The generation of hepatocytes from mesenchymal stem cells and engraftment into murine liver

Fasudil and viscosity of gelatin promote hepatic differentiation by regulating organelles in human umbilical cord matrix-mesenchymal stem cells

BACKGROUND

Human mesenchymal stem cells originating from umbilical cord matrix are a promising therapeutic resource, and their differentiated cells are spotlighted as a tissue regeneration treatment. However, there are limitations to the medical use of differentiated cells from human umbilical cord matrix-mesenchymal stem cells (hUCM-MSCs), such as efficient differentiation methods.

METHODS

To effectively differentiate hUCM-MSCs into hepatocyte-like cells (HLCs), we used the ROCK inhibitor, fasudil, which is known to induce endoderm formation, and gelatin, which provides extracellular matrix to the differentiated cells. To estimate a differentiation efficiency of early stage according to combination of gelatin and fasudil, transcription analysis was conducted. Moreover, to demonstrate that organelle states affect differentiation, we performed transcription, tomographic, and mitochondrial function analysis at each stage of hepatic differentiation. Finally, we evaluated hepatocyte function based on the expression of mRNA and protein, secretion of albumin, and activity of CYP3A4 in mature HLCs.

RESULTS

Fasudil induced endoderm-related genes (GATA4, SOX17, and FOXA2) in hUCM-MSCs, and it also induced lipid droplets (LDs) inside the differentiated cells. However, the excessive induction of LDs caused by fasudil inhibited mitochondrial function and prevented differentiation into hepatoblasts. To prevent the excessive LDs formation, we used gelatin as a coating material. When hUCM-MSCs were induced into hepatoblasts with fasudil on high-viscosity (1%) gelatin-coated dishes, hepatoblast-related genes (AFP and HNF4A) showed significant upregulation on high-viscosity gelatin-coated dishes compared to those treated with low-viscosity (0.1%) gelatin. Moreover, other germline cell fates, such as ectoderm and mesoderm, were repressed under these conditions. In addition, LDs abundance was also reduced, whereas mitochondrial function was increased. On the other hand, unlike early stage of the differentiation, low viscosity gelatin was more effective in generating mature HLCs. In this condition, the accumulation of LDs was inhibited in the cells, and mitochondria were activated. Consequently, HLCs originated from hUCM-MSCs were genetically and functionally more matured in low-viscosity gelatin.

CONCLUSIONS

This study demonstrated an effective method for differentiating hUCM-MSCs into hepatic cells using fasudil and gelatin of varying viscosities. Moreover, we suggest that efficient hepatic differentiation and the function of hepatic cells differentiated from hUCM-MSCs depend not only on genetic changes but also on the regulation of organelle states.

Approaching Thrombospondin-1 as a Potential Target for Mesenchymal Stromal Cells to Support Liver Regeneration after Partial Hepatectomy in Mouse and Humans

Extended liver resection carries the risk of post-surgery liver failure involving thrombospondin-1-mediated aggravation of hepatic epithelial plasticity and function. Mesenchymal stromal cells (MSCs), by interfering with thrombospondin-1 (THBS1), counteract hepatic dysfunction, though the mechanisms involved remain unknown. Herein, two-thirds partial hepatectomy in mice increased hepatic THBS1, downstream transforming growth factor-β3, and perturbation of liver tissue homeostasis. All these events were ameliorated by hepatic transfusion of human bone marrow-derived MSCs. Treatment attenuated platelet and macrophage recruitment to the liver, both major sources of THBS1. By mitigating THBS1, MSCs muted surgery-induced tissue deterioration and dysfunction, and thus supported post-hepatectomy regeneration. After liver surgery, patients displayed increased tissue THBS1, which is associated with functional impairment and may indicate a higher risk of post-surgery complications. Since liver dysfunction involving THBS1 improves with MSC treatment in various animal models, it seems feasible to also modulate THBS1 in humans to impede post-surgery acute liver failure.

Trends of regenerative tissue engineering for oral and maxillofacial reconstruction in veterinary medicine

Oral and maxillofacial (OMF) defects are not limited to humans and are often encountered in other species. Reconstructing significant tissue defects requires an excellent strategy for efficient and cost-effective treatment. In this regard, tissue engineering comprising stem cells, scaffolds, and signaling molecules is emerging as an innovative approach to treating OMF defects in veterinary patients. This review presents a comprehensive overview of OMF defects and tissue engineering principles to establish proper treatment and achieve both hard and soft tissue regeneration in veterinary practice. Moreover, bench-to-bedside future opportunities and challenges of tissue engineering usage are also addressed in this literature review.

Stem cell-derived hepatocyte therapy using versatile biomimetic nanozyme incorporated nanofiber-reinforced decellularized extracellular matrix hydrogels for the treatment of acute liver failure

Reactive oxygen species (ROS)-associated oxidative stress, inflammation storm, and massive hepatocyte necrosis are the typical manifestations of acute liver failure (ALF), therefore specific therapeutic interventions are essential for the devastating disease. Here, we developed a platform consisting of versatile biomimetic copper oxide nanozymes (Cu NZs)-loaded PLGA nanofibers (Cu NZs@PLGA nanofibers) and decellularized extracellular matrix (dECM) hydrogels for delivery of human adipose-derived mesenchymal stem/stromal cells-derived hepatocyte-like cells (hADMSCs-derived HLCs) (HLCs/Cu NZs@fiber/dECM). Cu NZs@PLGA nanofibers could conspicuously scavenge excessive ROS at the early stage of ALF, and reduce the massive accumulation of pro-inflammatory cytokines, herein efficiently preventing the deterioration of hepatocytes necrosis. Moreover, Cu NZs@PLGA nanofibers also exhibited a cytoprotection effect on the transplanted HLCs. Meanwhile, HLCs with hepatic-specific biofunctions and anti-inflammatory activity acted as a promising alternative cell source for ALF therapy. The dECM hydrogels further provided the desirable 3D environment and favorably improved the hepatic functions of HLCs. In addition, the pro-angiogenesis activity of Cu NZs@PLGA nanofibers also facilitated the integration of the whole implant with the host liver. Hence, HLCs/Cu NZs@fiber/dECM performed excellent synergistic therapeutic efficacy on ALF mice. This strategy using Cu NZs@PLGA nanofiber-reinforced dECM hydrogels for HLCs in situ delivery is a promising approach for ALF therapy and shows great potential for clinical translation.

Therapeutic Efficiency of Nasal Mucosa-Derived Ectodermal Mesenchymal Stem Cells in Rats with Acute Hepatic Failure

Background

Liver transplantation is limited by the insufficiency of liver organ donors when treating end-stage liver disease or acute liver failure (ALF). Ectodermal mesenchymal stem cells (EMSCs) derived from nasal mucosa have emerged as an alternative cell-based therapy. However, the role of EMSCs in acute liver failure remains unclear.

