Hydrogen Sulfide Causes Apoptosis in Human Pulp Stem Cells

The potential role of hydrogen sulfide in cancer cell apoptosis

For a long time, hydrogen sulfide (H2S) has been considered a toxic compound, but recent studies have found that H2S is the third gaseous signaling molecule which plays a vital role in physiological and pathological conditions. Currently, a large number of studies have shown that H2S mediates apoptosis through multiple signaling pathways to participate in cancer occurrence and development, for example, PI3K/Akt/mTOR and MAPK signaling pathways. Therefore, the regulation of the production and metabolism of H2S to mediate the apoptotic process of cancer cells may improve the effectiveness of cancer treatment. In this review, the role and mechanism of H2S in cancer cell apoptosis in mammals are summarized.

Hydrogen Sulfide Produced by Gut Bacteria May Induce Parkinson's Disease

Several bacterial species can generate hydrogen sulfide (H2S). Study evidence favors the view that the microbiome of the colon harbors increased amounts of H2S producing bacteria in Parkinson's disease. Additionally, H2S can easily penetrate cell membranes and enter the cell interior. In the cells, excessive amounts of H2S can potentially release cytochrome c protein from the mitochondria, increase the iron content of the cytosolic iron pool, and increase the amount of reactive oxygen species. These events can lead to the formation of alpha-synuclein oligomers and fibrils in cells containing the alpha-synuclein protein. In addition, bacterially produced H2S can interfere with the body urate metabolism and affect the blood erythrocytes and lymphocytes. Gut bacteria responsible for increased H2S production, especially the mucus-associated species of the bacterial genera belonging to the Desulfovibrionaceae and Enterobacteriaceae families, are likely play a role in the pathogenesis of Parkinson's disease. Special attention should be devoted to changes not only in the colonic but also in the duodenal microbiome composition with regard to the pathogenesis of Parkinson's disease. Influenza infections may increase the risk of Parkinson's disease by causing the overgrowth of H2S-producing bacteria both in the colon and duodenum.

Role of Hydrogen Sulfide in Oral Disease

Oral diseases are among the most common human diseases yet less studied. These diseases affect both the physical, mental, and social health of the patients resulting in poor quality of life. They affect all ages, although severe stages are mostly observed in older individuals. Poor oral hygiene, genetics, and environmental factors contribute enormously to the development and progression of these diseases. Although there are available treatment options for these diseases, the recurrence of the diseases hinders their efficiency. Oral volatile sulfur compounds (VSCs) are highly produced in oral cavity as a result of bacteria activities. Together with bacteria components such as lipopolysaccharides, VSCs participate in the progression of oral diseases by regulating cellular activities and interfering with the immune response. Hydrogen sulfide (H2S) is a gaseous neurotransmitter primarily produced endogenously and is involved in the regulation of cellular activities. The gas is also among the VSCs produced by oral bacteria. In numerous diseases, H2S have been reported to have dual effects depending on the cell, concentration, and donor used. In oral diseases, high production and subsequent utilization of this gas have been reported. Also, this high production is associated with the progression of oral diseases. In this review, we will discuss the production of H2S in oral cavity, its interaction with cellular activities, and most importantly its role in oral diseases.

Abdominal paracentesis drainage attenuates severe acute pancreatitis by enhancing cell apoptosis via PI3K/AKT signaling pathway

