Interferon-β Overexpression in Adipose Tissue-Derived Stem Cells Induces HepG2 and Macrophage Cell Death in Liver Tumor Organoids via Induction of TNF-Related Apoptosis-Inducing Ligand Expression

Liver tumor organoids derived from liver tumor tissues and pluripotent stem cells are used for liver tumor research but have several challenges in primary cell isolation and stem cell differentiation. Here, we investigated the potential of HepG2-based liver tumor organoids for screening anticancer drugs by evaluating their responsiveness to IFN-β produced by mesenchymal stem cells (MSCs). Liver tumor organoids were prepared in three days on Matrigel using HepG2, primary liver sinusoidal epithelial cells (LSECs), LX-2 human hepatic stellate cells, and THP-1-derived macrophages at a ratio of 4:4:1:1, with 105 total cells. Hepatocyte-related and M2 macrophage-associated genes increased in liver tumor organoids. IFN-β treatment decreased the viability of liver tumor organoids and increased M1 macrophage marker expression (i.e., TNF-α and iNOS) and TRAIL. TRAIL expression was increased in all four cell types exposed to IFN-β, but cell death was only observed in HepG2 cells and macrophages. Further, MSCs overexpressing IFN-β (ASC-IFN-β) also expressed TRAIL, contributing to the reduced viability of liver tumor organoids. In summary, IFN-β or ASC-IFN-β can induce TRAIL-dependent HepG2 and macrophage cell death in HepG2-based liver tumor organoids, highlighting these liver tumor organoids as suitable for anticancer drug screening and mechanistic studies.

Role of TGF-β and p38 MAPK in TSG-6 Expression in Adipose Tissue-Derived Stem Cells In Vitro and In Vivo

Mesenchymal stem cells (MSCs) regulate immune cell activity by expressing tumor necrosis factor-α (TNF-α)-stimulated gene 6 (TSG-6) in inflammatory environments; however, whether anti-inflammatory responses affect TSG-6 expression in MSCs is not well understood. Therefore, we investigated whether transforming growth factor-β (TGF-β) regulates TSG-6 expression in adipose tissue-derived stem cells (ASCs) and whether effective immunosuppression can be achieved using ASCs and TGF-β signaling inhibitor A83-01. TGF-β significantly decreased TSG-6 expression in ASCs, but A83-01 and the p38 inhibitor SB202190 significantly increased it. However, in septic C57BL/6 mice, A83-01 further reduced the survival rate of the lipopolysaccharide (LPS)-treated group and ASC transplantation did not improve the severity induced by LPS. ASC transplantation alleviated the severity of sepsis induced by LPS+A83-01. In co-culture of macrophages and ASCs, A83-01 decreased TSG-6 expression whereas A83-01 and SB202190 reduced Cox-2 and IDO-2 expression in ASCs. These results suggest that TSG-6 expression in ASCs can be regulated by high concentrations of pro-inflammatory cytokines in vitro and in vivo, and that A83-01 and SB202190 can reduce the expression of immunomodulators in ASCs. Therefore, our data suggest that co-treatment of ASCs with TGF-β or p38 inhibitors is not adequate to modulate inflammation.

Generation of Fibrotic Liver Organoids Using Hepatocytes, Primary Liver Sinusoidal Endothelial Cells, Hepatic Stellate Cells, and Macrophages

Liver organoids generated with single or multiple cell types have been used to investigate liver fibrosis development, toxicity, pathogenesis, and drug screening. However, organoid generation is limited by the availability of cells isolated from primary tissues or differentiated from various stem cells. To ensure cell availability for organoid formation, we investigated whether liver organoids could be generated with cell-line-based Huh-7 hepatocellular carcinoma cells, macrophages differentiated from THP-1 monocytes, and LX-2 hepatic stellate cells (HSCs) and primary liver sinusoidal endothelial cells (LSECs). In liver organoids, hepatocyte-, LSEC-, macrophage-, and HSC-related gene expression increased relative to that in two-dimensional (2D)-cultured Huh-7/LSEC/THP-1/LX-2 cells without Matrigel. Thioacetamide (TAA) increased α-smooth muscle actin expression in liver organoids but not in 2D-cultured cells, whereas in TAA-treated organoids, the expression of hepatic and LSEC markers decreased and that of macrophage and HSC markers increased. TAA-induced fibrosis was suppressed by treatment with N-acetyl-L-cysteine or tumor-necrosis-factor-stimulated gene 6 protein. The results showed that liver toxicants could induce fibrotic and inflammatory responses in liver organoids comprising Huh-7/LSEC/macrophages/LX-2 cells, resulting in fibrotic liver organoids. We propose that cell-line-based organoids can be used for disease modeling and drug screening to improve liver fibrosis treatment.

12-O-tetradecanoylphorbol-13-acetate Reduces Activation of Hepatic Stellate Cells by Inhibiting the Hippo Pathway Transcriptional Coactivator YAP

Although protein kinase C (PKC) regulates various biological activities, including cell proliferation, differentiation, migration, tissue remodeling, gene expression, and cell death, the antifibrotic effect of PKC in myofibroblasts is not fully understood. We investigated whether 12-O-tetradecanoylphorbol-13-acetate (TPA), a PKC activator, reduced the activation of hepatic stellate cells (HSCs) and explored the involvement of the Hippo pathway transcriptional coactivator YAP. We analyzed the effect of TPA on the proliferation and expression of α-smooth muscle actin (SMA) in the LX-2 HSC line. We also analyzed the phosphorylation of the Hippo pathway molecules YAP and LATS1 and investigated YAP nuclear translocation. We examined whether Gö 6983, a pan-PKC inhibitor, restored the TPA-inhibited activities of HSCs. Administration of TPA decreased the growth rate of LX-2 cells and inhibited the expression of α-SMA and collagen type I alpha 1 (COL1A1). In addition, TPA induced phosphorylation of PKCδ, LATS1, and YAP and inhibited the nuclear translocation of YAP compared with the control. These TPA-induced phenomena were mostly ameliorated by Gö 6983. Our results indicate that PKCδ exerts an antifibrotic effect by inhibiting the Hippo pathway in HSCs. Therefore, PKCδ and YAP can be used as therapeutic targets for the treatment of fibrotic diseases.

Skeletal muscle satellite cell-derived mesenchymal stem cells ameliorate acute alcohol-induced liver injury

Cultured human skeletal-muscle satellite cells have properties of mesenchymal stem cells (skeletal muscle satellite cell-derived mesenchymal stem cells, SkMSCs) and play anti-inflammatory roles by secreting prostaglandin E2 and hepatocyte growth factor (HGF). To evaluate the utility of SkMSCs in treating liver diseases, we determined whether SkMSCs could ameliorate acute liver and gut inflammation induced by binge ethanol administration. Binge drinking of ethanol led to weight loss in the body and spleen, liver inflammation and steatosis, and increased serum ALT and AST levels (markers of liver injury), along with increased IL-1β, TNF-α, and iNOS expression levels in mice. However, levels of these binge-drinking-induced indicators were reduced by a single intraperitoneal treatment of SkMSCs. Furthermore, levels of bacteria-derived lipopolysaccharide decreased in the livers and sera of ethanol-exposed mice after SkMSC administration. SkMSCs decreased the extent of tissue inflammation and reduced villus and crypt lengths in the small intestine after alcohol binge drinking. SkMSCs also reduced the leakage of blood albumin, an indicator of leaky gut, in the stool of ethanol-exposed mice. Alcohol-induced damage to human colonic Caco-2/tc7 cells was also alleviated by HGF. Therefore, a single treatment with SkMSCs can attenuate alcoholic liver damage by reducing inflammatory responses in the liver and gut, suggesting that SkMSCs could be used in cell therapy to treat alcoholic liver diseases.