Methods

EMSCs were obtained from the nasal mucosa tissue of rats. First, EMSCs were seeded on the gelatin-chitosan scaffolds, and the biocompatibility was evaluated. Next, the protective effects of EMSCs were investigated in carbon tetrachloride- (CCl₄-) induced ALF rats. Finally, we applied an indirect coculture system to analyze the paracrine effects of EMSCs on damaged hepatocytes. A three-step nontransgenic technique was performed to transform EMSCs into hepatocyte-like cells (HLCs) in vitro.

Results

EMSCs exhibited a similar phenotype to other mesenchymal stem cells along with self-renewal and multilineage differentiation capabilities. EMSC-seeded gelatin-chitosan scaffolds can increase survival rates and ameliorate liver function and pathology of ALF rat models. Moreover, transplanted EMSCs can secrete paracrine factors to promote hepatocyte regeneration, targeted migration, and transdifferentiate into HLCs in response to the liver's microenvironment, which will then repair or replace the damaged hepatocytes. Similar to mature hepatocytes, HLCs generated from EMSCs possess functions of expressing specific hepatic markers, storing glycogen, and producing urea.

Conclusions

These results confirmed the feasibility of EMSCs in acute hepatic failure treatment. To our knowledge, this is the first time that EMSCs are used in the therapy of liver diseases. EMSCs are expected to be a novel and promising cell source in liver tissue engineering.

Comparing the Therapeutic Mechanism and Immune Response of Human and Mouse Mesenchymal Stem Cells in Immunocompetent Mice With Acute Liver Failure

Current mesenchymal stem cell (MSC) research is based on xenotransplantation of human MSCs (hMSCs) in immunodeficient mice and cannot comprehensively predict MSC repair mechanisms and immunomodulatory effects in damaged tissue. This study compared the therapeutic efficacy, mechanisms, and immune response of hMSCs and mouse MSCs (mMSCs) in immunocompetent mice with CCl4-induced acute liver failure. mMSCs maintained F4/80+ hepatic macrophage recruitment into the damaged liver region, increased IL-6-dependent hepatocyte proliferation, and reduced inflammatory TNF-α cytokine secretion. Moreover, mMSCs reduced α-SMA+ myofibroblast activation by lowering TGF-β1 accumulation in damaged liver tissue. In contrast, hMSCs lowered TNF-α and TGF-β1 by reducing the recruitment of F4/80+ hepatic macrophages, which lost the ability to remove debris and induce IL-6 liver regeneration. Finally, hMSCs, but not mMSCs, caused a significant antibody response in immunocompetent mice; therefore, hMSCs are unsuitable for long-term MSC studies. This comparative study provides reference information for further MSC studies of immunocompetent mice.

Human Mesenchymal Stromal Cells Resolve Lipid Load in High Fat Diet-Induced Non-Alcoholic Steatohepatitis in Mice by Mitochondria Donation

Mesenchymal stromal cells (MSC) increasingly emerge as an option to ameliorate non-alcoholic steatohepatitis (NASH), a serious disease, which untreated may progress to liver cirrhosis and cancer. Before clinical translation, the mode of action of MSC needs to be established. Here, we established NASH in an immune-deficient mouse model by feeding a high fat diet. Human bone-marrow-derived MSC were delivered to the liver via intrasplenic transplantation. As verified by biochemical and image analyses, human mesenchymal stromal cells improved high-fat-diet-induced NASH in the mouse liver by decreasing hepatic lipid content and inflammation, as well as by restoring tissue homeostasis. MSC-mediated changes in gene expression indicated the switch from lipid storage to lipid utilization. It was obvious that host mouse hepatocytes harbored human mitochondria. Thus, it is feasible that resolution of NASH in mouse livers involved the donation of human mitochondria to the mouse hepatocytes. Therefore, human MSC might provide oxidative capacity for lipid breakdown followed by restoration of metabolic and tissue homeostasis.

Ectopic expansion and vascularization of engineered hepatic tissue based on heparinized acellular liver matrix and mesenchymal stromal cell spheroids

Engineered liver organogenesis is not yet a viable therapeutic option, but ectopic liver histogenesis may be possible. Accumulating evidence has suggested that cell-cell interactions and cell-matrix interactions play an important role in determining the properties of engineered hepatic tissue in vitro and in vivo. In the current study, we utilized heparinized decellularized liver scaffolds and bone marrow mesenchymal stromal cell spheroids to fabricate engineered hepatic tissue, which was subsequently implanted into the omentum of Sprague-Dawley rats with or without liver injury. The survival, liver-specific functions, differentiation level and regenerative potential of the implanted hepatocyte-like cells in this ectopic liver system were evaluated, together with the vascularization status and therapeutic potential of the engineered hepatic tissue. We demonstrated that these hepatic grafts could survive and possess hepatocyte specific function in this ectopic liver system but could also efficiently anastomose with host vascular networks. Furthermore, we found that hepatocyte-like cells within grafts expanded more than 9-fold over the course of 4 weeks in immunocompetent rats with injured livers. Immunostaining revealed that these hepatocyte-like cells could self-organize into cord-like structures in vivo. In addition, these hepatic grafts exhibited therapeutic potential in liver injury induced by CCl₄. To our knowledge, this is the first report demonstrating the generation of long-term vascularized hepatic parenchyma at ectopic sites based on decellularized liver scaffolds and stem cells. These results provide an economic and feasible method for engineering hepatic tissue from construction to transplantation. This methodology may be applicable in clinical medicine, especially metabolic liver diseases. STATEMENT OF SIGNIFICANCE: In this manuscript, we presented an optimized method for the hepatic engineered tissue (HET) from construction to transplantation. The core of this method is utilizing the combination of heparinized decellularized liver scaffolds and stem cell spheroids, which could provide necessary cell-cell and cell-extracellular matrix interactions for HET in vitro and in vivo. We proved that these hepatic grafts could possess hepatocyte specific function and exhibit strong proliferative activity in ectopic liver system, but also able to anastomose with the host vascular networks efficiently and be compatible with the host immune system. This methodology may be possible one day to apply in clinical medicine, especially metabolic liver diseases.

Mesenchymal stromal cells mitigate liver damage after extended resection in the pig by modulating thrombospondin-1/TGF-β

Post-surgery liver failure is a serious complication for patients after extended partial hepatectomies (ePHx). Previously, we demonstrated in the pig model that transplantation of mesenchymal stromal cells (MSC) improved circulatory maintenance and supported multi-organ functions after 70% liver resection. Mechanisms behind the beneficial MSC effects remained unknown. Here we performed 70% liver resection in pigs with and without MSC treatment, and animals were monitored for 24 h post surgery. Gene expression profiles were determined in the lung and liver. Bioinformatics analysis predicted organ-independent MSC targets, importantly a role for thrombospondin-1 linked to transforming growth factor-β (TGF-β) and downstream signaling towards providing epithelial plasticity and epithelial-mesenchymal transition (EMT). This prediction was supported histologically and mechanistically, the latter with primary hepatocyte cell cultures. MSC attenuated the surgery-induced increase of tissue damage, of thrombospondin-1 and TGF-β, as well as of epithelial plasticity in both the liver and lung. This suggests that MSC ameliorated surgery-induced hepatocellular stress and EMT, thus supporting epithelial integrity and facilitating regeneration. MSC-derived soluble factor(s) did not directly interfere with intracellular TGF-β signaling, but inhibited thrombospondin-1 secretion from thrombocytes and non-parenchymal liver cells, therewith obviously reducing the availability of active TGF-β.

