Basic fibroblast growth factor promotes the trans-differentiation of mouse bone marrow cells into hepatic lineage cells via multiple liver-enriched transcription factors

In Vitro Generated Equine Hepatic-Like Progenitor Cells as a Novel Potent Cell Pool for Equine Metabolic Syndrome (EMS) Treatment

Equine metabolic syndrome (EMS) is recognized as one of the leading cause of health threatening in veterinary medicine worldwide. Recently, PTP1B inhibition has been proposed as an interesting strategy for liver insulin resistance reversion in both equines and humans, however as being a multifactorial disease, proper management of EMS horses further necessities additional interventional approaches aiming at repairing and restoring liver functions. In this study, we hypothesized that in vitro induction of Eq_ASCs hepatogenic differentiation will generate a specialized liver progenitor-like cell population exhibiting similar phenotypic characteristics and regenerative potential as native hepatic progenitor cells. Our obtained data demonstrated that Eq_ASCs-derived liver progenitor cells (Eq_HPCs) displayed typical flattened polygonal morphology with packed fragmented mitochondrial net, lowered mesenchymal CD105 and CD90 surface markers expression, and significant high expression levels of specific hepatic lineage genes including PECAM-1, ALB, AFP and HNF4A. therewith, generated Eq_HPCs exhibited potentiated stemness and pluripotency markers expression (NANOG, SOX-2 and OCT-4). Hence, in vitro generation of hepatic progenitor-like cells retaining high differentiation capacity represents a promising new approach for the establishment of cell-based targeted therapies for the restoration of proper liver functions in EMS affected horses.

Systemic inflammatory regulators and risk of acute-on-chronic liver failure: A bidirectional mendelian-randomization study

Inflammation plays a role in the pathogenesis of acute-on-chronic liver failure (ACLF), however, whether there is a causal relationship between inflammation and ACLF remains unclear. A two-sample Mendelian randomization (MR) approach was used to investigate the causal relationship between systemic inflammatory regulators and ACLF. The study analyzed 41 cytokines and growth factors from 8,293 individuals extracted from a genome-wide association study (GWAS) meta-analysis database involving 253 ACLF cases and 456,095 controls. Our results showed that lower stem cell factor (SCF) levels, lower basic fibroblast growth factor (bFGF) levels and higher Interleukin-13 (IL-13) levels were associated with an increased risk of ACLF (OR = 0.486, 95% CI = 0.264-0.892, p = 0.020; OR = 0.323, 95% CI = 0.107-0.972, p = 0.044; OR = 1.492, 95% CI = 1.111-2.004, p = 0.008, respectively). In addition, genetically predicted ACLF did not affect the expression of systemic inflammatory regulators. Our results indicate that cytokines play a crucial role in the pathogenesis of ACLF. Further studies are needed to determine whether these biomarkers can be used to prevent and treat ACLF.

Unbalanced distribution of materials: the art of giving rise to hepatocytes from liver stem/progenitor cells

Liver stem/progenitor cells (LSPCs) are able to duplicate themselves and differentiate into each type of cells in the liver, including mature hepatocytes and cholangiocytes. Understanding how to accurately control the hepatic differentiation of LSPCs is a challenge in many fields from preclinical to clinical treatments. This review summarizes the recent advances made to control the hepatic differentiation of LSPCs over the last few decades. The hepatic differentiation of LSPCs is a gradual process consisting of three main steps: initiation, progression and accomplishment. The unbalanced distribution of the affecting materials in each step results in the hepatic maturation of LSPCs. As the innovative and creative works for generating hepatocytes with full functions from LSPCs are gradually accumulated, LSPC therapies will soon be a new choice for treating liver diseases.

