Mesenchymal stem cells protect islets from hypoxia/reoxygenation-induced injury

Hypoxia/reoxygenation (H/R)‐induced injury is the key factor associated with islet graft dysfunction. This study aims to examine the effect of mesenchymal stem cells (MSCs) on islet survival and insulin secretion under H/R conditions. Islets from rats were isolated, purified, cultured with or without MSCs, and exposed to hypoxia (O₂ ≤ 1%) for 8 h and reoxygenation for 24 and 48 h, respectively. Islet function was evaluated by measuring basal and glucose‐stimulated insulin secretion (GSIS). Apoptotic islet cells were quantified using Annexin V‐FITC. Anti‐apoptotic effects were confirmed by mRNA expression analysis of hypoxia‐resistant molecules, HIF‐1α, HO‐1, and COX‐2, using semi‐quantitative retrieval polymerase chain reaction (RT‐PCR). Insulin expression in the implanted islets was detected by immunohistological analysis. The main results show that the stimulation index (SI) of GSIS was maintained at higher levels in islets co‐cultured with MSCs. The MSCs protected the islets from H/R‐induced injury by decreasing the apoptotic cell ratio and increasing HIF‐1α, HO‐1, and COX‐2 mRNA expression. Seven days after islet transplantation, insulin expression in the MSC‐islets group significantly differed from that of the islets‐alone group. We proposed that MSCs could promote anti‐apoptotic gene expression by enhancing their resistance to H/R‐induced apoptosis and dysfunction. This study provides an experimental basis for therapeutic strategies based on enhancing islet function. Copyright © 2010 John Wiley & Sons, Ltd.     

Mesenchymal stem cells protect neurons against hypoxic-ischemic injury via inhibiting parthanatos,necroptosis, and apoptosis,but not autophagy

Cellular therapy with mesenchymal stem cells (MSCs) protects cortical neurons against hypoxic-ischemic injury of stroke. Although sorts of efforts have been made to confirm the neuroprotective effect of MSCs on neurons against hypoxic-ischemic injury, the mechanism is until now far away from clear. Here in this study, oxygen-glucose deprivation (OGD)-injured neuron model was applied to mimic the neuronal hypoxic-ischemic injury in vitro. Co-culturing with MSCs in a transwell co-culture system, the OGD injured neurons were rescued by 75.0 %. Further data demonstrated that co-culturing with MSCs protected the cortical neurons from the OGD-induced parthanatos by alleviating apoptosis-inducing factor (AIF) nuclear translocation; attenuated the neuronal necroptosis by down-regulating the expression of the two essential kinases in necroptosis, receptor interacting protein kinase1 (RIP1) and 3 (RIP3); rescued the neurons from apoptosis by deactivating caspase-3; whilst performed no significant influence on OGD-induced neuronal autophagy, according to its failed regulation on Beclin1. In conclusion, MSCs potentially protect the cortical neurons from OGD-injury in vitro, through rescuing neurons from the cell death of parthanatos, necroptosis, and apoptosis, but not autophagy, which could provide some evidence to the mechanism explanation on stem cell treatment for ischemic stroke.     

间充质干细胞治疗急性放射性损伤的研究

急性放射性损伤是组织损伤的一种重要类型,目前未有较理想的治疗方案。间充质干细胞（MSCs）能够多向分化、自我更新,且具有分泌多种细胞因子、抗炎、免疫调节等生物活性。其在促进组织修复的优势显而易见,而移植的时机、剂量长期以来莫衷一是。致瘤性等安全问题制约其临床研究的进一步开展。近年来,MSCs趋向于无细胞化移植取得了明显成效。这一研究新进展势必迎来急性放射性损伤治疗的新格局,本文对此研究现状及进展进行综述。     

SOCS2-enhanced ubiquitination of SLC7A11 promotes ferroptosis and radiosensitization in hepatocellular carcinoma