Inflammatory Regulation by TNF-α-Activated Adipose-Derived Stem Cells in the Human Bladder Cancer Microenvironment

Mesenchymal stem cells (MSCs), such as adipose-derived stem cells (ADSCs), have the most impressive ability to reduce inflammation through paracrine growth factors and cytokines that participate in inflammation. Tumor necrosis factor (TNF)-α bioactivity is a prerequisite in several inflammatory and autoimmune disease models. This study investigated the effects of TNF-α stimulate on ADSCs in the tumor microenvironment. The RNAseq analysis and cytokines assay demonstrated that TNF-α stimulated ADSCs proliferation and pro-inflammatory genes that correlated to leukocytes differentiation were upregulated. We found that upregulation of TLR2 or PTGS2 toward to IRF7 gene-associated with immunomodulatory and antitumor pathway under TNF-α treatment. In TNF-α-treated ADSCs cultured with the bladder cancer (BC) cell medium, the results showed that apoptosis ratio and OCT-4 and TLR2 genes which maintained the self-renewal ability of stem cells were decreased. Furthermore, the cell survival regulation genes including TRAF1, NF-kB, and IRF7 were upregulated in TNF-α-treated ADSCs. Additionally, these genes have not been upregulated in BC cell medium. A parallel study showed that tumor progressing genes were downregulated in TNF-α-treated ADSCs. Hence, the study suggests that TNF-α enhances the immunomodulatory potential of ADSCs during tumorigenesis and provides insight into highly efficacious MSC-based therapeutic options for BC.

Mitochondrial Transfer by Human Mesenchymal Stromal Cells Ameliorates Hepatocyte Lipid Load in a Mouse Model of NASH

Mesenchymal stromal cell (MSC) transplantation ameliorated hepatic lipid load; tissue inflammation; and fibrosis in rodent animal models of non-alcoholic steatohepatitis (NASH) by as yet largely unknown mechanism(s). In a mouse model of NASH; we transplanted bone marrow-derived MSCs into the livers; which were analyzed one week thereafter. Combined metabolomic and proteomic data were applied to weighted gene correlation network analysis (WGCNA) and subsequent identification of key drivers. Livers were analyzed histologically and biochemically. The mechanisms of MSC action on hepatocyte lipid accumulation were studied in co-cultures of hepatocytes and MSCs by quantitative image analysis and immunocytochemistry. WGCNA and key driver analysis revealed that NASH caused the impairment of central carbon; amino acid; and lipid metabolism associated with mitochondrial and peroxisomal dysfunction; which was reversed by MSC treatment. MSC improved hepatic lipid metabolism and tissue homeostasis. In co-cultures of hepatocytes and MSCs; the decrease of lipid load was associated with the transfer of mitochondria from the MSCs to the hepatocytes via tunneling nanotubes (TNTs). Hence; MSCs may ameliorate lipid load and tissue perturbance by the donation of mitochondria to the hepatocytes. Thereby; they may provide oxidative capacity for lipid breakdown and thus promote recovery from NASH-induced metabolic impairment and tissue injury.

Novel alternative transplantation therapy for orthotopic liver transplantation in liver failure: A systematic review

BACKGROUND

Orthotopic liver transplantation (OLT) is the only treatment for end-stage liver failure; however, graft shortage impedes its applicability. Therefore, studies investigating alternative therapies are plenty. Nevertheless, no study has comprehensively analyzed these therapies from different perspectives.

AIM

To summarize the current status of alternative transplantation therapies for OLT and to support future research.

METHODS

A systematic literature search was performed using PubMed, Cochrane Library and EMBASE for articles published between January 2010 and 2018, using the following MeSH terms: [(liver transplantation) AND cell] OR [(liver transplantation) AND differentiation] OR [(liver transplantation) AND organoid] OR [(liver transplantation) AND xenotransplantation]. Various types of studies describing therapies to replace OLT were retrieved for full-text evaluation. Among them, we selected articles including in vivo transplantation.

RESULTS

A total of 89 studies were selected. There are three principle forms of treatment for liver failure: Xeno-organ transplantation, scaffold-based transplantation, and cell transplantation. Xeno-organ transplantation was covered in 14 articles, scaffold-based transplantation was discussed in 22 articles, and cell transplantation was discussed in 53 articles. Various types of alternative therapies were discussed: Organ liver, 25 articles; adult hepatocytes, 31 articles; fetal hepatocytes, three articles; mesenchymal stem cells (MSCs), 25 articles; embryonic stem cells, one article; and induced pluripotent stem cells, three articles and other sources. Clinical applications were discussed in 12 studies: Cell transplantation using hepatocytes in four studies, five studies using umbilical cord-derived MSCs, three studies using bone marrow-derived MSCs, and two studies using hematopoietic stem cells.

CONCLUSION

The clinical applications are present only for cell transplantation. Scaffold-based transplantation is a comprehensive treatment combining organ and cell transplantations, which warrants future research to find relevant clinical applications.

Different approaches for transformation of mesenchymal stem cells into hepatocyte-like cells

Due to the prominent role of the liver in the body and detoxification, its functionality can be affected in an irreversible manner by diseases. This phenomenon renders the liver to stop working, leading to morbidity and mortality. Therefore, liver transplantation is the only way to tackle this issue.In order to compensate for the lack of adequate healthy liver tissue for transplantation, therapeutic approaches such as hepatocyte transplantation have been proposed as an alternative. Recognizing the fact that mesenchymal stem cells are adult stem cells with the capacity to differentiate into several cell types, different methods have been invented to produce hepatocyte-like cells from mesenchymal stem cells. They can be divided into three main categories, such as addition of cytokines and growth factors, genetic modifications, and adjustment of microenvironment as well as physical parameters.In this review, we attempted to introduce diverse efficient methods for differentiating mesenchymal stem cells and their capability for transformation into hepatocyte-like cells.

