Modification of histone acetylation facilitates hepatic differentiation of human bone marrow mesenchymal stem cells

Rapid identification of potential nonsteroidal anti-inflammatory drug overdose-induced liver toxicity and prediction of follow-up exposure: Integrating bioanalytical and population pharmacokinetic assay

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most frequently used drugs that can cause liver toxicity. The aim of this study was to integrate bioanalytical and population pharmacokinetic (PopPK) assay to rapidly screen and quantify the concentrations of NSAIDs in plasma and monitor clinical safety. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantification of acetaminophen (APAP), flurbiprofen (FLB), aspirin (ASP), and ibuprofen (IBP), four commonly used NSAIDs. The PopPK model of the signature toxicant was analyzed based on the published literature. The LC-MS/MS method was successfully validated and applied to determine NSAID concentrations in patient plasma samples. APAP, ASP, and IBP data were best fitted using a one-compartment model, and FLB data were best fitted using a two-compartment model. Bootstrapping and visual predictive checks suggested that a robust and reliable pharmacokinetic model was developed. A fast, simple, and sensitive LC-MS/MS method was developed and validated for determining APAP, FLB, ASP, and IBP in human plasma. Combined with the PopPK model, this method was applied to rapidly analyze the concentrations of NSAIDs in clinical samples from patients presenting to the emergency department with acute liver dysfunction and monitored NSAIDs clinical safety.

The role of epigenetic modifiers in the hepatic differentiation of human umbilical cord derived mesenchymal stem cells

Human umbilical cord (hUC) derived mesenchymal stem cells (MSCs) can be progressively differentiated into multiple lineages including hepatic lineages, and thus provide an excellent in vitro model system for the study of hepatic differentiation. At present, hepatic differentiation protocols are based on the use of soluble chemicals in the culture medium and provide immature hepatic like cells. Histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors (DNMTi) are two important epigenetic modifiers that regulate stem cell differentiation. Therefore, this study aimed to investigate the role of HDACi, valproic acid (VPA) and DNMTi,5-azacytidine (5-aza) along with a hepatic inducer in the hepatic differentiation of hUC-MSCs. hUC-MSCs were characterized via immunocytochemistry and flow cytometry. The final concentrations of VPA and 5-aza were optimized via MTT cytotoxicity assay. All treated groups were assessed for the presence of hepatic genes and proteins through qPCR and immunocytochemistry, respectively. The results showed that the pretreatment of epigenetic modifiers not only increased the hepatic genes but also increased the expression of the hepatic proteins. VPA induces hepatic differentiation in hUC-MSCs with significant gene expression of hepatic markers i.e., FOXA2 and CK8. Moreover, VPA pretreatment enhanced the expression of hepatic proteins AFP and TAT. The pretreatment of 5-aza shows significant gene expression of hepatic marker LDL-R. However, 5-aza treatment failed to induce hepatic protein expression. The results of the current study highlighted the effectiveness of epigenetic modifiers in the hepatic differentiation of hUC-MSCs. These differentiated cells can be employed in cell-based therapeutics for hepatic diseases in future.

The Role of Histone Acetylation in Mesenchymal Stem Cell Differentiation

The mechanism and action concerning epigenetic modifications, especially that of histone modifications, are not fully understood. However, it is clear that histone modifications play an essential role in several biological processes that are involved in cell proliferation and differentiation. In this article, we focused on how histone acetylation may result in differentiation into mesenchymal stem cells as well as histone acetylation function. Moreover, histone acetylation followed by the action of histone deacetylase inhibitors, which can result in the differentiation of stem cells into other types of cells such as adipocytes, chondrocytes, osteocytes, neurons, and other lineages, were also reviewed.