Cultured human skeletal muscle satellite cells exhibit characteristics of mesenchymal stem cells and play anti-inflammatory roles through prostaglandin E2 and hepatocyte growth factors

Skeletal muscle satellite cells (SkMSCs) play crucial roles in muscle fiber maintenance, repair, and remodeling; however, it remains unknown if these properties are preserved in cultured SkMSCs. In this study, we investigated the characteristics of cultured SkMSCs and their ability to regulate the activity of M1 macrophages. SkMSCs grew well with an average population doubling time of 26.26 ± 6.85 h during 10 passages (P). At P5, Pax7, MyoD, cluster of differentiation (CD)34, and CD56 were not expressed in SkMSCs, but the MSC markers CD73, CD105, and CD90 were expressed and the cells were differentiated into adipocytes and osteoblasts. When SkMSCs were cocultured with macrophages, interleukin (IL)-1β secretion was decreased, prostaglandin (PG)E2 was produced in coculture, and cyclooxygenase-2 protein was induced in an SkMSC-dependent manner. Hepatocyte growth factor (HGF) was highly secreted by monocultured SkMSCs; interferon-γ and lipopolysaccharide reduced its expression level. However, HGF expression recovered when SkMSCs and macrophages were cocultured. Although exogenous PGE2 upregulated macrophage pro-IL-1β expression, it suppressed the secretion of cleaved IL-1β. In contrast, HGF decreased active IL-1β secretion without affecting pro-IL-1β expression. Co-treatment of macrophages with HGF and PGE2 reduced pro-IL-1β expression level and active IL-1β secretion. Our results suggest that SkMSCs lose their satellite cell properties during serial passaging but acquire mesenchymal stem cell properties including the ability to exert an anti-inflammatory response for macrophages through PGE2 and HGF.

TRAIL-overexpressing Adipose Tissue-derived Mesenchymal Stem Cells Efficiently Inhibit Tumor Growth in an H460 Xenograft Model

BACKGROUND/AIM

Mesenchymal stem cell-based tumor therapy is still limited due to the insufficient secretion of effectors and discrepancies between their in vitro and in vivo efficacy. We investigated whether genetically engineered adipose tissue-derived mesenchymal stem cells (ASCs) overexpressing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) had inhibitory effects on H460 tumor growth both in vitro and in an H460 xenograft model.

MATERIALS AND METHODS

Genetically engineered adipose tissue-derived mesenchymal stem cells (ASCs) overexpressing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) were obtained from plasmid transfection with pCMV3-TRAIL and -interferon (IFN)-β (producing ASC-TRAIL and ASC-IFN-β, respectively). Death of H460 cells co-cultured with ASCs, ASC-TRAIL, and ASC-IFN-β or exposed to their conditioned medium was evaluated via apoptosis and cytotoxicity assays. In addition, in an H460 xenograft model (n=10 per group), the antitumor potential of TRAIL-overexpressing, and IFN-β-overexpressing ASCs was investigated.

RESULTS

Conditioned medium obtained from ASC-IFN-β increased apoptosis of H460 cells more than did ASC-TRAIL. Additionally, in H460 xenograft models, while native ASCs promoted tumor growth, ASC-TRAIL and ASC-IFN-β both dramatically suppressed tumor growth. Interestingly, in the context of ASC-IFN-β, tumors were detected only in 20% of nude mice, with smaller sizes and lower weights than those of the control group.

CONCLUSION

TRAIL-overexpressing ASCs can be used to treat tumors; ASC-IFN-β in particular secrete a higher level of TRAIL.

DNA-binding Cell-penetrating Peptide-based TRAIL Over-expression in Adipose Tissue-derived Mesenchymal Stem Cells Inhibits Glioma U251MG Growth

BACKGROUND/AIM

Genetic manipulation of stem cells using non-viral vectors is still limited due to low transfection efficiency. We investigated whether the DNA-binding cell-permeation peptides (CPP) can enhance the transfection efficiency of non-viral vectors in adipose tissue-derived mesenchymal stem cells (ASCs) and whether ASCs over-expressing TRAIL through CPP can inhibit the growth of glioma U251MG cells in vitro and in vivo.

MATERIALS AND METHODS

ASCs were genetically engineered to over-express TRAIL by using CPP, pCMV3-TRAIL and lipid-based transfection reagents (X-tremeGENE).

RESULTS

The transfection efficiency of ASCs increased by approximately 7% using CPP; 53.9% of ASCs were transfected and TRAIL expression in ASCs increased by approximately 3 times compared to X-tremeGENE alone. ASCs over-expressing TRAIL using CPP inhibited growth of glioma U251MG cells both in vitro and in the U251MG xenograft model.

CONCLUSION

CPP can be used as an enhancer for genetically manipulating ASCs and tumor treatment.

Mesenchymal Stem Cells for the Treatment of Liver Disease: Present and Perspectives

Mesenchymal stem cell transplantation is an emerging therapy for treating chronic liver diseases. The potential of this treatment has been evaluated in preclinical and clinical studies. Although the mechanisms of mesenchymal stem cell transplantation are still not completely understood, accumulating evidence has revealed that their immunomodulation, differentiation, and antifibrotic properties play a crucial role in liver regeneration. The safety and therapeutic effects of mesenchymal stem cells in patients with chronic liver disease have been observed in many clinical studies. However, only modest improvements have been seen, partly because of the limited feasibility of transplanted cells at present. Here, we discuss several strategies targeted at improving viable cell engraftment and the potential challenges in the use of extracellular vesicle-based therapies for liver disease in the future.

Bone Marrow-Derived Mesenchymal Stem Cells Isolated from Patients with Cirrhosis and Healthy Volunteers Show Comparable Characteristics

Background and Objectives

Autologous or allogeneic bone marrow-derived mesenchymal stem cells (BMSCs) have been applied in clinical trials to treat liver disease. However, only a few studies are comparing the characteristics of autologous MSCs from patients and allogeneic MSCs from normal subjects.

Methods and Results

We compared the characteristics of BMSCs (BCs and BPs, respectively) isolated from six healthy volunteers and six patients with cirrhosis. In passage 3 (P3), senescent population and expression of p53 and p21 were slightly higher in BPs, but the average population doubling time for P3–P5 in BPs was approximately 65.3±11.1 h, which is 18.4 h shorter than that in BCs (83.7±9.2 h). No difference was observed in the expression of CD73, CD90, or CD105 between BCs and BPs. Adipogenic differentiation slightly increased in BCs, but the expression levels of leptin, peroxisome proliferator-activated receptor γ, and CCAAT-enhancer-binding protein α did not vary between differentiated BCs and BPs. While ATP and reactive oxygen species levels were slightly lower in BPs, mitochondrial membrane potential, oxygen consumption rate, and expression of mitochondria-related genes such as cytochrome c oxidase 1 were not significantly different between BCs and BPs.

Conclusions

Taken together, there are marginal differences in the proliferation, differentiation, and mitochondrial activities of BCs and BPs, but both BMSCs from patients with cirrhosis and healthy volunteers show comparable characteristics.