Our previous studies have shown that abdominal paracentesis drainage (APD) is a safe and effective strategy for patients with severe acute pancreatitis (SAP). However, the underlying mechanisms behind APD treatment remain poorly understood. Given that apoptosis is a critical pathological response of SAP, we here aim to investigate the effect of APD on cell apoptosis in pancreatic tissues during SAP and to explore its potential molecular mechanism. SAP was induced by 5% sodium-taurocholate retrograde while APD group was inserted a drainage tube into the right lower abdomen of rats immediately after SAP induction. Histopathological staining, serum amylase, endotoxin and inflammatory mediators were measured. Cell apoptosis, apoptosis-related proteins and signaling pathway were also evaluated. Our results demonstrated that APD treatment significantly attenuated pancreatic damage and decreased the serum levels of amylase, endotoxin, TNF-α, IL-1 and IL-6 in rats with SAP. Notably, APD treatment enhanced cell apoptosis and reduced necrosis in pancreatic tissues, as evidenced by Tunnel staining, the increased pro-apoptosis proteins (Cleaved-caspase-3 and bax) and decreased anti-apoptosis protein (Bcl-2). Moreover, the effect of APD on cell apoptosis was further confirmed by the regulatory pathway of PI3K/AKT and NF-kB signaling pathway. These results suggest that APD attenuates the severity of SAP by enhancing cell apoptosis via suppressing PI3K/AKT signaling pathway. Our findings provide new insights for understanding the effectiveness of APD in patients with SAP.

Hydrogen sulfide: An endogenous regulator of the immune system

Hydrogen sulfide (H₂S) is now recognized as an endogenous signaling gasotransmitter in mammals. It is produced by mammalian cells and tissues by various enzymes - predominantly cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST) - but part of the H₂S is produced by the intestinal microbiota (colonic H₂S-producing bacteria). Here we summarize the available information on the production and functional role of H₂S in the various cell types typically associated with innate immunity (neutrophils, macrophages, dendritic cells, natural killer cells, mast cells, basophils, eosinophils) and adaptive immunity (T and B lymphocytes) under normal conditions and as it relates to the development of various inflammatory and immune diseases. Special attention is paid to the physiological and the pathophysiological aspects of the oral cavity and the colon, where the immune cells and the parenchymal cells are exposed to a special "H₂S environment" due to bacterial H₂S production. H₂S has many cellular and molecular targets. Immune cells are "surrounded" by a "cloud" of H₂S, as a result of endogenous H₂S production and exogenous production from the surrounding parenchymal cells, which, in turn, importantly regulates their viability and function. Downregulation of endogenous H₂S producing enzymes in various diseases, or genetic defects in H₂S biosynthetic enzyme systems either lead to the development of spontaneous autoimmune disease or accelerate the onset and worsen the severity of various immune-mediated diseases (e.g. autoimmune rheumatoid arthritis or asthma). Low, regulated amounts of H₂S, when therapeutically delivered by small molecule donors, improve the function of various immune cells, and protect them against dysfunction induced by various noxious stimuli (e.g. reactive oxygen species or oxidized LDL). These effects of H₂S contribute to the maintenance of immune functions, can stimulate antimicrobial defenses and can exert anti-inflammatory therapeutic effects in various diseases.

H2S inhalation-induced energy metabolism disturbance is involved in LPS mediated hepatocyte apoptosis through mitochondrial pathway

Hydrogen sulfide (H₂S) is a toxic gas and one of the air pollutants of great concern. High-concentrated H₂S can induce energy metabolism disturbance and apoptosis. However, the mechanism of H₂S-induced liver injuries is unknown. Lipopolysaccharide (LPS), the main component of endotoxin, can cause fulminant hepatitis. Here, we evaluated the effects of H₂S combined with LPS on the energy metabolism and apoptosis pathway in the liver using a one-day-old chicken as a model. Our results showed that the expression levels of energy metabolism-related genes (AMP-activated protein kinase (AMPK), Hypoxia-inducible factor-1 (HIF-1), aconitase 2 (ACO2), hexokinase1 (HK1), hexokinase 2 (HK2), lactate dehydrogenase A (LDHA), lactate dehydrogenase B (LDHB), phosphofructokinase (PFK), pyruvate kinase (PK) and succinate dehydrogenase B (SDHB)) tended to decrease, that the status of apoptosis increased, and that the expression levels of apoptosis-related genes (caspase3, BCL2, and bax) increased in H₂S group, suggesting that H₂S exposure disturbed the energy metabolism in the liver and induced hepatocyte apoptosis through the mitochondrial pathway. In addition, H₂S combined with the LPS aggravated the level of energy metabolism disorders and apoptosis, indicating that H₂S inhalation-induced energy metabolism disturbance is involved in LPS-mediated hepatocyte apoptosis through the mitochondrial pathway.

