Valproic acid promotes differentiation of hepatocyte-like cells from whole human umbilical cord-derived mesenchymal stem cells

Mesenchymal stem cell-derived extracellular vesicles in skin wound healing: roles, opportunities and challenges

Skin wounds are characterized by injury to the skin due to trauma, tearing, cuts, or contusions. As such injuries are common to all human groups, they may at times represent a serious socioeconomic burden. Currently, increasing numbers of studies have focused on the role of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) in skin wound repair. As a cell-free therapy, MSC-derived EVs have shown significant application potential in the field of wound repair as a more stable and safer option than conventional cell therapy. Treatment based on MSC-derived EVs can significantly promote the repair of damaged substructures, including the regeneration of vessels, nerves, and hair follicles. In addition, MSC-derived EVs can inhibit scar formation by affecting angiogenesis-related and antifibrotic pathways in promoting macrophage polarization, wound angiogenesis, cell proliferation, and cell migration, and by inhibiting excessive extracellular matrix production. Additionally, these structures can serve as a scaffold for components used in wound repair, and they can be developed into bioengineered EVs to support trauma repair. Through the formulation of standardized culture, isolation, purification, and drug delivery strategies, exploration of the detailed mechanism of EVs will allow them to be used as clinical treatments for wound repair. In conclusion, MSC-derived EVs-based therapies have important application prospects in wound repair. Here we provide a comprehensive overview of their current status, application potential, and associated drawbacks.

Comparison of two hepatocyte differentiation protocols in human umbilical cord mesenchymal stem cells: In vitro study

Human umbilical cord mesenchymal stromal cells (HUCMSCs) are an emerging source of cell therapy due to their self-renew and differentiation ability. They can differentiate into three germ layers, including the potential to generate hepatocytes. This study determined the transplantation efficiency and suitability of HUCMSCs-derived hepatocyte-like cells (HLCs) for their therapeutic application for liver diseases. This study aims to formulate ideal conditions to induce HUCMSCs into the hepatic lineage and investigate the efficiency of the differentiated HLCs based on their expression characteristics and capacity to integrate into the damaged liver of CCl4-challenged mice. Hepatocyte growth factor (HGF) and Activin A, Wnt3a were found to optimally promote the endodermal expansion of HUCMSCs, which showed phenomenal expression of hepatic markers upon differentiation in the presence of oncostatin M and dexamethasone. HUCMSCs expressed MSC-related surface markers and could undergo tri-lineage differentiations. Two hepatogenic differentiation protocols (differentiated hepatocyte protocol 1 [DHC1]: 32 days and DHC2: 15 days) were experimented with. The proliferation rate was faster in DHC2 than in DHC1 on day 7 of differentiation. The migration capability was the same in both DHC1 and DHC2. Hepatic markers like CK18, CK19, ALB, and AFP were upregulated. The mRNA levels of albumin, α1AT, αFP, CK18, TDO2, CYP3A4, CYP7A1, HNF4A, CEBPA, PPARA, and PAH were even higher in the HUCMSCs-derived HCLs than in the primary hepatocytes. Western blot confirmed HNF3B and CK18 protein expression in a step-wise manner differentiated from HUCMSCs. The metabolic function of differentiated hepatocytes was evident by increasing PAS staining and urea production. Pre-treating HUCMSCs with a hepatic differentiation medium containing HGF can drive their differentiation towards endodermal and hepatic lineages, enabling efficient integration into the damaged liver. This approach represents a potential alternative protocol for cell-based therapy that could enhance the integration potential of HUCMSC-derived HLCs.

Wharton's jelly mesenchymal stem cells: a concise review of their secretome and prospective clinical applications

Accumulating evidence indicates that most primary Wharton's jelly mesenchymal stem cells (WJ-MSCs) therapeutic potential is due to their paracrine activity, i.e., their ability to modulate their microenvironment by releasing bioactive molecules and factors collectively known as secretome. These bioactive molecules and factors can either be released directly into the surrounding microenvironment or can be embedded within the membrane-bound extracellular bioactive nano-sized (usually 30-150 nm) messenger particles or vesicles of endosomal origin with specific route of biogenesis, known as exosomes or carried by relatively larger particles (100 nm-1 μm) formed by outward blebbing of plasma membrane called microvesicles (MVs); exosomes and MVs are collectively known as extracellular vesicles (EVs). The bioactive molecules and factors found in secretome are of various types, including cytokines, chemokines, cytoskeletal proteins, integrins, growth factors, angiogenic mediators, hormones, metabolites, and regulatory nucleic acid molecules. As expected, the secretome performs different biological functions, such as immunomodulation, tissue replenishment, cellular homeostasis, besides possessing anti-inflammatory and anti-fibrotic effects. This review highlights the current advances in research on the WJ-MSCs' secretome and its prospective clinical applications.

Immunological characteristics of human umbilical cord mesenchymal stem cells after hepatogenic differentiation

BACKGROUND

Acute liver failure is one of the most intractable clinical problems. The use of bioartificial livers may solve donor shortage problems. Human umbilical cord mesenchymal stem cells (hUCMSCs) are an excellent seed cell choice for artificial livers because they change their characteristics to resemble hepatocyte-like cells (HLCs) following artificial liver transplantation.

OBJECTIVE

This study aimed to determine whether the immunological characteristics of hUCMSCs are changed after being transformed into hepatocyte-like cells.

METHODS

HUCMSCs were isolated by the adherent method. The following hUCMSC surface markers were detected using flow cytometry: CD45, CD90, CD105, CD34, and octamer-binding transcription factor 4 (OCT-4). Functional detection of adipogenic differentiation was performed. The hUCMSCs were cultured in complete medium (control group) or induction medium (induction group), and flow cytometry was used to detect cell surface markers. Peritoneal lavage fluid was collected after intraperitoneal injection of 1 × 106 cells/mouse over 40 minutes. The leukocyte count, labeled CD45, CD3, CD4 and CD8 antibodies, and flow detection of T lymphocyte subsets were determined using the peritoneal lavage fluid.

RESULTS

Using phenotypic and functional identification, hUCMSCs were successfully isolated using a two-step induction method. The surface markers of the hUCMSCs cells changed after HLC induction. In vivo immune results showed that hUCMSCs and HLsC induced leukocyte production.

CONCLUSION

Hepatic induction of hUCMSCs changes their cell surface markers. Both HLCs and hUCMSCs cause leukocytosis in vivo, but the immune response induced by HLCs is slightly stronger.