Ca2+-activated mitochondrial biogenesis and functions improve stem cell fate in Rg3-treated human mesenchymal stem cells

Although mitochondrial functions are essential for cell survival, their critical roles in stem cell fate, including proliferation, differentiation, and senescence, remain elusive. Ginsenoside Rg3 exhibits various biological activities and reportedly increases mitochondrial biogenesis and respiration. Herein, we observed that Rg3 increased proliferation and suppressed senescence of human bone marrow-derived mesenchymal stem cells. Osteogenic, but not adipogenic, differentiation was facilitated by Rg3 treatment. Rg3 suppressed reactive oxygen species production and upregulated mitochondrial biogenesis and antioxidant enzymes, including superoxide dismutase. Consistently, Rg3 strongly augmented basal and ATP synthesis-linked respiration with high spare respiratory capacity. Rg3 treatment elevated cytosolic Ca²⁺ concentration contributing to mitochondrial activation. Reduction of intracellular or extracellular Ca²⁺ levels strongly inhibited Rg3-induced activation of mitochondrial respiration and biogenesis. Taken together, Rg3 enhances capabilities of mitochondrial and antioxidant functions mainly through a Ca²⁺-dependent pathway, which improves the proliferation and differentiation potentials and prevents the senescence of human mesenchymal stem cells.

M1 Macrophages Promote TRAIL Expression in Adipose Tissue-Derived Stem Cells, Which Suppresses Colitis-Associated Colon Cancer by Increasing Apoptosis of CD133+ Cancer Stem Cells and Decreasing M2 Macrophage Population

We have previously reported that adipose tissue-derived stem cells (ASCs) cultured at high cell density can induce cancer cell death through the expression of type I interferons and tumor necrosis factor (TNF)-related apoptosis-inducing ligands (TRAIL). Here, we investigated whether TRAIL-expressing ASCs induced by M1 macrophages can alleviate colitis-associated cancer in an azoxymethane (AOM)/dextran sodium sulfate (DSS) animal model. M1 macrophages significantly increased the TRAIL expression in ASCs, which induced the apoptosis of LoVo cells in a TRAIL-dependent manner. However, CD133^knockout LoVo cells, generated using the CRISPR-Cas9 gene-editing system, were resistant to TRAIL. In the AOM/DSS-induced colitis-associated cancer model, the intraperitoneal transplantation of TRAIL-expressing ASCs significantly suppressed colon cancer development. Moreover, immunohistochemical staining revealed a low CD133 expression in tumors from the AOM/DSS + ASCs group when compared with tumors from the untreated group. Additionally, the ASC treatment selectively reduced the number of M2 macrophages in tumoral (45.7 ± 4.2) and non-tumoral mucosa (30.3 ± 1.5) in AOM/DSS + ASCs-treated animals relative to those in the untreated group (tumor 71.7 ± 11.2, non-tumor 94.3 ± 12.5; p < 0.001). Thus, TRAIL-expressing ASCs are promising agents for anti-tumor therapy, particularly to alleviate colon cancer by inducing the apoptosis of CD133⁺ cancer stem cells and decreasing the M2 macrophage population.

Transient receptor potential channel TRPV4 mediates TGF-β1-induced differentiation of human ventricular fibroblasts

BACKGROUND

Cardiac fibroblasts (CFs) are principal extracellular matrix-producing cells. In response to injury, CFs transdifferentiate into myofibroblasts. Intracellular calcium (Ca2+) signaling, involved in fibroblast proliferation and differentiation, is activated in fibroblasts through transient receptor potential (TRP) channels, but the function of these channels has not been investigated in human ventricular CFs. Under evaluation in this study, was the role of TRP channels in the differentiation of human ventricular CFs induced by transforming the growth factor beta (TGF-β), a pro-fibrotic cytokine.

METHODS

Human ventricular CFs were used in this study. The differentiation of CFs into myofibroblast was induced with TGF-β and was identified by the expression of smooth muscle actin.

RESULTS

Results indicate that Ca2+ signaling was an essential component of ventricular CF dif-ferentiation. CFs treated with TGF-β demonstrated increased expression of a TRP channel, TRPV4, both at the mRNA and protein levels, which corresponded with CF-myofibroblast trans-differentiation, as evidenced by the upregulation of α-smooth muscle actin, a myofibroblast marker, and plasminogen activator inhibitor-1, which are fibrogenesis markers. An agonist of TRPV4 induced the conversion of CFs into myofibroblasts, whereas it's antagonist as well a Ca2+ chelating agent reduced it, indicating that the Ca2+ influx throughTRPV4 is required for CF trans-differentiation. Overall, these results dem-onstrate that TRPV4-mediated Ca2+ influx participates in regulating the differentiation of human ventricular CFs into myofibroblasts through the MAPK/ERK pathway.

CONCLUSIONS

Overall, these results demonstrate that TRPV4-mediated Ca2+ influx participates in regulating the differentiation of human ventricular CFs into myofibroblasts through the MAPK/ERK pathway.

Mesenchymal stem cells to treat liver diseases

Mesenchymal stem cells (MSCs) are being developed for stem cell therapy and can be efficiently used in regenerative medicine. To date, more than 1,000 clinical trials have used MSCs; of these, more than 80 clinical trials have targeted liver disease. MSCs migrate to damaged liver tissues, differentiate into hepatocytes, reduce liver inflammatory responses, reduce liver fibrosis, and act as antioxidants. According to the reported literature, MSCs are safe, have no side effects, and improve liver function; however, their regenerative therapeutic effects are unsatisfactory. Here, we explain, in detail, the basic therapeutic effects and recent clinical advances of MSCs. Furthermore, we discuss future research directions for improving the regenerative therapeutic effects of MSCs.

Adipose Tissue-Derived Mesenchymal Stem Cells Suppress Growth of Huh7 Hepatocellular Carcinoma Cells via Interferon (IFN)-β-Mediated JAK/STAT1 Pathway in vitro

Interferon (IFN)-β and/or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) secreted by adipose tissue-derived mesenchymal stem cells (ASCs) have been proposed as key mechanistic factors in anti-cancer efficacy in lung cancer and breast cancer cells, where they act through paracrine signaling. We hypothesized that IFN-β and TRAIL produced by ASCs suppress proliferation of hepatocellular carcinoma cells (HCCs). The present study evaluated the anti-cancer effects of ASCs on HCCs in vitro. We found that indirect co-culture with ASCs diminished growth of Huh7 hepatocellular carcinoma cells with increased protein levels of p53/p21 and phosphorylated STAT1 (pSTAT1), without apoptosis. Treatment with ASC-conditioned medium (ASC-CM) also decreased growth of Huh7 cells through elevated p53/p21 and pSTAT1 signaling. ASC-CM-mediated inhibition of cell growth was neutralized in Huh7 cells treated with anti-IFN-β antibody compared to that in ASC-CM-treated Huh7 cells incubated with an anti-TRAIL antibody. Treatment with JAK1/JAK2 inhibitors recovered inhibition of growth in Huh7 cells incubated in ASC-CM or IFN-β via down-regulation of pSTAT1/p53/p21. However, treatment of IFN-β resulted in no alterations in resistance of Huh7 cells to TRAIL. Our findings suggest that ASCs decrease growth through activated STAT1-mediated p53/p21 by IFN-β, but not TRAIL, in Huh7 cells.

Effects of Oxytocin on Cell Proliferation in a Corticotroph Adenoma Cell Line

BACKGROUND

Oxytocin (OXT) has been reported to act as a growth regulator in various tumor cells. However, there is a paucity of data on the influence of OXT on cell proliferation of corticotroph adenomas. This study aimed to examine whether OXT affects cell growth in pituitary tumor cell lines (AtT20 and GH3 cells) with a focus on corticotroph adenoma cells.

METHODS

Reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay were conducted with AtT20 cells to confirm the effects of OXT on hormonal activity; flow cytometry was used to assess changes in the cell cycle after OXT treatment. Moreover, the impact of OXT on proliferating cell nuclear antigen (PCNA), nuclear factor κB, and mitogen-activated protein kinase signaling pathway was analyzed by Western blot.