Multilineage potential and proteomic profiling of human dental stem cells derived from a single donor

Dental tissues provide an alternative autologous source of mesenchymal stem cells (MSCs) for regenerative medicine. In this study, we isolated human dental MSCs of follicle, pulp and papilla tissue from a single donor tooth after impacted third molar extraction by excluding the individual differences. We then compared the morphology, proliferation rate, expression of MSC-specific and pluripotency markers, and in vitro differentiation ability into osteoblasts, adipocytes, chondrocytes and functional hepatocyte-like cells (HLCs). Finally, we analyzed the protein expression profiles of undifferentiated dental MSCs using 2DE coupled with MALDI-TOF-MS. Three types of dental MSCs largely shared similar morphology, proliferation potential, expression of surface markers and pluripotent transcription factors, and differentiation ability into osteoblasts, adipocytes, and chondrocytes. Upon hepatogenic induction, all MSCs were transdifferentiated into functional HLCs, and acquired hepatocyte functions by showing their ability for glycogen storage and urea production. Based on the proteome profiling results, we identified nineteen proteins either found commonly or differentially expressed among the three types of dental MSCs. In conclusion, three kinds of dental MSCs from a single donor tooth possessed largely similar cellular properties and multilineage potential. Further, these dental MSCs had similar proteomic profiles, suggesting their interchangeable applications for basic research and call therapy.

Safety evaluation of stem cells used for clinical cell therapy in chronic liver diseases; with emphasize on biochemical markers

There are several issues to be considered to reduce the risk of rejection and minimize side effects associated with liver cell transplantation in chronic liver diseases. The source and the condition of stem cell proliferation and differentiation ex vivo and the transplantation protocols are important safety considerations for cell based therapy. The biochemical and molecular markers are important tools for safety evaluation of different processes of cell expansion and transplantation. Studies show that hepatocytes differentiated from adult and embryonic stem cells exhibit biochemical and metabolic properties resembling mature hepatocytes. Therefore these assays can help to assess the biological and metabolic performance of hepatocytes and progenitor stem cells. The assays also help in testing the contribution of transplanted hepatocytes in improving the repair and function of damaged liver in the recipient. Here we review the biochemical and metabolic markers, which are implicated in evaluation of safety issues of stem cells used for therapeutic purposes in chronic liver diseases and regeneration of damaged liver. We also highlight application of biochemical tests for assessment of liver cell transplantation.

Enhanced expression of fibroblast growth factor 2 in bone marrow cells and its potential role in the differentiation of hepatic epithelial stem-like cells into the hepatocyte lineage

The transplantation of bone marrow cells (BMCs) has been applied in liver regenerative cell therapy. However, details of the interaction between the transplanted BMCs and hepatic stem cells have not been elucidated. The aim of the present study was to investigate the interaction of BMCs with hepatic stem-like cells (HSLCs) and to determine the BMC factor that steers HSLC differentiation into the hepatocyte lineage. Both BMCs and HSLCs were obtained from an adult Sprague-Dawley rat, and a co-culture system was established. Cell proliferation was analyzed by a proliferation assay, and the differentiation of HSLCs into the hepatocyte lineage was evaluated by the detection of cellular mRNA for liver-specific proteins. DNA microarray analysis was applied to BMCs co-cultured with HSLCs to determine the genes upregulated by their interaction. The proliferation of HSLCs co-cultured with BMCs was significantly higher than that of HSLCs cultured alone, and the expression of mRNAs for both albumin and tryptophan-2,3-dioxygenase was detectable in the co-cultured HSLCs. DNA microarray analysis showed the upregulated expression of fibroblast growth factor 2 (FGF2) mRNA in BMCs co-cultured with HSLCs, and the expression of mRNAs for both albumin and tyrosine aminotransferase became detectable in HSLCs cultured with FGF2. Thus, BMCs stimulate both the proliferation of HSLCs and their differentiation into the hepatocyte lineage. FGF2 is one of the factors that is produced by the interacting BMCs and that stimulates this differentiation.