Therapeutic Potential of Mesenchymal Stem Cells in the Treatment of Epilepsy and Their Interaction with Antiseizure Medications

Epilepsy is a life-threatening neurological disease that affects approximately 70 million people worldwide. Although the vast majority of patients may be successfully managed with currently used antiseizure medication (ASM), the search for alternative therapies is still necessary due to pharmacoresistance in about 30% of patients with epilepsy. Here, we review the effects of ASMs on stem cell treatment when they could be, as expected, co-administered. Indeed, it has been reported that ASMs produce significant effects on the differentiation and determination of stem cell fate. In addition, we discuss more recent findings on mesenchymal stem cells (MSCs) in pre-clinical and clinical investigations. In this regard, their ability to differentiate into various cell types, reach damaged tissues and produce and release biologically active molecules with immunomodulatory/anti-inflammatory and regenerative properties make them a high-potential therapeutic tool to address neuroinflammation in different neurological disorders, including epilepsy. Overall, the characteristics of MSCs to be genetically engineered, in order to replace dysfunctional elements with the aim of restoring normal tissue functioning, suggested that these cells could be good candidates for the treatment of epilepsy refractory to ASMs. Further research is required to understand the potential of stem cell treatment in epileptic patients and its interaction with ASMs.

The role of epigenetic modifiers in the hepatic differentiation of human umbilical cord derived mesenchymal stem cells

Human umbilical cord (hUC) derived mesenchymal stem cells (MSCs) can be progressively differentiated into multiple lineages including hepatic lineages, and thus provide an excellent in vitro model system for the study of hepatic differentiation. At present, hepatic differentiation protocols are based on the use of soluble chemicals in the culture medium and provide immature hepatic like cells. Histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors (DNMTi) are two important epigenetic modifiers that regulate stem cell differentiation. Therefore, this study aimed to investigate the role of HDACi, valproic acid (VPA) and DNMTi,5-azacytidine (5-aza) along with a hepatic inducer in the hepatic differentiation of hUC-MSCs. hUC-MSCs were characterized via immunocytochemistry and flow cytometry. The final concentrations of VPA and 5-aza were optimized via MTT cytotoxicity assay. All treated groups were assessed for the presence of hepatic genes and proteins through qPCR and immunocytochemistry, respectively. The results showed that the pretreatment of epigenetic modifiers not only increased the hepatic genes but also increased the expression of the hepatic proteins. VPA induces hepatic differentiation in hUC-MSCs with significant gene expression of hepatic markers i.e., FOXA2 and CK8. Moreover, VPA pretreatment enhanced the expression of hepatic proteins AFP and TAT. The pretreatment of 5-aza shows significant gene expression of hepatic marker LDL-R. However, 5-aza treatment failed to induce hepatic protein expression. The results of the current study highlighted the effectiveness of epigenetic modifiers in the hepatic differentiation of hUC-MSCs. These differentiated cells can be employed in cell-based therapeutics for hepatic diseases in future.

Mesenchymal Stem Cell-Derived Extracellular Vesicles for Bone Defect Repair

The repair of critical bone defects is a hotspot of orthopedic research. With the development of bone tissue engineering (BTE), there is increasing evidence showing that the combined application of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) (MSC-EVs), especially exosomes, with hydrogels, scaffolds, and other bioactive materials has made great progress, exhibiting a good potential for bone regeneration. Recent studies have found that miRNAs, proteins, and other cargo loaded in EVs are key factors in promoting osteogenesis and angiogenesis. In BTE, the expression profile of the intrinsic cargo of EVs can be changed by modifying the gene expression of MSCs to obtain EVs with enhanced osteogenic activity and ultimately enhance the osteoinductive ability of bone graft materials. However, the current research on MSC-EVs for repairing bone defects is still in its infancy, and the underlying mechanism remains unclear. Therefore, in this review, the effect of bioactive materials such as hydrogels and scaffolds combined with MSC-EVs in repairing bone defects is summarized, and the mechanism of MSC-EVs promoting bone defect repair by delivering active molecules such as internal miRNAs is further elucidated, which provides a theoretical basis and reference for the clinical application of MSC-EVs in repairing bone defects.

Changes in the hepatic differentiation potential of human mesenchymal stem cells aged in vitro

Background

Due to their multipotency and ability for self-renewal, human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) hold great promise for generating hepatocytes. Previous research has successfully generated hepatocytes from early-passage [i.e., passage (P)3] hUC-MSCs; however, the populations of early-passage cells are limited, and these cells cannot produce sufficient functional hepatocytes for large-scale application in clinical therapy. Thus, a thorough investigation of the hepatic differentiation potential of in vitro-aged hUC-MSCs is needed.

Methods

hUC-MSCs were passaged in vitro and subcultured every 3 days up to P8, and their morphology, proliferative capacity, liver-specific marker expression, and liver function at the end of each passage were analyzed. The efficiency of the hepatogenic differentiation of hUC-MSCs driven by a functional hit 1 (FH1)-based strategy at different passages was also evaluated.

Results

The in vitro-aged hUC-MSCs gradually displayed morphological inhomogeneity, had reduced proliferative capability, and exhibited senescent properties while maintaining adipogenic and osteogenic differentiation potential. Additionally, senescence also decreased the expression of messenger RNA (mRNA) levels in albumin (ALB) and alpha 1-antitrpsin (A1AT) in these cells and their relative protein expression, which is the marker of a mature hepatocyte. The liver function of the in vitro-aged hUC-MSCs also deteriorated gradually. Finally, the percentage of hepatocyte-like cells (HLCs) generated from in vitro-aged hUC-MSCs reduced significantly, and the mature hepatocyte functions, such as ALB secretion, glycogen synthesis, low-density lipoprotein (LDL) intake, and indocyanine green (ICG) uptake, also changed.

Conclusions

hUC-MSCs possess mature hepatocytes’ specific markers and functions, which change gradually as they undergo cell senescence. Due to the loss of these properties within in vitro subcultures, the hepatic differentiation efficiency of in vitro-aged hUC-MSCs decreased dramatically in the late passage (P8). The current study provides valuable information can inform future research on liver disease.

Functional hit 1 (FH1)-based rapid and efficient generation of functional hepatocytes from human mesenchymal stem cells: a novel strategy for hepatic differentiation

Background

Because the liver is central to the physiology of the body, primary hepatocytes are widely used in liver pathology and physiological research, such as liver drug screening, bioartificial liver support system, and cell therapy for liver diseases. However, the source of primary hepatocytes is limited. We describe a novel non-transgenic protocol that facilitates the rapid generation of hepatocyte-like cells from human umbilical cord-derived mesenchymal stem cells (hUC-MSCs), providing a new source of functional hepatocytes.