Endogenous Hydrogen Sulfide Promotes Apoptosis via Mitochondrial Pathways in the Livers of Broilers with Selenium Deficiency Exudative Diathesis Disease

Hydrogen sulfide (H₂S), an endogenous gasotransmitter, plays an important role in apoptosis. Exudative diathesis (ED) disease is associated with dietary selenium (Se) deficiency in broilers. The liver is one of the target organs of Se deficiency; however, little is known about the effect of H₂S on apoptosis via mitochondrial pathways in the livers of broilers with ED disease. In the present study, we aimed to investigate the correlation between endogenous H₂S and mitochondrial-mediated apoptosis in the livers of broilers with ED disease, as induced by Se deficiency. One hundred twenty healthy, 1-day-old broilers were randomly assigned to one of two groups (60 each) based on diet: Basal diet (control group, 0.2 mg/kg Se) or a low-Se diet (-Se group, 0.033 mg/kg Se). At day 20, 15 broilers of a similar weight were sacrificed from the control group, while the same number of broilers were euthanatized from the -Se group when displaying typical symptoms of ED between days 18 and 25. The livers were collected, and apoptosis was measured using a TUNEL assay. Additionally, H₂S concentration, the expression of H₂S synthases of cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MST), as well as mitochondrial apoptosis-related genes of Bcl-2, Bax, Bak, Cyt-C, Caspase-9, Caspase-3, and p53, were examined in livers. The results indicated that Se deficiency could induce apoptosis in the livers of broilers. Swelling, fractures, and vacuolization were visible in the mitochondrial cristae in the livers of the -Se group. The expression of H₂S synthase-related genes and H₂S concentration was significantly enhanced (P < 0.05) in the livers of the -Se group compared to controls. Moreover, a low-Se diet downregulated (P < 0.05) the level of Bcl-2 and upregulated (P < 0.05) the levels of Bax, Bak, Cyt-C, Caspase-9, Caspase-3, and p53. These results suggest that an H₂S increase in the livers of ED broilers, which was induced by Se deficiency, is related to apoptosis mediated by mitochondrial pathways.

Hydrogen sulfide maintains dental pulp stem cell function via TRPV1-mediated calcium influx

Hydrogen sulfide (H₂S), an endogenous gasotransmitter, mediated a variety of biological processes through multiple signaling pathways, and aberrant H₂S metabolism has been associated with mesenchymal stem cell (MSC) dysfunction. Here we employed the small interfering RNA treatment for cystathionine β-synthase (CBS), cystathionine γ-lyase, the main enzymes to synthesize H₂S, and CBS-knockout mice to analyze the effect of H₂S on dental pulp homeostasis. We showed that H₂S deficiency attenuated dental pulp stem cell (DPSC) osteogenic/dentinogenic differentiation in vitro and in vivo with enhanced cell proliferation. Mechanically, H₂S facilitated the transient receptor potential action channel subfamily V member 1-mediated calcium (Ca²⁺⁾ influx, which subsequently activated the β-catenin pathway. While H₂S deficiency decreased Ca²⁺, resulting in glycogen synthase kinase-3β-mediated β-catenin degradation, which controls proliferation and differentiation of DPSCs. Consistently, H₂S-deficient mice displayed disturbed pattern of dental pulp and less dentin formation. In this study, we identified a previously unknown mechanism by which H₂S regulates DPSC lineage determination and dental pulp homeostasis.

Caspase‑9 was involved in cell apoptosis in human dental pulp stem cells from deciduous teeth

As one type of adult stem cells (ASCs), human dental pulp stem cells (HDPSCs) have several properties, including high proliferation rate, self‑renewal capability, and multi‑lineage differentiation. However, the apoptotic mechanism underlying the development of dental pulp cells remains unclear. In the present study, a significant increase of apoptosis was observed in HDPSCs from the deciduous teeth compared with that from adult permanent teeth. In addition, the occurrence of cytochrome c expression and mitochondrial‑mediated apoptosis pathway activity in HDPSCs were confirmed by quantitative polymerase chain reaction, and western blotting. Although caspase‑8 and caspase‑9 showed higher expression in deciduous teeth than in adult permanent teeth, only the knockdown of caspase‑9 via RNA interference in HDPSC cells exhibited a significant reduction in apoptosis, and caspase‑3 expression and activity. All these results revealed that caspase‑9 and activated caspase‑3 predominantly regulates cell apoptosis in HDPSCs from deciduous teeth.

