Differentiation of rat bone marrow cells cultured on artificial basement membrane containing extracellular matrix into a liver cell lineage

Bone marrow cell-based regenerative therapy for liver cirrhosis

Bone marrow cells are capable of differentiation into liver cells. Therefore, transplantation of bone marrow cells has considerable potential as a future therapy for regeneration of damaged liver tissue. Autologous bone marrow infusion therapy has been applied to patients with liver cirrhosis, and improvement of liver function parameters has been demonstrated. In this review, we summarize clinical trials of regenerative therapy using bone marrow cells for advanced liver diseases including cirrhosis, as well as topics pertaining to basic in vitro or in vivo approaches in order to outline the essentials of this novel treatment modality.

Hepatic differentiation of rat mesenchymal stem cells by a small molecule

Mesenchymal stem cells (MSCs) are capable of self-renewal and multilineage differentiation. A periodic acid-Schiff (PAS) stain-based assay was developed to screen for small-molecule inducers of hepatic differentiation of bone marrow MSCs. 2-(4-Bromophenyl)-N-(4-fluorophenyl)-3-propyl-3H-imidazo[4,5-b]pyridin-5-amine (SJA710-6) was identified as a novel small molecule able to induce the differentiation of rat MSCs (rMSCs) toward hepatocyte-like cells in vitro, where rMSCs treated with SJA710-6 have typical morphological and functional characteristics of hepatic cells, including glycogen storage, urea secretion, uptake of low density lipoprotein (LDL) and expression of hepatocyte-specific genes and proteins. Expression of FoxH1 (FAST1/2) induces the differentiation of rMSCs towards hepatocyte-like cells, suggesting that this gene plays an important role in the hepatic fate specification of rMSCs.

Potential therapeutic application of intravenous autologous bone marrow infusion in patients with alcoholic liver cirrhosis

The present study was conducted to evaluate the application and efficacy of autologous bone marrow infusion (ABMi) for improvement of liver function in patients with alcoholic liver cirrhosis (ALC). Five subjects and 5 control patients with ALC who had abstained from alcohol intake for 24 weeks before the study were enrolled. Autologous bone marrow cells were washed and injected intravenously, and the changes in serum liver function parameters, and the level of the type IV collagen 7S domain as a marker of fibrosis, were monitored for 24 weeks. The distribution of activated bone marrow was assessed by indium-111-chloride bone marrow scintigraphy. The number of cells infused was 8.0±7.3×10(9) (mean±standard error). The serum levels of albumin and total protein and the prothrombin time were significantly higher during the follow-up period after ABMi than during the observation period in treated patients, whereas no such changes were observed in the controls. In the patients who received ABMi, the Child-Pugh score decreased in all 3 who were classified as class B; the serum levels of type IV collagen 7S domain improved in 4 of the 5 patients; and bone marrow scintigraphy demonstrated an increase of indium-111-chloride uptake in 3 of the 4 patients tested. ABMi for patients with ALC helps improve liver function parameters in comparison with observation during abstinence and ameliorates the degree of fibrosis in terms of serum markers and bone marrow activation in most cases.

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.

In vitro human bone marrow analog: clinical potential

Bone marrow is the primary site of hematopoiesis in adult humans. Bone marrow can be cultured in vitro but few simple culture systems fully support hematopoiesis beyond a few months. Human bone marrow analogs are long-term in vitro cultures of marrow stromal and hematopoietic stem cells that can be used to produce cells and products normally harvested from human donors. Bone marrow analog systems should exhibit confluence of the stromal cell populations, persistence of hematopoietic progenitor cells, presence of active regions of hematopoiesis and capacity to produce mature cell types for extended periods of time. Although we are still years away from realizing clinical application of products formed by artificial bone marrow analogs, the process of transitioning this research tool from bench to bedside should be fairly straightforward. The most obvious application of artificial marrow would be for production of autologous hematopoietic CD34(+) stem cells as a stem cell therapy for individuals experiencing bone marrow failure due to disease or injury. Another logical application is for 'blood farming', a process for large-scale in vitro production of red blood cells, white blood cells or platelets, for transfusion or treatment. Other possibilities include production of nonhematopoietic stem cells such as osteogenic stromal cells, osteoblasts and rare pluripotent stem cells. Bone marrow analogs also have great potential as ex vivo human test systems and could play a critical role in drug discovery, drug development and toxicity testing in the future.

Serum levels of stem cell factor and their clinical significances in patients with severe hepatitis

AIM: To investigate the serum levels of stem cell factor (SCF) and their clinical significances in patients with severe hepatitis.