Control of mesenchymal stem cell biology by histone modifications

Mesenchymal stem cells (MSCs) are considered the most promising seed cells for regenerative medicine because of their considerable therapeutic properties and accessibility. Fine-tuning of cell biological processes, including differentiation and senescence, is essential for achievement of the expected regenerative efficacy. Researchers have recently made great advances in understanding the spatiotemporal gene expression dynamics that occur during osteogenic, adipogenic and chondrogenic differentiation of MSCs and the intrinsic and environmental factors that affect these processes. In this context, histone modifications have been intensively studied in recent years and have already been indicated to play significant and universal roles in MSC fate determination and differentiation. In this review, we summarize recent discoveries regarding the effects of histone modifications on MSC biology. Moreover, we also provide our insights and perspectives for future applications.

Concise Review: The Regulatory Mechanism of Lysine Acetylation in Mesenchymal Stem Cell Differentiation

Nowadays, the use of MSCs has attracted considerable attention in the global science and technology field, with the self-renewal and multidirectional differentiation potential for diabetes, obesity treatment, bone repair, nerve repair, myocardial repair, and so on. Epigenetics plays an important role in the regulation of mesenchymal stem cell differentiation, which has become a research hotspot in the medical field. This review focuses on the role of lysine acetylation modification on the determination of MSC differentiation direction. During this progress, the recruitment of lysine acetyltransferases (KATs) and lysine deacetylases (KDACs) is the crux of transcriptional mechanisms in the dynamic regulation of key genes controlling MSC multidirectional differentiation.

Differentiation of Human Mesenchymal Stem Cells towards Neuronal Lineage: Clinical Trials in Nervous System Disorders

Mesenchymal stem cells (MSCs) have been proposed as an alternative therapy to be applied into several pathologies of the nervous system. These cells can be obtained from adipose tissue, umbilical cord blood and bone marrow, among other tissues, and have remarkable therapeutic properties. MSCs can be isolated with high yield, which adds to their ability to differentiate into non-mesodermal cell types including neuronal lineage both in vivo and in vitro. They are able to restore damaged neural tissue, thus being suitable for the treatment of neural injuries, and possess immunosuppressive activity, which may be useful for the treatment of neurological disorders of inflammatory etiology. Although the long-term safety of MSC-based therapies remains unclear, a large amount of both pre-clinical and clinical trials have shown functional improvements in animal models of nervous system diseases following transplantation of MSCs. In fact, there are several ongoing clinical trials evaluating the possible benefits this cell-based therapy could provide to patients with neurological damage, as well as their clinical limitations. In this review we focus on the potential of MSCs as a therapeutic tool to treat neurological disorders, summarizing the state of the art of this topic and the most recent clinical studies.

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.

Human bone marrow-derived mesenchymal stromal cells in combination with silymarin regulate hepatocyte growth factor expression and genotoxicity in carbon tetrachloride induced hepatotoxicity in Wistar rats

BACKGROUND

To evaluate the antimutagenic potential of combination treatment of human bone marrow-derived mesenchymal stromal cells (BM-MSCs) and silymarin and its effect on hepatocyte growth factor levels in CCl₄ induced hepatotoxicity in Wistar rats.

METHODS

Hepatotoxicity was induced in adult female Wistar rats using carbon tetrachloride (CCl₄ ). Thirty-six rats were randomly divided into six groups with six rats in each group: Group 1 (normal control group), Group 2 (received only CCl ₄ ), Group 3 (CCl ₄ +low dose BM-MSCs), Group 4 (CCl ₄ +high dose BM-MSCs), Group 5 (CCl ₄  + silymarin), Group 6 (CCl ₄ +silymarin+high dose BM-MSCs). Thirty days after the treatment, blood samples were collected for hepatocyte growth factor estimation. The rats were then killed, bone marrow was extracted for chromosomal aberration assay. Liver tissue was processed for evaluating the DNA fragmentation assay, histopathology, and scanning electron microscopy study.

RESULTS

Combination treatment of silymarin and high dose BM-MSCs significantly (P < 0.05) restored the plasma hepatocyte growth factor levels which were comparable with normal levels and exhibited significant antimutagenic and antiapoptotic activity by decreasing the frequency of structural chromosomal aberrations and suppressing the DNA fragmentation in liver tissue samples. The combination treatment produced significant hepatoprotective effect which was supported by histopathology and scanning electron microscopy study.