Angiotensin‑(1‑7) attenuates caerulein‑induced pancreatic acinar cell apoptosis

Extensive apoptosis of pancreatic acinar cells frequently occurs in acute pancreatitis (AP), and has been identified to be closely associated with the decrease of pancreatic parenchymal cells and pancreatic damage. The present study aimed to investigate the possible effect of angiotensin (Ang)‑(1‑7) on caerulein (CAE)‑induced pancreatic acinar cell apoptosis. Mouse pancreatic acinar cancer cells (MPC‑83) were divided into 4 groups: Control group; CAE group; CAE + Ang‑(1‑7) group; and CAE + Ang‑(1‑7) antagonist (A779) group. The control group consisted of normal MPC‑83 cells without special treatment. The CAE group was stimulated with 10 nmol/l CAE and harvested at 2, 6, 12, 24 and 48 h. For the CAE + Ang‑(1‑7) group and CAE + A779 group, the CAE‑induced pancreatic acinar cells were mock pretreated or pretreated with different concentrations of Ang‑(1‑7) or A779 (10‑7, 10‑6 or 10‑5 mol/l) for 30 min. Caspase‑3 is a critical executioner of apoptosis, as it is either partly or completely responsible for the proteolytic cleavage of numerous key proteins including the nuclear enzyme poly (ADP‑ribose) polymerase. Activation of caspase‑3 requires proteolytic processing of its inactive zymogen into activated p17 and p12 fragments. Thus, the present study investigated the apoptotic markers, including cleaved caspase‑3, B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑like protein 4 (Bax) and renin‑angiotensin system (RAS) pathway related proteins (ACE2 and Mas receptor). The results demonstrated that the cleaved caspase‑3 levels were increased in the CAE group (P<0.05), peaking at 24 h, and declined when incubated with Ang‑(1‑7). Following treatment with Ang‑(1‑7), levels of the anti‑apoptotic protein Bcl‑2 rose dramatically in a dose‑dependent manner. The ratio of the pro‑apoptotic protein Bax to the anti‑apoptotic protein Bcl‑2 dropped notably, which demonstrated a tendency towards curbing apoptosis. In addition, the cleaved caspase‑3 levels, and the ratio of Bax to Bcl‑2 in the CAE + A779 group presented a significant rise compared with the CAE group. It was concluded that Ang‑(1‑7) may possess an inhibitory effect on CAE‑induced pancreatic acinar cell apoptosis and that appropriate interventions in RAS may attenuate pancreatic injury during AP.

Hydrogen sulfide enhances pancreatic β-cell differentiation from human tooth under normal and glucotoxic conditions

Aim: Glucotoxicity obstructs pancreatic differentiation from adult stem cells. The aim was to develop a novel protocol for differentiation of dental pulp stem cells (DPSCs) into pancreatic β cells and determine the effect of H2S on glucotoxicity. Materials & methods: DPSCs were differentiated with media containing 5.5 or 25.0 mM glucose, exposed to 1 ng/ml H2S. Glucotoxicity, expression of β-cell markers, INS, PDX1 and GLUT2, and PI3K/AKT pathway were assessed. Results: H2S exposure increased insulin and C-peptide, and protected DPSC-derived pancreatic β-like cells from glucotoxicity and upregulated INS, PDX1 and GLUT2, and genes of PI3K/AKT pathway. Conclusion: H2S improved effects of glucotoxicity on β-like cells via PI3K/AKT pathway. The protocol for pancreatic β-cell differentiation might have applications in regenerative medicine rather than swine pancreas transplantation.