METHODS: A total of 45 hepatitis patients (including 15 cases of acute hepatitis, 16 cases of chronic hepatitis and 14 cases of severe hepatitis) and 15 healthy subjects (as controls) were collected from our hospital . The severe hepatitis patients were divided into survival subgroup (n = 4) and death subgroup (n = 10). Serum levels of SCF were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS: The levels of serum SCF were significantly higher in severe hepatitis than those in acute hepatitis, chronic hepatitis and the controls (2403.1 ± 42.8 ng/L vs 2354.9 ± 19.0 ng/L, 2376.7 ± 16.4 ng/L, 2358.4 ± 16.0 ng/L; all P < 0.05), and also higher in the death subgroup than those in the survival subgroup (2418.1 ± 50.7 ng/L vs 2376.3 ± 11.7 ng/L, P < 0.05). The levels of serum SCF showed significantly positive correlation (r = 0.38, P < 0.01) with those of hepatocyte growth factor (HGF) and significantly negative correlation with those of albumin and prothrombin time activity (PTA).

CONCLUSION: Serum levels of SCF may reflect the degree of hepatic injury and the prognosis of severe hepatitis patients, indicating that stem cells may be required for liver regeneration in severe hepatitis patients.

Serum levels of stem cell factor and thrombopoietin are markedly decreased in fulminant hepatic failure patients with a poor prognosis

BACKGROUND AND AIM

Hematopoietic growth factors including stem cell factor (SCF), thrombopoietin (TPO) and granulocyte colony stimulating factor (G-CSF) have a potential role in inducing bone marrow hematopoietic stem cells to move into the circulation, and the association of these factors with liver regeneration has received a lot of attention recently. The aim of this study was to determine the serum levels of such factors in patients with acute liver injury.

METHODS

The subjects were 25 patients with acute hepatitis (AH) who had a favorable prognosis and 26 patients with fulminant hepatitis (FH), of whom 11 were alive and 15 had died. Sixty-six healthy subjects matched for age and sex served as controls. Serum samples were collected before treatment, and the levels of SCF, TPO and G-CSF were measured using enzyme-linked immunosorbant assays.

RESULTS

The levels of SCF and TPO were significantly lower in FH patients than in AH patients and the controls, and were also significantly lower in the FH patients who died, compared to the surviving patients. The G-CSF levels did not differ among them.

CONCLUSIONS

These results suggest that low serum levels of SCF and TPO may be linked to poor prognosis in patients with severe liver injury.

In vivo visualization and portally repeated transplantation of bone marrow cells in rats with liver damage

Recent reports have raised concerns over the feasibility of differentiating bone marrow cells (BMCs) into functional hepatocytes. Such augmentation is considered necessary for potential clinical use of these cells in liver diseases. The present investigation was designed to determine the kinetics of transplanted BMCs and evaluate the effects of repeated bone marrow transplantation (BMT) in rat models of CCl(4)-induced liver damage. The early kinetics of transplanted BMCs was evaluated with a charge-coupled-device (CCD) camera using BMCs obtained from green fluorescent protein (GFP) transgenic (Tg) rats and followed up with in vivo imaging system (IVIS) using BMCs obtained from firefly luciferase (luc) Tg rats. We used a portal infusion system for repeated BMT. BMCs were transplanted via a peripheral vein or the portal vein (PV) once or repeatedly using this system. The results revealed that BMCs accumulated more in the damaged liver than in the intact liver. In the experimental group receiving repeated BMT via the PV, the liver fibrosis was milder than that in the group not receiving BMT, and large clusters of albumin-producing cells were detected by albumin staining. The injected BMCs were shown to accumulate in the damaged liver. This strategy of repeated BMT has potential clinical use in enhancing the number of albumin-producing cells and suppressing liver fibrosis. This combination of beneficial effects may contribute to the benefits of cell transplantation therapy. Demonstration of the benefits of BMT in this study may be expected to have great significance for clinical trials.