Radioresistance is a principal culprit for the failure of radiotherapy in hepatocellular carcinoma (HCC). Insights on the regulation genes of radioresistance and underlying mechanisms in HCC are awaiting for profound investigation. In this study, the suppressor of cytokine signaling 2 (SOCS2) were screened out by RNA-seq and bioinformatics analyses as a potential prognosis predictor of HCC radiotherapy and then were determined to promote radiosensitivity in HCC both in vivo or in vitro. Meanwhile, the measurements of ferroptosis negative regulatory proteins of solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4), intracellular lipid peroxidation and Fe²⁺ concentration suggested that a high level of ferroptosis contributed to the radiosensitization of HCC. Moreover, SOCS2 and SLC7A11 were expressed oppositely in HCC clinical tissues and tumour xenografts with different radiosensitivities. Mechanistically, the N-terminal domain of SLC7A11 was specifically recognized by the SH2-structural domain of SOCS2. While the L162 and C166 of SOCS2-BOX region could bind elongin B/C compound to co-form a SOCS2/elongin B/C complex to recruit ubiquitin molecules. Herein, SOCS2 served as a bridge to transfer the attached ubiquitin to SLC7A11 and promoted K48-linked polyubiquitination degradation of SLC7A11, which ultimately led to the onset of ferroptosis and radiosensitization of HCC. In conclusion, it was demonstrated for the first time that high-expressed SOCS2 was one of the biomarkers predicting radiosensitivity of HCC by advancing the ubiquitination degradation of SLC7A11 and promoting ferroptosis, which indicates that targeting SOCS2 may enhance the efficiency of HCC radiotherapy and improve the prognosis of patients.Subject terms: Diagnostic markers, Tumour biomarkers     

Hypoxia blocks ferroptosis of hepatocellular carcinoma via suppression of METTL14 triggered YTHDF2-dependent silencing of SLC7A11

Residue hepatocellular carcinoma (HCC) cells enduring hypoxic environment triggered by interventional embolization obtain more malignant potential with little clarified mechanism. The N⁶-methyladenosine (m⁶A) biological activity plays essential roles in diverse physiological processes. However, its role under hypoxic condition remains largely unexplored. RT-qPCR and Western blot were used to evaluate METTL14 expression in hypoxic HCC cells. MDA assay and electronic microscopy photography were used to evaluate ferroptosis. The correlation between SLC7A11 and METTL14 was conducted by bioinformatical analysis. Flow cytometry was used to verify the effect of SLC7A11 on ROS production. Cell counting kit-8 assay was performed to detect cells proliferation ability. Hypoxia triggered suppression of METTL14 in a HIF-1α–dependent manner potently abrogated ferroptosis of HCC cells. Mechanistic investigation identified SLC7A11 was a direct target of METTL14. Both in vitro and in vivo assay demonstrated that METTL14 induced m⁶A modification at 5’UTR of SLC7A11 mRNA, which in turn underwent degradation relied on the YTHDF2-dependent pathway. Importantly, ectopic expression of SLC7A11 strongly blocked METTL14-induced tumour-suppressive effect in hypoxic HCC. Our investigations lay the emphasis on the hypoxia-regulated ferroptosis in HCC cells and identify the HIF-1α /METTL14/YTHDF2/SLC7A11 axis as a potential therapeutic target for the HCC interventional embolization treatment.     

Protecting mitochondria via inhibiting VDAC1 oligomerization alleviates ferroptosis in acetaminophen-induced acute liver injury

Cell Biology and Toxicology - Acetaminophen (APAP) overdose is a common cause of drug-induced liver injury (DILI). Ferroptosis has been recently implicated in APAP-induced liver injury (AILI)....     

Sorafenib attenuates liver fibrosis by triggering hepatic stellate cell ferroptosis via HIF‐1α/SLC7A11 pathway

ObjectivesEvidences demonstrate that sorafenib alleviates liver fibrosis via inhibiting HSC activation and ECM accumulation. The underlying mechanism remains unclear. Ferroptosis, a novel programmed cell death, regulates diverse physiological/pathological processes. In this study, we aim to investigate the functional role of HSC ferroptosis in the anti‐fibrotic effect of sorafenib.Materials and MethodsThe effects of sorafenib on HSC ferroptosis and ECM expression were assessed in mouse model of liver fibrosis induced by CCl₄. In vitro, Fer‐1 and DFO were used to block ferroptosis and then explored the anti‐fibrotic effect of sorafenib by detecting α‐SMA, COL1α1 and fibronectin proteins. Finally, HIF‐1α siRNA, plasmid and stabilizers were applied to assess related signalling pathway.ResultsSorafenib attenuated liver injury and ECM accumulation in CCl₄‐induced fibrotic livers, accompanied by reduction of SLC7A11 and GPX4 proteins. In sorafenib‐treated HSC‐T6 cells, ferroptotic events (depletion of SLC7A11, GPX4 and GSH; accumulation iron, ROS and MDA) were discovered. Intriguingly, these ferroptotic events were not appeared in hepatocytes or macrophages. Sorafenib‐elicited HSC ferroptosis and ECM reduction were abrogated by Fer‐1 and DFO. Additionally, both HIF‐1α and SLC7A11 proteins were reduced in sorafenib‐treated HSC‐T6 cells. SLC7A11 was positively regulated by HIF‐1α, inactivation of HIF‐1α/SLC7A11 pathway was required for sorafenib‐induced HSC ferroptosis, and elevation of HIF‐1α could inhibit ferroptosis, ultimately limited the anti‐fibrotic effect.ConclusionsSorafenib triggers HSC ferroptosis via HIF‐1α/SLC7A11 signalling, which in turn attenuates liver injury and fibrosis.     