Cinnamaldehyde Ameliorates Cadmium-Inhibited Root Elongation in Tobacco Seedlings via Decreasing Endogenous Hydrogen Sulfide Production

Cinnamaldehyde (CA) is natural plant-derived compound that has been highly appreciated for its medicinal properties. However, little information is known about the regulation of plant intrinsic physiology by CA. To address these gaps, physiological, histochemical, and biochemical approaches were applied to investigate CA-facilitated cadmium (Cd) tolerance in the roots of tobacco (Nicotiana tabacum) seedlings. Treatment with CdCl₂ at 20 μM for 72 h resulted in the significant decrease in root elongation by 40.39% as compared to control. CA alleviated Cd-inhibited root elongation in dose- and time-dependent manners. The addition of CA at 20 μM induced significant increase in root elongation by 42.58% as compared to Cd treatment alone. CA abolished Cd-induced ROS (reactive oxygen species) accumulation, lipid peroxidation, loss of membrane integrity, cell death, and free Cd2+ accumulation in roots. CA blocked the Cd-induced increase in the endogenous H₂S level through the down-regulation of d-cysteine desulfhydrase (DCD) expression. H₂S scavenger hypotaurine (HT) or potent H₂S-biosynthetic inhibitor dl-propargylglicine (PAG) were able mimic the action of CA on the blockade of Cd-induced H₂S accumulation, cell death, and growth inhibition. Enhancement of the endogenous H₂S level with NaHS (H₂S donor) abrogated all the beneficial capabilities of CA, HT, and PAG. Collectively, these results suggest that CA has great potential to confer plant tolerance against Cd stress, which is closely associated with its capability to inhibit Cd-induced H₂S production. This study not only provides evidences for the regulation of plant physiology by CA but also sheds new light on the cross-talk between CA and H₂S in physiological modulations.

Hydrogen Sulfide Regulates Homeostasis of Mesenchymal Stem Cells and Regulatory T Cells

Hydrogen sulfide (H₂S) has long been known as a toxic gas. However, recently accumulated evidence suggests that H₂S contributes to a variety of physiologic and pathologic processes. Endogenous H₂S production is regulated by multiple enzymes that are differentially expressed in the cardiovascular, neuronal, immune, renal, respiratory, gastrointestinal, reproductive, liver, and endocrine systems. Alteration of H₂S metabolism may affect multiple signaling pathways and tissue homeostasis. The growing number of diverse targets for which H₂S serves as a gasotransmitter has been extensively reviewed elsewhere. In this review, the authors discuss current emerging evidence that H₂S regulates mesenchymal stem cell and T-cell functions.

Transcriptional response to sulfide in the Echiuran Worm Urechis unicinctus by digital gene expression analysis

Background

Urechis unicinctus, an echiuran worm inhabiting the U-shaped burrows in the coastal mud flats, is an important commercial and ecological invertebrate in Northeast Asian countries, which has potential applications in the study of animal evolution, coastal sediment improvement and marine drug development. Furthermore, the worm can tolerate and utilize well-known toxicant-sulfide. However, knowledge is limited on the molecular mechanism of U. unicinctus responding to sulfide due to deficiency of its genetic information.

Methods

In this study, we performed Illumina sequencing to obtain the first Urechis unicinctus transcriptome data. Sequenced reads were assembled and then annotated using blast searches against Nr, Nt, Swiss-Prot, KEGG and COG. The clean tags from four digital gene expression (DGE) libraries were mapped to the U. unicinctus transcriptome. DGE analysis and functional annotation were then performed to reveal its response to sulfide. The expressions of 12 candidate genes were validated using quantitative real-time PCR. The results of qRT-PCR were regressed against the DGE analysis, with a correlation coefficient and p-value reported for each of them.

Results

Here we first present a draft of U. unicinctus transcriptome using the Illumina HiSeq^TM 2000 platform and 52,093 unique sequences were assembled with the average length of 738 bp and N50 of 1131 bp. About 51.6 % of the transcriptome were functionally annotated based on the databases of Nr, Nt, Swiss-Prot, KEGG and COG. Then based on the transcriptome, the digital gene expression analysis was conducted to examine the transcriptional response to sulfide during 6, 24 and 48 h exposure, and finally 1705, 1181 and 1494 tag-mapped genes were identified as differentially expressed genes in the 6-h, 24-h and 48-h libraries, then were further subjected to pathway analyses.