CONCLUSION

Results indicate that the treatment of BM-MSCs in combination with silymarin had a better hepatoprotective and antimutagenic effect and represents a novel strategy for the treatment of hepatotoxicity.

Pancreatic endocrine-like cells differentiated from human umbilical cords Wharton's jelly mesenchymal stem cells using small molecules

Following success of pancreatic islet transplantation in the treatment of Type I diabetes mellitus, there is a growing interest in using cell-based treatment approaches. However, severe shortage of donor islets-pancreas impeded the growth, and made researchers to search for an alternative treatment approaches. In this context, recently, stem cell-based therapy has gained more attention. The current study demonstrated that epigenetic modification improves the in vitro differentiation of Wharton's jelly mesenchymal stem cells (WJMSCs) into pancreatic endocrine-like cells. Here we used two histone deacetylase (HDAC) inhibitors namely trichostatin A (TSA) and TMP269. TSA inhibits both class I and II HDACs whereas TMP269 inhibits only class IIa HDACs. WJMSCs were differentiated using a multistep protocol in a serum-free condition with or without TSA pretreatment. A marginal improvement in differentiation was observed after TSA pretreatment though it was not significant. However, exposing endocrine precursor-like cells derived from WJMSCs to TMP269 alone has significantly improved the differentiation toward insulin-producing cells. Further, increase in the expression of paired box 4 (PAX4), insulin, somatostatin, glucose transporter 2 (GLUT2), MAF bZIP transcription factor A (MAFA), pancreatic duodenal homeobox 1 (PDX-1), and NKX6.1 was observed both at messenger RNA and protein levels. Nevertheless, TMP269-treated cells secreted higher insulin upon glucose challenge, and demonstrated increased dithizone staining. These findings suggest that TMP269 may improve the in vitro differentiation of WJMSCs into insulin-producing cells.

Epigenetic changes in mesenchymal stem cells differentiation

Epigenetic factors are known to play a major role in determining stem cell fate and differentiation. Mesenchymal stem cells are the most studied population of stem cells due to their important applications in experimental biology and regenerative medicine. After a brief overview on mesenchymal stem cells, this review aims to highlight the role of epigenetic changes on mesenchymal stem cells biology and differentiation protocols with a focus on osteocytic, chondrocytic and adipocytic differentiation. Chromatin remodeling, DNA methylation, histone modifications and miRNA expression will be investigated. The impact of epigenetics on transdifferentiation of mesenchymal stem cells will also be discussed. Indeed, epigenetic modulation appears to constitute a promising experimental target in stem cell basic and translational research.

The Impact of Epigenetics on Mesenchymal Stem Cell Biology

Changes in epigenetic marks are known to be important regulatory factors in stem cell fate determination and differentiation. In the past years, the investigation of the epigenetic regulation of stem cell biology has largely focused on embryonic stem cells (ESCs). Contrarily, less is known about the epigenetic control of gene expression during differentiation of adult stem cells (AdSCs). Among AdSCs, mesenchymal stem cells (MSCs) are the most investigated stem cell population because of their enormous potential for therapeutic applications in regenerative medicine and tissue engineering. In this review, we analyze the main studies addressing the epigenetic changes in MSC landscape during in vitro cultivation and replicative senescence, as well as follow osteocyte, chondrocyte, and adipocyte differentiation. In these studies, histone acetylation, DNA methylation, and miRNA expression are among the most investigated phenomena. We describe also epigenetic changes that are associated with in vitro MSC trans-differentiation. Although at the at initial stage, the epigenetics of MSCs promise to have profound implications for stem cell basic and applied research. J. Cell. Physiol. 231: 2393-2401, 2016. © 2016 Wiley Periodicals, Inc.