Mesenchymal stem cells alleviate experimental immune-mediated liver injury via chitinase 3-like protein 1-mediated T cell suppression

Liver diseases with different pathogenesis share common pathways of immune-mediated injury. Chitinase-3-like protein 1 (CHI3L1) was induced in both acute and chronic liver injuries, and recent studies reported that it possesses an immunosuppressive ability. CHI3L1 was also expressed in mesenchymal stem cells (MSCs), thus we investigates the role of CHI3L1 in MSC-based therapy for immune-mediated liver injury here. We found that CHI3L1 was highly expressed in human umbilical cord MSCs (hUC-MSCs). Downregulating CHI3L1 mitigated the ability of hUC-MSCs to inhibit T cell activation, proliferation and inflammatory cytokine secretion in vitro. Using Concanavalin A (Con A)-induced liver injury mouse model, we found that silencing CHI3L1 significantly abrogated the hUC-MSCs-mediated alleviation of liver injury, accompanying by weakened suppressive effects on infiltration and activation of hepatic T cells, and secretion of pro-inflammatory cytokines. In addition, recombinant CHI3L1 (rCHI3L1) administration inhibited the proliferation and function of activated T cells, and alleviated the Con A-induced liver injury in mice. Mechanistically, gene set enrichment analysis showed that JAK/STAT signalling pathway was one of the most significantly enriched gene pathways in T cells co-cultured with hUC-MSCs with CHI3L1 knockdown, and further study revealed that CHI3L1 secreted by hUC-MSCs inhibited the STAT1/3 signalling in T cells by upregulating peroxisome proliferator-activated receptor δ (PPARδ). Collectively, our data showed that CHI3L1 was a novel MSC-secreted immunosuppressive factor and provided new insights into therapeutic treatment of immune-mediated liver injury.Subject terms: T cells, Mesenchymal stem cells, Autoimmune hepatitis     

Cystine transporter SLC7A11/xCT in cancer:ferroptosis,nutrient dependency,and cancer therapy

The cystine/glutamate antiporter SLC7A11 (also com-monly known as xCT) functions to import cystine for glutathione biosynthesis and antioxidant defense and is overexpressed in multiple human cancers.Recent studies revealed that SLC7A11 overexpression pro-motes tumor growth partly through suppressing fer-roptosis,a form of regulated cell death induced by excessive lipid peroxidation.However,cancer cells with high expression of SLC7A11 (SLC7A11high) also have to endure the significant cost associated with SLC7A11-mediated metabolic reprogramming,leading to glucose-and glutamine-dependency in SLC7A11high cancer cells,which presents potential metabolic vulnerabilities for therapeutic targeting in SLC7A11high cancer.In this review,we summarize diverse regulatory mechanisms of SLC7A11 in cancer,discuss ferroptosis-dependent and-independent functions of SLC7A11 in promoting tumor development,explore the mechanistic basis of SLC7A11-induced nutrient dependency in cancer cells,and conceptualize therapeutic strategies to target SLC7A11 in cancer treatment.This review will provide the foundation for further understanding SLC7A11 in ferroptosis,nutrient dependency,and tumor biology and for developing novel effective cancer therapies.     

