Nrf-2 overexpression in mesenchymal stem cells reduces oxidative stress-induced apoptosis and cytotoxicity

The most prominent capabilities of mesenchymal stem cells (MCSs) which make them promising for therapeutic applications are their capacity to endure and implant in the target tissue. However, the therapeutic applications of these cells are limited due to their early death within the first few days following transplantation. Therefore, to improve cell therapy efficacy, it is necessary to manipulate MSCs to resist severe stresses imposed by microenvironment. In this study, we manipulated MSCs to express a cytoprotective factor, nuclear factor erythroid-2 related factor 2 (Nrf2) to address this issue. Full-length human Nrf2 cDNA was isolated and TOPO cloned into TOPO cloning vector and then transferred to gateway adapted adenovirus expression vector by LR recombination reaction. Afterwards, the Nrf2 bearing recombinant virus was prepared in appropriate mammalian cell line and used to infect MSCs. The viability and apoptosis of the Nrf2 expressing MSCs were evaluated following hypoxic and oxidative stress conditions. Transient expression of Nrf2 by MSCs protected them against cell death and the apoptosis triggered by hypoxic and oxidative stress conditions. Nrf2 also enhanced the activity of SOD and HO-1. These findings could be used as a strategy for prevention of graft cell death in MSC-based cell therapy. It also indicates that management of cellular stress responses can be used for practical applications.     

Lipocalin-2-mediated upregulation of various antioxidants and growth factors protects bone marrow-derived mesenchymal stem cells against unfavorable microenvironments

Despite many advantages of mesenchymal stem cells (MSCs) that make them suitable for cell therapy purposes, their therapeutic application has been limited due to their susceptibility to several stresses (e.g., nutrient-poor environment, oxidative stress, and hypoxic and masses of cytotoxic factors) to which they are exposed during their preparation and following transplantation. Hence, reinforcing MSCs against these stresses is a challenge for both basic and clinician scientists. Recently, much attention has been directed toward equipping MSCs with cytoprotective factors to strengthen them against unfavorable microenvironments. Here, we engineered MSCs with lipocalin 2 (Lcn2), a cytoprotective factor that is naturally induced following exposure of cells to stresses imposed by the microenvironment. Lcn2 overexpression not only did not interfere with the multidifferentiation capacity of the MSCs but also granted many protective properties to them. Lcn2 potentiated MSCs to withstand oxidative, hypoxia, and serum deprivation (SD) conditions via antagonizing their induced cytotoxicity and apoptosis. Adhesion rate of MSCs to coated culture plates was also enhanced by Lcn2 overexpression. In addition, Lcn2 induced antioxidants and upregulated some growth factors in MSCs. Our findings suggested a new strategy for prevention of graft cell death in MSC-based cell therapy.     

Mitochondria-targeted antioxidant mito-TEMPO alleviate oxidative stress induced by antimycin A in human mesenchymal stem cells

The cell therapy of damaged tissue, which is linked to hypoxia condition might fail, in large part due to the emergence of oxidative stress (OS) and/or mitochondrial dysfunctions. Thus, the invigoration of stem cells against oxidative stress could be a reliable strategy to improve the cell therapy outcome. Of various antioxidants, mito-Tempo (mito-T) is one of the potent antioxidants that could target and neutralize the mitochondrial oxidative stress. In this study, for the induction of hypoxia and oxidative stress in mitochondria of the mesenchymal stem cells (MSCs) isolated from human adipose tissue, antimycin A (AMA) was used and then several parameters were analyzed, including cell viability and cell cycle arrest of MSCs exposed to AMA, mito-T, antioxidant potential, redox homeostasis, and signaling pathways in MSCs under oxidative stress. Based on our findings, the treated MSCs were found to impose a high resistance to the OS-induced apoptosis, which correlated with the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway required to manage OS. Upon exposure of the MSCs to high oxidative stress conditions using AMA, the cells failed to scavenge. The use of mito-T was found to alleviate the damage induced by oxidative stress through both direct functions of the free radical scavenging and the interplay in terms of cell signaling pathways including the upregulation of the Nrf2 pathway. These findings may pave the way in the stem cell therapy for the hypoxia-mediated tissue damage.     