Human skin-derived ABCB5+ stem cell injection improves liver disease parameters in Mdr2KO mice

Although liver transplantation is a potential effective cure for patients with end-stage liver diseases, this strategy has several drawbacks including high cost, long waiting list, and limited availability of liver organs. Therefore, stem cell-based therapy is presented as an alternative option, which showed promising results in animal models of acute and chronic liver injuries. ABCB5+ cells isolated from skin dermis represent an easy accessible and expandable source of homogenous stem cell populations. In addition, ABCB5+ cells showed already promising results in the treatment of corneal and skin injury. To date, the effect of these cells on liver injury is still unknown. In the current study, sixteen weeks old Mdr2KO mice were i.v. injected with 500,000 ABCB5+ cells using different experimental setups. The effects of cellular therapy on inflammation, fibrosis, apoptosis, and proliferation were analyzed in the collected liver tissues. Toxicity of ABCB5+ cells was additionally investigated in mice with partial liver resection. In vitro, the fibrosis- and inflammatory-modulating effects of supernatant from ABCB5+ cells were examined in the human hepatic stellate cell line (LX-2). Cell injections into fibrotic Mdr2KO mice as well as into mice upon partial liver resection have no signs of toxicity with regard to cell transformation, cellular damage, fibrosis or inflammation as compared to controls. We next investigated the effects of ABCB5+ cells on established biliary liver fibrosis in the Mdr2KO mice. ABCB5+ cells to some extent influenced the shape of the liver inflammatory response and significantly reduced the amount of collagen deposition, as estimated from quantification of sirius red staining. Furthermore, reduced apoptosis and enhanced death compensatory proliferation resulted from ABCB5+ cell transformation. The stem cells secreted several trophic factors that activated TGF-β family signaling in cultured LX-2 hepatic stellate cells (HSCs), therewith shaping cell fate to an αSMAhigh, Vimentinlow phenotype. Taken together, ABCB5+ cells can represent a safe and feasible strategy to support liver regeneration and to reduce liver fibrosis in chronic liver diseases.

Hydrogels for Liver Tissue Engineering

Bioengineered livers are promising in vitro models for drug testing, toxicological studies, and as disease models, and might in the future be an alternative for donor organs to treat end-stage liver diseases. Liver tissue engineering (LTE) aims to construct liver models that are physiologically relevant. To make bioengineered livers, the two most important ingredients are hepatic cells and supportive materials such as hydrogels. In the past decades, dozens of hydrogels have been developed to act as supportive materials, and some have been used for in vitro models and formed functional liver constructs. However, currently none of the used hydrogels are suitable for in vivo transplantation. Here, the histology of the human liver and its relationship with LTE is introduced. After that, significant characteristics of hydrogels are described focusing on LTE. Then, both natural and synthetic materials utilized in hydrogels for LTE are reviewed individually. Finally, a conclusion is drawn on a comparison of the different hydrogels and their characteristics and ideal hydrogels are proposed to promote LTE.

Long noncoding RNA ANCR inhibits the differentiation of mesenchymal stem cells toward definitive endoderm by facilitating the association of PTBP1 with ID2

The generation of definitive endoderm (DE) cells in sufficient numbers is a prerequisite for cell-replacement therapy for liver and pancreatic diseases. Previously, we reported that human adipose-derived mesenchymal stem cells (hAMSCs) can be induced to DE lineages and subsequent functional cells. Clarifying the regulatory mechanisms underlying the fate conversion from hAMSCs to DE is helpful for developing new strategies to improve the differentiation efficiency from hAMSCs to DE organs. Long noncoding RNAs (lncRNAs) have been shown to play pivotal roles in developmental processes, including cell fate determination and differentiation. In this study, we profiled the expression changes of lncRNAs and found that antidifferentiation noncoding RNA (ANCR) was downregulated during the differentiation of both hAMSCs and embryonic stem cells (ESCs) to DE cells. ANCR knockdown resulted in the elevated expression of DE markers in hAMSCs, but not in ESCs. ANCR overexpression reduced the efficiency of hAMSCs to differentiate into DE cells. Inhibitor of DNA binding 2 (ID2) was notably downregulated after ANCR knockdown. ID2 knockdown enhanced DE differentiation, whereas overexpression of ID2 impaired this process in hAMSCs. ANCR interacts with RNA-binding polypyrimidine tract-binding protein 1 (PTBP1) to facilitate its association with ID2 mRNA, leading to increased ID2 mRNA stability. Thus, the ANCR/PTBP1/ID2 network restricts the differentiation of hAMSCs toward DE. Our work highlights the inherent discrepancies between hAMSCs and ESCs. Defining hAMSC-specific signaling pathways might be important for designing optimal differentiation protocols for directing hAMSCs toward DE.

Microgravity-induced hepatogenic differentiation of rBMSCs on board the SJ-10 satellite

Bone marrow-derived mesenchymal stem cells (BMSCs) are able to differentiate into functional hepatocytelike cells, which are expected to serve as a potential cell source in regenerative medicine, tissue engineering, and clinical treatment of liver injury. Little is known about whether and how space microgravity is able to direct the hepatogenic differentiation of BMSCs in the actual space microenvironment. In this study, we examined the effects of space microgravity on BMSC hepatogenic differentiation on board the SJ-10 Recoverable Scientific Satellite. Rat BMSCs were cultured and induced in hepatogenic induction medium for 3 and 10 d in custom-made space cell culture hardware. Cell growth was monitored periodically in orbit, and the fixed cells and collected supernatants were retrieved back to the Earth for further analyses. Data indicated that space microgravity improves the differentiating capability of the cells by up-regulating hepatocyte-specific albumin and cytokeratin 18. The resulting cells tended to be maturated, with an in-orbit period of up to 10 d. In space, mechanosensitive molecules of β1-integrin, β-actin, α-tubulin, and Ras homolog gene family member A presented enhanced expression, whereas those of cell-surface glycoprotein CD44, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, vinculin, cell division control protein 42 homolog, and Rho-associated coiled-coil kinase yielded reduced expression. Also observed in space were the depolymerization of actin filaments and the accumulation of microtubules and vimentin through the altered expression and location of focal adhesion complexes, Rho guanosine 5'-triphosphatases, as well as the enhanced exosome-mediated mRNA transfer. This work furthers the understanding of the underlying mechanisms of space microgravity in directing hepatogenic differentiation of BMSCs.-Lü, D., Sun, S., Zhang, F., Luo, C., Zheng, L., Wu, Y., Li, N., Zhang, C., Wang, C., Chen, Q., Long, M. Microgravity-induced hepatogenic differentiation of rBMSCs on board the SJ-10 satellite.

Progress in mesenchymal stem cell-based therapy for acute liver failure

Acute liver failure is a life-threatening clinical syndrome characterized by rapid development of hepatocellular necrosis leading to high mortality and resource costs. Numerous treatment strategies for acute liver failure simply prevent complications and decelerate disease progression. The only curative treatment for acute liver failure is liver transplantation, but there are many restrictions on the application of liver transplantation. In recent years, a growing number of studies have shown that stem cells can effectively treat acute liver failure. Several types of stem cells have been used to study liver diseases; mesenchymal stem cells are most commonly used because they are easy to obtain and present no ethical problems. The aims of this article are to review the current knowledge regarding therapeutic mechanisms of mesenchymal stem cells in acute liver failure, to discuss recent advancements in preclinical and clinical studies in the treatment of mesenchymal stem cells, and to summarize the methodological improvement of mesenchymal stem cell transplantation in treating liver failure.