Conclusions

In the DGE database of U. unicinctus, the alterations in certain known sulfide-related pathways indicate similar changes in response to sulfide. For more than 80 % of the identified pathway members, this is the first report on their association with sulfide stress, among which glycolysis pathway and PIDD involving pathways were unique and discussed in details, and were thought to play important roles in the sulfide tolerance of U. unicinctus. All the results are helpful to explain the mechanism of sulfide tolerance and detoxification.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2094-z) contains supplementary material, which is available to authorized users.

The differential expression of mgl mRNA by Porphyromonas gingivalis affects the production of methyl mercaptan

OBJECTIVE

A large number of individuals have halitosis. The total amount of volatile sulfur compounds, which are the main cause of halitosis, has been correlated with periodontitis following bacterial infection. In this study, Porphyromonas gingivalis (Pg), a major periodontopathogenic bacterium, was isolated from patients with halitosis by the amplification of 16S rRNA, and the ability of isolated Pg to produce methyl mercaptan (CH3 SH) was determined to clarify the relationship between halitosis and Pg infection.

MATERIALS AND METHODS

CH3 SH concentrations were measured in patients using Oral Chroma. The production of CH3 SH by Pg standard and clinical strains was also measured in vitro. Real-time PCR was performed to compare the expression of mgl mRNA (which encoded l-methionine-a-deamino-g-mercaptomethane-lyase) among the Pg strains. The production of CH3 SH and the expression of mgl mRNA were also determined to assess the effects of oriental medicine.

RESULTS

The production of CH3 SH and the expression of mgl mRNA strongly correlated with each other in the presence of l-methionine. The expression of mgl mRNA by Pg W83 was strongly inhibited by magnoliaceae.

CONCLUSION

The production of CH3 SH was correlated with the expression of mgl. Furthermore, the oriental medicine, magnoliaceae, may represent a potential treatment for halitosis.

Oxidative stress and volatile organic compounds: interplay in pulmonary, cardio-vascular, digestive tract systems and cancer

Oxidative stress (OS) can be defined as an imbalance between antioxidant systems and various pro-oxidants. This loss of balance is closely associated with initiation and development of a wide range of systemic or organ specific diseases.

Exhaled breath of healthy humans contains a large number of volatile organic compounds (VOCs) derived from cellular metabolism, released by microorganisms or taken up from the environment. Qualitative or quantitative changes in their composition are associated with diseases and various pathological conditions, also characterized by increased production of reactive oxygen species (ROS), such as superoxide radical, hydrogen peroxide, hydroxyl anion, peroxinitrite, etc. Several volatile organic compounds such as ethane and pentane are direct end-products of the reaction of ROS with various biological compounds (e.g., lipid peroxidation, DNA or protein damage). Being able to accurately identify ROS-generated VOCs could be of particular importance in devising sensitive tests that can diagnose and follow-up oxidative stress-related diseases.

This review describes current knowledge on the associations between oxidative stress and free radicals and the release of several marker volatile organic compounds in a number of diseases. A special focus will be placed on such VOCs in the cardiovascular pathologies, pulmonary diseases and gastro-intestinal tract affections.

Detection of volatile malodorous compounds in breath: current analytical techniques and implications in human disease

For the last few decades intense scientific research has been placed on the relationship between trace substances found in exhaled breath such as volatile organic compounds (VOC) and a wide range of local or systemic diseases. Although currently there is no general consensus, results imply that VOC have a different profile depending on the organ or disease that generates them. The association between a specific pathology and exhaled breath odor is particularly evident in patients with medical conditions such as liver, renal or oral diseases. In other cases the unpleasant odors can be associated with the whole body and have a genetic underlying cause. The present review describes the current advances in identifying and quantifying VOC used as biomarkers for a number of systemic diseases. A special focus will be placed on volatiles that characterize unpleasant breath 'fingerprints' such as fetor hepaticus; uremic fetor; fetor ex ore or trimethylaminuria.