Methods

In this study, we used hUC-MSCs and human induced pluripotent cells (iPSCs) derived mesenchymal stem cells (iMSCs) to investigate the new induction strategy. Passage 3 MSCs were induced into hepatocyte-like cells using small-molecule compounds combined with cell factors in vitro. Functional hit 1 (FH1), a promising small molecule compound was achieved to replace HGF in the hepatocyte maturation stage to induce the hepatocyte-like cells differentiation.

Results

We rapidly induced hUC-MSCs and human iMSCs into hepatocyte-like cells within 10 days in vitro, and the cells were morphologically similarly to both hepatocytes derived from the hepatocyte growth factor (HGF)-based method and the primary hepatocytes. They expressed mature hepatocyte special genes and achieved functions such as glycogen storage, albumin expression, urea secretion, cytochrome P450 activity, Low-density lipoprotein (LDL) uptake, and indocyanine green (ICG) uptake.

Conclusions

We successfully established a small-molecule protocol without using HGF to differentiate MSCs into hepatocyte-like cells, which provides a rapid and cost-effective platform for in vitro studies of liver disease.

Endothelin-1 enhances the regenerative capability of human bone marrow-derived mesenchymal stem cells in a sciatic nerve injury mouse model

We expanded the application of endothelin-1 (EDN1) by treating human mesenchymal stem cell (hMSC) organotypic spinal cord slice cultures with EDN1. EDN1-treated hMSCs significantly enhanced neuronal outgrowth. The underlying mechanism of this effect was evaluated via whole-genome methylation. EDN1 increased whole-genome demethylation and euchromatin. To observe demethylation downstream of EDN1, deaminases and glycosylases were screened, and APOBEC1 was found to cause global demethylation and OCT4 gene activation. The sequence of methyl-CpG-binding domain showed similar patterns between EDN1- and APOBEC1-induced demethylation. SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin subfamily A member 4 (SMARC A4) and SMARC subfamily D, member 2 (SMARC D2) were screened via methyl-CpG-binding domain sequencing as a modulator in response to EDN1. Chromatin immunoprecipitation of the H3K9me3, H3K27me3, and H3K4me4 binding sequences on the APOBEC1 promoter was analyzed following treatment with or without siSMARC A4 or siSMARC D2. The results suggested that SMARC A4 and SMARC D2 induced a transition from H3K9me3 to H3K4me3 in the APOBEC1 promoter region following EDN1 treatment. Correlations between EDN1 pathways and therapeutic efficacy in hBM-MSCs were determined in a sciatic nerve injury mouse model. Thus, EDN1 may be a useful novel-concept bioactive peptide and biomaterial component for improving hMSC regenerative capability.

Elevated levels of expression of cytochrome P450 3A4 in a human liver epithelial cell line in differentiation-inducing conditions

Cytochrome P450 (CYP) enzymes, especially CYP3A4 play a major role in the metabolism of xenobiotics in human liver. CYP3A4-expressing human liver or hepatoma cell lines may be good cell substitutes of human hepatocytes for drug metabolism studies. However, there are only a few cell lines expressing high levels of CYP3A4. The aim of this study is to investigate the expression of CYP3A4 and its mechanism in an immortalized non-tumorigenic human liver epithelial cell line, THLE-5b in differentiation-inducing conditions. When THLE-5b cells were cultivated in culture medium supplemented with hepatocytic differentiation-inducing factors, they showed hepatocytic morphology. In addition, elevated levels of expression not only of α1-antitrypsin (AAT) and albumin (ALB) mRNAs, but also of CYP3A4 mRNA, which are functional hepatocyte markers, were observed compared with the control. Among hepatocytic differentiation-inducing factors, dexamethasone (DEX) and insulin-transferrin-sodium selenite (ITS) seemed to be involved in elevation of expression of CYP3A4 mRNA. The mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) inhibitor U0126 or the phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002 reduced CYP3A4 mRNA levels of THLE-5b cells. Furthermore, the CpG site of the CYP3A4 promoter region in THLE-5b cells was found to be unmethylated, although in low CYP3A4-expressing HepG2 cells, the site was methylated. In conclusion, THLE-5b cells, which are unmethylated at the CpG site of the CYP3A4 promoter region, express CYP3A4 mRNA through the MEK/ERK1/2 and PI3K/Akt signaling pathways and acquire hepatocytic functions in differentiation-inducing conditions. Thus, THLE-5b cells could be a useful cell system for the study of drug metabolism.

Application of Mesenchymal Stem Cells in Inflammatory and Fibrotic Diseases

Mesenchymal stem cells (MSCs) are multipotent stem cells that can be isolated from various tissues in the adult body. MSCs should be characterized by three criteria for regenerative medicine. MSCs must (1) adhere to plastic surfaces, (2) express specific surface antigens, and (3) differentiate into mesodermal lineages, including chondrocytes, osteoblasts, and adipocytes, in vitro. Interestingly, MSCs have immunomodulatory features and secrete trophic factors and immune receptors that regulate the microenvironment in host tissue. These specific and unique therapeutic properties make MSCs ideal as therapeutic agents in vivo. Specifically, pre-clinical and clinical investigators generated inflammatory and fibrotic diseases models, and then transplantation of MSCs into diseases models for therapeutic effects investigation. In this review, we characterize MSCs from various tissues and describe their applications for treating various inflammation and fibrotic diseases.

Mesenchymal stem cell therapy for liver disease: full of chances and challenges

Liver disease is a major health problem that endangers human health worldwide. Currently, whole organ allograft transplantation is the gold standard for the treatment of end-stage liver disease. A shortage of suitable organs, high costs and surgical complications limit the application of liver transplantation. Mesenchymal stem cell therapy has been considered as a promising alternative approach for end-stage liver disease. Some clinical trials have confirmed the effectiveness of MSC therapy for liver disease, but its application has not been promoted and approved. There are still many issues that should be solved prior to using MSC therapy in clinical applications. The types of liver disease that are most suitable for MSC application should be determined, and the preparation and engraftment of MSCs should be standardized. These may be bottlenecks that limit the use of MSCs. We investigated 22 completed and several ongoing clinical trials to discuss these questions from a clinical perspective. We also discussed the important mechanisms by which MSCs play a therapeutic role in liver disease. Finally, we also proposed novel prospective approaches that can improve the therapeutic effect of MSCs.