Critical Role of Tumor Necrosis Factor Signaling in Mesenchymal Stem Cell-Based Therapy for Autoimmune and Inflammatory Diseases

Mesenchymal stem cells (MSCs) have been broadly used as a therapy for autoimmune disease in both animal models and clinical trials. MSCs inhibit T effector cells and many other immune cells, while activating regulatory T cells, thus reducing the production of pro-inflammatory cytokines, including tumor necrosis factor (TNF), and repressing inflammation. TNF can modify the MSC effects via two TNF receptors, i.e., TNFR1 in general mediates pro-inflammatory effects and TNFR2 mediates anti-inflammatory effects. In the central nervous system, TNF signaling plays a dual role, which enhances inflammation via TNFR1 on immune cells while providing cytoprotection via TNFR2 on neural cells. In addition, the soluble form of TNFR1 and membrane-bound TNF also participate in the regulation to fine-tune the functions of target cells. Other factors that impact TNF signaling and MSC functions include the gender of the host, disease course, cytokine concentrations, and the length of treatment time. This review will introduce the fascinating progress in this aspect of research and discuss remaining questions and future perspectives.

Humanized mice reveal an essential role for human hepatocytes in the development of the liver immune system

The liver is an immunological organ with a distinct immune cell profile. Although the composition and function of liver immune cells have been widely investigated, the mechanisms regulating the development and homeostasis of the specialized immune system, especially in humans, remain largely unknown. Herein, we address this question in humanized mice (hu-mice) that were constructed by transplantation of human fetal thymus and CD34+ hematopoietic stem/progenitor cells in immunodeficient mice with or without autologous human hepatocyte engraftment. Although the levels of human immune cell reconstitution in peripheral blood and spleen were comparable between hu-mice with and without human hepatocyte engraftment, the former group showed that human immune cell reconstitution in the liver was significantly improved. Notably, human immune cells, including Kupffer cells, dendritic cells and natural killer cells, were shown to be closely colocalized with human hepatocytes in the liver. Human hepatocytes engrafted in the mouse liver were found to produce IL-3, IL-15, GM-CSF, M-CSF, MCP-1, CXCL-1 and CXCL-10, which are known to be important for immune cell development, differentiation, tissue migration and retention, and have no or poor cross-reaction between humans and mice. Furthermore, human hepatocytes were able to support human immune cell survival and expansion in an in vitro co-culture assay. This study demonstrates an essential role for hepatocytes in the development and maintenance of the liver immune cell profile. The hu-mouse model with human autologous immune cell and hepatocyte reconstitution has potential for use in studies of the pathogenesis of liver immune disorders such as hepatotropic virus infections.

Differentiation of umbilical cord derived mesenchymal stem cells to hepatocyte cells by transfection of miR-106a, miR-574-3p, and miR-451

Studying the profile of micro RNAs (miRs) elucidated the highest expressed miRs in hepatic differentiation. In this study, we investigated to clarify the role of three embryonic overexpressed miRs (miR-106a, miR-574-3p and miR-451) during hepatic differentiation of human umbilical cord derived mesenchymal stem cells (UC-MSCs). We furthermore, aimed to explore whether overexpression of any of these miRs alone is sufficient to induce the differentiation of the UC-MSCs into hepatocyte-like cells. UC-MSCs were transfected either alone or together with miR-106a, miR-574-3p and miR-451 and their potential hepatic differentiation and alteration in gene expression profile, morphological changes and albumin secretion ability were investigated. We found that up-regulation of any of these three miRs alone cannot induce expression of all hepatic specific genes. Transfection of each miR alone, led to Sox17, FoxA2 expression that are related to initiation step of hepatic differentiation. However, concurrent ectopic overexpression of three miRs together can induce UC-MSCs differentiation into functionally mature hepatocytes. These results show that miRs have the capability to directly convert UC-MSCs to a hepatocyte phenotype in vitro.

Hepatocyte transplantation and advancements in alternative cell sources for liver-based regenerative medicine

Human hepatocyte transplantation has been actively perused as an alternative to liver replacement for acute liver failure and liver-based metabolic defects. Current challenges in this field include a limited cell source, reduced cell viability following cryopreservation and poor engraftment of cells into the recipient liver with consequent limited life span. As a result, alternative stem cell sources such as pluripotent stem cells, fibroblasts, hepatic progenitor cells, amniotic epithelial cells and mesenchymal stem/stromal cells (MSCs) can be used to generate induced hepatocyte like cells (HLC) with each technique exhibiting advantages and disadvantages. HLCs may have comparable function to primary human hepatocytes and could offer patient-specific treatment. However, long-term functionality of transplanted HLCs and the potential oncogenic risks of using stem cells have yet to be established. The immunomodulatory effects of MSCs are promising, and multiple clinical trials are investigating their effect in cirrhosis and acute liver failure. Here, we review the current status of hepatocyte transplantation, alternative cell sources to primary human hepatocytes and their potential in liver regeneration. We also describe recent clinical trials using hepatocytes derived from stem cells and their role in improving the phenotype of several liver diseases.

Liver cell therapy: is this the end of the beginning?

The prevalence of liver diseases is increasing globally. Orthotopic liver transplantation is widely used to treat liver disease upon organ failure. The complexity of this procedure and finite numbers of healthy organ donors have prompted research into alternative therapeutic options to treat liver disease. This includes the transplantation of liver cells to promote regeneration. While successful, the routine supply of good quality human liver cells is limited. Therefore, renewable and scalable sources of these cells are sought. Liver progenitor and pluripotent stem cells offer potential cell sources that could be used clinically. This review discusses recent approaches in liver cell transplantation and requirements to improve the process, with the ultimate goal being efficient organ regeneration. We also discuss the potential off-target effects of cell-based therapies, and the advantages and drawbacks of current pre-clinical animal models used to study organ senescence, repopulation and regeneration.

MiR-375 inhibits the hepatocyte growth factor-elicited migration of mesenchymal stem cells by downregulating Akt signaling

The migration of mesenchymal stem cells (MSCs) is critical for their use in cell-based therapies. Accumulating evidence suggests that microRNAs are important regulators of MSC migration. Here, we report that the expression of miR-375 was downregulated in MSCs treated with hepatocyte growth factor (HGF), which strongly stimulates the migration of these cells. Overexpression of miR-375 decreased the transfilter migration and the migration velocity of MSCs triggered by HGF. In our efforts to determine the mechanism by which miR-375 affects MSC migration, we found that miR-375 significantly inhibited the activation of Akt by downregulating its phosphorylation at T308 and S473, but had no effect on the activity of mitogen-activated protein kinases. Further, we showed that 3'phosphoinositide-dependent protein kinase-1 (PDK1), an upstream kinase necessary for full activation of Akt, was negatively regulated by miR-375 at the protein level. Moreover, miR-375 suppressed the phosphorylation of focal adhesion kinase (FAK) and paxillin, two important regulators of focal adhesion (FA) assembly and turnover, and decreased the number of FAs at cell periphery. Taken together, our results demonstrate that miR-375 inhibits HGF-elicited migration of MSCs through downregulating the expression of PDK1 and suppressing the activation of Akt, as well as influencing the tyrosine phosphorylation of FAK and paxillin and FA periphery distribution.