Identification of the small molecule compound which induces hepatic differentiation of human mesenchymal stem cells

Human mesenchymal stem cells (MSCs) are expected to have utility as a cell source in regenerative medicine. Because we previously reported that suppression of the Wnt/β-catenin signal enhances hepatic differentiation of human MSCs, we synthesized twenty-three derivatives of small molecule compounds originally reported to suppress the Wnt/β-catenin signal in human colorectal cancer cells. We then screened these compounds for their ability to induce hepatic differentiation of human UE7T-13 MSCs. After screening using WST assay, TCF reporter assay, and albumin mRNA expression, IC-2, a derivative of ICG-001, was identified as a potent inducer of hepatic differentiation of human MSCs. IC-2 potently induced the expression of albumin, complement C3, tryptophan 2,3-dioxygenase (TDO2), EpCAM, C/EBPα, glycogen storage, and urea production. Furthermore, we examined the effects of IC-2 on human bone marrow mononuclear cell fractions sorted according to CD90 and CD271 expression. Consequently, CD90⁺ CD271⁺ cells were found to induce the highest production of urea and glycogen, important hepatocyte functions, in response to IC-2 treatment. CD90⁺ CD271⁺ cells also highly expressed albumin mRNA. As the CD90⁺ CD271⁺ population has been reported to contain a rich fraction of MSCs, IC-2 apparently represents a potent inducer of hepatic differentiation of human MSCs.

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We screened newly synthesized derivatives of small molecule compounds generated from known Wnt/β-catenin signal inhibitors.

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IC-2 was identified as an inducer of the differentiation of human mesenchymal stem cells into hepatocytes.

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IC-2 potently induces hepatic differentiation of human bone marrow mononuclear CD90⁺ CD271⁺ cells.

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.

Valproic Acid Arrests Proliferation but Promotes Neuronal Differentiation of Adult Spinal NSPCs from SCI Rats

Although the adult spinal cord contains a population of multipotent neural stem/precursor cells (NSPCs) exhibiting the potential to replace neurons, endogenous neurogenesis is very limited after spinal cord injury (SCI) because the activated NSPCs primarily differentiate into astrocytes rather than neurons. Valproic acid (VPA), a histone deacetylase inhibitor, exerts multiple pharmacological effects including fate regulation of stem cells. In this study, we cultured adult spinal NSPCs from chronic compressive SCI rats and treated with VPA. In spite of inhibiting the proliferation and arresting in the G0/G1 phase of NSPCs, VPA markedly promoted neuronal differentiation (β-tubulin III(+) cells) as well as decreased astrocytic differentiation (GFAP(+) cells). Cell cycle regulator p21(Cip/WAF1) and proneural genes Ngn2 and NeuroD1 were increased in the two processes respectively. In vivo, to minimize the possible inhibitory effects of VPA to the proliferation of NSPCs as well as avoid other neuroprotections of VPA in acute phase of SCI, we carried out a delayed intraperitoneal injection of VPA (150 mg/kg/12 h) to SCI rats from day 15 to day 22 after injury. Both of the newborn neuron marker doublecortin and the mature neuron marker neuron-specific nuclear protein were significantly enhanced after VPA treatment in the epicenter and adjacent segments of the injured spinal cord. Although the impaired corticospinal tracks had not significantly improved, Basso-Beattie-Bresnahan scores in VPA treatment group were better than control. Our study provide the first evidence that administration of VPA enhances the neurogenic potential of NSPCs after SCI and reveal the therapeutic value of delayed treatment of VPA to SCI.

Fate determination in mesenchymal stem cells: a perspective from histone-modifying enzymes

Mesenchymal stem cells (MSCs) hold great promise for therapeutic use in regenerative medicine and tissue engineering. A detailed understanding of the molecular processes governing MSC fate determination will be instrumental in the application of MSCs. Much progress has been made in recent years in defining the epigenetic events that control the differentiation of MSCs into different lineages. A complex network of transcription factors and histone modifiers, in concert with specific transcriptional co-activators and co-repressors, activates or represses MSC differentiation. In this review, we summarize recent progress in determining the effects of histone-modifying enzymes on the multilineage differentiation of MSCs. In addition, we propose that the manipulation of histone signatures associated with lineage-specific differentiation by small molecules has immense potential for the advancement of MSC-based regenerative medicine.

