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.     

VEGF improves survival of mesenchymal stem cells in infarcted hearts

Bone marrow-derived mesenchymal stem cells (MSC) are a promising source for cell-based treatment of myocardial infarction (MI), but existing strategies are restricted by low cell survival and engraftment. We examined whether vascular endothelial growth factor (VEGF) improve MSC viability in infracted hearts. We found long-term culture increased MSC-cellular stress: expressing more cell cycle inhibitors, p16^INK, p21 and p19^ARF. VEGF treatment reduced cellular stress, increased pro-survival factors, phosphorylated-Akt and Bcl-xL expression and cell proliferation. Co-injection of MSCs with VEGF to MI hearts increased cell engraftment and resulted in better improvement of cardiac function than that injected with MSCs or VEGF alone. In conclusion, VEGF protects MSCs from culture-induce cellular stress and improves their viability in ischemic myocardium, which results in improvements of their therapeutic effect for the treatment of MI.     

Correction to: Computational analysis of viable parameter regions in models of synthetic biological systems

Background

Myocardial infarction (MI) is a common cause of mortality in people. Mesenchymal stem cell (MSC) has been shown to exert therapeutic potential to treat myocardial infarction (MI). However, in patients with diabetes, the diabetic environment affected MSCs activity and could impair the efficacy of treatment. Interleukin-10 (IL-10) has been shown to attenuate MI by suppressing inflammation. In current study, the combination of MSC transplantation with IL-10 was evaluated in a diabetic mice model with MI.

Methods

We engineered bone marrow derived MSCs (BM-MSCs) to overexpress IL-10 by using CRISPR activation. We established the diabetic mice model with MI and monitored the IL-10 expression after BM-MSCs transplantation. We also evaluated the effects of BM-MSCs transplantation on inflammatory response, cell apoptosis, cardiac function and angiogenesis.

Results

CRISPR activation system enabled overexpression of IL-10 in BM-MSCs. Transplantation of BM-MSCs overexpressing IL-10 resulted in IL-10 expression in heart after transplantation. Transplantation of BM-MSCs overexpressing IL-10 inhibited inflammatory cell infiltration and pro-inflammatory cytokines production, improved cardiac functional recovery, alleviated cardiac injury, decreased apoptosis of cardiac cells and increased angiogenesis.

Conclusion

In summary, we have demonstrated the therapeutic potential of IL-10 overexpressed BM-MSCs in the treatment of MI in diabetic mice.

     

Duration of in vitro storage affects the key stem cell features of human bone marrow-derived mesenchymal stromal cells for clinical transplantation

Background aimsMesenchymal stromal cells (MSCs) have the ability to self-renew and differentiate into various cell types. Their plasticity and easy availability make them promising candidates for regenerative medicine. However, for successful clinical application, MSCs need to be expanded under a Good Manufacturing Practices-compliant system to obtain a large quantity of these cells. Although the viability and potency of these in vitro-expanded MSCs need to be maintained during preparation and transportation before transplantation, these characteristics have not thoroughly been examined. Our goal in this study was to standardize MSC preparation and storage before their clinical application to ensure reproducible quality and potency for their clinically intended purpose.MethodsWe examined the viability, self-renewal capacity and differentiation capability of MSCs on short-term in vitro storage in saline or dextrose solution at 4°C and room temperature.ResultsMSCs harvested and suspended in saline for 1–2 h showed >90% viability regardless of storage temperature. However, when cells were stored for >2 h in saline, their viability decreased gradually over time. The viability of cells in dextrose deteriorated rapidly. MSCs lost colony-forming unit and differentiation capacities rapidly as storage time increased. Collectively, we found that a storage period >2 h resulted in a significant decrease in cell viability, cell proliferation capacity and differentiation potency.ConclusionsStorage of culture-harvested MSCs for >2 h is likely to result in suboptimal MSC-mediated tissue regeneration because of decreased cell viability and differentiation capacity.     

Polyphenols suppress hydrogen peroxide‐induced oxidative stress in human bone‐marrow derived mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) are considered a highly promising candidate cell type for cell‐based tissue engineering and regeneration because of their self‐renewal and multi‐lineage differentiation characteristics. Increased levels of reactive oxygen/nitrogen species (ROS/RNS) are associated with tissue injury and inflammation, impact a number of cellular processes, including cell adhesion, migration, and proliferation, and have been linked to cellular senescence in MSCs, potentially compromising their activities. Naturally occurring polyphenolic compounds (polyphenols), epigallocatechin‐3‐gallate (EGCG), and curcumin, block ROS/RNS and are potent inflammation‐modulating agents. However, their potential protective effects against oxidative stress in hMSCs have not been examined. In this study, we carried out a systematic analysis of the effects of polyphenols on hMSCs in their response to oxidative stress in the form of treatment with H₂O₂ and S‐nitroso‐N‐acetylpenicillamine (SNAP), respectively. Parameters measured included colony forming activity, apoptosis, and the levels of antioxidant enzymes and free reactive species. We found that polyphenols reversed H₂O₂‐induced loss of colony forming activity in hMSCs. In a dose‐dependent manner, polyphenols inhibited increased levels of ROS and NO, produced by H₂O₂ or SNAP, respectively, in MSCs. Notably, polyphenols rapidly and almost completely blocked H₂O₂‐induced ROS in the absence of significant direct effect on H₂O₂ itself. Polyphenols also protected the antioxidant enzymes and reduced apoptotic cell death caused by H₂O₂ exposure. Taken together, these findings demonstrate that EGCG and curcumin are capable of suppressing inducible oxidative stress in hMSCs, and suggest a possible new approach to maintain MSC viability and potency for clinical application. J. Cell. Biochem. 114: 1163–1173, 2013. © 2012 Wiley Periodicals, Inc.     