Cytotherapy using stromal cells: Current and advance multi-treatment approaches

The research in stem cells gives a proper information about basic mechanisms of human development and differentiation. The use of stem cells in new medicinal therapies includes treatment of different conditions such as spinal cord injury, diabetes mellitus, Parkinsonism, and cardiac disorders. These cells exhibit two unique properties: self-renewal and differentiation. The major stem cells been used for approximately about 10-14 years for cellular therapy are mesenchymal stem cells. Mesenchymal stem cells can individualize into many lineage, i.e. into both mesenchymal and non-mesenchymal lineage, such as into osteoblasts, chondrocytes, myocytes, adipocytes, neurons, etc. This review focuses on the history, types of stem cells and their targets and mechanisms of mesenchymal stem cells. Mesenchymal stem cells are the significant futuristic carrier for treating diseases associated not only with regeneration but also immunomodulation.

Mammalian MSC from selected species: Features and applications

Mesenchymal stromal/stem cells (MSC) are promising candidates for cellular therapy of different diseases in humans and in animals. Following the guidelines of the International Society for Cell Therapy, human MSC may be identified by expression of a specific panel of cell surface markers (CD105+, CD73+, CD90+, CD34-, CD14-, or CD11b-, CD79- or CD19-, HLA-DR-). In addition, multiple differentiation potential into at least the osteogenic, adipogenic, and chondrogenic lineage is a main criterion for MSC definition. Human MSC and MSC of a variety of mammals isolated from different tissues meet these criteria. In addition to the abovementioned, they express many more cell surface markers. Yet, these are not uniquely expressed by MSC. The gross phenotypic appearance like marker expression and differentiation potential is similar albeit not identical for MSC from different tissues and species. Similarly, MSC may feature different biological characteristics depending on the tissue source and the isolation and culture procedures. Their versatile biological qualities comprising immunomodulatory, anti-inflammatory, and proregenerative capacities rely largely on the migratory and secretory capabilities of MSC. They are attracted to sites of tissue lesion and secrete factors to promote self-repair of the injured tissue. This is a big perspective for clinical MSC applications in both veterinary and human medicine. Phase I/II clinical trials have been initiated to assess safety and feasibility of MSC therapies in acute and chronic disease settings. Yet, since the mode of MSC action in a specific disease environment is still unknown at large, it is mandatory to unravel the response of MSC from a given source onto a specific disease environment in suitable animal models prior to clinical applications. © 2017 International Society for Advancement of Cytometry.

Properties of porcine adipose-derived stem cells and their applications in preclinical models

Adipose-derived stem cells represent a reliable adult stem cell source thanks to their abundance, straightforward isolation, and broad differentiation abilities. Consequently, human adipose-derived stem cells (hASCs) have been used in vitro for several innovative cellular therapy and regenerative medicine applications. However, the translation of a novel technology from the laboratory to the clinic requires first to evaluate its safety, feasibility, and potential efficacy through preclinical studies in animals. The anatomy and physiology of pigs and humans are very similar, establishing pigs as an attractive and popular large animal model for preclinical studies. Knowledge of the properties of porcine adipose-derived stem cells (pASCs) used in preclinical studies is critical for their success. While hASCs have been extensively studied this past decade, only a handful of reports relate to pASCs. The aim of this concise review is to summarize the current findings about the isolation of pASCs, their culture, proliferation, and immunophenotype. The differentiation abilities of pASCs and their applications in porcine preclinical models will also be reported.

Umbilical Cord MSCs Reverse D-Galactose-Induced Hepatic Mitochondrial Dysfunction via Activation of Nrf2/HO-1 Pathway

Mitochondria are the central hubs for cellular bioenergetics and are crucial to cell survival. It is well accepted that compromised mitochondrial function is linked with hepatocytes injury and contribute to progression of liver diseases. Despite the therapeutic potential of mesenchymal stem cells (MSCs) transplantation on hepatic disorders have been extensively investigated, the effects of MSCs on mitochondrial function in liver injury models remain unknown. Here we investigated the effects of treatment with umbilical cord (UC) MSC in a rat model of D-galactose (D-Gal) induced liver injury, characterized by organ damage, oxidative stress and mitochondrial dysfunction. Our results showed that UC-MSCs treatment significantly alleviated histological lesion and attenuated the elevation of liver biochemical markers, demonstrating its protective effects on D-Gal induced hepatic disorders. Mitochondria isolated from the liver of D-Gal models exhibited decreased antioxidant capacity as well as compromised bioenergetics functions, as shown by a loss of mitochondrial membrane potential, elevation of reactive oxygen species (ROS) production, reduction of mitochondrial respiration complexes and ATP decrement. Treatment of rats with UC-MSCs remarkably blunted these changes and rescued mitochondrial efficiency. Mechanistically, we found that the protective potential of UC-MSCs administration was mediated by nuclear factor-E2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway, but not FOXO3a pathway. In conclusion, the attenuating effects of UC-MSCs on hepatic damage partially rely on normalizing mitochondrial function and preventing a state of energetic deficit via activation of Nrf2/HO-1 pathway.

Mesenchymal Stem Cells Contribute to Hepatic Maturation of Human Induced Pluripotent Stem Cells

<b><i>Background:</i></b> Induced pluripotent stem cells (iPSCs) are human somatic cells that have been reprogrammed to a pluripotent state. Several methods have been used to generate hepatocyte-like cells from iPSCs. However, these hepatic cells have limited clinical application because of their immature function compared to primary hepatocytes. Mesenchymal stem cells (MSCs) have been reported to inhibit apoptosis of hepatic cells and to improve hepatic regeneration in acute liver injury. Therefore, we expected that MSCs had the potential to positively contribute to the maturation of hepatic cells. Here we demonstrate the effect of MSCs on the maturation of hepatoblasts derived from human iPSCs. <b><i>Methods:</i></b> MSCs were isolated from human bone marrow and cultured to 70-80% confluence. MSC-conditioned medium (MSC-CM) was collected 48 h after culture in hepatic maturation medium. Human iPSC-derived hepatoblasts were then cultured for 6 days with MSC-CM. Hepatic functions were analyzed and compared to those from cells cultured in general maturation medium. <b><i>Results:</i></b> Cells in both groups had a cuboidal morphology typical of hepatocytes. The proportion of Oct4-positive cells was decreased and those of albumin- and alpha-fetoprotein-positive cells were increased in the MSC-CM group. Albumin secretion and urea synthesis as well as cytochrome P450 (CYP) 3A4 activity were enhanced in the MSC-CM group. The gene expressions of some CYP enzymes were upregulated as demonstrated by RT-PCR. <b><i>Conclusion:</i></b> Secreted molecules from human MSCs could enhance the hepatic function of human iPSC-derived hepatocyte-like cells. Although more technological innovations are needed, MSC-CM will be useful as a novel efficient strategy for clinically relevant hepatic cell maturation.