Wharton's Jelly-derived Mesenchymal Stem Cells can Differentiate into Hepatocyte-like Cells by HepG2 Cell Line Extract

BACKGROUND

Wharton's jelly is an unlimited source of stem cells that can be used in cell therapy and tissue engineering without any ethical concern. It has been revealed the cell-free extract could be effective to induce cell differentiation. The objective of this study was to induce Wharton's jelly-derived mesenchymal stem cells (MSCs) into hepatocyte-like cells by premeabilization of the cells in the presence of HepG2 cell line extract.

METHODS

MSCs were isolated from the umbilical cord, CD marker profile and their differentiation potential into adipogenic and osteogenic lineages were determined. The cells were then, permeabilized by streptolysin O in the presence of HepG cell extract. The treated cells were cultured for 17 days. The cell phenotype was evaluated and the hepatocyte specific markers were detected by immunofluorescence and immunocytochemistry. The Periodic Acid Schiff (PAS) reaction and the cellular uptake of indocyanine green were performed to evaluate the functional behavior of the differentiated cells.

RESULTS

The phenotype of extract-treated MSCs changed into a round or polygonal cells with few short processes and they could express high level of albumin, cytokeratin 18 and 19. The MSCs also could store glycogen and uptake and release indocyanine green.

CONCLUSION

We demonstrated for the first time that Wharton's jelly-derived MSCs could differentiate into hepatocyte-like cells by premeabilization of them in the presence of HepG2 cell extract. This study suggests a feasible method to differentiate MSCs into functional hepatocyte-like cells.

MicroRNA-26a induced by hypoxia targets HDAC6 in myogenic differentiation of embryonic stem cells

The importance of epigenetic regulation for maintenance of embryonic stem cell (ESC) pluripotency or for initiation of differentiation is widely accepted. However, the molecular mechanisms are poorly understood. We recently reported that a hypoxic microenvironment induces ESC differentiation. In the present study, we found that hypoxia-responsive histone deacetylase 6 (HDAC6) performs an essential signaling function for myogenic differentiation of ESCs. HDAC6 was downregulated in hypoxic ESCs or during differentiation. A knock-down of HDAC6 in ESCs resulted in induction of myogenic markers, including Pax7. Suppression of HDAC6 increased acetylation of core histones H3 and H4, leading to enhanced binding of RNA polymerase II to the Pax7 promoter. Transplantation of HDAC6 knock-down cells facilitated muscle regeneration in vivo. Importantly, the downregulation of HDAC6 by hypoxia was not mediated by HIF1α or HIF2α, master transcription regulators under hypoxia, but by induction of microRNA-26a that directly targeted the 3'-untranslated region (3'-UTR) of HDAC6. A point mutation of the microRNA-26a-binding sequence in the HDAC6 3'-UTR diminished the luciferase reporter activity. Taken together, these results suggest that environmental cues of differentiation modulate the epigenetic machinery and guide stem cells to commit to a specific lineage.

Role of Bone Marrow Mesenchymal Stem Cells in the Treatment of CCL4 Induced Liver Fibrosis in Albino Rats: A Histological and Immunohistochemical Study

BACKGROUND AND OBJECTIVES

Variety of pathological factors including viral hepatitis, alcohol and drug abuse, metabolic diseases, autoimmune diseases and congenital abnormalities can cause hepatic injury. Liver transplantation is the treatment of choice for end-stage liver diseases, however, it faces several difficulties. So the aim of the work is to evaluate the effect of bone marrow derived mesenchymal stem cells (BM-MSCs) on the liver structure in carbon tetra chloride CCL4 induced liver fibrosis in rats.

