In vitro hepatic differentiation of human umbilical cord blood and bone marrow cells

Progress and Challenges in the Use of a Liver-on-a-Chip for Hepatotropic Infectious Diseases

The liver is a target organ of life-threatening pathogens and prominently contributes to the variation in drug responses and drug-induced liver injury among patients. Currently available drugs significantly decrease the morbidity and mortality of liver-dwelling pathogens worldwide; however, emerging clinical evidence reveals the importance of host factors in the design of safe and effective therapies for individuals, known as personalized medicine. Given the primary adherence of cells in conventional two-dimensional culture, the use of these one-size-fit-to-all models in preclinical drug development can lead to substantial failures in assessing therapeutic safety and efficacy. Advances in stem cell biology, bioengineering and material sciences allow us to develop a more physiologically relevant model that is capable of recapitulating the human liver. This report reviews the current use of liver-on-a-chip models of hepatotropic infectious diseases in the context of precision medicine including hepatitis virus and malaria parasites, assesses patient-specific responses to antiviral drugs, and designs personalized therapeutic treatments to address the need for a personalized liver-like model. Second, most organs-on-chips lack a monitoring system for cell functions in real time; thus, the review discusses recent advances and challenges in combining liver-on-a-chip technology with biosensors for assessing hepatocyte viability and functions. Prospectively, the biosensor-integrated liver-on-a-chip device would provide novel biological insights that could accelerate the development of novel therapeutic compounds.

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.

Tonsil-derived mesenchymal stem cells ameliorate CCl4-induced liver fibrosis in mice via autophagy activation

Liver transplantation is the treatment of choice for chronic liver failure, although it is complicated by donor shortage, surgery-related complications, and immunological rejection. Cell transplantation is an alternative, minimally invasive treatment option with potentially fewer complications. We used human palatine tonsil as a novel source of mesenchymal stem cells (T-MSCs) and examined their ability to differentiate into hepatocyte-like cells in vivo and in vitro. Carbon tetrachloride (CCl₄) mouse model was used to investigate the ability of T-MSCs to home to the site of liver injury. T-MSCs were only detected in the damaged liver, suggesting that they are disease-responsive. Differentiation of T-MSCs into hepatocyte-like cells was confirmed in vitro as determined by expression of hepatocyte markers. Next, we showed resolution of liver fibrosis by T-MSCs via reduction of TGF-β expression and collagen deposition in the liver. We hypothesized that autophagy activation was a possible mechanism for T-MSC-mediated liver recovery. In this report, we demonstrate for the first time that T-MSCs can differentiate into hepatocyte-like cells and ameliorate liver fibrosis via autophagy activation and down-regulation of TGF-β. These findings suggest that T-MSCs could be used as a novel source for stem cell therapy targeting liver diseases.

HGF/c-Met signaling mediated mesenchymal stem cell-induced liver recovery in intestinal ischemia reperfusion model

PURPOSE

Liver injury triggered by intestinal ischemia-reperfusion (IIR) usually presage multiorgan dysfunction and death in patients. Recent studies suggest mesenchymal stem cells (MSCs) possess a protective potential against organ damage. Since relative evidence is insufficient and the mechanism is not well understood, we investigated the effect of hepatocyte growth factor c-Met signaling (HGF/c-Met) on recruitment of MSCs and subsequent protection against liver injury triggered by IIR in a rat model.

METHODS

IIR models were built as rats were subjected to 75 min of superior mesenteric artery occlusion and subsequent 4 h reperfusion. Either of pure MSCs and MSCs pretreated with HGF or SU11274 (c-Met inhibitor) were injected into rat models. Biochemical and pathologic alterations of liver in IIR model were measured to evaluate the therapeutic effect of MSCs and drug treatment. Concurrently, the effect of HGF and SU11274 on c-Met and phosphorylated Met expression in MSCs and MSCs migration were assessed in in vitro experiment.

RESULTS

IIR-induced liver injury was manifested by significant increase in serum ALT, AST and HGF levels as well as pathological change. MSCs with highly c-Met expression ameliorated the increase of serum transaminase levels and hepatic histopathological change, while SU11274 weaken these effects. HGF upregulated c-Met and phosphorylated Met expression in MSCs and enhanced its liver protection effect. Transwell assays demonstrated HGF promoted MSCs migration, which was blocked by SU11274.

CONCLUSIONS

HGF/c-Met signaling pathway plays an essential role in the homing of MSCs towards injured liver triggered by intestinal ischemia-reperfusion, and then mediates MSC-induced liver repair.

Mesenchymal stem cells restore CCl4-induced liver injury by an antioxidative process

We have investigated BM (bone marrow)-derived MSCs (mesenchymal stem cells) for the treatment of liver injury. It was hypothesized that MSC-mediated resolution of liver injury could occur through an antioxidative process. After being injected with CCl4 (carbon tetrachloride), mice were injected with syngenic BM-derived MSCs or normal saline. Oxidative stress activity of the MSCs was determined by the analysis of ROS (reactive oxygen species) and SOD (superoxide dismutase) activity. In addition, cytoprotective genes of the liver tissue were assessed by real-time PCR and ARE (antioxidant-response element) reporter assay. Up-regulated ROS of CCl4-treated liver cells was attenuated by co-culturing with MSCs. Suppression of SOD by adding an SOD inhibitor decreased the effect of MSCs on injured liver cells. MSCs significantly increased SOD activity and inhibited ROS production in the injured liver. The gene expression levels of Hmox-1 (haem oxygenase-1), BI-1 (Bax inhibitor-1), HGF (hepatocyte growth factor), GST (glutathione transferase) and Nrf2 (nuclear factor-erythoid 2 p45 subunit-related factor 20), attenuated by CCl4, were increased up to basal levels after MSC transplantation. In addition, MSCs induced an ARE, shown by luciferase activity, which represented a cytoprotective response in the injured liver. Evidence of a new cytoprotective effect is shown in which MSCs promote an antioxidant response and supports the potential of using MSC transplantation as an effective treatment modality for liver disease.