Inhibition of hydrogen sulfide synthesis provides protection for severe acute pancreatitis rats via apoptosis pathway

We aimed to investigate the relationship between the synthesis of hydrogen sulfide (H(2)S) and the pancreatic acinar cell apoptosis in severe acute pancreatitis (SAP) rats, as well as analyse the potential apoptotic pathway involved in this process. Sixty rats had been equally divided into four groups: sham, SAP, SAP + sodium hydrosulfide (NaHS) and SAP + DL-propargylglycine (PAG). 24 h after SAP induction, all surviving animals of each group were sacrificed to collect blood and tissue samples for the following measurements: the level of serum H(2)S as well as the levels of tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), H(2)S synthesizing activity, CSE mRNA and protein expression, maleic dialdehyde (MDA) and myeloperoxidase (MPO) activity, the expression of Bax, Bcl-2, caspase-3, -8 and -9, the release of cytochrome c and the activation of nuclear factor-kappa B (NF-κB), ERK1/2, JNK1/2 and p38 in pancreas. Furthermore, in situ detection of cell apoptosis was examined and the severity of pancreatic damage was analyzed by pathological grading and scoring. Results Significant differences in every index except IL-10 had been found between the SAP, NaHS and PAG groups (P < 0.05). Treatment with PAG obviously induced the pancreatic acinar cell apoptosis as well as improved all the pathological changes and inflammatory parameters. In contrast, administration of NaHS significantly attenuated apoptosis in the pancreas and aggravated the severity of pancreatic damage. Moreover, the expressions of caspase-3, -8, -9 and the release of cytochrome c were all increased in the apoptotic cells, and the activity of NF-κB as well as the phosphorylation of ERK1/2, JNK1/2 and p38 decreased accompanying with the reduction of the serum H(2)S level. H(2)S plays a pivotal role in the regulation of pancreatic acinar cell apoptosis in SAP rats. The present results showed that inhibition of H(2)S synthesis provided protection for SAP rats via inducing acinar cell apoptosis. This process acted through both extrinsic and intrinsic apoptotic pathways, and may be regulated by reducing the activity of NF-κB.

High-purity hepatic lineage differentiated from dental pulp stem cells in serum-free medium

INTRODUCTION

We have previously differentiated hepatocyte like cells from deciduous tooth pulp stem and extracted third molar pulp stem cells with a protocol that used fetal bovine serum, but it showed high contaminations of nondifferentiated cells. Both the lower purity of hepatically differentiated cells and usage of serum are obstacles for application of cell therapy or regenerative medicine. Objective of this study was to investigate the capacity for and purity of hepatocyte-like differentiation of CD117-positive dental pulp stem cells without serum.

METHODS

Mesenchymal cells from human deciduous and extracted third molar pulp were isolated and expanded in vitro. We separated CD117-positive cells by using a magnetic-activated cell sorter. The cells were characterized immunofluorescently by using known stem cell markers. For hepatic differentiation, the media were supplemented with hepatic growth factor, insulin-transferrin-selenium-x, dexamethasone, and oncostatin M. Expression of hepatic markers alpha fetoprotein, albumin, hepatic nuclear factor-4 alpha, insulin-like growth factor-1, and carbamoyl phosphate synthetase was examined immunofluorescently after differentiation. The amount of differentiated cells was assessed by using flow cytometry. Glycogen storage and urea concentration in the medium were defined.

RESULTS

Both cell cultures demonstrated a number of cells positive for all tested hepatic markers after differentiation, ie, albumin-positive cells were almost 90% of differentiated deciduous pulp cells. The concentration of urea in the media increased significantly after differentiation. Significant amount of cytoplasmic glycogen storage was found in the cells.

CONCLUSIONS

Without serum both cell types differentiated into high-purity hepatocyte-like cells. These cells offer a source for hepatocyte lineage differentiation for transplantation in the future.