MATERIALS AND RESULTS

BM-MSCs were isolated and characterized from long bones of twenty male albino rats. Sixty female rats were divided into the following two groups: Group I; thirty rats which were the control group. Group II; thirty rats were injected intra-peritoneal (IP) by CCL4 twice weekly for four weeks and was further subdivided into the following three subgroups: Subgroup IIA (CCL4 alone); included ten rats which were sacrificed after this four weeks. Subgroup IIB (CCL4/MSCs); included ten rats which were IP injected by a single dose of BM-MSCs and were sacrificed after four weeks. Subgroup IIC (CCL4/recovery); included ten rats which were left for another four weeks without any intervention. Histological examination of liver specimens showed that CCl4 caused variable pathological changes with elevated liver enzymes. Injection of BM-MSCs revealed an improvement in the histological picture of the liver and its enzymatic profile. On the other hand, most of the pathological lesion were still detected in rats of recovery group.

CONCLUSIONS

BM-MSC could restore the liver structure and function in experimental model of liver fibrosis.

Histone deacetylase inhibitor valproic acid promotes the differentiation of human induced pluripotent stem cells into hepatocyte-like cells

In this study, we aimed to elucidate the effects and mechanism of action of valproic acid on hepatic differentiation from human induced pluripotent stem cell-derived hepatic progenitor cells. Human induced pluripotent stem cells were differentiated into endodermal cells in the presence of activin A and then into hepatic progenitor cells using dimethyl sulfoxide. Hepatic progenitor cells were matured in the presence of hepatocyte growth factor, oncostatin M, and dexamethasone with valproic acid that was added during the maturation process. After 25 days of differentiation, cells expressed hepatic marker genes and drug-metabolizing enzymes and exhibited drug-metabolizing enzyme activities. These expression levels and activities were increased by treatment with valproic acid, the timing and duration of which were important parameters to promote differentiation from human induced pluripotent stem cell-derived hepatic progenitor cells into hepatocytes. Valproic acid inhibited histone deacetylase activity during differentiation of human induced pluripotent stem cells, and other histone deacetylase inhibitors also enhanced differentiation into hepatocytes. In conclusion, histone deacetylase inhibitors such as valproic acid can be used to promote hepatic differentiation from human induced pluripotent stem cell-derived hepatic progenitor cells.

Hydrogen sulphide increases hepatic differentiation of human tooth pulp stem cells compared with human bone marrow stem cells

AIM

To determine the differences in stem cell properties, in hepatic differentiation and in the effects of hydrogen sulphide (H2 S) on hepatic differentiation between human bone marrow stem cells (hBMC) and stem cells from human exfoliated primary tooth pulp (SHED).

METHODOLOGY

CD117(+) cells were magnetically separated and subjected to hepatic differentiation. CD117(+) cell lineages were characterized for transcription factors indicative of stem cells by qRT-PCR. For the last 9 days of the differentiation, the test cells were exposed to 0.1 ng mL(-1) H2 S. Immunocytochemistry and flow cytometry of albumin, alpha-fetoprotein and carbamoyl phosphate synthetase were carried out after differentiation. Urea concentration and glycogen synthesis were also determined.

RESULTS

Genes expressed in SHED were also expressed in BMC. No difference in expression level of hepatic markers was shown by immunofluorescence. SHED showed more positive cells than hBMC (P < 0.01). H2 S increased the number of positive cells in both cultures (P < 0.01). Urea concentration and glycogen synthesis increased significantly after H2 S exposure (P < 0.001 and P < 0.05, respectively). Real-time PCR data were analysed by RT(2) profiler RT-PCR Array Data Analysis version 3.5 (Qiagen), and ELISA data were analysed by Bonferroni's multiple comparison using Windows spss version 16 (SPSS Inc, Chicago, IL, USA). Bonferroni's multiple comparison test was also carried out after angle transformation for the percentage data of flow cytometer using Windows spss(®) version 16 (SPSS Inc). Statistical significance was accepted at P < 0.05.

CONCLUSIONS

Stem cells from human exfoliated primary tooth pulp and BMC have similar properties. The level of hepatic differentiation in SHED compared with BMC was the same or higher. H2 S increased the level of hepatic differentiation.