Effect of Chromatin-Remodeling Agents in Hepatic Differentiation of Rat Bone Marrow-Derived Mesenchymal Stem Cells In Vitro and In Vivo. Stem Cells Int. 2016;2016:3038764. [PMID: 27242905 PMCID: PMC4876003 DOI: 10.1155/2016/3038764]

Combination of the modulators of epigenetic machinery and specific cell signaling pathways as a promising approach for cell reprogramming

During embryogenesis and further development, mammalian epigenome undergoes global remodeling, which leads to the emergence of multiple fate-restricted cell lines as well as to their further differentiation into different specialized cell types. There are multiple lines of evidence suggesting that all these processes are mainly controlled by epigenetic mechanisms such as DNA methylation, histone covalent modifications, and the regulation of ATP-dependent remolding of chromatin structure. Based on the histone code hypothesis, distinct chromatin covalent modifications can lead to functionally distinct chromatin structures and thus distinctive gene expression that determine the fate of the cells. A large amount of recently accumulated data showed that small molecule biologically active compounds that involved in the regulation of chromatin structure and function in discriminative signaling environments can promote changes in cells fate. These data suggest that agents that involved in the regulation of chromatin modifying enzymes combined with factors that modulate specific cell signaling pathways could be effective tools for cell reprogramming. The goal of this review is to gather the most relevant and most recent literature that supports this proposition.

Genetic and Epigenetic Modification of Rat Liver Progenitor Cells via HNF4α Transduction and 5' Azacytidine Treatment: An Integrated miRNA and mRNA Expression Profile Analysis

Neonatal liver-derived rat epithelial cells (rLEC) from biliary origin are liver progenitor cells that acquire a hepatocyte-like phenotype upon sequential exposure to hepatogenic growth factors and cytokines. Undifferentiated rLEC express several liver-enriched transcription factors, including the hepatocyte nuclear factors (HNF) 3β and HNF6, but not the hepatic master regulator HNF4α. In this study, we first investigated the impact of the ectopic expression of HNF4α in rLEC on both mRNA and microRNA (miR) level by means of microarray technology. We found that HNF4α transduction did not induce major changes to the rLEC phenotype. However, we next investigated the influence of DNA methyl transferase (DNMT) inhibition on the phenotype of undifferentiated naïve rLEC by exposure to 5' azacytidine (AZA), which was found to have a significant impact on rLEC gene expression. The transduction of HNF4α or AZA treatment resulted both in significantly downregulated C/EBPα expression levels, while the exposure of the cells to AZA had a significant effect on the expression of HNF3β. Computationally, dysregulated miRNAs were linked to target mRNAs using the microRNA Target Filter function of Ingenuity Pathway Analysis. We found that differentially regulated miRNA-mRNA target associations predict ectopic HNF4α expression in naïve rLEC to interfere with cell viability and cellular maturation (miR-19b-3p/NR4A2, miR30C-5p/P4HA2, miR328-3p/CD44) while it predicts AZA exposure to modulate epithelial/hepatic cell proliferation, apoptosis, cell cycle progression and the differentiation of stem cells (miR-18a-5p/ESR1, miR-503-5p/CCND1). Finally, our computational analysis predicts that the combination of HNF4α transduction with subsequent AZA treatment might cause changes in hepatic cell proliferation and maturation (miR-18a-5p/ESR1, miR-503-5p/CCND1, miR-328-3p/CD44) as well as the apoptosis (miR-16-5p/BCL2, miR-17-5p/BCL2, miR-34a-5p/BCL2 and miR-494-3p/HMOX1) of naïve rLEC.

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

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

Platelet‑derived growth factor D promotes the angiogenic capacity of endothelial progenitor cells