Ataxia telangiectasia mutated inhibits oxidative stress-induced apoptosis by regulating heme oxygenase-1 expression

Ataxia telangiectasia (AT) is caused by mutational inactivation of the ataxia telangiectasia mutated (Atm) gene, which is involved in DNA repair. Increased oxidative stress has been shown in human AT cells and neuronal tissues of Atm-deficient mice. Heme oxygenase-1 (HO-1) is an inducible antioxidant enzyme and protects cells against oxidative stress. The purpose of this study is to determine whether ATM induces antioxidant enzyme HO-1 and protects cells from oxidative stress-mediated apoptosis by driving the activation of PKC-δ and NF-κB, by increasing cell viability, and by downregulating DNA fragmentation and apoptotic indicators (apoptosis-inducing factor and cleaved caspase-3). AT fibroblasts stably transfected with human full-length ATM cDNA (YZ5 cells) or the empty vector (MOCK cells) were treated with H₂O₂ as a source of reactive oxygen species (ROS). As a result, transfection with ATM inhibited ROS-induced cell death and DNA fragmentation in MOCK cells. Transfection with ATM induced expression of HO-1 which was mediated by PKC-δ and NF-κB in H₂O₂-treated MOCK cells. ZnPP, an HO-1 inhibitor, and transfection with HO-1 siRNA increased ROS levels and apoptosis, whereas hemin, an HO-1 activator, reduced ROS levels and apoptosis in H₂O₂-treated YZ5 cells. Rottlerin, a PKC-δ inhibitor, inhibited NF-κB activation and HO-1 expression in H₂O₂-treated YZ5 cells. MOCK cells showed increased cell death, DNA fragmentation, and apoptotic indicators compared to YZ5 cells exposed to H₂O₂. In addition, transfection with p65 siRNA increased ROS levels and DNA fragmentation, but decreased HO-1 protein levels in H₂O₂-treated YZ5 cells. In conclusion, ATM induces HO-1 expression via activation of PKC-δ and NF-κB and inhibits oxidative stress-induced apoptosis. A loss of HO-1 induction may explain why AT patients are vulnerable to oxidative stress.     

miR-210 over-expression enhances mesenchymal stem cell survival in an oxidative stress environment through antioxidation and c-Met pathway activation

microRNA-210(miR-210)has generally been reported to be associated with cell survival under hypoxia.However,there are few data regarding the role of miR-210 in the survival of mesenchymal stem cells(MSCs)under oxidative stress conditions.Thus,we sought to investigate whether miR-210 over-expression could protect MSCs against oxidative stress injury and what the primary mechanisms involved are.The results showed that over-expression of miR-210 significantly reduced the apoptosis of MSCs under oxidative stress,accompanied by obvious increases in cell viability and superoxide dismutase activity and remarkable decreases in malonaldehyde content and reactive oxygen species production,resulting in a noticeable reduction of apoptotic indices when compared with the control.Moreover,the above beneficial effects of miR-210 could be significantly reduced by c-Met pathway repression.Collectively,these results showed that miR-210 over-expression improved MSC survival under oxidative stress through antioxidation and c-Met pathway activation,indicating the potential development of a novel approach to enhance the efficacy of MSC-based therapy for injured myocardium.     

Over-expression of HO-1 on mesenchymal stem cells promotes angiogenesis and improves myocardial function in infarcted myocardium

Heme oxygenase-1 (HO-1) is a stress-inducible enzyme with diverse cytoprotective effects, and reported to have an important role in angiogenesis recently. Here we investigated whether HO-1 transduced by mesenchymal stem cells (MSCs) can induce angiogenic effects in infarcted myocardium. HO-1 was transfected into cultured MSCs using an adenoviral vector. 1 × 10⁶ Ad-HO-1-transfected MSCs (HO-1-MSCs) or Ad-Null-transfected MSCs (Null-MSCs) or PBS was respectively injected into rat hearts intramyocardially at 1 h post-myocardial infarction. The results showed that HO-1-MSCs were able to induce stable expression of HO-1 in vitro and in vivo. The capillary density and expression of angiogenic growth factors, VEGF and FGF2 were significantly enhanced in HO-1-MSCs-treated hearts compared with Null-MSCs-treated and PBS-treated hearts. However, the angiogenic effects of HO-1 were abolished by treating the animals with HO inhibitor, zinc protoporphyrin. The myocardial apoptosis was marked reduced with significantly reduced fibrotic area in HO-1-MSCs-treated hearts; Furthermore, the cardiac function and remodeling were also significantly improved in HO-1-MSCs-treated hearts. Our current findings support the premise that HO-1 transduced by MSCs can induce angiogenic effects and improve heart function after acute myocardial infarction.     