A novel antifibrotic strategy utilizing conditioned media obtained from miR-150-transfected adipose-derived stem cells: validation of an animal model of liver fibrosis

The limitations of stem cells have led researchers to investigate the secretome, which is the secretory materials in stem cells, since the principal mechanism of action of stem cells is mediated by the secretome. In this study, we determined the antifibrotic potential of the secretome released from miR-150-transfected adipose-derived stromal cells (ASCs). The secretome released from ASCs that were transfected with antifibrotic miR-150 was obtained (referred to as the miR-150 secretome). To validate the antifibrotic effects of the miR-150 secretome, we generated in vitro and in vivo models of liver fibrosis by treating human hepatic stellate cells (LX2 cells) with thioacetamide (TAA) and subcutaneous injection of TAA into mice, respectively. In the in vitro model, more significant reductions in the expression of fibrosis-related markers, such as TGFβ, Col1A1, and α-SMA, were observed by using the miR-150 secretome than the control secretome, specifically in TAA-treated LX2 cells. In the in vivo model, infusion of the miR-150 secretome into mice with liver fibrosis abrogated the increase in serum levels of systemic inflammatory cytokines, such as IL-6 and TNF-α, and induced increased expression of antifibrotic, proliferation, and antioxidant activity markers in the liver. Our in vitro and in vivo experiments indicate that the miR-150 secretome is superior to the naive secretome in terms of ameliorating liver fibrosis, minimizing systemic inflammatory responses, and promoting antioxidant enzyme expression. Therefore, we conclude that miR-150 transfection into ASCs has the potential to induce the release of secretory materials with enhanced antifibrotic, proliferative, and antioxidant properties.

A mixture of molecules produced by genetically modified stem cells could help repair the damage associated with liver fibrosis. Fat-derived adipose stem cells (ASCs) secrete proteins and nucleic acids that can facilitate tissue regeneration, but the natural mixture of molecules secreted (the ‘secretome’) is insufficient to reverse advanced fibrosis. Researchers led by Say-June Kim of the Catholic University of Korea, Seoul, South Korea, have boosted the potency of this cell-derived treatment by engineering ASCs to produce an RNA called miR-150. This RNA inhibits biological processes that drive fibrosis. Experiments in cultured cells and a mouse model of fibrosis confirmed that miR-150 consistently improved the ASC secretome’s capacity to control liver fibrosis and minimize systemic inflammatory responses. This approach could thus offer a safe strategy for promoting tissue regeneration and preventing liver failure.

Alternative Cell Sources for Liver Parenchyma Repopulation: Where Do We Stand?

Acute and chronic liver failure is a highly prevalent medical condition with high morbidity and mortality. Currently, the therapy is orthotopic liver transplantation. However, in some instances, chiefly in the setting of metabolic diseases, transplantation of individual cells, specifically functional hepatocytes, can be an acceptable alternative. The gold standard for this therapy is the use of primary human hepatocytes, isolated from livers that are not suitable for whole organ transplantations. Unfortunately, primary human hepatocytes are scarcely available, which has led to the evaluation of alternative sources of functional hepatocytes. In this review, we will compare the ability of most of these candidate alternative cell sources to engraft and repopulate the liver of preclinical animal models with the repopulation ability found with primary human hepatocytes. We will discuss the current shortcomings of the different cell types, and some of the next steps that we believe need to be taken to create alternative hepatocyte progeny capable of regenerating the failing liver.

A study of the differentiation of stem cells from human exfoliated deciduous teeth on 3D silk fibroin scaffolds using static and dynamic culture paradigms

Stem cells from human exfoliated deciduous teeth (SHED) are considered the best current source of human stem cells due to their ability to differentiate into multiple cell lineages. Dynamic co-culture systems can improve the culture environment, as they provide cells with signaling factors, extracellular matrixes, and cellular shear force, as well as enable the formation of heterotypic clusters. We seeded SHED in 3D silk fibroin porous scaffolds under static and dynamic cultures for 28 days, using the NIH3T3 cultivated medium as an induction agent. Many hepatospheres formed in these porous scaffolds, and cellular viability was shown to continually increase by MTT assays. Hepatic AFP and ALB gene expression, as well as glycogen storage, albumin secretion, and urea synthesis, were greater in cells in the 3D porous scaffold under a dynamic culture than in those cultured under 3D static culture and petri dish conditions. However, the 3D static culture is still superior to the traditional petri dish culture. The NIH3T3 cultivated medium can significantly induce hepatic differentiation of SHED, while the 3D dynamic culture system significantly enhances hepatic differentiation of SHED. This study provides alternative sources of hepatocytes for liver disease treatment.

A Novel Hepatic Anti-Fibrotic Strategy Utilizing the Secretome Released from Etanercept-Synthesizing Adipose-Derived Stem Cells

Tumor necrosis factor-α (TNF-α)-driven inflammatory reaction plays a crucial role in the initiation of liver fibrosis. We herein attempted to design genetically engineered adipose-derived stem cells (ASCs) producing etanercept (a potent TNF-α inhibitor), and to determine the anti-fibrotic potential of the secretome released from the etanercept-synthesizing ASCs (etanercept-secretome). First, we generated the etanercept-synthesizing ASCs by transfecting the ASCs with mini-circle plasmids containing the gene insert encoding for etanercept. We subsequently collected the secretory material released from the etanercept-synthesizing ASCs and determined its anti-fibrotic effects both in vitro (in thioacetamide [TAA]-treated AML12 and LX2 cells) and in vivo (in TAA-treated mice) models of liver fibrosis. We observed that while etanercept-secretome increased the viability of the TAA-treated AML12 hepatocytes (p = 0.021), it significantly decreased the viability of the TAA-treated LX2 HSCs (p = 0.021). In the liver of mice with liver fibrosis, intravenous administration of the etanercept-secretome induced significant reduction in the expression of both fibrosis-related and inflammation-related markers compared to the control group (all Ps < 0.05). The etanercept-secretome group also showed significantly lower serum levels of liver enzymes as well as pro-inflammatory cytokines, such as TNF-α (p = 0.020) and IL-6 (p = 0.021). Histological examination of the liver showed the highest reduction in the degree of fibrosis in the entanercept-secretome group (p = 0.006). Our results suggest that the administration of etanercept-secretome improves liver fibrosis by inhibiting TNF-α-driven inflammation in the mice with liver fibrosis. Thus, blocking TNF-α-driven inflammation at the appropriate stage of liver fibrosis could be an efficient strategy to prevent fibrosis.

Ameliorating liver fibrosis in an animal model using the secretome released from miR-122-transfected adipose-derived stem cells

BACKGROUND

Recently, the exclusive use of mesenchymal stem cell (MSC)-secreted molecules, called secretome, rather than cells, has been evaluated for overcoming the limitations of cell-based therapy, while maintaining its advantages. However, the use of naïve secretome may not fully satisfy the specificity of each disease. Therefore, it appears to be more advantageous to use the functionally reinforced secretome through a series of processes involving physico-chemical adjustments or genetic manipulation rather than to the use naïve secretome.

AIM

To determine the therapeutic potential of the secretome released from miR-122-transfected adipose-derived stromal cells (ASCs).