RESULTS

OXT treatment of 50 nM changed the gene expression of OXT receptor and pro-opiomelanocortin within a short time. In addition, OXT significantly reduced adrenocorticotropic hormone secretion within 1 hour. S and G2/M populations of AtT20 cells treated with OXT for 24 hours were significantly decreased compared to the control. Furthermore, OXT treatment decreased the protein levels of PCNA and phosphorylated extracellular-signal-regulated kinase (P-ERK) in AtT20 cells.

CONCLUSION

Although the cytotoxic effect of OXT in AtT20 cells was not definite, OXT may blunt cell proliferation of corticotroph adenomas by altering the cell cycle or reducing PCNA and P-ERK levels. Further research is required to investigate the role of OXT as a potential therapeutic target in corticotroph adenomas.

Regulatory Dendritic Cells Induced by Mesenchymal Stem Cells Ameliorate Dextran Sodium Sulfate-Induced Chronic Colitis in Mice

Background/Aims

Regulatory dendritic cells (rDCs), which can be induced by mesenchymal stem cells (MSCs), play an important role in inducing and maintaining homeostasis of regulatory T cells and exhibit anti-inflammatory functions. In this study, we investigated whether MSCs could differentiate DCs into rDCs and compared the therapeutic effects of rDCs and MSCs on dextran sodium sulfate (DSS)-induced chronic colitis mice.

Methods

Immature DCs (imDCs) and lipopolysaccharide (LPS)-treated mature DCs (mDCs) were co-cultured with MSCs for 48 hours, and then the profiles of surface markers and cytokines and regulatory roles of these DCs for primary splenocytes were analyzed. In addition, the therapeutic effects of MSCs and DCs co-cultured with MSCs were compared in chronic colitis mice.

Results

After co-culture of imDCs (MSC-DCs) or LPS-treated mDCs (LPS+MSC-DCs) with MSCs, the expression of CD11c, CD80, CD86, interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ), was decreased, but that of CD11b, IL-10, and transforming growth factor-β (TGF-β) was increased. Furthermore, MSC-DCs and LPS+MSC-DCs induced the expression of CD4, CD25, and Foxp3 in primary splenocytes isolated from mice. In DSS-induced colitis mice, MSCs and MSC-DCs increased colon length, body weight, and survival rate and induced histological improvement. Moreover, in the colon tissues, the expression of IL-6, TNF-α, and IFN-γ decreased, but that of IL-10, TGF-β, and Foxp3 increased in the MSC- and MSC-DC-injected groups.

Conclusions

Our data suggest that MSCs differentiate DCs into rDCs, which ameliorate chronic colitis. Thus, rDCs stimulated by MSCs may be therapeutically useful for the treatment of chronic inflammatory diseases.

Expression of Fibroblast Growth Factor 21 and β-Klotho Regulates Hepatic Fibrosis through the Nuclear Factor-κB and c-Jun N-Terminal Kinase Pathways

Background/Aims

Fibroblast growth factor (FGF) 21 is associated with hepatic inflammation and fibrosis. However, little is known regarding the effects of inflammation and fibrosis on the β-Klotho and FGF21 pathway in the liver.

Methods

Enrolled patients had biopsy-confirmed viral or alcoholic hepatitis. FGF19, FGF21 and β-Klotho levels were evaluated using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and Western blotting. Furthermore, we explored the underlying mechanisms for this process by evaluating nuclear factor-κB (NF-κB) and c-Jun N-terminal kinase (JNK) pathway involvement in Huh-7 cells.

Results

We observed that the FGF19 and FGF21 serum and mRNA levels in the biopsied liver tissue gradually increased and were correlated with fibrosis stage. Inflammatory markers (interleukin 1β [IL-1β], IL-6, and tumor necrosis factor-α) were positively correlated, while β-Klotho expression was negatively correlated with the degree of fibrosis. In Huh-7 cells, IL-1β increased FGF21 levels and decreased β-Klotho levels. NF-κB and JNK inhibitors abolished the effect of IL-1β on both FGF21 and β-Klotho expression. FGF21 protected IL-1β-induced growth retardation in Huh-7 cells.

Conclusions

These results indicate that the inflammatory response during fibrogenesis increases FGF21 levels and suppresses β-Klotho via the NF-κB and JNK pathway. In addition, FGF21 likely protects hepatocytes from hepatic inflammation and fibrosis.

Mesenchymal stromal cell therapy for liver diseases

The therapeutic potential of mesenchymal stromal cells (MSCs) in the treatment of liver fibrosis is predominantly based on their immunosuppressive properties, and their ability to secrete various trophic factors. This potential has been investigated in clinical and preclinical studies. Although the therapeutic mechanisms of MSC transplantation are still not fully characterised, accumulating evidence has revealed that various trophic factors secreted by MSCs play key therapeutic roles in regeneration by alleviating inflammation, apoptosis, and fibrosis as well as stimulating angiogenesis and tissue regeneration in damaged liver. In this review, we summarise the safety, efficacy, potential transplantation routes and therapeutic effects of MSCs in patients with liver fibrosis. We also discuss some of the key strategies to enhance the functionality of MSCs, which include sorting and/or priming with factors such as cytokines, as well as genetic engineering.

Role of the renin-angiotensin system in hepatic fibrosis and portal hypertension

The renin-angiotensin system (RAS) is an important regulator of cirrhosis and portal hypertension. As hepatic fibrosis progresses, levels of the RAS components angiotensin (Ang) II, Ang-(1-7), angiotensin-converting enzyme (ACE), and Ang II type 1 receptor (AT1R) are increased. The primary effector Ang II regulates vasoconstriction, sodium homoeostasis, fibrosis, cell proliferation, and inflammation in various diseases, including liver cirrhosis, through the ACE/Ang II/AT1R axis in the classical RAS. The ACE2/Ang-(1-7)/Mas receptor and ACE2/Ang-(1-9)/AT2R axes make up the alternative RAS and promote vasodilation, antigrowth, proapoptotic, and anti-inflammatory effects; thus, countering the effects of the classical RAS axis to reduce hepatic fibrogenesis and portal hypertension. Patients with portal hypertension have been treated with RAS antagonists such as ACE inhibitors, Ang receptor blockers, and aldosterone antagonists, with very promising hemodynamic results. In this review, we examine the RAS, its roles in hepatic fibrosis and portal hypertension, and current therapeutic approaches based on the use of RAS antagonists in patients with portal hypertension.

Adipose-derived stem cells ameliorate colitis by suppression of inflammasome formation and regulation of M1-macrophage population through prostaglandin E2

Inflammatory bowel disease (IBD) is an idiopathic disease caused by a dysregulated immune response to intestinal microbes in an individual with a genetic predisposition. Therefore, alleviation of inflammation is very important to treat IBD. Mesenchymal stem cells (MSCs) have been highlighted as new candidates for treating autoimmune disease based on their immunomodulatory properties. In this study, we investigated the anti-inflammatory mechanism and therapeutic effects of adipose tissue-derived MSCs (ASCs) using THP-1 macrophages and dextran sodium sulfate (DSS)-induced mice with chronic colitis. LPS-treated THP-1 cells expressed mRNA of CD11b, an M1 macrophage marker, at day 2. However, THP-1 co-cultured with ASCs expressed mRNA of CD206, CD68, CCL18, legumain, and IL-10, markers of M2 macrophages. In THP-1 cells co-cultured with ASCs, precursor (pro)-IL-1β, Cox-2, and NLRP3 increased dramatically compared to LPS-treated THP-1 cells. Secretion of IL-1β and IL-18 was significantly inhibited by ASCs, but PGE2 production was highly increased in co-culture conditions of THP-1 and ASCs. IL-18 secretion was inhibited by PGE2 treatment, and PGE2 inhibited inflammasome complex (ASC/Cas-1/NLRP3) formation in THP-1 cells. In the DSS-induced chronic colitis model, ASCs ameliorated colitis by decreasing the total number of macrophages and the M1 macrophage population. Our results suggest that ASCs can suppress the inflammatory response by controlling the macrophage population, and ASCs may be therapeutically useful for the treatment of IBD.

