating. TrypLE and CDB-detached MSC suppressed CD3(+)CD4(+)CD25(-) T-cell proliferation, although TrypLE-detached MSC exhibited superior suppression at 1:20 ratio. CDB detachment retained surface chemokine receptor expression and consequently increased migration to CCL22, CXCL12 and CCL4, in contrast with TrypLE-detached MSC.

CONCLUSIONS

This study demonstrates that non-enzymatic detachment of MSC with the use of CDB minimizes the negative impact on cell viability, multipotency and immunomodulation while retaining chemokine-dependent migration, which may be of importance in MSC delivery and engraftment in sites of injury.

Advances in mesenchymal stem cells combined with traditional Chinese medicine therapy for liver fibrosis

Liver fibrosis is a primary cause of liver cirrhosis, and even hepatocarcinoma. Recently, the usage of mesenchymal stem cells (MSCs) has been investigated to improve liver fibrosis. It has been reported that the differentiation, proliferation and migration of MSCs can be regulated by traditional Chinese medicine treatment; however, the mechanisms are still unclear. In this article, the authors review the characteristics of MSCs such as multidirectional differentiation and homing, and its application in animal experiments and clinical trials. The authors also list areas that need further investigation, andlook at the future prospects of clinical application of MSCs.

Mesenchymal stem cell therapy in patients with small bowel transplantation: Single center experience

AIM: To study the effects of mesenchymal stem cell (MSC) therapy on the prevention of acute rejection and graft vs host disease following small bowel transplantation.

METHODS: In our transplantation center, 6 isolated intestinal transplants have been performed with MSC therapy since 2009. The primary reasons for transplants were short gut syndrome caused by surgical intestine resection for superior mesenteric artery thrombosis (n = 4), Crohn’s disease (n = 1) and intestinal aganglionosis (n = 1). Two of the patients were children. At the time of reperfusion, the first dose of MSCs cultured from the patient’s bone marrow was passed into the transplanted intestinal artery at a dose of 1000000 cells/kg. The second and third doses of MSCs were given directly into the mesenteric artery through the arterial anastomosis using an angiography catheter on day 15 and 30 post-transplant.

RESULTS: The median follow-up for these patients was 10.6 mo (min: 2 mo-max: 30 mo). Three of the patients developed severe acute rejection. One of these patients did not respond to bolus steroid therapy. Although the other two patients did respond to anti-rejection treatment, they developed severe fungal and bacterial infections. All of these patients died in the 2^nd and 3^rd months post-transplant due to sepsis. The remaining patients who did not have acute rejection had good quality of life with no complications observed during the follow-up period. In addition, their intestinal grafts were functioning properly in the 13^th, 25^th and 30^th month post-transplant. The patients who survived did not encounter any problems related to MSC transplantation.

CONCLUSION: Although this is a small case series and not a randomized study, it is our opinion that small bowel transplantation is an effective treatment for intestinal failure, and MSC therapy may help to prevent acute rejection and graft vs host disease following intestinal transplantation.

Immunological basis of stem cell therapy in liver diseases

Unbalanced immune cell populations or immune cell infiltration of the liver can disrupt the immune-privileged state of the liver, resulting in liver injury or fibrosis. Therefore, the treatment for liver diseases involves not only hepatic regeneration but also immunological regulation. Recent studies demonstrated that stem cells, especially mesenchymal stem cells, have the capacity for not only hepatic differentiation but also immunomodulation. In this respect, stem cell therapy could be a realistic aim for liver diseases by modulating the liver regenerative processes and down-regulating immune-mediated liver damage. In this review, we discuss in detail the importance of immune cells in liver injury and repair; the mechanism by which stem cells demonstrate an immune-tolerant phenotype that can be used for allogeneic transplantation; the effect of stem cell transplantation on immune-mediated diseases, especially liver diseases; and the mechanism by which stem cells improve the hepatic microenvironment.