Neovascularization and re-endothelialization rely on endothelial progenitor cells (EPCs). However, the recruitment and angiogenic roles of EPCs are subject to regulation through the vascular microenvironment, which remains largely unknown. Platelet-derived growth factor D (PDGF-D) is a new member of the PDGF family that binds the PDGFR-β homodimer. However, it remains unknown whether and how it affects the angiogenic capacity of EPCs and participates in tube-like formation. EPCs were derived from rat bone marrow cells, and the gain-of-function approach was used to study the effects of PDGF-D on the biological activities of EPCs. EPCs that stably express PDGF-D were generated by lentiviral-mediated transduction, and the expression levels were evaluated by western blotting and reverse transcription, followed by real-time quantitative polymerase chain reaction (RT-qPCR). The biological activities of EPCs evaluated in the present study included proliferation, adhesion, migration, tube formation and senescence. Furthermore, the downstream signaling of PDGF-D was explored by western blot analysis. The results revealed that the lentiviral-mediated expression of PDGF-D in the microenvironment promoted the migration, proliferation, adhesion and tube formation of EPCs. In addition, PDGF-D suppressed the senescence of EPCs. Mechanistically, PDGF-D induced the phosphorylation of several signaling molecules, including STAT3, AKT, ERK1/2, mTOR and GSK-3β, suggesting that PDGF-D enhanced the angiogenic function of EPCs through PDGF receptor-dependent and -independent signaling pathways. In conclusion, PDGF-D promotes the angiogenic capacity of EPCs, including proliferation, migration, adhesion and tube formation, and thereby contributes to angiogenesis.

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

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

Reversal of Experimental Liver Damage after Transplantation of Stem-Derived Cells Detected by FTIR Spectroscopy

The transplantation of autologous BM-MSCs holds great potential for treating end-stage liver diseases. The aim of this study was to compare the efficiency of transplanted rBM-MSCs and rBM-MSC-derived differentiated stem cells (rBM-MSC-DSCs) for suppression of dimethylnitrosamine-injured liver damage in rat model. Synchrotron radiation Fourier-transform infrared (SR-FTIR) microspectroscopy was applied to investigate changes in the macromolecular composition. Transplantation of rBM-MSC-DSCs into liver-injured rats restored their serum albumin level and significantly suppressed transaminase activity as well as the morphological manifestations of liver disease. The regenerative effects of rBM-MSC-DSCs were corroborated unequivocally by the phenotypic difference analysis between liver tissues revealed by infrared spectroscopy. Spectroscopic changes in the spectral region from 1190–970 cm⁻¹ (bands with absorbance maxima at 1150 cm⁻¹, 1081 cm⁻¹, and 1026 cm⁻¹) indicated decreased levels of carbohydrates, in rBM-MSC-DSC-transplanted livers, compared with untreated and rBM-MSC--transplanted animals. Principal component analysis (PCA) of spectra acquired from liver tissue could readily discriminate rBM-MSC-DSC-transplanted animals from the untreated and rBM-MSC-transplanted animals. We conclude that the transplantation of rBM-MSC-DSCs effectively treats liver disease in rats and SR-FTIR microspectroscopy provides important insights into the fundamental biochemical alterations induced by the stem-derived cell transplantation, including an objective “signature” of the regenerative effects of stem cell therapy upon liver injury.

Adipose-derived stromal cells resemble bone marrow stromal cells in hepatocyte differentiation potential in vitro and in vivo

AIM

To investigate whether mesenchymal stem cells (MSCs) from adipose-derived stromal cells (ADSCs) and bone marrow stromal cells (BMSCs) have similar hepatic differentiation potential.

METHODS

Mouse ADSCs and BMSCs were isolated and cultured. Their morphological and phenotypic characteristics, as well as their multiple differentiation capacity were compared. A new culture system was established to induce ADSCs and BMSCs into functional hepatocytes. Reverse transcription polymerase chain reaction, Western blot, and immunofluorescence analyses were performed to identify the induced hepatocyte-like cells. CM-Dil-labeled ADSCs and BMSCs were then transplanted into a mouse model of CCl₄-induced acute liver failure. Fluorescence microscopy was used to track the transplanted MSCs. Liver function was tested by an automatic biochemistry analyzer, and liver tissue histology was observed by hematoxylin and eosin (HE) staining.

RESULTS

ADSCs and BMSCs shared a similar morphology and multiple differentiation capacity, as well as a similar phenotype (with expression of CD29 and CD90 and no expression of CD11b or CD45). Morphologically, ADSCs and BMSCs became round and epithelioid following hepatic induction. These two cell types differentiated into hepatocyte-like cells with similar expression of albumin, cytokeratin 18, cytokeratin 19, alpha fetoprotein, and cytochrome P450. Fluorescence microscopy revealed that both ADSCs and BMSCs were observed in the mouse liver at different time points. Compared to the control group, both the function of the injured livers and HE staining showed significant improvement in the ADSC- and BMSC-transplanted mice. There was no significant difference between the two MSC groups.

CONCLUSION

ADSCs share a similar hepatic differentiation capacity and therapeutic effect with BMSCs in an acute liver failure model. ADSCs may represent an ideal seed cell type for cell transplantation or a bio-artificial liver support system.