Hepatic stem cells and liver development

The liver consists of many cell types with specialized functions. Hepatocytes are one of the main players in the organ and therefore are the most vulnerable cells to damage. Since they are not everlasting cells, they need to be replenished throughout life. Although the capacity of hepatocytes to contribute to their own maintenance has long been recognized, recent studies have indicated the presence of both intrahepatic and extrahepatic stem/progenitor cell populations that serve to maintain the normal organ and to regenerate damaged parenchyma in response to a variety of insults.The intrahepatic compartment most likely derives primarily from the biliary tree, particularly the most proximal branches, i.e. the canals of Hering and smallest ductules. The extrahepatic compartment is at least in part derived from diverse populations of cells from the bone marrow. Embryonic stem cells (ES's) are considered as a part of the extrahepatic compartment. Due to their pluripotent capabilities, ES cell-derived cells form a potential future source of hepatocytes, to replace or restore hepatic tissues that have been damaged by disease or injury. Progressing knowledge about stem cells in the liver would allow a better understanding of the mechanisms of hepatic homeostasis and regeneration. Although a human stem cell-derived cell type equivalent to primary hepatocytes does not yet exist, the promising results obtained with extrahepatic stem cells would open the way to cell-based therapy for liver diseases.

Bone marrow stem cells and the liver: are they relevant?

The contribution of bone marrow stem cell responses to liver homeostasis, injury and malignancy is discussed in this review. Pluripotent stem cells or their more committed progenitor progeny are essential to tissue development, regeneration and repair and are widely implicated in the pathogenesis of malignancy. Stem cell responses to injury are the focus of intense research efforts in the hope of future therapeutic manipulation. Stem cells occur within tissues, such as the liver, or arise from extrahepatic sites, in particular, the bone marrow. As the largest reservoir of stem cells in the adult, the bone marrow has been implicated in the stem cell response associated with liver injury. However, in liver injury, the relative contribution of bone marrow stem cells compared to intrahepatic progenitor responses is poorly characterized. Intrahepatic progenitor responses have been recently reviewed elsewhere. In this review, we have summarized liver-specific extrahepatic stem cell responses originating from the bone marrow. The physiological relevance of bone marrow stem cell responses to adult liver homeostasis, injury and malignancy is discussed with emphasis on mechanisms of bone marrow stem cell recruitment to sites of liver injury and its contribution to intrahepatic malignancy.

Mesenchymal stem cells from human umbilical cords ameliorate mouse hepatic injury in vivo

AIMS

To investigate human umbilical cord-derived mesenchymal stem cells (hUCMSCs) for use in the reversal of mouse hepatic injury.

METHODS

Human umbilical cord-derived mesenchymal stem cells, characterized by flow cytometry, were transplanted into carbon tetrachloride (CCl(4))-injured mice, and then followed for determination of localization and differentiation. Reverse transcriptase-polymerase chain reaction for the human 17alpha gene and fluorescence in situ hybridization analysis for the human X chromosome were used to locate exogenous hUCMSCs in mouse livers. Peripheral blood and liver specimens were collected at 7, 14 and 21 days after transplantation. For evaluating the recovery of injured liver tissues, serum aminotransferase was measured, and the pathological state of the hepatocytes was assessed.

RESULTS

The hUCMSCs were positive for the human MSC-specific markers CD13, CD29, CD44, CD105 and nerve growth factor receptor, but negative for the haematopoietic lineage markers CD31, CD34, CD38, CD45 and HLA-DR. Under conditions favouring differentiation in vivo, the expression of tryptophan 2,3-dioxygenase, human alpha-fetoprotein, cytokeratin 18, fibroblast secretory protein 1 and alpha-smooth-muscle-actin was detectable after hUCMSCs administration to mice subjected to liver injury. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labelling and proliferating cell nuclear antigen staining showed that transplanted hUCMSCs could inhibit hepatocyte apoptosis and facilitate proliferation. Serum aminotransferases were decreased after transplantation of hUCMSCs into the injured mice, and hepatocyte denaturation was reduced.

CONCLUSIONS

Human umbilical cord-derived mesenchymal stem cells can enhance recovery of CCl(4)-injured mouse liver, providing evidence that such therapy could be useful for liver disorders or injury.