Apoptosis of mesenchymal stem cells induced by hydrogen peroxide concerns both endoplasmic reticulum stress and mitochondrial death pathway through regulation of caspases,p38 and JNK

Poor survival of mesenchymal stem cells (MSCs) compromised the efficacy of stem cell therapy for myocardial infarction. The increase of exogenous reactive oxygen species (ROS) in infracted heart is one of the important factors that challenged the survival of donor MSCs. In the study we aimed to evaluate the effect of oxidative stress on the cell death of MSCs and investigate its mechanisms in order to help with the identification of new biological compounds to reduce donor cells damage. Apoptosis of MSCs were evaluated with Hoechst 33342 staining and flow cytometry analysis. The mitochondrial membrane potential of MSCs was analyzed with JC‐1 staining. Signaling pathways involved in H₂O₂ induced apoptosis were analyzed with Western blot. H₂O₂ induced apoptosis of MSCs in a dose‐ and time‐dependent manner. H₂O₂ induced apoptosis of MSCs via both endoplasmic reticulum (ER) and mitochondrial pathways rather than extrinsic apoptosis pathway. H₂O₂ caused transient rather than sustained activation of p38 and JNK with no effect on ERK1/2 pathway. P38 was involved in the regulation of early apoptosis of MSCs while JNK was involved in the late apoptosis. P38 directed both ER stress and mitochondria death pathway in the early apoptosis. In conclusion, exogenous ROS was a major factor to induce apoptosis of MSCs. Both ER stress and mitochondria death pathway were involved in the apoptosis of MSCs. H₂O₂ activated p38 that directed the above two pathways in the regulation of early apoptosis of MSCs while JNK was involved in the late apoptosis of MSCs. J. Cell. Biochem. 111: 967–978, 2010. © 2010 Wiley‐Liss, Inc.     

Heme Oxygenase-1 Protects Retinal Endothelial Cells against High Glucose- and Oxidative/Nitrosative Stress-Induced Toxicity

Diabetic retinopathy is a leading cause of visual loss and blindness, characterized by microvascular dysfunction. Hyperglycemia is considered the major pathogenic factor for the development of diabetic retinopathy and is associated with increased oxidative/nitrosative stress in the retina. Since heme oxygenase-1 (HO-1) is an enzyme with antioxidant and protective properties, we investigated the potential protective role of HO-1 in retinal endothelial cells exposed to high glucose and oxidative/nitrosative stress conditions. Retinal endothelial cells were exposed to elevated glucose, nitric oxide (NO) and hydrogen peroxide (H(2)O(2)). Cell viability and apoptosis were assessed by MTT assay, Hoechst staining, TUNEL assay and Annexin V labeling. The production of reactive oxygen species (ROS) was detected by the oxidation of 2',7'-dichlorodihydrofluorescein diacetate. The content of HO-1 was assessed by immunobloting and immunofluorescence. HO activity was determined by bilirubin production. Long-term exposure (7 days) of retinal endothelial cells to elevated glucose decreased cell viability and had no effect on HO-1 content. However, a short-time exposure (24 h) to elevated glucose did not alter cell viability, but increased both the levels of intracellular ROS and HO-1 content. Moreover, the inhibition of HO with SnPPIX unmasked the toxic effect of high glucose and revealed the protection conferred by HO-1. Oxidative/nitrosative stress conditions increased cell death and HO-1 protein levels. These effects of elevated glucose and HO inhibition on cell death were confirmed in primary endothelial cells (HUVECs). When cells were exposed to oxidative/nitrosative stress conditions there was also an increase in retinal endothelial cell death and HO-1 content. The inhibition of HO enhanced ROS production and the toxic effect induced by exposure to H(2)O(2) and NOC-18 (NO donor). Overexpression of HO-1 prevented the toxic effect induced by H(2)O(2) and NOC-18. In conclusion, HO-1 exerts a protective effect in retinal endothelial cells exposed to hyperglycemic and oxidative/nitrosative stress conditions.     