Remote Ischemic Conditioning by Effluent Collected from a Novel Isolated Hindlimb Model Reduces Infarct Size in an Isolated Heart Model

Background and Objectives

Experimental protocols for remote ischemic conditioning (RIC) utilize models in which a tourniquet is placed around the hindlimb or effluent is collected from an isolated heart. In analyzing the humoral factors that act as signal transducers in these models, sampled blood can be influenced by systemic responses, while the effluent from an isolated heart might differ from that of the hindlimb. Thus, we designed a new isolated hindlimb model for RIC and tested whether the effluent from this model could affect ischemia/reperfusion (IR) injury and if the reperfusion injury salvage kinase (RISK) and survivor activating factor enhancement (SAFE) pathways are involved in RIC.

Materials and Methods

After positioning needles into the right iliac artery and vein of rats, Krebs-Henseleit buffer was perfused using a Langendorff apparatus, and effluent was collected. The RIC protocol consisted of 3 cycles of IR for 5 minutes. In the RIC effluent group, collected effluent was perfused in an isolated heart for 10 minutes before initiating IR injury.

Results

Compared with the control group, the infarct area in the RIC effluent group was significantly smaller (31.2%±3.8% vs. 20.6%±1.8%, p<0.050), while phosphorylation of signal transducer and activation of transcription-3 (STAT-3) was significantly increased. However, there was a trend of increased phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 in this group.

Conclusion

This is the first study to investigate the effect of effluent from a new isolated hindlimb model after RIC on IR injury in an isolated heart model. The RIC effluent was effective in reducing the IR injury, and the cardioprotective effect was associated with activation of the SAFE pathway.

1-Methyl-L-tryptophan promotes the apoptosis of hepatic stellate cells arrested by interferon-γ by increasing the expression of IFN-γRβ, IRF-1 and FAS

Liver fibrosis, a precursor to cirrhosis, is the result of the deposition of extracellular matrix (ECM) proteins and is mediated primarily by activated hepatic stellate cells (HSCs). In this study, we investigated the anti-fibrotic effects of interferon (IFN)-γ in activated HSCs in vitro and whether cell viability would be decreased by the inhibition of indoleamine 2,3-dioxygemase (IDO), which is responsible for cell cycle arrest. Following treatment with IFN-γ, cell signaling pathways and DNA content were analyzed to assess the inactivation of HSCs or the decrease in HSC proliferation. The IDO inhibitor, 1-methyl-L-tryptophan (1-MT), was used to determine whether IDO plays a key role in the regulation of activated HSCs, as IFN-γ increases the expression of IDO. IFN-γ significantly inhibited the growth of HSCs and downregulated the expression of α-smooth muscle actin (α-SMA) in the HSCs. IDO expression was markedly increased by IFN-γ through signal transducer and activator of transcription 1 (STAT1) activation and resulted in the depletion of tryptophan. This depletion induced G1 cell cycle arrest. When the cells were released from IFN-γ-mediated G1 cell cycle arrest by treatment with 1-MT, the apoptosis of the HSCs was markedly increased through the induction of IFN-γRβ, interferon regulatory factor (IRF-1) and FAS. Our results thus suggest that the inhibition of IDO enhances the suppression of activated HSCs, and therefore co-treatment with IFN-γ and 1-MT may be applied to ameliorate liver fibrosis.

Isoproterenol Enhances Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand-Induced Apoptosis in Human Embryonic Kidney Cells through Death Receptor 5 up-Regulation

BACKGROUND AND OBJECTIVES

Chronic impairment of β-adrenergic receptor signaling increases cardiac apoptosis, hypertrophy and fibrosis. The aim of this study was to investigate whether isoproterenol (ISO), an agonist of the adrenergic receptor, can enhance tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human embryonic kidney (HEK) 293 cells.

MATERIALS AND METHODS

HEK 293 cells were treated with ISO and/or TRAIL for 24 hours. Cell viability was evaluated by microscopy and an established viability assay, and apoptotic cell death was analyzed by staining with fluorescein isothiocynate-annexin-V/propidium iodide (PI) and caspase activation. To confirm the mechanism of cell death induced by co-treatment with ISO and TRAIL, expression of TRAIL receptor 2 (death receptor 5, DR5) was evaluated by immunoblotting.

RESULTS

Although ISO or TRAIL treatment decreased HEK 293 cell viability by 13% and 17%, respectively, co-treatment with ISO and TRAIL resulted in a markedly higher death rate of 35% after 24 hours. Increases were evident in early apoptotic cells (i.e., annexin-V positive/PI negative; 19.4%), late apoptotic cells (i.e., annexin-V positive/PI positive; 6.3%) and dead cells (i.e., annexin-V negative/PI positive; 1.1%) when cells were co-treated with ISO and TRAIL, compared to cells treated with either ISO or TRAIL. In addition, marked increases of cleaved cas-3, cleaved poly (adenosine diphosphate-ribose) polymerase and DR5 were observed in HEK 293 cells co-treated with ISO and TRAIL.

CONCLUSION

Treatments combining ISO with TRAIL may be responsible for death of HEK 293 cells through DR5 up-regulation. Activation of adrenergic receptors is responsible for the synergistic cell death observed with TRAIL.

Therapeutic Effects of Mesenchymal Stem Cells for Patients with Chronic Liver Diseases: Systematic Review and Meta-analysis

Based on their ability to differentiate into multiple cell types including hepatocytes, the transplantation of mesenchymal stem cells (MSCs) has been suggested as an effective therapy for chronic liver diseases. The aim of this study was to evaluate the safety, efficacy and therapeutic effects of MSCs in patients with chronic liver disease through a literature-based examination. We performed a systematic review (SR) and meta-analysis (MA) of the literature using the Ovid-MEDLINE, EMBASE and Cochrane Library databases (up to November 2014) to identify clinical studies in which patients with liver diseases were treated with MSC therapy. Of the 568 studies identified by the initial literature search, we analyzed 14 studies and 448 patients based on our selection criteria. None of the studies reported the occurrence of statistically significant adverse events, side effects or complications. The majority of the analyzed studies showed improvements in liver function, ascites and encephalopathy. In particular, an MA showed that MSC therapy improved the total bilirubin level, the serum albumin level and the Model for End-stage Liver Disease (MELD) score after MSC treatment. Based on these results, MSC transplantation is considered to be safe for the treatment of chronic liver disease. However, although MSCs are potential therapeutic agents that may improve liver function, in order to obtain meaningful insights into their clinical efficacy, further robust clinical studies must be conducted to evaluate the clinical outcomes, such as histological improvement, increased survival and reduced liver-related complications, in patients with chronic liver disease.

Mesenchymal stem cell therapy for cirrhosis: Present and future perspectives

Cirrhosis occurs as a result of various chronic liver injuries, which may be caused by viral infections, alcohol abuse and the administration of drugs and chemicals. Recently, bone marrow cells (BMCs), hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) have been used for developing treatments for cirrhosis. Clinical trials have investigated the therapeutic potential of BMCs, HSCs and MSCs for the treatment of cirrhosis based on their potential to differentiate into hepatocytes. Although the therapeutic mechanisms of BMC, HSC and MSC treatments are still not fully characterized, the evidence thus far has indicated that the potential therapeutic mechanisms of MSCs are clearer than those of BMCs or HSCs with respect to liver regenerative medicine. MSCs suppress inflammatory responses, reduce hepatocyte apoptosis, increase hepatocyte regeneration, reverse liver fibrosis and enhance liver functionality. This paper summarizes the clinical studies that have used BMCs, HSCs and MSCs in patients with liver failure or cirrhosis. We also present the potential therapeutic mechanisms of BMCs, HSCs and MSCs for the improvement of liver function.