Transplantation of basic fibroblast growth factor-pretreated adipose tissue-derived stromal cells enhances regression of liver fibrosis in mice

Adipose tissue-derived stromal cells (ADSC) potentially differentiate into various cell types similar to bone marrow-derived mesenchymal stromal cells (BMSC). Unlike BMSC, ADSC can be harvested easily and repeatedly. However, the advantages of ADSC for cell transplantation in liver disease remain unclear. To investigate this, we developed a novel culture system for ADSC, as well as effective methods for transplantation of ADSC into mice liver. ADSC were isolated from subcutaneous adipose tissues of male C57BL6/J mice and cultured on plastic dishes with or without basic fibroblast growth factor (bFGF). In the in vivo study, ADSC isolated from green fluorescent protein-transgenic mice were transplanted into carbon tetrachloride-injured C57BL6/J mice liver. bFGF-treated ADSC expressed several liver-specific marker genes and demonstrated liver-related functions such as albumin secretion, glycogen synthesis, urea production, and low-density lipoprotein uptake. Importantly, pretreatment of ADSC with bFGF for 1 wk enhanced the repopulation rate of ADSC in mice liver, attenuated liver fibrosis, and restored normal serum alanine aminotransferase and albumin levels. The results indicate that basic FGF facilitates transdifferentiation of ADSC into hepatic lineage cells in vitro and that transplantation of bFGF-pretreated ADSC reduced hepatic fibrosis in mice. ADSC are a potentially valuable source of cells for transplantation therapy.

Establishment and characterization of hepatic stem-like cell lines from normal adult rat liver

The liver is a unique organ with the potential to regenerate from injury. Hepatic stem cells contribute to liver regeneration when surviving hepatocytes in injured liver are unable to proliferate. To investigate the mechanism of liver regeneration in vitro, we established hepatic stem cell lines named HY1, HY2 and HY3, derived from a healthy liver of adult rat. HY cells showed an expression pattern similar to oval cells, and efficiently induced hepatic differentiation following sequential treatment with type I collagen, transforming growth factor-beta1 (TGF-beta1), and hepatocyte growth factor (HGF) or oncostatin M (OSM). These results suggested that HY cells are liver stem cells representing an excellent tool for in vitro studies on liver regeneration.

Stem cells for end stage liver disease: how far have we got?

End stage liver disease (ESLD) is a health problem worldwide. Liver transplantation is currently the only effective therapy, but its many drawbacks include a shortage of donors, operative damage, risk of rejection and in some cases recidivism of the pre-transplant disease. These factors account for the recent growing interest in regenerative medicine. Experiments have sought to identify an optimal source of stem cells, sufficient to generate large amounts of hepatocytes to be used in bioartificial livers or injected in vivo to repair the diseased organ. This update aims to give non-stem cell specialists an overview of the results obtained to date in this fascinating field of biomedical research.

Stem cell-based therapy in gastroenterology and hepatology

Protagonists of a new scientific era, stem cells are promising tools on which regenerative medicine relies for the treatment of human pathologies. Stem cells can be obtained from various sources, including embryos, fetal tissues, umbilical cord blood, and also terminally differentiated organs. Once forced to expand and differentiate into functional progenies, stem cells may become suitable for cell replacement and tissue engineering. The manipulation and/or stimulation of adult stem cells seems to be particularly promising, as it could improve the endogenous regenerative potential without risks of rejection and overcome the ethical and political issues related to embryonic stem cell research. Stem cells are already leaving the bench and reaching the bedside, despite an incomplete knowledge of the genetic control program driving their fate and plasticity. 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. Nonetheless, critical aspects need to be further addressed, including the long-term safety, tolerability and efficacy of cell-based treatments, as well as their carcinogenic potential. Aim of this review is to summarize the state-of-the-arts on gastrointestinal and hepatic stem cells and on stem cell-based therapies in gastroenterology and hepatology, highlighting both the benefits and the potential risks of these new tools for the treatment and prevention of human diseases.