肝细胞生长因子基因修饰的间充质干细胞治疗肝损伤的研究进展

减轻肝脏损伤、促进肝脏修复和再生始终是肝脏疾病研究中的重点。间充质干细胞(MSCs)是众多具有组织修复和再生能力细胞中的明星细胞,合成的多种细胞因子经旁分泌途径发挥调控细胞生存,调节炎症反应,促进血管再生和减轻纤维化等多种生物学效应,肝细胞生长因子(HGF)便是重点细胞因子之一。基于HGF的信号调控作用,再结合MSCs的干细胞优势,HGF基因修饰间充质干细胞(HGF-MSCs)作为一种干细胞治疗新策略能够发挥“1+1>2”的效果。本文就HGF-MSCs在减轻和修复肝损伤中的研究进展作综述。     

Exosomes from human-bone-marrow-derived mesenchymal stem cells protect against renal ischemia/reperfusion injury via transferring miR-199a-3p

Renal ischemia/reperfusion (I/R) injury is the main reason for acute kidney injury (AKI) and is closely related to high morbidity and mortality. In this study, we found that exosomes from human-bone-marrow-derived mesenchymal stem cells (hBMSC-Exos) play a protective role in hypoxia/reoxygenation (H/R) injury. hBMSC-Exos were enriched in miR-199a-3p, and hBMSC-Exo treatment increased the expression level of miR-199a-3p in renal cells. We further explored the function of miR-199a-3p on H/R injury. miR-199a-3p was knocked down in hBMSCs with a miR-199a-3p inhibitor. HK-2 cells cocultured with miR-199a-3p-knockdown hBMSCs were more susceptible to H/R injury and showed more apoptosis than those cocultured with hBMSCs or miR-199a-3p-overexpressing hBMSCs. Meanwhile, we found that HK-2 cells exposed to H/R treatment incubated with hBMSC-Exos decreased semaphorin 3A (Sema3A) and activated the protein kinase B (AKT) and extracellular-signal-regulated kinase (ERK) pathways. However, HK-2 cells cocultured with miR-199a-3p-knockdown hBMSCs restored Sema3A expression and blocked the activation of the AKT and ERK pathways. Moreover, knocking down Sema3A could reactivate the AKT and ERK pathways suppressed by a miR-199a-3p inhibitor. In vivo, we injected hBMSC-Exos into mice suffering from I/R injury; this treatment induced functional recovery and histologic protection and reduced cleaved caspase-3 and Sema3A expression levels, as shown by immunohistochemistry. On the whole, this study demonstrated an antiapoptotic effect of hBMSC-Exos, which protected against I/R injury, via delivering miR-199a-3p to renal cells, downregulating Sema3A expression and thereby activating the AKT and ERK pathways. These findings reveal a novel mechanism of AKI treated with hBMSC-Exos and provide a therapeutic method for kidney diseases.     

Tonsil-derived mesenchymal stem cells alleviate concanavalin A-induced acute liver injury

Acute liver failure, the fatal deterioration of liver function, is the most common indication for emergency liver transplantation, and drug-induced liver injury and viral hepatitis are frequent in young adults. Stem cell therapy has come into the limelight as a potential therapeutic approach for various diseases, including liver failure and cirrhosis. In this study, we investigated therapeutic effects of tonsil-derived mesenchymal stem cells (T-MSCs) in concanavalin A (ConA)- and acetaminophen-induced acute liver injury. ConA-induced hepatitis resembles viral and immune-mediated hepatic injury, and acetaminophen overdose is the most frequent cause of acute liver failure in the United States and Europe. Intravenous administration of T-MSCs significantly reduced ConA-induced hepatic toxicity, but not acetaminophen-induced liver injury, affirming the immunoregulatory capacity of T-MSCs. T-MSCs were successfully recruited to damaged liver and suppressed inflammatory cytokine secretion. T-MSCs expressed high levels of galectin-1 and -3, and galectin-1 knockdown which partially diminished interleukin-2 and tumor necrosis factor α secretion from cultured T-cells. Galectin-1 knockdown in T-MSCs also reversed the protective effect of T-MSCs on ConA-induced hepatitis. These results suggest that galectin-1 plays an important role in immunoregulation of T-MSCs, which contributes to their protective effect in immune-mediated hepatitis. Further, suppression of T-cell activation by frozen and thawed T-MSCs implies great potential of T-MSC banking for clinical utilization in immune-mediated disease.     