Mesenchymal stem cell therapy for liver fibrosis

Currently, the most effective treatment for end-stage liver fibrosis is liver transplantation; however, transplantation is limited by a shortage of donor organs, surgical complications, immunological rejection, and high medical costs. Recently, mesenchymal stem cell (MSC) therapy has been suggested as an effective alternate approach for the treatment of hepatic diseases. MSCs have the potential to differentiate into hepatocytes, and therapeutic value exists in their immune-modulatory properties and secretion of trophic factors, such as growth factors and cytokines. In addition, MSCs can suppress inflammatory responses, reduce hepatocyte apoptosis, increase hepatocyte regeneration, regress liver fibrosis and enhance liver functionality. Despite these advantages, issues remain; MSCs also have fibrogenic potential and the capacity to promote tumor cell growth and oncogenicity. This paper summarizes the properties of MSCs for regenerative medicine and their therapeutic mechanisms and clinical application in the treatment of liver fibrosis. We also present several outstanding risks, including their fibrogenic potential and their capacity to promote pre-existing tumor cell growth and oncogenicity.

L-ascorbic acid 2-phosphate and fibroblast growth factor-2 treatment maintains differentiation potential in bone marrow-derived mesenchymal stem cells through expression of hepatocyte growth factor

l-ascorbic acid 2-phosphate (Asc-2P) acts as an antioxidant and a stimulator of hepatocyte growth factor (HGF) production. Previously, we reported that depletion of growth factors such as fibroblast growth factor (FGF)-2, epidermal growth factor (EGF), FGF-4 and HGF during serial passage could induce autophagy, senescence and down-regulation of stemness (proliferation via FGF-2/-4 and differentiation via HGF). In this study, we investigated the proliferation and differentiation potential of BMSCs by FGF-2 and Asc-2P. Co-treatment with FGF-2 and Asc-2P induced optimal proliferation of BMSCs and increased the accumulation rate of BMSC numbers during a 2-month culture period. Moreover, differentiation potential was maintained by co-treatment with FGF-2 and Asc-2P via HGF expression. Adipogenic differentiation potential by FGF-2 and Asc-2P was dramatically suppressed by c-Met inhibitors (SU11274). These data suggest that co-treatment with FGF-2 and Asc-2P would be beneficial in obtaining BMSCs that possess "stemness" during long-term culture.

Adipose tissue-derived mesenchymal stem cells cultured at high density express IFN-β and suppress the growth of MCF-7 human breast cancer cells

Although it has been reported that mesenchymal stem cells (MSCs) suppress tumor growth in vitro and in vivo, little is known about the underlying molecular mechanisms. We found that type I interferon is expressed in adipose tissue-derived stem cells (ASCs) cultured at high density, and ASCs and their conditioned medium (ASC-CM) suppress the growth of MCF-7 cells in vitro. Growth inhibition was amplified by glucose deprivation that resulted from high density culture of ASCs after 3days. The cytotoxic effect of the ASC-CM obtained from high density culture of ASCs was neutralized by anti-IFN-β antibody. STAT1 was phosphorylated in MCF-7 cells treated with ASC-CM, and JAK1/JAK2 inhibitor treatment decreased STAT1 phosphorylation. The cytotoxic effect of ASC-CM was reduced especially by JAK1 inhibitors in MCF-7 cells. Our findings suggest that ASCs cultured at high density express type I interferons, which suppresses tumor growth via STAT1 activation resulting from IFN-β secretion in MCF-7 breast cancer cells.

The role of growth factors in maintenance of stemness in bone marrow-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are an active topic of research in regenerative medicine due to their ability to secrete a variety of growth factors and cytokines that promote healing of damaged tissues and organs. In addition, these secreted growth factors and cytokines have been shown to exert an autocrine effect by regulating MSC proliferation and differentiation. We found that expression of EGF, FGF-4 and HGF were down-regulated during serial passage of bone marrow-derived mesenchymal stem cells (BMSCs). Proliferation and differentiation potentials of BMSCs treated with these growth factors for 2 months were evaluated and compared to BMSCs treated with FGF-2, which increased proliferation of BMSCs. FGF-2 and -4 increased proliferation potentials at high levels, about 76- and 26-fold, respectively, for 2 months, while EGF and HGF increased proliferation of BMSCs by less than 2.8-fold. Interestingly, differentiation potential, especially adipogenesis, was maintained only by HGF treatment. Treatment with FGF-2 rapidly induced activation of AKT and later induced ERK activation. The basal level of phosphorylated ERK increased during serial passage of BMSCs treated with FGF-2. The expression of LC3-II, an autophagy marker, was gradually increased and the population of senescent cells was increased dramatically at passage 7 in non-treated controls. But FGF-2 and FGF-4 suppressed LC3-II expression and down-regulated senescent cells during long-term (i.e. 2month) cultures. Taken together, depletion of growth factors during serial passage could induce autophagy, senescence and down-regulation of stemness (proliferation via FGF-2/-4 and differentiation via HGF) through suppression of AKT and ERK signaling.

Histological improvement following administration of autologous bone marrow-derived mesenchymal stem cells for alcoholic cirrhosis: a pilot study

BACKGROUND

In experimental models, bone marrow-derived mesenchymal stem cells (BM-MSCs) have the capacity to differentiate into hepatocytes and exhibit antifibrotic effects. However, there have been no studies in humans with alcoholic cirrhosis.

AIM

The aim of this study was to elucidate the antifibrotic effect of BM-MSCs in patients with alcoholic cirrhosis, as a phase II clinical trial.

METHODS

Twelve patients (11 males, 1 female) with baseline biopsy-proven alcoholic cirrhosis who had been alcohol free for at least 6 months were enrolled. BM-MSCs were isolated from each patient's BM and amplified for 1 month, and 5 × 10(7) cells were then injected twice, at weeks 4 and 8, through the hepatic artery. One patient was withdrawn because of ingestion of alcohol. Finally, 11 patients completed the follow-up biopsy and laboratory tests at 12 weeks after the second injection. The primary outcome was improvement in the patients' histological features.

RESULTS

According to the Laennec fibrosis system, histological improvement was observed in 6 of 11 patients (54.5%). The Child-Pugh score improved in ten patients (90.9%) and the levels of transforming growth factor-β1, type 1 collagen and α-smooth muscle actin significantly decreased (as assessed by real-time reverse transcriptase polymerase chain reaction) after BM-MSCs therapy (P < 0.05). No significant complications or side effects were observed during this study.

CONCLUSIONS

Bone marrow-derived mesenchymal stem cells therapy in alcoholic cirrhosis induces a histological and quantitative improvement of hepatic fibrosis.

Ultrasonographic scoring system score versus liver stiffness measurement in prediction of cirrhosis

BACKGROUND/AIMS

We compared the cirrhosis-prediction accuracy of an ultrasonographic scoring system (USSS) combining six representative sonographic indices with that of liver stiffness measurement (LSM) by transient elastography, and prospectively investigated the correlation between the USSS score and LSM in predicting cirrhosis.