Adult-Derived Human Liver Stem/Progenitor Cells Infused 3 Days Postsurgery Improve Liver Regeneration in a Mouse Model of Extended Hepatectomy

There is growing evidence that cell therapy constitutes a promising strategy for liver regenerative medicine. In the setting of hepatic cancer treatments, cell therapy could prove a useful therapeutic approach for managing the acute liver failure that occurs following extended hepatectomy. In this study, we examined the influence of delivering adult-derived human liver stem/progenitor cells (ADHLSCs) at two different early time points in an immunodeficient mouse model (Rag2-/-IL2Rγ-/-) that had undergone a 70% hepatectomy procedure. The hepatic mesenchymal cells were intrasplenically infused either immediately after surgery (n = 26) or following a critical 3-day period (n = 26). We evaluated the cells' capacity to engraft at day 1 and day 7 following transplantation by means of human Alu qPCR quantification, along with histological assessment of human albumin and α-smooth muscle actin. In addition, cell proliferation (anti-mouse and human Ki-67 staining) and murine liver weight were measured in order to evaluate liver regeneration. At day 1 posttransplantation, the ratio of human to mouse cells was similar in both groups, whereas 1 week posttransplantation this ratio was significantly improved (p < 0.016) in mice receiving ADHLSC injection at day 3 posthepatectomy (1.7%), compared to those injected at the time of surgery (1%). On the basis of liver weight, mouse liver regeneration was more extensive 1 week posttransplantation in mice transplanted with ADHLSCs (+65.3%) compared to that of mice from the sham vehicle group (+42.7%). In conclusion, infusing ADHLSCs 3 days after extensive hepatectomy improves the cell engraftment and murine hepatic tissue regeneration, thereby confirming that ADHLSCs could be a promising cell source for liver cell therapy and hepatic tissue repair.

Hepatocyte cell therapy in liver disease

Liver disease is a leading cause of morbidity and mortality. Liver transplantation remains the only proven treatment for end-stage liver failure but is limited by the availability of donor organs. Hepatocyte cell therapy, either with bioartificial liver devices or hepatocyte transplantation, may help address this by delaying or preventing liver transplantation. Early clinical studies have shown promising results, however in most cases, the benefit has been short lived and so further research into these therapies is required. Alternative sources of hepatocytes, including stem cell-derived hepatocytes, are being investigated as the isolation of primary human hepatocytes is limited by the same shortage of donor organs. This review summarises the current clinical experience of hepatocyte cell therapy together with an overview of possible alternative sources of hepatocytes. Current and future areas for research that might lead towards the realisation of the full potential of hepatocyte cell therapy are discussed.

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

OBJECTIVE

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Equine Mesenchymal Stromal Cells from Different Sources Efficiently Differentiate into Hepatocyte-Like Cells

Adult equine hepatocytes have proven challenging to culture long term in vitro as they rapidly lose their morphology and functionality, thus limiting studies on liver function and response to disease. In this study, we describe for the first time the differentiation of equine mesenchymal stromal cells (MSC) from a variety of sources into functional hepatocyte-like cells (HLC). First, we differentiated equine umbilical cord blood (UCB)-derived MSC into HLC and found that these cells exhibited a distinct polygonal morphology, stored glycogen as visualized by periodic acid Schiff's reagent staining, and were positive for albumin and other hepatocyte-specific genes. Second, we demonstrated that UCB-HLC could be revived following cryopreservation and retained their phenotype for at least 10 days. Third, we differentiated three sets of MSC from bone marrow (BM), adipose tissue (AT), and peripheral blood (PB), matched within the same horse. We achieved a 100% differentiation success rate with BM, 0% with AT, and 66% with PB. An additional set of nine PB-MSC samples resulted in an overall success rate of 42% (n = 12), and age or gender did not seem to have an effect on the success of hepatic differentiation from that source. In a final set of experiments, we evaluated the use of these HLC as tools in different fields of biomedical research like virology, to study viral growth, and toxicology, to study chemicals with hepatic toxicity. Equine HLC were found susceptible for infection with the equine herpesviruses type 1 (EHV-1), -2, and -5, and exhibited a more sensitive dose-dependent response to arsenic toxicity than the commonly used human hepatocellular cell line HepG2. Taken together, these data indicate that equine MSC can be efficiently differentiated into HLC and these equine HLC could be a useful tool for in vitro studies.

Hepatocytic Differentiation Potential of Human Fetal Liver Mesenchymal Stem Cells: In Vitro and In Vivo Evaluation

In line with the search of effective stem cell population that would progress liver cell therapy and because the rate and differentiation potential of mesenchymal stem cells (MSC) decreases with age, the current study investigates the hepatogenic differentiation potential of human fetal liver MSCs (FL-MSCs). After isolation from 11-12 gestational weeks' human fetal livers, FL-MSCs were shown to express characteristic markers such as CD73, CD90, and CD146 and to display adipocytic and osteoblastic differentiation potential. Thereafter, we explored their hepatocytic differentiation potential using the hepatogenic protocol applied for adult human liver mesenchymal cells. FL-MSCs differentiated in this way displayed significant features of hepatocyte-like cells as demonstrated in vitro by the upregulated expression of specific hepatocytic markers and the induction of metabolic functions including CYP3A4 activity, indocyanine green uptake/release, and glucose 6-phosphatase activity. Following transplantation, naive and differentiated FL-MSC were engrafted into the hepatic parenchyma of newborn immunodeficient mice and differentiated in situ. Hence, FL-MSCs appeared to be interesting candidates to investigate the liver development at the mesenchymal compartment level. Standardization of their isolation, expansion, and differentiation may also support their use for liver cell-based therapy development.

Mouse white adipose tissue-derived mesenchymal stem cells gain pericentral and periportal hepatocyte features after differentiation in vitro, which are preserved in vivo after hepatic transplantation

AIM

Mesenchymal stem cells may differentiate into hepatocyte-like cells in vitro and in vivo. Therefore, they are considered a novel cell resource for the treatment of various liver diseases. Here, the aim was to demonstrate that mesenchymal stem cells may adopt both perivenous and periportal hepatocyte-specific functions in vitro and in vivo.

METHODS

Adipose tissue-derived mesenchymal stem cells were isolated from immunodeficient C57BL/6 (B6.129S6-Rag2(tm1Fwa) Prf1(tm1Clrk) ) mice and differentiated into the hepatocytic phenotype by applying a simple protocol. Their physiological and metabolic functions were analysed in vitro and after hepatic transplantation in vivo.

RESULTS

Mesenchymal stem cells changed their morphology from a fibroblastoid into shapes of osteocytes, chondrocytes, adipocytes and hepatocytes. Typical for mesenchymal stem cells, hematopoietic marker genes were not expressed. CD90, which is not expressed on mature hepatocytes, decreased significantly after hepatocytic differentiation. Markers indicative for liver development like hepatic nuclear factor 4 alpha, or for perivenous hepatocyte specification like cytochrome P450 subtype 3a11, and CD26 were significantly elevated. Periportal hepatocyte-specific markers like carbamoylphosphate synthetase 1, the entry enzyme of the urea cycle, were up-regulated. Consequently, cytochrome P450 enzyme activity and urea synthesis increased significantly to values comparable to cultured primary hepatocytes. Both perivenous and periportal qualities were preserved after hepatic transplantation and integration into the host parenchyma.

CONCLUSIONS

Adult mesenchymal stem cells from adipose tissue differentiated into hepatocyte-like cells featuring both periportal and perivenous functions. Hence, they are promising candidates for the treatment of region-specific liver cell damage and may support organ regeneration in acute and chronic liver diseases.