METHODS

We collected secretory materials released from ASCs that had been transfected with antifibrotic miR-122 (MCM) and compared their antifibrotic effects with those of the naïve secretome (CM). MCM and CM were intravenously administered to the mouse model of thioacetamide-induced liver fibrosis, and their therapeutic potentials were compared.

RESULTS

MCM infusion provided higher therapeutic potential in terms of: (A) Reducing collagen content in the liver; (B) Inhibiting proinflammatory cytokines; and (C) Reducing abnormally elevated liver enzymes than the infusion of the naïve secretome. The proteomic analysis of MCM also indicated that the contents of antifibrotic proteins were significantly elevated compared to those in the naïve secretome.

CONCLUSION

We could, thus, conclude that the secretome released from miR-122-transfected ASCs has higher antifibrotic and anti-inflammatory properties than the naïve secretome. Because miR-122 transfection into ASCs provides a specific way of potentiating the antifibrotic properties of ASC secretome, it could be considered as an enhanced method for reinforcing secretome effectiveness.

Dimethyloxaloylglycine-stimulated human bone marrow mesenchymal stem cell-derived exosomes enhance bone regeneration through angiogenesis by targeting the AKT/mTOR pathway

Background

Mesenchymal stem cell (MSC)-derived exosomes have been recognized as new candidate agents for treating critical-sized bone defects; they promote angiogenesis and may be an alternative to cell therapy. In this study, we evaluated whether exosomes derived from bone marrow-derived MSCs (BMSCs) preconditioned with a low dose of dimethyloxaloylglycine (DMOG), DMOG-MSC-Exos, exert superior proangiogenic activity in bone regeneration and the underlying mechanisms involved.

Methods

To investigate the effects of these exosomes, scratch wound healing, cell proliferation, and tube formation assays were performed in human umbilical vein endothelial cells (HUVECs). To test the effects in vivo, a critical-sized calvarial defect rat model was established. Eight weeks after the procedure, histological/histomorphometrical analysis was performed to measure bone regeneration, and micro-computerized tomography was used to measure bone regeneration and neovascularization.

Results

DMOG-MSC-Exos activated the AKT/mTOR pathway to stimulate angiogenesis in HUVECs. This contributed to bone regeneration and angiogenesis in the critical-sized calvarial defect rat model in vivo.

Conclusions

Low doses of DMOG trigger exosomes to exert enhanced proangiogenic activity in cell-free therapeutic applications.

Mechanisms Underlying Cell Therapy in Liver Fibrosis: An Overview

Fibrosis is a common feature in most pathogenetic processes in the liver, and usually results from a chronic insult that depletes the regenerative capacity of hepatocytes and activates multiple inflammatory pathways, recruiting resident and circulating immune cells, endothelial cells, non-parenchymal hepatic stellate cells, and fibroblasts, which become activated and lead to excessive extracellular matrix accumulation. The ongoing development of liver fibrosis results in a clinically silent and progressive loss of hepatocyte function, demanding the constant need for liver transplantation in clinical practice, and motivating the search for other treatments as the chances of obtaining compatible viable livers become scarcer. Although initially cell therapy has emerged as a plausible alternative to organ transplantation, many factors still challenge the establishment of this technique as a main or even additional therapeutic tool. Herein, the authors discuss the most recent advances and point out the corners and some controversies over several protocols and models that have shown promising results as potential candidates for cell therapy for liver fibrosis, presenting the respective mechanisms proposed for liver regeneration in each case.

Human umbilical cord mesenchymal stem cells ameliorate liver fibrosis in vitro and in vivo: From biological characteristics to therapeutic mechanisms

Liver fibrosis is a wound-healing response to chronic injuries, characterized by the excessive accumulation of extracellular matrix or scar tissue within the liver; in addition, its formation is associated with multiple cytokines as well as several cell types and a variety of signaling pathways. When liver fibrosis is not well controlled, it can progress to liver cirrhosis, but it is reversible in principle. Thus far, no efficient therapy is available for treatment of liver fibrosis. Although liver transplantation is the preferred strategy, there are many challenges remaining in this approach, such as shortage of donor organs, immunological rejection, and surgical complications. Hence, there is a great need for an alternative therapeutic strategy. Currently, mesenchymal stem cell (MSC) therapy is considered a promising therapeutic strategy for the treatment of liver fibrosis; advantageously, the characteristics of MSCs are continuous self-renewal, proliferation, multipotent differentiation, and immunomodulatory activities. The human umbilical cord-derived (hUC)-MSCs possess not only the common attributes of MSCs but also more stable biological characteristics, relatively easy accessibility, abundant source, and no ethical issues (e.g., bone marrow being the adult source), making hUC-MSCs a good choice for treatment of liver fibrosis. In this review, we summarize the biological characteristics of hUC-MSCs and their paracrine effects, exerted by secretion of various cytokines, which ultimately promote liver repair through several signaling pathways. Additionally, we discuss the capacity of hUC-MSCs to differentiate into hepatocyte-like cells for compensating the function of existing hepatocytes, which may aid in amelioration of liver fibrosis. Finally, we discuss the current status of the research field and its future prospects.

Decellularized and solubilized pancreatic stroma promotes the in vitro proliferation, migration and differentiation of BMSCs into IPCs

Bone marrow-derived mesenchymal stem cells (BMSCs) have the ability to differentiate into insulin-producing cells (IPCs). Bio-scaffolds derived from decellularized organs can act as a carrier for seed cells and may have broad applications in regenerative medicine. This study investigated the effect of native pancreatic stroma obtained from decellularized pancreas on the proliferation, migration and differentiation of BMSCs into IPCs, and explored the potential underlying molecular mechanism. The decellularized pancreas bio-scaffold was obtained by perfusion with Triton X-100/ammonium hydroxide, followed by digestion with a mixture of pepsin and hydrochloric acid to prepare the stroma solution. Islet-like cells were differentiated from BMSCs by a three-step induction method. The differences on the cytological behavior with or without stroma were evaluated by morphological observation, insulin release assay, qRT-PCR assay and western blot analysis. Our results showed that, stroma derived from decellularized pancreas could promote the proliferation and migration of BMSCs. Furthermore, the formation of IPCs could also be promoted, which possessed similar morphology to endogenous islets. During the induced differentiation process, the presence of stroma significantly increased the expression of insulin 1, insulin 2 and Pdx-1, as well as insulin release. This was accompanied by an increase in the phosphorylation of Akt and ERK in third stage cell clusters, which was prevented by the addition of the inhibitors PD98059 and LY294002, respectively. In summary, decellularized pancreatic stroma could promote the proliferation, migration and differentiation of BMSCs into IPCs, and this involved the activation of Akt and ERK signal pathways.