METHODS

Two hundred and thirty patients with chronic liver diseases (187 men, 43 women; age, 50.4±9.5 y, mean±SD) were enrolled in this prospective study. The USSS produces a combined score for nodularity of the liver surface and edge, parenchyma echogenicity, presence of right-lobe atrophy, spleen size, splenic vein diameter, and abnormality of the hepatic vein waveform. The correlations of the USSS score and LSM with that of a pathological liver biopsy (METAVIR scoring system: F0-F4) were evaluated.

RESULTS

The mean USSS score and LSM were 7.2 and 38.0 kPa, respectively, in patients with histologically overt cirrhosis (F4, P=0.017) and 4.3 and 22.1 kPa in patients with fibrotic change without overt cirrhosis (F0-F3) (P=0.025). The areas under the receiver operating characteristic (ROC) curves of the USSS score and LSM for F4 patients were 0.849 and 0.729, respectively. On the basis of ROC curves, criteria of USSS ≥6: LSM ≥17.4 had a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 89.2%:77.6%, 69.4%:61.4%, 86.5%:83.7%, 74.6%:51.9% and 0.83:0.73, respectively, in predicting F4.

CONCLUSIONS

The results indicate that this USSS has comparable efficacy to LSM in the diagnosis of cirrhosis.

Ultrasonographic scoring system score versus liver stiffness measurement in prediction of cirrhosis

Background/Aims

We compared the cirrhosis-prediction accuracy of an ultrasonographic scoring system (USSS) combining six representative sonographic indices with that of liver stiffness measurement (LSM) by transient elastography, and prospectively investigated the correlation between the USSS score and LSM in predicting cirrhosis.

Methods

Two hundred and thirty patients with chronic liver diseases (187 men, 43 women; age, 50.4±9.5 y, mean±SD) were enrolled in this prospective study. The USSS produces a combined score for nodularity of the liver surface and edge, parenchyma echogenicity, presence of right-lobe atrophy, spleen size, splenic vein diameter, and abnormality of the hepatic vein waveform. The correlations of the USSS score and LSM with that of a pathological liver biopsy (METAVIR scoring system: F0-F4) were evaluated.

Results

The mean USSS score and LSM were 7.2 and 38.0 kPa, respectively, in patients with histologically overt cirrhosis (F4, P=0.017) and 4.3 and 22.1 kPa in patients with fibrotic change without overt cirrhosis (F0-F3) (P=0.025). The areas under the receiver operating characteristic (ROC) curves of the USSS score and LSM for F4 patients were 0.849 and 0.729, respectively. On the basis of ROC curves, criteria of USSS ≥6: LSM ≥17.4 had a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 89.2%:77.6%, 69.4%:61.4%, 86.5%:83.7%, 74.6%:51.9% and 0.83:0.73, respectively, in predicting F4.

Conclusions

The results indicate that this USSS has comparable efficacy to LSM in the diagnosis of cirrhosis.

Rapid isolation of adipose tissue-derived stem cells by the storage of lipoaspirates

PURPOSE

This study examined a rapid isolation method decreasing the time and cost of the clinical application of adipose tissue-derived stem cells (ASCs).

MATERIALS AND METHODS

Aliquots (10 g) of the lipoaspirates were stored at 4°C without supplying oxygen or nutrients. At the indicated time points, the yield of mononuclear cells was evaluated and the stem cell population was counted by colony forming unit-fibroblast assays. Cell surface markers, stem cell-related transcription factors, and differentiation potentials of ASCs were analyzed.

RESULTS

When the lipoaspirates were stored at 4°C, the total yield of mononuclear cells decreased, but the stem cell population was enriched. These ASCs expressed CD44, CD73, CD90, CD105, and HLA-ABC but not CD14, CD31, CD34, CD45, CD117, CD133, and HLA-DR. The number of ASCs increased 1×10(14) fold for 120 days. ASCs differentiated into osteoblasts, adipocytes, muscle cells, or neuronal cells.

CONCLUSION

ASCs isolated from lipoaspirates and stored for 24 hours at 4°C have similar properties to ASCs isolated from fresh lipoaspirates. Our results suggest that ASCs can be isolated with high frequency by optimal storage at 4°C for 24 hours, and those ASCs are highly proliferative and multipotent, similar to ASCs isolated from fresh lipoaspirates. These ASCs can be useful for clinical application because they are time- and cost-efficient, and these cells maintain their stemness for a long time, like ASCs isolated from fresh lipoaspirates.

Effective myotube formation in human adipose tissue-derived stem cells expressing dystrophin and myosin heavy chain by cellular fusion with mouse C2C12 myoblasts

Stem cell therapy for muscular dystrophies requires stem cells that are able to participate in the formation of new muscle fibers. However, the differentiation steps that are the most critical for this process are not clear. We investigated the myogenic phases of human adipose tissue-derived stem cells (hASCs) step by step and the capability of myotube formation according to the differentiation phase by cellular fusion with mouse myoblast C2C12 cells. In hASCs treated with 5-azacytidine and fibroblast growth factor-2 (FGF-2) for 1 day, the early differentiation step to express MyoD and myogenin was induced by FGF-2 treatment for 6 days. Dystrophin and myosin heavy chain (MyHC) expression was induced by hASC conditioned medium in the late differentiation step. Myotubes were observed only in hASCs undergoing the late differentiation step by cellular fusion with C2C12 cells. In contrast, hASCs that were normal or in the early stage were not involved in myotube formation. Our results indicate that stem cells expressing dystrophin and MyHC are more suitable for myotube formation by co-culture with myoblasts than normal or early differentiated stem cells expressing MyoD and myogenin.

Sulforaphane Sensitizes Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand (TRAIL)–Resistant Hepatoma Cells to TRAIL-Induced Apoptosis through Reactive Oxygen Species–Mediated Up-regulation of DR5

Sulforaphane is a chemopreventive agent present in various cruciferous vegetables, including broccoli. Here, we show that treatment with tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) in combination with subtoxic doses of sulforaphane significantly induces rapid apoptosis in TRAIL-resistant hepatoma cells. Neither TNF-alpha- nor Fas-mediated apoptosis was sensitized in hepatoma cells by cotreatment with sulforaphane, suggesting that sulforaphane can selectively sensitize cells to TRAIL-induced apoptosis but not to apoptosis mediated by other death receptors. We found that sulforaphane treatment significantly up-regulated mRNA and protein levels of DR5, a death receptor of TRAIL. This was accompanied by an increase in the generation of reactive oxygen species (ROS). Pretreatment with N-acetyl-l-cysteine and overexpression of catalase inhibited sulforaphane-induced up-regulation of DR5 and almost completely blocked the cotreatment-induced apoptosis. Furthermore, the sulforaphane-mediated sensitization to TRAIL was efficiently reduced by administration of a blocking antibody or small interfering RNAs for DR5. These results collectively indicate that sulforaphane-induced generation of ROS and the subsequent up-regulation of DR5 are critical for triggering and amplifying TRAIL-induced apoptotic signaling. We also found that sulforaphane can sensitize both Bcl-xL- and Bcl-2-overexpressing hepatoma cells to TRAIL-induced apoptosis, indicating that treatment with a combination of TRAIL and sulforaphane may be a safe strategy for treating resistant hepatomas.