Heme oxygenase-1 inhibits TNF-alpha-induced apoptosis in cultured fibroblasts

Heme oxygenase (HO)-1 catalyzes the oxidative cleavage of heme to yield equimolar amounts of biliverdin, iron, and carbon monoxide. HO-1 is a stress response protein, the induction of which is associated with protection against oxidative stress. The mechanism(s) of protection is not completely elucidated, although it is suggested that one or more of the catalytic by-products provide antioxidant functions either directly or indirectly. The involvement of reactive oxygen species in apoptosis raised the question of a possible role for HO-1 in programmed cell death. Using the tetracycline-regulated expression system, we show here that conditional overexpression of HO-1 prevents tumor necrosis factor-alpha-induced apoptosis in murine L929 fibroblasts. Inhibition of apoptosis was not observed in the presence of tin protoporphyrin, a specific inhibitor of HO activity, and in cells overexpressing antisense HO-1. Interestingly, exogenous administration of a low concentration of carbon monoxide also prevented tumor necrosis factor-alpha-induced apoptosis in L929 fibroblasts. Inhibition of tumor necrosis factor-alpha-induced apoptosis by HO-1 overexpression was reversed by 1H-(1,2, 4)oxadiazolo(4,3-a)quinoxalin-1-one, an inhibitor of guanylate cyclase, which is a target enzyme for carbon monoxide. Taken together, our data suggest that the antiapoptotic effect of HO-1 may be mediated via carbon monoxide.     

Heme oxygenase-1 is an important modulator in limiting glucose-induced apoptosis in human umbilical vein endothelial cells

Hyperglycaemia is associated with oxidative stress. The inducible isoform of heme oxygenase (HO-1) is an effective system to counteract oxidative stress, yet it is unclear how hyperglycaemia affects HO-1. In this study, we explored: 1) the HO-1 protein content and HO activity in human umbilical vein endothelial cells (HUVECs) exposed to different glucose concentrations, and 2) the mechanisms which account for the high glucose-induced effects on HO-1. We evaluated HO-1 protein expression, HO activity, apoptosis and reactive oxygen species (ROS) in HUVECs treated for 48 h with 5.5, 10 and 20 mM glucose. A dose-dependent production of reactive oxygen species was observed. At 10 mM glucose, an increase of HO-1 protein expression and HO activity was observed, whereas at 20 mM, there was no change in protein content and activity relative to at 5.5 mM glucose. HO-1 protein expression in HUVECs exposed to 20 mM of glucose was increased in the presence of 20 U/ml superoxide dismutase (SOD). HO-1 gene silencing augments ROS production both at 5.5 and 10 mM glucose, leading to an increased apoptosis. We conclude that, in endothelial cells, the regulation of HO-1 by glucose is dependent upon levels of glucose itself. Lack of homeostatic HO-1 upregulation fails to protect from oxidative damage and results in a higher rate of apoptotic cell death.     

Regulation of alternative macrophage activation by MSCs derived hypoxic conditioned medium,via the TGF-β1/Smad3 pathway

Macrophages are re-educated and polarized in response to myocardial infarction (MI). The M2 anti-inflammatory phenotype is a known dominator of late stage MI. Mesenchymal stem cells (MSCs) represent a promising tool for cell therapy, particularly heart related diseases. In general, MSCs induce alteration of the macrophage subtype from M1 to M2, both in vitro and in vivo. We conjectured that hypoxic conditions can promote secretome productivity of MSCs. Hypoxia induces TGF-β1 expression, and TGF-β1 mediates M2 macrophage polarization for anti-inflammation and angiogenesis in infarcted areas. We hypothesized that macrophages undergo advanced M2 polarization after exposure to MSCs in hypoxia. Treatment of MSCs derived hypoxic conditioned medium (hypo-CM) promoted M2 phenotype and neovascularization through the TGF-β1/Smad3 pathway. In addition, hypo-CM derived from MSCs improved restoration of ischemic heart, such as attenuating cell apoptosis and fibrosis, and ameliorating microvessel density. Based on our results, we propose a new therapeutic method for effective MI treatment using regulation of macrophage polarization.      