Pharmacological modulation of cell functional activity with valproic acid and erythropoietin

Introduction: Valproic acid (VA) is carboxylic acid with a branched chain, which is used as an antiepileptic drug.

Valproic acid influence on cells in vivo: VA, which is an antiepileptic drug, is also a teratogen, which causes defects of a neural tube and an axial skeleton, although the mechanisms are not yet fully clear.

Valproic acid influence on mesenchymal stem cells (MSC) in vitro: It is shown that valproic acid reduces the intracellular level of oxygen active forms.

Valproic acid effect on tumor cells: VA inhibits tumor growth through several mechanisms, including the cell cycle stop, differentiation induction and inhibition of growth of tumor vessels.

Valproic acid influence on enzymes: It affects mainly GSK-3.

Valproic acid influence on animals’ cells: It is shown that VA can significantly improve an ability to develop in vitro and improve nuclear reprogramming of embryos.

Erythropoietin (EPO): Is an hypoxia-induced hormone and a cytokine, which is necessary for normal erythropoiesis. EPO is widely used in in vitro experiments.

Conclusion: Thus, the influence of VA and EPO on cells can be used in cell technologies.

Enhanced Hepatogenic Differentiation of Human Wharton's Jelly-Derived Mesenchymal Stem Cells by Using Three-Step Protocol

Currently, human Wharton’s jelly-derived mesenchymal stem cells (hWJ-MSCs) are an attractive source of stem cells for cell-based therapy, owing to their ability to undergo self-renewal and differentiate into all mesodermal, some neuroectodermal, and endodermal progenies, including hepatocytes. Herein, this study aimed to investigate the effects of sodium butyrate (NaBu), an epigenetic regulator that directly inhibits histone deacetylase, on hepatic endodermal lineage differentiation of hWJ-MSCs. NaBu, at 1 mM, optimally promoted endodermal differentiation of hWJ-MSCs, along with epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) supplementation. CXCR4, HNF3β, SOX17 (endodermal), and GATA6 (mesendodermal) mRNAs were also up-regulated (p < 0.001). Immunocytochemistry and a Western blot analysis of SOX17 and HNF3β confirmed that the 1 mM NaBu along with EGF and bFGF supplementation condition was appropriately pre-treated with hWJ-MSCs before hepatogenic differentiation. Furthermore, the hepatic differentiation medium with NaBu pre-treatment up-regulated hepatoblast (AFP and HNF3β) and hepatic (CK18 and ALB) markers, and increased the proportion of mature hepatocyte functions, including G6P, C/EBPα, and CYP2B6 mRNAs, glycogen storage and urea secretion. The hepatic differentiation medium with NaBu in the pre-treatment step can induce hWJ-MSC differentiation toward endodermal, hepatoblastic, and hepatic lineages. Therefore, the hepatic differentiation medium with NaBu pre-treatment for differentiating hWJ-MSCs could represent an alternative protocol for cell-based therapy and drug screening in clinical applications.

Exosomes Derived from Human Bone Marrow Mesenchymal Stem Cells Stimulated by Deferoxamine Accelerate Cutaneous Wound Healing by Promoting Angiogenesis

The exosomes are derived from mesenchymal stem cells (MSCs) and may be potentially used as an alternative for cell therapy, for treating diabetic wounds, and aid in angiogenesis. This study, aimed to investigate whether exosomes originated from bone marrow-derived MSCs (BMSCs) preconditioned by deferoxamine (DFO-Exos) exhibited superior proangiogenic property in wound repair and to explore the underlying mechanisms involved. Human umbilical vein endothelial cells (HUVECs) were used for assays involving cell proliferation, scratch wound healing, and tube formation. To test the effects in vivo, streptozotocin-induced diabetic rats were established. Two weeks after the procedure, histological analysis was used to measure wound-healing effects, and the neovascularization was evaluated as well. Our findings demonstrated that DFO-Exos activate the PI3K/AKT signaling pathway via miR-126 mediated PTEN downregulation to stimulate angiogenesis in vitro. This contributed to enhanced wound healing and angiogenesis in streptozotocin-induced diabetic rats in vivo. Our results suggest that, in cell-free therapies, exosomes derived from DFO preconditioned stem cells manifest increased proangiogenic ability.

Knockdown of FOXA2 enhances the osteogenic differentiation of bone marrow-derived mesenchymal stem cells partly via activation of the ERK signalling pathway

Forkhead box protein A2 (FOXA2) is a core transcription factor that controls cell differentiation and may have an important role in bone metabolism. However, the role of FOXA2 during osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) remains largely unknown. In this study, decreased expression of FOXA2 was observed during osteogenic differentiation of rat BMSCs (rBMSCs). FOXA2 knockdown significantly increased osteoblast-specific gene expression, the number of mineral deposits and alkaline phosphatase activity, whereas FOXA2 overexpression inhibited osteogenesis-specific activities. Moreover, extracellular signal-regulated protein kinase (ERK) signalling was upregulated following knockdown of FOXA2. The enhanced osteogenesis due to FOXA2 knockdown was partially rescued by an ERK inhibitor. Using a rat tibial defect model, a rBMSC sheet containing knocked down FOXA2 significantly improved bone healing. Collectively, these findings indicated that FOXA2 had an essential role in osteogenic differentiation of BMSCs, partly by activation of the ERK signalling pathway.

Comparison of the characteristics of canine adipose tissue-derived mesenchymal stem cells extracted from different sites and at different passage numbers

Mesenchymal stem cells (MSCs) have desirable characteristics for use in therapy in animal models and veterinary medicine, due to their capacity of inducing tissue regeneration and immunomodulation. The objective of this study was to evaluate the differences between canine adipose tissue-derived MSCs (AD-MSCs) extracted from subcutaneous (Sc) and visceral (Vs) sites. Surface antigenic markers, in vitro differentiation, and mineralized matrix quantification of AD-MSCs at different passages (P₄, P₆, and P₈) were studied. Immunophenotypic analysis showed that AD-MSCs from both sites were CD44+, CD90+, and CD45-. Moreover, they were able, in vitro, to differentiate into fat, cartilage, and bone. Sc-AD-MSCs preserve in vitro multipotentiality up to P₈, but Vs-AD-MSCs only tri-differentiated up to P₄. In addition, compared to Vs-AD-MSCs, Sc-AD-MSCs had greater capacity for in vitro mineralized matrix synthesis. In conclusion, Sc-AD-MSCs have advantages over Vs-AD-MSCs, as Sc AD-MSCs preserve multipotentiality during a greater number of passages, have more osteogenic potential, and require less invasive extraction.