The subtype CD200-positive, chorionic mesenchymal stem cells from the placenta promote regeneration of human hepatocytes

Human placental mesenchymal stem cells (hPMSCs), for the treatment of fulminant hepatic failure, have been widely studied. Only a few studies have investigated the effect of the subtype CD200(+)hPMSCs on regeneration of human hepatocytes. CD200(+)hPMSCs can down-regulate activity of several immunocytes and suppress TNF-α secretion from macrophages via the CD200-CD200R axis. We have investigated the influence of CD200-positive human placenta chorionic mesenchymal stem cells (CD200(+)hPCMSCs) on metabolism, proliferation and apoptosis of human hepatocytes in vitro. CD200(+)hPCMSCs promote urea synthesis, albumin secretion and hepatocytes proliferation at co-culture ratios of 1:1 and 3:1. Additionally, CD200(+)hPCMSCs inhibit hepatocyte apoptosis via up-regulation of an anti-apoptotic protein, Bcl-xL. Thus, CD200(+)hPCMSCs can provide supportive benefit for the regeneration of human hepatocytes and also have immunosuppressive properties. Therefore, CD200(+)hPCMSCs may be an ideal candidate for stem cell-based therapy in hepatic failure.

Transplantation of mesenchymal stem cells for the treatment of liver diseases, is there enough evidence?

Mesenchymal stem cells or multipotent mesenchymal stromal cells (MSCs) have been extensively investigated in small animal models to treat both acute and chronic liver injuries. Mechanisms of action are not clearly elucidated but may include their ability to differentiate into hepatocyte-like cells, to reduce inflammation, and to enhance tissue repair at the site of injury. This approach is controversial and evidence in large animals is missing. Side effects of MSC infusion such as the contribution to a fibrotic process have been reported in experimental settings. Nevertheless, MSCs moved quickly from bench to bedside and over 280 clinical trials are registered, of which 28 focus on the treatment of liver diseases. If no severe side-effects were observed so far, long-term benefits remain uncertain. More preclinical data regarding mechanisms of action, long term safety and efficacy are warranted before initiating large scale clinical application. The proposal of this review is to visit the current state of knowledge regarding mechanisms behind the therapeutic effects of MSCs in the treatment of experimental liver diseases, to address questions about efficacy and risk, and to discuss recent clinical advances involving MSC-based therapies.

The therapeutic potential of umbilical cord mesenchymal stem cells in mice premature ovarian failure

Mesenchymal stem cells, which are poorly immunogenic and have potent immunosuppressive activities, have emerged as promising cellular therapeutics for the treatment of several diseases. Mesenchymal-like cells derived from Wharton's Jelly, called umbilical cord matrix stem cells (UCMSCs), reportedly secrete a variety of cytokines and growth factors, acting as trophic suppliers. Here, we used UCMSCs to treat premature ovarian failure (POF). Ovarian function was evaluated by ovulation and the number of follicles. Apoptosis of the granulosa cells (GC) was analyzed by TUNEL staining. We found that after transplantation of the UCMSCs, apoptosis of cumulus cells in the ovarian damage model was reduced and the function of the ovary had been recovered. The sex hormone level was significantly elevated in mice treated with UCMSCs. The number of follicles in the treated group was higher than in the control group. Our results demonstrate that UCMSCs can effectively restore ovary functionality and reduce apoptosis of granulosa cells. We compared the RNA expression of the UCMSCs treated group with the POF model and wild-type control group and found that the UCMSC group is most similar to the wild-type group. Our experiments provide new information regarding the treatment of ovarian function failure.