Transplantation of bone marrow mesenchymal stem cells decreases oxidative stress,apoptosis, and hippocampal damage in brain of a spontaneous stroke model

Stroke is the most common cause of motor disabilities and is a major cause of mortality worldwide. Adult stem cells have been shown to be effective against neuronal degeneration through mechanisms that include both the recovery of neurotransmitter activity and a decrease in apoptosis and oxidative stress. We chose the lineage stroke-prone spontaneously hypertensive rat (SHRSP) as a model for stem cell therapy. SHRSP rats can develop such severe hypertension that they generally suffer a stroke at approximately 1 year of age. The aim of this study was to evaluate whether mesenchymal stem cells (MSCs) decrease apoptotic death and oxidative stress in existing SHRSP brain tissue. The results of qRT-PCR assays showed higher levels of the antiapoptotic Bcl-2 gene in the MSC-treated animals, compared with untreated. Our study also showed that superoxide, apoptotic cells, and by-products of lipid peroxidation decreased in MSC-treated SHRSP to levels similar those found in the animal controls, Wistar Kyoto rats. In addition, we saw a repair of morphological damage at the hippocampal region after MSC transplantation. These data suggest that MSCs have neuroprotective and antioxidant potential in stroke-prone spontaneously hypertensive rats.     

Peroxynitrite induces HO-1 expression via PI3K/Akt-dependent activation of NF-E2-related factor 2 in PC12 cells

Peroxynitrite is a strong oxidant produced by rapid interaction between superoxide anion and nitric oxide radicals and induces oxidative stress and cell death. Treatment of PC12 cells with 3-morpholinosydnonimine (SIN-1), a generator of peroxynitrite, induced the expression of heme oxygenase-1 (HO-1), an antioxidant cytoprotective enzyme. Inhibition of the HO activity by zinc protoporphyrin IX or knockdown of HO-1 gene expression with siRNA exacerbated the SIN-1-induced apoptosis. After SIN-1 treatment, there was a time-related increase in nuclear localization and subsequent binding of NF-E2-related factor 2 (Nrf2) to the antioxidant-responsive element (ARE). Transfection of PC12 cells with dominant-negative Nrf2 abolished the SIN-1-induced increase in Nrf2-ARE binding and subsequent upregulation of HO-1 expression, leading to enhanced cell death. Upon exposure of PC12 cells to SIN-1, the phosphatidylinositol 3-kinase (PI3K) activity was increased in a time-dependent manner. Pretreatment of cells with LY294002, a pharmacologic inhibitor of PI3K or transfection with the kinase-dead mutant Akt abrogated the SIN-1-induced Nrf2 activation and HO-1 expression. Taken together, these results suggest that peroxynitrite activates Nrf2 via PI3K/Akt signaling and enhances Nrf2-ARE binding, which leads to upregulation of HO-1 expression. The SIN-1-induced HO-1 upregulation may confer the adaptive survival response against nitrosative stress.     

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.     

Induction of heat shock proteins (HSPs) by sodium arsenite in cultured astrocytes and reduction of hydrogen peroxide-induced cell death