Direct differentiation of human embryonic stem cells to hepatocyte-like cells exhibiting functional activities

The utilization of human hepatocytes for biomedical research, drug discovery, and treatment of liver diseases is hindered by the limited availability of donated livers and the variability of their derived hepatocytes. Human embryonic stem cells (hESCs) are pluripotent and provide a unique, unlimited resource for human hepatocytes. However, differentiation of hESCs to hepatocytes remains a challenge. We have developed a multistage procedure by which hESCs can be directly differentiated to hepatocyte-like cells without embryoid body formation and the requirement of sodium butyrate. The hESC-derived hepatocyte-like cells (HLCs) exhibited characteristic hepatocyte morphology, expressed hepatocyte markers, including alpha-fetoprotein, albumin, and hepatocyte nuclear factor 4alpha, and possessed hepatocyte-specific activities, such as p450 metabolism, albumin production, glycogen storage, and uptake and excretion of indocyanine green. Hepatocyte growth factor was found to play a positive role in promoting hepatocyte differentiation. Our differentiation system has shown that hESCs can be differentiated to hepatocyte-like cells capable of executing a range of hepatocyte functions. Therefore, it presents a proof-of-principle of potential applications of using the hESC-derived hepatocytes. Additionally, the hESC-derived HLCs provide a unique model to study the mechanisms involved in human hepatocyte differentiation and liver function.

Transdifferentiation of mouse BM cells into hepatocyte-like cells

BACKGROUND

During the past few years multiple studies have revealed that adult stem cells, including BM origin stem cells, can be transdifferentiated into various cell types, including hepatocyte-like cells, under proper treatments or in a suitable microenvironment. However, little is known about the mechanism of the transdifferentiation, and the treatments employed seem to be very complicated and require simplification. It is important to determine the suitable conditions in which BM cells would be efficiently differentiated into hepatocytes.

METHODS

Mouse BM cells were isolated from femurs and tibias and cultured in IMDM supplemented with 10% FBS. Hepatic differentiation was induced in a differentiation medium containing 20 ng/mL HGF, 10 ng/mL FGF-4, 10 ng/mL Oncostatin M (OSM) and different concentrations of liver-injured mouse sera. The differentiated hepatic cells were characterized by the expression of liver-associated mRNA and proteins and morphologic and functional features.

RESULTS

BM cell-derived polygonal cell colonies appeared after several days of culture, and these hepatocyte-like cells expressed AFP, HNF-3beta, CK19, CK18, ALB, TAT and G-6-Pase at mRNA and protein levels, and the cells also had some hepatic cellular functions, such as glycogen storage and urea production. Interestingly, suitable concentrations of sera from liver-injured mice added to this system showed strong stimulation on the in vitro transdifferentiation of mouse BM cells into hepatocytes.

DISCUSSION

In the present study we have established an effective hepatic differentiation system by a combination of HGF, FGF-4, OSM and liver-injured mouse sera in vitro. Accordingly, it will be a useful resource not only for understanding the mechanisms of transdifferentiation but also for efficient amplification of hepatocyte progenitor cells of BM origin.

Two populations of Thy1-positive mesenchymal cells regulate in vitro maturation of hepatic progenitor cells

We previously reported that the in vitro maturation of CD49f(+)Thy1(-)CD45(-) (CD49f positive) fetal hepatic progenitor cells (HPCs) is supported by Thy1-positive mesenchymal cells derived from the fetal liver. These mesenchymal cell preparations contain two populations, one of a cuboidal shape and the other spindle shaped in morphology. In this study, we determined that the mucin-type transmembrane glycoprotein gp38 could distinguish cuboidal cells from spindle cells by immunocytochemistry. RT-PCR analysis revealed differences between isolated CD49f(+/-)Thy1(+)gp38(+)CD45(-) (gp38 positive) cells and CD49f(+/-)Thy1(+)gp38(-)CD45(-) (gp38 negative) cells, whereas both cells expressed mesenchymal cell markers. The coculture with gp38-positive cells promoted the maturation of CD49f-positive HPCs, which was estimated by positivity for periodic acid-Schiff (PAS) staining, whereas the coculture with gp38-negative cells maintained CD49f-positive HPCs negative for PAS staining. The expression of mature hepatocyte markers, such as tyrosine aminotransferase, tryptophan-2,3-dioxygenase, and glucose-6-phosphatase, were upregulated on HPCs by coculture with gp38-positive cells. Furthermore, transmission electron microscopy revealed the acquisition of mature hepatocyte features by HPCs cocultured with gp38-positive cells. This effect on maturation of HPCs was inhibited by the addition of conditioned medium derived from gp38-negative cells. By contrast, the upregulation of bromodeoxyuridine incorporation by HPCs demonstrated the proliferative effect of coculture with gp38-negative cells. In conclusion, these results suggest that in vitro maturation of HPCs promoted by gp38-positive cells may be opposed by an inhibitory effect of gp38-negative cells, which likely maintain the immature, proliferative state of HPCs.

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.