Cellular behaviour of hepatocyte-like cells from nude mouse bone marrow-derived mesenchymal stem cells on galactosylated poly(D,L-lactic-co-glycolic acid)

Previously, the galactosylation of poly(d,l-lactic-co-glycolic acid) (PLGA) surface was accomplished by grafting allylamine (AA), using inductively coupled plasma-assisted chemical vapour deposition (ICP-CVD) and conjugating lactobionic acid (LA) with AA via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide (EDC/NHS) activation for hepatic tissue-engineering purposes. As a continuation study, the cellular behaviour of hepatocyte-like cells (HLCs) on the surface of the galactosylated PLGA were investigated. Nude mouse bone marrow-derived mesenchymal stem cells (MSCs) were cultured under hepatogenic conditions and the differentiated cells were characterized by reverse-transcription polymerase chain reaction (RT-PCR), immunofluorescence and periodic acid-Schiff (PAS) staining. Galactosylated PLGA enhanced the proliferation rate of HLCs compared to the control; HLCs on the surface of the sample became aggregated and formed spheroids after 3 days of culture. A large number of cells on the surface of the sample exhibited increased liver-specific functional activities, such as albumin and urea secretions. In addition, multicellular spheroids in the sample strongly expressed phospholyated focal adhesion kinase (pFAK) (cell-matrix interactions), E-cadherin (cell-cell interactions) and connexin 32 (Cox32; gap junction).

Targeting androgen receptor in bone marrow mesenchymal stem cells leads to better transplantation therapy efficacy in liver cirrhosis

Transplantation of bone marrow mesenchymal stem cells (BM-MSCs) has been considered as an alternative therapy, replacing liver transplantation in clinical trials, to treat liver cirrhosis, an irreversible disease that may eventually lead to liver cancer development. However, low survival rate of the BM-MSCs leading to unsatisfactory efficacy remains a major concern. Gender differences have been suggested in BM-MSCs therapeutic application, but the effect of the androgen receptor (AR), a key factor in male sexual phenotype, in this application is not clear. Using two liver cirrhosis mouse models induced by CCl4 or thioacetamide, we showed that targeting AR in the BM-MSCs improved their self-renewal and migration potentials and increased paracrine effects to exert anti-inflammatory and anti-fibrotic actions to enhance liver repair. Mechanism dissection studies suggested that knocking out AR in BM-MSCs led to improved self-renewal and migration by alteration of the signaling of epidermal growth factor receptor and matrix metalloproteinase 9 and resulted in suppression of infiltrating macrophages and hepatic stellate cell activation through modulation of interleukin (IL)1R/IL1Ra signaling. Therapeutic approaches using either AR/small interfering RNA or the AR degradation enhancer, ASC-J9, to target AR in BM-MSCs all led to increased efficacy for liver repair.

CONCLUSION

Targeting AR, a key factor in male sexual phenotype, in BM-MSCs improves transplantation therapeutic efficacy for treating liver fibrosis.

Human decidua-derived mesenchymal stromal cells differentiate into hepatic-like cells and form functional three-dimensional structures

BACKGROUND AIMS

Previously, we have shown that human decidua-derived mesenchymal stromal cells (DMSC) are mesenchymal stromal cells (MSC) with a clonal differentiation capacity for the three embryonic layers. The endodermal capacity of DMSC was revealed by differentiation into pulmonary cells. In this study, we examined the hepatic differentiation of DMSC.

METHODS

DMSC were cultured in hepatic differentiation media or co-cultured with murine liver homogenate and analyzed with phenotypic, molecular and functional tests.

RESULTS AND CONCLUSIONS

DMSC in hepatic differentiation media changed their fibroblast morphology to a hepatocyte-like morphology and later formed a 3-dimensional (3-D) structure or hepatosphere. Moreover, the hepatocyte-like cells and the hepatospheres expressed liver-specific markers such as synthesis of albumin (ALB), hepatocyte growth factor receptor (HGFR), α-fetoprotein (AFP) and cytokeratin-18 (CK-18), and exhibited hepatic functions including glycogen storage capacity and indocyanine green (ICG) uptake/secretion. Human DMSC co-cultured with murine liver tissue homogenate in a non-contact in vitro system showed hepatic differentiation, as evidenced by expression of AFP and ALB genes. The switch in the expression of these two genes resembled liver development. Indeed, the decrease in AFP and increase in ALB expression throughout the co-culture were consistent with the expression pattern observed during normal liver organogenesis in the embryo. Interestingly, AFP and ALB expression was significantly higher when DMSC were co-cultured with injured liver tissue, indicating that DMSC respond differently under normal and pathologic micro-environmental conditions. In conclusion, DMSC-derived hepatospheres and DMSC co-cultured with liver homogenate could be suitable in vitro models for toxicologic, developmental and pre-clinical hepatic regeneration studies.