Hepatogenic differentiation of human mesenchymal stem cells from adipose tissue in comparison with bone marrow mesenchymal stem cells

AIM: To investigate and compare the hepatogenic transdifferentiation of adipose tissue-derived stem cells (ADSC) and bone marrow-derived mesenchymal stem cells (BMSC) in vitro. Transdifferentiation of BMSC into hepatic cells in vivo has been described. Adipose tissue represents an accessible source of ADSC, with similar characteristics to BMSC.

METHODS: BMSCs were obtained from patients undergoing total hip arthroplasty and ADSC from human adipose tissue obtained from lipectomy. Cells were grown in medium containing 15% human serum. Cultures were serum deprived for 2 d before cultivating under similar pro-hepatogenic conditions to those of liver development using a 2-step protocol with sequential addition of growth factors, cytokines and hormones. Hepatic differentiation was RT-PCR-assessed and liver-marker genes were immunohistochemically analysed.

RESULTS: BMSC and ADSC exhibited a fibroblastic morphology that changed to a polygonal shape when cells differentiated. Expression of stem cell marker Thy1 decreased in differentiated ADSC and BMSC. However, the expression of the hepatic markers, albumin and CYPs increased to a similar extent in differentiated BMSC and ADSC. Hepatic gene activation could be attributed to increased liver-enriched transcription factors (C/EBPβ and HNF4α), as demonstrated by adenoviral expression vectors.

CONCLUSION: Mesenchymal stem cells can be induced to hepatogenic transdifferentiation in vitro. ADSCs have a similar hepatogenic differentiation potential to BMSC, but a longer culture period and higher proliferation capacity. Therefore, adipose tissue may be an ideal source of large amounts of autologous stem cells, and may become an alternative for hepatocyte regeneration, liver cell transplantation or preclinical drug testing.

Inducing hepatic differentiation of human mesenchymal stem cells in pellet culture

Extensive cell-cell or cell-matrix interaction in three-dimensional (3D) culture is important for the maintenance of adult hepatocyte function and the maturation of hepatic progenitors. However, although there is significant interest in inducing the transdifferentiation of adult stem cells into the hepatic lineage, very few studies have been conducted in a 3D culture configuration. The aim of this study is to investigate the differentiation of mesenchymal stem cells (MSC) into hepatocytes in a pellet configuration, with or without the presence of small intestinal submucosa (SIS). After 4 weeks of differentiation with growth factors bFGF, HGF, and OsM, we obtained hepatocyte-like cells that expressed a subset of hepatic genes, secreted albumin and urea, stored glycogen, and showed inducible CYP3A4 mRNA levels. When these cells were implanted into livers of hepatectomized rats, they secreted human albumin into the bloodstream. The hepatic differentiation of MSC was faster in cell pellets without SIS. The plausible explanations for this finding may be related to the mass transport issues of the two different pellets and the role of cell-cell contact over cell-matrix interactions. The findings of this study should help in the design of optimal culture configurations for efficient hepatic differentiation of adult stem cells.

Stem cells for the treatment of liver disease

Stem cells tantalise. They alone have the capacity to divide exponentially, recreate the stem cell compartment as well as create differentiated cells to build tissues. They should be the natural candidates to provide a renewable source of cells for transplantation. Does the reality support the promise of this exciting alternative to conventional therapies for metabolic and degenerative liver disease? Can techniques be developed to provide the large number of cells that could be required? Must there be "space" in the liver to accept the cells? To what extent is the liver immunoprivileged, and is immunosuppression necessary for stem cell therapy? Is it better to use haematopoietic stem cells, fetal stem cells, mesenchymal cells, embryonic stem cells, hepatocytes or all of the above, but for different disease indications? This paper discusses why the exploration of stem cells for the treatment of liver disease is of great potential, and delineates some of the hurdles that need to be overcome before patients see benefits from laboratory-based research into stem cell transplantation and function.