Induction of heat shock proteins (HSPs) protects cells from oxidative injury. Here Hsp72, Hsp27 and heme oxygenase-1 (HO-1) were induced in cultured rat astrocytes, and protection against oxidative stress was investigated. Astrocytes were treated with sodium arsenite (20-50 micro m) for 1 h, which was non-toxic to cells, 24 h later they were exposed to 400 micro m H2O2 for 1 h, and cell death was evaluated at different time points. Arsenite triggered strong induction of HSPs, which was prevented by 1 micro g/mL cycloheximide (CXH). H2O2 caused cell loss and increased cell death with features of apoptosis, i.e. TdT-mediated dUTP nick-end labelling (TUNEL) reaction and caspase-3 activation. These features were abrogated by pre-treatment with arsenite, which prevented cell loss and significantly reduced the number of dead cells. The protective effect of arsenite was not detected in the presence of CHX. Pre-treatment with arsenite increased protein kinase B (Akt) and extracellular signal regulated kinase 1/2 (ERK1/2) phosphorylation after H2O2. However, while Akt phosphorylation was prevented by CHX, Erk1/2 phosphorylation was further enhanced by CHX. The results show that transient arsenite pre-treatment induces Hsp72, HO-1 and, to a lesser extent, Hsp27; it reduces H2O2-induced astrocyte death; and it causes selective activation of Akt following H2O2. It is suggested that HSP expression at the time of H2O2 exposure protects astrocytes from oxidative injury and apoptotic cell death by means of pro-survival Akt.     

Melatonin protects ADSCs from ROS and enhances their therapeutic potency in a rat model of myocardial infarction

Myocardial infarction (MI) is a major cause of death and disability worldwide. In the last decade, mesenchymal stem cells (MSCs) based cell therapy has emerged as a promising therapeutic strategy. Although great advance have been made using MSCs to treat MI, the low viability of transplanted MSCs severely limits the efficiency of MSCs therapy. Here, we show evidence that ex vivo pre‐treatment with melatonin, an endogenous hormone with newly found anti‐oxidative activity, could improve survival and function of adipose tissue derived MSCs (ADSCs) in vitro as well as in vivo. ADSCs with 5 μM melatonin pre‐treatment for 24 hrs showed increased expression of the antioxidant enzyme catalase and Cu/Zn superoxide dismutase (SOD‐1), as well as pro‐angiogenic and mitogenic factors like insulin‐like growth factor 1, basic fibroblast growth factor, hepatocyte growth factor (HGF), epidermal growth factor. Furthermore, melatonin pre‐treatment protected MSCs from reactive oxygen species (ROS) induced apoptosis both directly by promoting anti‐apoptosis kinases like p‐Akt as well as blocking caspase cascade, and indirectly by restoring the ROS impaired cell adhesion. Using a rat model of MI, we found that melatonin pre‐treatment enhanced the viability of engrafted ADSCs, and promoted their therapeutic potency. Hopefully, our results may shed light on the design of more effective therapeutic strategies treating MI by MSCs in clinic.     

TNF‐α promotes survival and migration of MSCs under oxidative stress via NF‐κB pathway to attenuate intimal hyperplasia in vein grafts

The oxidative stress caused by endothelial injury is involved in intimal hyperplasia (IH) in vein grafts. Mesenchymal stem cells (MSCs) can home to injured intima and promote endothelial repair. However, MSC apoptosis is increased accompanied by decreased functional activity under oxidative stress. Thus, we investigate whether tumour necrosis factor‐α (TNF‐α) can promote the survival and activity of MSCs under oxidative stress to reduce IH more effectively, and establish what role the NF‐κB pathway plays in this. In this study, we preconditioned MSCs with TNF‐α (^{TNF‐α‐PC}MSCs) for 24 hrs and measured the activation of the IKK/NF‐κB pathway. EdU and transwell assays were performed to assess proliferation and migration of ^{TNF‐α‐PC}MSCs. Apoptosis and migration of ^{TNF‐α‐PC}MSCs were evaluated in conditions of oxidative stress by analysis of the expression of Bcl‐2 and CXCR4 proteins. ^{TNF‐α‐PC}MSCs were transplanted into a vein graft model, so that cell homing could be tracked, and endothelial apoptosis and IH of vein grafts were measured. The results demonstrated that TNF‐α promotes proliferation and migration of MSCs. Furthermore, survival and migration of ^{TNF‐α‐PC}MSCs under oxidative stress were both enhanced. A greater number of MSCs migrated to the intima of vein grafts after preconditioning with TNF‐α, and the formation of neointima was significantly reduced. These effects could be partially abolished by IKK XII (NF‐κB inhibitor). All these results indicate that preconditioning with TNF‐α can promote survival and migration of MSCs under oxidative stress via the NF‐κB pathway and thus attenuate IH of vein grafts.