Transplantation of bone marrow cells reduces CCl4 -induced liver fibrosis in mice

BACKGROUND

We investigated the reversibility of liver fibrosis induced with a CCl(4) injection and the role of stem cells in reversing the hepatic injury. Furthermore, the most effective cell fraction among bone marrow cells (BMCs) in the repair process was analysed.

METHODS

C57BL/6 mice were divided into four groups after 5 weeks of injection of CCl(4) : control, sacrificed after 5 weeks, sacrificed at 10 weeks and sacrificed 5 weeks later after GFP-donor BM transplantation. Liver function tests and real-time polymerase chain reaction (PCR) of markers indicating liver fibrosis were compared between the groups. To identify the most effective BMC fraction that repairs liver injury, the mice were divided into three groups after the injection of CCl(4) for 2 days: granulocyte colony stimulating factor (G-CSF) only, mononuclear cell (MNC) transplantation and Lin-Sca-1+c-kit+haematopoietic stem cell (HSC) transplantation. Eight days after transplantation, the mice were harvested and morphometric, immunohistochemical analyses were performed to compare the expression of extracellular matrix and liver fibrosis-related factors.

RESULTS

The liver fibrosis induced by CCl(4) was not spontaneously recovered but was persistent until 10 weeks, but the group injected with BMCs had less fibrosis and better liver function. Mobilization with G-CSF increased the recovery of the injured liver and the best results were seen in those mice administered the MNC fraction and Lin-Sca-1+c-kit+HSC fraction, with no difference between the two groups.

CONCLUSION

BMC transplantation and stem cell mobilization with G-CSF effectively treats liver injury in mice. These are promising techniques for autologous transplantation in humans with liver fibrosis.

Pluripotent plasticity of stem cells and liver repopulation

Different types of stem cells have a role in liver regeneration or fibrous repair during and after several liver diseases. Otherwise, the origin of hepatic and/or extra-hepatic stem cells in reactive liver repopulation is under controversy. The ability of the human body to self-repair and replace the cells and tissues of some organs is often evident. It has been estimated that complete renewal of liver tissue takes place in about a year. Replacement of lost liver tissues is accomplished by proliferation of mature hepatocytes, hepatic oval stem cells differentiation, and sinusoidal cells as support. Hepatic oval cells display a distinct phenotype and have been shown to be a bipotential progenitor of two types of epithelial cells found in the liver, hepatocytes, and bile ductular cells. In gastroenterology and hepatology, the first attempts to translate stem cell basic research into novel therapeutic strategies have been made for the treatment of several disorders, such as inflammatory bowel diseases, diabetes mellitus, celiachy, and acute or chronic hepatopaties. In the future, pluripotent plasticity of stem cells will open a variety of clinical application strategies for the treatment of tissue injuries, degenerated organs. The promise of liver stem cells lie in their potential to provide a continuous and readily available source of liver cells that can be used for gene therapy, cell transplant, bio-artificial liver-assisted devices, drug toxicology testing, and use as an in vitro model to understand the developmental biology of the liver.

Differentiation of human umbilical cord mesenchymal stromal cells into low immunogenic hepatocyte-like cells

BACKGROUND AIMS

Mesenchymal stromal cells (MSC) isolated from several human tissues have been known to differentiate into the hepatic lineage in vitro, but the immunogenicity of the differentiated hepatocyte-like cells (DHC) has not been reported. Umbilical cord (UC) MSC are thought to be an attractive cell source for cell therapy because of their young age and low infection rate compared with adult tissue MSC.

METHODS

Hepatic differentiation of UC-MSC was induced with a 2-step protocol. The expressions of hepatic markers were detected by RT-PCR and immunofluorescence staining. Albumin production and urea secretion were measured by ELISA and colorimetric assay respectively. The immunosuppressive properties of DHC was detected by mixed lymphocyte culture.

RESULTS

After incubation with specific growth factors, including hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF), UC MSC exhibited a high hepatic differentiation ability in an adherent culture condition. The differentiated UC MSC showed hepatocyte-like morphology and expressed several liver-specific markers at gene and protein levels. Furthermore, the DHC exhibited hepatocyte-specific functions, including albumin secretion, low-density lipoprotein uptake and urea production. More importantly, DHC did not express major histocompatibility complex (MHC) II antigen and were not able to induce lymphocyte proliferation in mixed lymphocyte culture, as undifferentiated UC MSC did.

CONCLUSIONS

Our results indicate that UC MSC are able to differentiate into functional hepatocyte-like cells that still retain their low immunogenicity in vitro. More importantly, DHC incorporated into the parenchyma of liver when transplanted into mice with CCl(4)-induced liver injury. Therefore, DHC may be an ideal source for cell therapy of liver diseases.