Liver Anti-Fibrosis Therapy with Mesenchymal Stem Cells Secreting Hepatocyte Growth Factor

The objective of this study is to investigate the anti-fibrotic effect of combined mesencymal stem cells (MSCs) and gene therapy on liver fibrosis. When transfected by the complex with a plasmid DNA of hepatocyte growth factor (HGF) and the spermine-introduced pullulan of gene carrier, MSCs secreted HGF protein over 1 week. The HGF secreted from transfected MSC had the biological activity to promote the albumin production of hepatocytes. After intravenous injection, the HGF-secreting MSCs (HGF-MSC) accumulated in the liver. The injection of HGF-MSC decreased the fibrosis area in a rat model of liver fibrosis to a significantly great extent compared with that of original MSC. In the in vitro experiment, the higher number of HGF-transfected MSCs was migrated by stromal cell-derived factor (SDF)-1α more strongly than the original MSC. Considering the promotion of SDF-1α secretion in the liver fibrosis, it is possible that, when transplanted, genetically-engineered MSCs are accumulated in the liver due to their higher response to SDF-1α. It is concluded that the intravenous injection of genetically-engineered MSCs is a promising therapy for liver fibrosis.

Impaired therapeutic capacity of autologous stem cells in a model of type 2 diabetes

Endogenous stem cells in the bone marrow respond to environmental cues and contribute to tissue maintenance and repair. In type 2 diabetes, a multifaceted metabolic disease characterized by insulin resistance and hyperglycemia, major complications are seen in multiple organ systems. To evaluate the effects of this disease on the endogenous stem cell population, we used a type 2 diabetic mouse model (db/db), which recapitulates these diabetic phenotypes. Bone marrow-derived mesenchymal stem cells (MSCs) from db/db mice were characterized in vitro using flow cytometric cell population analysis, differentiation, gene expression, and proliferation assays. Diabetic MSCs were evaluated for their therapeutic potential in vivo using an excisional splint wound model in both nondiabetic wild-type and diabetic mice. Diabetic animals possessed fewer MSCs, which were proliferation and survival impaired in vitro. Examination of the recruitment response of stem and progenitor cells after wounding revealed that significantly fewer endogenous MSCs homed to the site of injury in diabetic subjects. Although direct engraftment of healthy MSCs accelerated wound closure in both healthy and diabetic subjects, diabetic MSC engraftment produced limited improvement in the diabetic subjects and could not produce the same therapeutic outcomes as in their nondiabetic counterparts in vivo. Our data reveal stem cell impairment as a major complication of type 2 diabetes in mice and suggest that the disease may stably alter endogenous MSCs. These results have implications for the efficiency of autologous therapies in diabetic patients and identify endogenous MSCs as a potential therapeutic target.

Clinical applications of bone marrow stem cells to treat liver diseases: recent progress

In recent years, great advances have been made in the treatment of liver diseases, such as fulminant and chronic hepatic failure, end-stage liver disease and inherited metabolic disorders, by bone marrow stem cell transplantation. Stem cell transplantation possesses advantages of low cost, easy obtainment of stem cells, and little or no immune rejection and therefore has good efficacy, safety and tolerability. Although liver transplantation is an effective way for the treatment of end-stage liver disease, it has limited clinical applications due to the shortage of organ donors, complicated operation procedure, severe complications, immunological rejection and high cost. Therefore, bone marrow stem cell transplantation has shed light on the treatment of end-stage liver diseases. In this article we review the clinical applications of bone marrow stem cell transplantation in the treatment of liver diseases.