Implication of the small GTPase Rac1 in the apoptosis induced by UV in Rat-2 fibroblasts

Exposure of mammalian cells to ultraviolet (UV) light elicits a cellular response and also lead to apoptotic cell death. However, the role of Rac, a member of Rho family GTPases, in the UV-induced apoptosis has never been examined. In UV-irradiated Rat-2 fibroblasts, nuclear fragmentation began to be observed within 2 h and the total viability of Rat-2 cells were only about 15% at 6 h following by UV irradiation, whereas the total viability in Rat2-Rac(N17) cells stably expressing RacN17, a dominant negative Rac1 mutant, was almost close to 67%. Pretreatment with SB203580, a specific inhibitor of p38 kinase, likewise attenuated UV-induced cell death, but PD98059, a MEK inhibitor, did not. Thus, Rac1 and p38 kinase appear to be components in the apoptotic signaling pathway induced by UV irradiation in Rat-2 fibroblasts. In addition, our results show that p38 kinase stimulation by UV is dramatically inhibited by RacN17, suggesting that p38 kinase is situated downstream of Rac1 in the UV signaling to apoptosis.

Rac and p38 kinase mediate 5-lipoxygenase translocation and cell death

5-Lipoxygenase (5-LO) is a key enzyme involved in the synthesis of leukotrienes from arachidonic acid, and its activation is usually followed by translocation to the nuclear envelope. The details of mechanisms involved in the translocation of 5-LO are not well understood, though Ca(2+) is known to be essential. Here we show that ionomycin, a Ca(2+) ionophore, induces 5-LO translocation and necrotic cell death in Rat-2 fibroblasts, suggesting a potential relationship between activation of 5-LO and cell death. These effects were markedly attenuated in Rat2-Rac(N17) cells expressing a dominant negative Rac1 mutant. Pretreatment with SB203580, a specific inhibitor of p38 MAP kinase, or EGTA, a Ca(2+) chelator, likewise diminished ionomycin-induced 5-LO translocation and cell death, but PD98059, a MEK inhibitor, did not. Thus, Rac and p38 MAP kinase appear to be components in a Ca(2+)-dependent pathway leading to 5-LO translocation and necrotic cell death in Rat-2 fibroblasts.

Role of Hck in the pathogenesis of encephalomyocarditis virus-induced diabetes in mice

Soluble mediators such as interleukin-1beta, tumor necrosis factor alpha (TNF-alpha), and inducible nitric oxide synthase (iNOS) produced from activated macrophages play an important role in the destruction of pancreatic beta cells in mice infected with a low dose of the D variant of encephalomyocarditis (EMC-D) virus. The tyrosine kinase signaling pathway was shown to be involved in EMC-D virus-induced activation of macrophages. This investigation was initiated to determine whether the Src family of kinases plays a role in the activation of macrophages, subsequently resulting in the destruction of beta cells, in mice infected with a low dose of EMC-D virus. We examined the activation of p59/p56(Hck), p55(Fgr), and p56/p53(Lyn) in macrophages from DBA/2 mice infected with the virus. We found that p59/p56(Hck) showed a marked increase in both autophosphorylation and kinase activity at 48 h after infection, whereas p55(Fgr) and p56/p53(Lyn) did not. The p59/p56(Hck) activity was closely correlated with the tyrosine phosphorylation level of Vav. Treatment of EMC-D virus-infected mice with the Src kinase inhibitor, PP2, resulted in the inhibition of p59/p56(Hck) activity and almost complete inhibition of the production of TNF-alpha and iNOS in macrophages and the subsequent prevention of diabetes in mice. On the basis of these observations, we conclude that the Src kinase, p59/p56(Hck), plays an important role in the activation of macrophages and the subsequent production of TNF-alpha and nitric oxide, leading to the destruction of pancreatic beta cells, which results in the development of diabetes in mice infected with a low dose of EMC-D virus.

Tumor necrosis factor-alpha generates reactive oxygen species via a cytosolic phospholipase A2-linked cascade

Reactive oxygen species (ROS) are important regulatory molecules implicated in the signaling cascade triggered by tumor necrosis factor (TNF)-alpha, although the events through which TNF-alpha induces ROS generation are not yet well characterized. We therefore investigated selected candidates likely to mediate TNF-alpha-induced ROS generation. Consistent with the role of Rac in that process, stable expression of Rac(Asn-17), a dominant negative Rac1 mutant, completely blocked TNF-alpha-induced ROS generation. To understand better the mediators downstream of Rac, we investigated the involvement of cytosolic phospholipase A(2) (cPLA(2)) activation and metabolism of the resultant arachidonic acid (AA) by 5-lipoxygenase (5-LO). TNF-alpha-induced ROS generation was blocked by inhibition of cPLA(2) or 5-LO, but not cyclooxygenase, suggesting that TNF-alpha-induced ROS generation is dependent on synthesis of AA and its subsequent metabolism to leukotrienes. Consistent with that hypothesis, TNF-alpha Rac-dependently stimulated endogenous production of leukotriene B(4) (LTB(4)), while exogenous application of LTB(4) increased levels of ROS. In contrast, application of leukotrienes C(4), D(4), and E(4) or prostaglandin E(2) had little effect. Our findings suggest that LTB(4) production by 5-LO is situated downstream of the Rac-cPLA(2) cascade, and we conclude that Rac, cPLA(2), and LTB(4) play pivotal roles in the ROS-generating cascade triggered by TNF-alpha.

Role of cytosolic phospholipase A(2) as a downstream mediator of Rac in the signaling pathway to JNK stimulation

Rac is an important regulatory molecule implicated in c-jun N-terminal kinase (JNK) activation in response to stress and cytokines. However, the signaling events that mediate the activation of JNK by Rac are not yet well characterized. To broaden our understanding of downstream mediators that link Rac signals to the JNK pathway, we investigated whether cytosolic phospholipase A(2) (cPLA(2)) is involved in Rac activation of JNK. In this report we demonstrate that either co-transfection with antisense cPLA(2) oligonucleotide or pretreatment with arachidonyltrifluoromethyl ketone (AACOCF3), a potent and specific inhibitor of cPLA(2), inhibits Rac-mediated JNK activation, implying a potential role of cPLA(2) in Rac-signaling to JNK activation. In accordance with this observation, we demonstrate that the addition of exogenous arachidonic acid (AA), a principal product of Rac-activated cPLA(2), or leukotrienes, products of 5-lipoxygenase (5-LO) of AA, caused a specific stimulation of JNK. Together, our findings suggest that cPLA(2) mediates, at least partly, the signaling cascade by which Rac stimulates JNK.

Cdc2 and Cdk2 kinase activated by transforming growth factor-beta1 trigger apoptosis through the phosphorylation of retinoblastoma protein in FaO hepatoma cells

The signaling pathway leading to TGF-beta1-induced apoptosis was investigated using a TGF-beta1-sensitive hepatoma cell line, FaO. Cell cycle analysis demonstrated that the accumulation of apoptotic cells was preceded by a progressive decrease of the cell population in the G(1) phase concomitant with a slight increase of the cell population in the G(2)/M phase in response to TGF-beta1. TGF-beta1 induced a transient increase in the expression of Cdc2, cyclin A, cyclin B, and cyclin D1 at an early phase of apoptosis. During TGF-beta1-induced apoptosis, the transient increase in cyclin-dependent kinase (Cdk) activities coincides with a dramatic increase in the hyperphosphorylated forms of RB. Treatment with roscovitine or olomoucine, inhibitors of Cdc2 and Cdk2, blocked TGF-beta1-induced apoptosis by inhibiting RB phosphorylation. Overexpression of Bcl-2 or adenovirus E1B 19K suppressed TGF-beta1-induced apoptosis by blocking the induction of Cdc2 mRNA and the subsequent activation of Cdc2 kinase, whereas activation of Cdk2 was not affected, suggesting that Cdc2 plays a more critical role in TGF-beta1-induced apoptosis. In conclusion, we present the evidence that Cdc2 and Cdk2 kinase activity transiently induced by TGF-beta1 phosphorylates RB as a physiological target in FaO cells and that RB hyperphosphorylation may trigger abrupt cell cycle progression, leading to irreversible cell death.