Preconditioning influences mesenchymal stem cell properties in vitro and in vivo

Various diseases and toxic factors easily impair cellular and organic functions in mammals. Organ transplantation is used to rescue organ function, but is limited by scarce resources. Mesenchymal stem cell (MSC)-based therapy carries promising potential in regenerative medicine because of the self-renewal and multilineage potency of MSCs; however, MSCs may lose biological functions after isolation and cultivation for a long time in vitro. Moreover, after they are injected in vivo and migrate into the damaged tissues or organs, they encounter a harsh environment coupled with death signals due to the inadequate tensegrity structure between the cells and matrix. Preconditioning, genetic modification and optimization of MSC culture conditions are key strategies to improve MSC functions in vitro and in vivo, and all of these procedures will contribute to improving MSC transplantation efficacy in tissue engineering and regenerative medicine. Preconditioning with various physical, chemical and biological factors is possible to preserve the stemness of MSCs for further application in studies and clinical tests. In this review, we mainly focus on preconditioning and the corresponding mechanisms for improving MSC activities in vitro and in vivo; we provide a glimpse into the promotion of MSC-based cell therapy development for regenerative medicine. As a promising consequence, MSC transplantation can be applied for the treatment of some terminal diseases and can prolong the survival time of patients in the near future.

Historical Perspectives and Advances in Mesenchymal Stem Cell Research for the Treatment of Liver Diseases

Liver transplantation is the only effective therapy for patients with decompensated cirrhosis and fulminant liver failure. However, due to a shortage of donor livers and complications associated with immune suppression, there is an urgent need for new therapeutic strategies for patients with end-stage liver diseases. Given their unique function in self-renewal and differentiation potential, stem cells might be used to regenerate damaged liver tissue. Recent studies have shown that stem cell-based therapies can improve liver function in a mouse model of hepatic failure. Moreover, acellular liver scaffolds seeded with hepatocytes produced functional bioengineered livers for organ transplantation in preclinical studies. The therapeutic potential of stem cells or their differentiated progenies will depend on their capacity to differentiate into mature and functional cell types after transplantation. It will also be important to devise methods to overcome their genomic instability, immune reactivity, and tumorigenic potential. We review directions and advances in the use of mesenchymal stem cells and their derived hepatocytes for liver regeneration. We also discuss the potential applications of hepatocytes derived from human pluripotent stem cells and challenges to using these cells in treating end-stage liver disease.

Human umbilical cord-derived mesenchymal stem cells in acute liver injury: Hepatoprotective efficacy, subchronic toxicity, tumorigenicity, and biodistribution

Umbilical cord-derived mesenchymal stem cells (UC-MSCs) therapy might be an alternative to liver transplantation for acute or chronic liver injury. The aim of this study was to evaluate the efficacy of human UC-MSCs on carbon tetrachloride (CCl₄)-induced acute liver injury. In addition, its toxicity, tumorigenicity, and biodistribution were determined. Significant hepatoprotective effects of hUC-MSCs with decreased levels of hepatocellular necrosis and lobular neutrophilic infiltration were found. Regarding the safety of hUC-MSCs, no serious hUC-MSCs-related changes (body weight, food/water consumption, clinical symptom, urinalysis, hematology, clinical chemistry, organ weight, and histopathology) were observed in a 13-week subchronic toxicity study. In a 26-week tumorigenicity study, no mice developed tumor related to hUC-MSCs transplantation up to 1 × 10⁸ cells/kg. In particular, human mitochondrial sequence detection revealed that most hUC-MSCs were cleared from the major organs of the mice at 13 weeks after transplantation. There was no systemic toxicity or neoplastic finding either. Taken together, these results suggested that hUC-MSCs have great potential for future clinical treatment of acute liver disease.

Lacrimal Gland Repair Using Progenitor Cells

In humans, the lacrimal gland (LG) is the primary contributor to the aqueous layer of the tear film. Production of tears in insufficient quantity or of inadequate quality may lead to aqueous‐deficiency dry eye (ADDE). Currently there is no cure for ADDE. The development of strategies to reliably isolate LG stem/progenitor cells from the LG tissue brings great promise for the design of cell replacement therapies for patients with ADDE. We analyzed the therapeutic potential of epithelial progenitor cells (EPCPs) isolated from adult wild‐type mouse LGs by transplanting them into the LGs of TSP‐1^−/− mice, which represent a novel mouse model for ADDE. TSP‐1^−/− mice are normal at birth but progressively develop a chronic form of ocular surface disease, characterized by deterioration, inflammation, and secretory dysfunction of the lacrimal gland. Our study shows that, among c‐kit‐positive epithelial cell adhesion molecule (EpCAM⁺) populations sorted from mouse LGs, the c‐kit⁺dim/EpCAM⁺/Sca1⁻/CD34⁻/CD45⁻ cells have the hallmarks of an epithelial cell progenitor population. Isolated EPCPs express pluripotency factors and markers of the epithelial cell lineage Runx1 and EpCAM, and they form acini and ducts when grown in reaggregated three‐dimensional cultures. Moreover, when transplanted into injured or “diseased” LGs, they engraft into acinar and ductal compartments. EPCP‐injected TSP‐1^−/− LGs showed reduction of cell infiltration, differentiation of the donor EPCPs within secretory acini, and substantial improvement in LG structural integrity and function. This study provides the first evidence for the effective use of adult EPCP cell transplantation to rescue LG dysfunction in a model system. Stem Cells Translational Medicine2017;6:88–98

A new standardized clinical-grade protocol for banking human umbilical cord tissue cells

BACKGROUND

Mesenchymal stromal cells (MSCs) isolated from human umbilical cord tissue (UCT) can be considered the perfect candidates for cell-based therapies and regenerative medicine. UCT-derived MSCs can be cryogenically stored in cell banks and expanded as needed for therapeutic uses.

STUDY DESIGN AND METHODS

We developed a new method for UCT-MSC isolation, cryopreservation, and expansion, following all criteria required by a stem cell bank. UCT-MSCs were isolated either by manual dissociation (MM) or by a semiautomatic dissociation system (SAM). In both protocols UCTs were treated enzymatically using Type IV collagenase good manufacturing practices (GMP) graded and hyaluronidase (medicinal product). Isolated UCT-MSCs were cryopreserved and analyzed after thawing for phenotype; for proliferation rate; and for their osteogenic, adipogenic, and chondrogenic differentiation capabilities.

RESULTS

We found that SAM reduced the time of tissue enzyme exposure and enabled us to obtain a homogeneous single-cell suspension deprived of tissue fragments. The isolated cells in both groups showed high expression of MSC markers CD105, CD73, and CD90 and similar differentiation capabilities, phenotype, and proliferation potential. Moreover, the final yield of MSCs was comparable between the two techniques.