In Situ Transplantation of Alginate Bioencapsulated Adipose Tissues Derived Stem Cells (ADSCs) via Hepatic Injection in a Mouse Model

Objective

Adipose tissue derived stem cells (ADSCs) transplantation has recently gained widespread enthusiasm, particularly in the perspective to use them as potential alternative cell sources for hepatocytes in cell based therapy, mainly because of their capability of hepatogenic differentiation in vitro and in vivo. But some challenges remain to be addressed, including whether ADSCs can be provided effectively to the target organ and whether subsequent proliferation of transplanted cells can be achieved. To date, intrasplenic injection is the conventional method to deliver ADSCs into the liver; however, a number of donor cells retained in the spleen has been reported. In this study, our objective is to evaluate a novel route to transplant ADSCs specifically to the liver. We aimed to test the feasibility of in situ transplantation of ADSCs by injecting bioencapsulated ADSCs into the liver in mouse model.

Methods

The ADSCs isolated from human alpha 1 antitrypsin (M-hAAT) transgenic mice were used to allow delivered ADSCs be readily identified in the liver of recipient mice, and alginate was selected as a cell carrier. We first evaluated whether alginate microspheres are implantable into the liver tissue by injection and whether ADSCs could migrate from alginate microspheres (study one). Once proven, we then examined the in vivo fate of ADSCs loaded microspheres in the liver. Specifically, we evaluated whether transplanted, undifferentiated ASDCs could be induced by the local microenvironment toward hepatogenic differentiation and the distribution of surviving ADSCs in major tissue organs (study two).

Results

Our results indicated ADSCs loaded alginate microspheres were implantable into the liver. Both degraded and residual alginate microspheres were observed in the liver up to three weeks. The viable ADSCs were detectable surrounding degraded and residual alginate microspheres in the liver and other major organs such as bone marrow and the lungs. Importantly, transplanted ADSCs underwent hepatogenic differentiation to become cells expressing albumin in the liver. These findings improve our understanding of the interplay between ADSCs (donor cells), alginate (biomaterial), and local microenvironment in a hepatectomized mouse model, and might improve the strategy of in situ transplantation of ADSCs in treating liver diseases.

Microbial-derived lithocholic acid and vitamin K2 drive the metabolic maturation of pluripotent stem cells-derived and fetal hepatocytes

The liver is the main organ responsible for the modification, clearance, and transformational toxicity of most xenobiotics owing to its abundance in cytochrome P450 (CYP450) enzymes. However, the scarcity and variability of primary hepatocytes currently limits their utility. Human pluripotent stem cells (hPSCs) represent an excellent source of differentiated hepatocytes; however, current protocols still produce fetal-like hepatocytes with limited mature function. Interestingly, fetal hepatocytes acquire mature CYP450 expression only postpartum, suggesting that nutritional cues may drive hepatic maturation. We show that vitamin K2 and lithocholic acid, a by-product of intestinal flora, activate pregnane X receptor (PXR) and subsequent CYP3A4 and CYP2C9 expression in hPSC-derived and isolated fetal hepatocytes. Differentiated cells produce albumin and apolipoprotein B100 at levels equivalent to primary human hepatocytes, while demonstrating an 8-fold induction of CYP450 activity in response to aryl hydrocarbon receptor (AhR) agonist omeprazole and a 10-fold induction in response to PXR agonist rifampicin. Flow cytometry showed that over 83% of cells were albumin and hepatocyte nuclear factor 4 alpha (HNF4α) positive, permitting high-content screening in a 96-well plate format. Analysis of 12 compounds showed an R(2) correlation of 0.94 between TC50 values obtained in stem cell-derived hepatocytes and primary cells, compared to 0.62 for HepG2 cells. Finally, stem cell-derived hepatocytes demonstrate all toxicological endpoints examined, including steatosis, apoptosis, and cholestasis, when exposed to nine known hepatotoxins.

CONCLUSION

Our work provides fresh insights into liver development, suggesting that microbial-derived cues may drive the maturation of CYP450 enzymes postpartum. Addition of these cues results in the first functional, inducible, hPSC-derived hepatocyte for predictive toxicology.

The role of the microenvironment on the fate of adult stem cells

Adult stem cells (SCs) exist in all tissues that promote tissue growth, regeneration, and healing throughout life. The SC niche in which they reside provides signals that direct them to proliferate, differentiate, or remain dormant; these factors include neighboring cells, the extracellular matrix, soluble molecules, and physical stimuli. In disease and aging states, stable or transitory changes in the microenvironment can directly cause SC activation or inhibition in tissue healing as well as functional regulation. Here, we discuss the microenvironmental regulation of the behavior of SC and focus on plasticity approaches by which various environmental factors can enhance the function of SCs and more effectively direct the fate of SCs.

Pluripotency maintenance of amniotic fluid-derived stem cells cultured on biomaterials

Human amniotic fluid-derived stem cells can maintain their pluripotency when cultured on soft hydrogels.

Mesenchymal stem cells promote liver regeneration and prolong survival in small-for-size liver grafts: involvement of C-Jun N-terminal kinase, cyclin D1, and NF-κB

Background

The therapeutic potential of mesenchymal stem cells (MSCs) has been highlighted recently for treatment of acute or chronic liver injury, by possibly differentiating into hepatocyte-like cells, reducing inflammation, and enhancing tissue repair. Despite recent progress, exact mechanisms of action are not clearly elucidated. In this study, we attempted to explore whether and how MSCs protected hepatocytes and stimulated allograft regeneration in small-for-size liver transplantation (SFSLT).

Methods

SFSLT model was established with a 30% partial liver transplantation (30PLT) in rats. The differentiation potential and characteristics of bone marrow derived MSCs were explored in vitro. MSCs were infused transvenously immediately after graft implantation in therapy group. Expressions of apoptosis-, inflammatory-, anti-inflammatory-, and growth factor-related genes were measured by RT-PCR, activities of transcription factors AP-1 and NF-κB were analyzed by EMSA, and proliferative responses of the hepatic graft were evaluated by immunohistochemistry and western blot.

Results

MSCs were successfully induced into hepatocyte-like cells, osteoblasts and adipocytes in vitro. MSCs therapy could not only alleviate ischemia reperfusion injury and acute inflammation to promote liver regeneration, but also profoundly improve one week survival rate. It markedly up-regulated the mRNA expressions of HGF, Bcl-2, Bcl-XL, IL-6, IL-10, IP-10, and CXCR2, however, down-regulated TNF-α. Increased activities of AP-1 and NF-κB, as well as elevated expressions of p-c-Jun, cyclin D1, and proliferating cell nuclear antigen (PCNA), were also found in MSCs therapy group.

Conclusion

These data suggest that MSCs therapy promotes hepatocyte proliferation and prolongs survival in SFSLT by reducing ischemia reperfusion injury and acute inflammation, and sustaining early increased expressions of c-Jun N-terminal Kinase, Cyclin D1, and NF-κB.