Mesenchymal stem cells increase heme oxygenase 1-activated autophagy in treatment of acute liver failure

In recent years, transplantation of mesenchymal stem cells (MSCs) has attracted much attention as a potential cell-based therapy for acute liver failure (ALF). As an inducible enzyme, heme oxygenase 1 (HO-1) has been reported to have cytoprotective, anti-apoptotic and immunoregulatory effects. Autophagy, a conserved catabolic process in cells, may be an important pathway for MSCs to treat ALF. In this study, we aimed to explore whether MSCs treat ALF by regulating autophagy and whether HO-1 was involved in the same pathway. Bone marrow-derived MSCs were isolated from Sprague-Dawley rats and cultured according to an established protocol. Co-culture systems of MSCs and hepatocytes were used to assess autophagy in the treatment of ALF. Meanwhile, MSCs were transplanted into rats with d-galactosamine (Gal)-induced ALF. Autophagy inhibitor (3-methyladenine, 3-MA), HO-1 inhibitor (zinc protoporphyrin, ZnPP) and PI3K specific inhibitor (LY294002) were employed in the study. Blood samples and liver tissues were collected before euthanasia. Survival rate, liver function, inflammatory factors, histology, Ki67 and TUNEL staining were determined. MSCs transplantation alleviated ALF both in vivo and in vitro. Autophagy and autophagy-related proteins were significantly up-regulated during MSCs treatment. 3-MA attenuated the therapeutic effect of MSCs. Administration of LY294002 before ALF induction inhibited hepatocyte autophagy. During the MSCs treatment, the HO-1 expression was increased, while inhibiting HO-1 attenuated the therapeutic effect of MSCs as well as hepatocyte autophagy. These findings suggested MSCs could alleviate ALF by increasing the HO-1 expression, which played an important role in activating autophagy through PI3K/AKT signaling pathway.     

IL-10 and TGF-beta redundantly protect against severe liver injury and mortality during acute schistosomiasis

The cytokines IL-10 and TGF-beta regulate immunity and inflammation. IL-10 is known to suppress the extent of hepatic damage caused by parasite ova during natural infection with Schistosoma mansoni, but the role of TGF-beta is less clear. Cytokine blockade studies in mice revealed that anti-IL-10R mAb treatment during acute infection modestly increased cytokine production and liver damage, whereas selective anti-TGF-beta mAb treatment had marginal effects. In contrast, mice administered both mAbs developed severe hepatic inflammation, with enlarged, necrotic liver granulomas, cachexia, and >80% mortality by 8 wk postinfection, despite increased numbers of CD4(+)CD25(+)Foxp3(+) T regulatory cells. Blocking both IL-10 and TGF-beta at the onset of egg production also significantly increased IL-4, IL-6, TNF, IFN-gamma, and IL-17 production and markedly increased hepatic, peritoneal, and splenic neutrophilia. In contrast, coadministration of anti-IL-10R and TGF-beta mAbs had little effect upon parasite ova-induced intestinal pathology or development of alternatively activated macrophages, which are required to suppress intestinal pathology. This suggests that inflammation is controlled during acute S. mansoni infection by two distinct, organ-specific mechanisms: TGF-beta and IL-10 redundantly suppress hepatic inflammation while intestinal inflammation is regulated by alternatively activated macrophages.     

SLC9A3R1 stimulates autophagy via BECN1 stabilization in breast cancer cells

Autophagy, a self-catabolic process, has been found to be involved in abrogating the proliferation and metastasis of breast cancer. SLC9A3R1 (solute carrier family 9, subfamily A [NHE3, cation proton antiporter 3], member 3 regulator 1), a multifunctional scaffold protein, is involved in suppressing breast cancer cells proliferation and the SLC9A3R1-related signaling pathway regulates the activation of autophagy processes. However, the precise regulatory mechanism and signaling pathway of SLC9A3R1 in the regulation of autophagy processes in breast cancer cells remains unknown. Here, we report that the stability of BECN1, the major component of the autophagic core lipid kinase complex, is augmented in SLC9A3R1-overexpressing breast cancer MDA-MB-231 cells, subsequently stimulating autophagy by attenuating the interaction between BECN1 and BCL2. Initially, we found that SLC9A3R1 partially stimulated autophagy through the PTEN-PI3K-AKT1 signaling cascade in MDA-MB-231 cells. SLC9A3R1 then attenuated the interaction between BECN1 and BCL2 to stimulate the autophagic core lipid kinase complex. Further findings revealed that SLC9A3R1 bound to BECN1 and subsequently blocked ubiquitin-dependent BECN1 degradation. And the deletion of the C-terminal domain of SLC9A3R1 resulted in significantly reduced binding to BECN1. Moreover, the lack of C-terminal of SLC9A3R1 neither reduced the ubiquitination of BECN1 nor induced autophagy in breast cancer cells. The decrease in BECN1 degradation induced by SLC9A3R1 resulted in the activity of autophagy stimulation in breast cancer cells. These findings indicate that the SLC9A3R1-BECN1 signaling pathway participates in the activation of autophagy processes in breast cancer cells.