CONCLUSION

In this study, we have established a reliable and standardized protocol to isolate UCT-MSCs from UCT for cell banking purposes. Processing the whole umbilical tissue with GMP-graded enzymes using a semiautomatic dissociator allowed us to obtain a single-cell suspension product with a known number of isolated cells that can be cryopreserved right after isolation and thawed as needed for expansion and clinical use.

Role of CX3CR1 in repair of injured intestinal epithelial cells by bone marrow mesenchymal stem cells

AIM: To investigate the role of chemokine receptor CX3CR1 in the repair of injured intestinal epithelial cells by bone marrow mesenchymal stem cells (BM-MSCs).

METHODS: BM-MSCs were cultured and identified in vitro. Caco-2 cells were exposed to tumor necrosis factor alpha (TNF-α) to establish a cell model of injured intestinal epithelium. Cells were divided into six groups: BM-MSCs, Caco-2 cells, Caco-2 cells treated with TNF-α, co-cultured BM-MSCs and Caco-2 cells, co-cultured BM-MSCs and Caco-2 cells treated with TNF-α, and co-cultured BM-MSCs and Caco-2 cells treated with anti-CX3CR1 and TNF-α. The expression of tight junction proteins and mRNAs in Caco-2 cells, and CX3CR1 protein and mRNA in BM-MSCs was detected by immunofluorescence, Western blot and RT-PCR.

RESULTS: We selected 100 ng/mL TNF-α for 48 h to establish the injured model, because the expression of zonula occluden 1(ZO-1) and Occludin was reduced significantly at this time point (P < 0.05). The protein and mRNA levels of ZO-1, Occludin and CX3CR1 had no significant changes when BM-MSCs were co-cultured with untreated Caco-2 cells, but increased when BM-MSCs were co-cultured with injured Caco-2 cells (P < 0.05). When CX3CR1 was blocked, the protein and mRNA levels of ZO-1 and Occludin decreased significantly.

CONCLUSION: CX3CR1 participates in the repair of injured intestinal epithelial cells by BM-MSCs.

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

BACKROUND/OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Human mesenchymal stem cells - current trends and future prospective

Stem cells are cells specialized cell, capable of renewing themselves through cell division and can differentiate into multi-lineage cells. These cells are categorized as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and adult stem cells. Mesenchymal stem cells (MSCs) are adult stem cells which can be isolated from human and animal sources. Human MSCs (hMSCs) are the non-haematopoietic, multipotent stem cells with the capacity to differentiate into mesodermal lineage such as osteocytes, adipocytes and chondrocytes as well ectodermal (neurocytes) and endodermal lineages (hepatocytes). MSCs express cell surface markers like cluster of differentiation (CD)29, CD44, CD73, CD90, CD105 and lack the expression of CD14, CD34, CD45 and HLA (human leucocyte antigen)-DR. hMSCs for the first time were reported in the bone marrow and till now they have been isolated from various tissues, including adipose tissue, amniotic fluid, endometrium, dental tissues, umbilical cord and Wharton's jelly which harbours potential MSCs. hMSCs have been cultured long-term in specific media without any severe abnormalities. Furthermore, MSCs have immunomodulatory features, secrete cytokines and immune-receptors which regulate the microenvironment in the host tissue. Multilineage potential, immunomodulation and secretion of anti-inflammatory molecules makes MSCs an effective tool in the treatment of chronic diseases. In the present review, we have highlighted recent research findings in the area of hMSCs sources, expression of cell surface markers, long-term in vitro culturing, in vitro differentiation potential, immunomodulatory features, its homing capacity, banking and cryopreservation, its application in the treatment of chronic diseases and its use in clinical trials.

The multiple functional roles of mesenchymal stem cells in participating in treating liver diseases

Mesenchymal stem cells (MSCs) are a group of stem cells derived from the mesodermal mesenchyme. MSCs can be obtained from a variety of tissues, including bone marrow, umbilical cord tissue, umbilical cord blood, peripheral blood and adipose tissue. Under certain conditions, MSCs can differentiate into many cell types both in vitro and in vivo, including hepatocytes. To date, four main strategies have been developed to induce the transdifferentiation of MSCs into hepatocytes: addition of chemical compounds and cytokines, genetic modification, adjustment of the micro-environment and alteration of the physical parameters used for culturing MSCs. Although the phenomenon of transdifferentiation of MSCs into hepatocytes has been described, the detailed mechanism is far from clear. Generally, the mechanism is a cascade reaction whereby stimulating factors activate cellular signalling pathways, which in turn promote the production of transcription factors, leading to hepatic gene expression. Because MSCs can give rise to hepatocytes, they are promising to be used as a new treatment for liver dysfunction or as a bridge to liver transplantation. Numerous studies have confirmed the therapeutic effects of MSCs on hepatic fibrosis, cirrhosis and other liver diseases, which may be related to the differentiation of MSCs into functional hepatocytes. In addition to transdifferentiation into hepatocytes, when MSCs are used to treat liver disease, they may also inhibit hepatocellular apoptosis and secrete various bioactive molecules to promote liver regeneration. In this review, the capacity and molecular mechanism of MSC transdifferentiation, and the therapeutic effects of MSCs on liver diseases are thoroughly discussed.

Role of liver stem cells in hepatocarcinogenesis

Liver cancer is an aggressive disease with a high mortality rate. Management of liver cancer is strongly dependent on the tumor stage and underlying liver disease. Unfortunately, most cases are discovered when the cancer is already advanced, missing the opportunity for surgical resection. Thus, an improved understanding of the mechanisms responsible for liver cancer initiation and progression will facilitate the detection of more reliable tumor markers and the development of new small molecules for targeted therapy of liver cancer. Recently, there is increasing evidence for the “cancer stem cell hypothesis”, which postulates that liver cancer originates from the malignant transformation of liver stem/progenitor cells (liver cancer stem cells). This cancer stem cell model has important significance for understanding the basic biology of liver cancer and has profound importance for the development of new strategies for cancer prevention and treatment. In this review, we highlight recent advances in the role of liver stem cells in hepatocarcinogenesis. Our review of the literature shows that identification of the cellular origin and the signaling pathways involved is challenging issues in liver cancer with pivotal implications in therapeutic perspectives. Although the dedifferentiation of mature hepatocytes/cholangiocytes in hepatocarcinogenesis cannot be excluded, neoplastic transformation of a stem cell subpopulation more easily explains hepatocarcinogenesis. Elimination of liver cancer stem cells in liver cancer could result in the degeneration of downstream cells, which makes them potential targets for liver cancer therapies. Therefore, liver stem cells could represent a new target for therapeutic approaches to liver cancer in the near future.