Mesenchymal stem cells restore CCl4‐induced liver injury by an antioxidative process

We have investigated BM (bone marrow)‐derived MSCs (mesenchymal stem cells) for the treatment of liver injury. It was hypothesized that MSC‐mediated resolution of liver injury could occur through an antioxidative process. After being injected with CCl₄ (carbon tetrachloride), mice were injected with syngenic BM‐derived MSCs or normal saline. Oxidative stress activity of the MSCs was determined by the analysis of ROS (reactive oxygen species) and SOD (superoxide dismutase) activity. In addition, cytoprotective genes of the liver tissue were assessed by real‐time PCR and ARE (antioxidant‐response element) reporter assay. Up‐regulated ROS of CCl₄‐treated liver cells was attenuated by co‐culturing with MSCs. Suppression of SOD by adding an SOD inhibitor decreased the effect of MSCs on injured liver cells. MSCs significantly increased SOD activity and inhibited ROS production in the injured liver. The gene expression levels of Hmox‐1 (haem oxygenase‐1), BI‐1 (Bax inhibitor‐1), HGF (hepatocyte growth factor), GST (glutathione transferase) and Nrf2 (nuclear factor‐erythoid 2 p45 subunit‐related factor 20), attenuated by CCl₄, were increased up to basal levels after MSC transplantation. In addition, MSCs induced an ARE, shown by luciferase activity, which represented a cytoprotective response in the injured liver. Evidence of a new cytoprotective effect is shown in which MSCs promote an antioxidant response and supports the potential of using MSC transplantation as an effective treatment modality for liver disease.     

miR‐155‐5p inhibition rejuvenates aged mesenchymal stem cells and enhances cardioprotection following infarction

Aging impairs the functions of human mesenchymal stem cells (MSCs), thereby severely reducing their beneficial effects on myocardial infarction (MI). MicroRNAs (miRNAs) play crucial roles in regulating the senescence of MSCs; however, the underlying mechanisms remain unclear. Here, we investigated the significance of miR‐155‐5p in regulating MSC senescence and whether inhibition of miR‐155‐5p could rejuvenate aged MSCs (AMSCs) to enhance their therapeutic efficacy for MI. Young MSCs (YMSCs) and AMSCs were isolated from young and aged donors, respectively. The cellular senescence of MSCs was evaluated by senescence‐associated β‐galactosidase (SA‐β‐gal) staining. Compared with YMSCs, AMSCs exhibited increased cellular senescence as evidenced by increased SA‐β‐gal activity and decreased proliferative capacity and paracrine effects. The expression of miR‐155‐5p was much higher in both serum and MSCs from aged donors than young donors. Upregulation of miR‐155‐5p in YMSCs led to increased cellular senescence, whereas downregulation of miR‐155‐5p decreased AMSC senescence. Mechanistically, miR‐155‐5p inhibited mitochondrial fission and increased mitochondrial fusion in MSCs via the AMPK signaling pathway, thereby resulting in cellular senescence by repressing the expression of Cab39. These effects were partially reversed by treatment with AMPK activator or mitofusin2‐specific siRNA (Mfn2‐siRNA). By enhancing angiogenesis and promoting cell survival, transplantation of anti‐miR‐155‐5p‐AMSCs led to improved cardiac function in an aged mouse model of MI compared with transplantation of AMSCs. In summary, our study shows that miR‐155‐5p mediates MSC senescence by regulating the Cab39/AMPK signaling pathway and miR‐155‐5p is a novel target to rejuvenate AMSCs and enhance their cardioprotective effects.     

Bone marrow mesenchymal stem cells for post-myocardial infarction cardiac repair: microRNAs as novel regulators

Transplantation of bone marrow-derived mesenchymal stem cells (MSCs) is safe and may improve cardiac function and structural remodelling in patients following myocardial infarction (MI). Cardiovascular cell differentiation and paracrine effects to promote endogenous cardiac regeneration, neovascularization, anti-inflammation, anti-apoptosis, anti-remodelling and cardiac contractility, may contribute to MSC-based cardiac repair following MI. However, current evidence indicates that the efficacy of MSC transplantation was unsatisfactory, due to the poor viability and massive death of the engrafted MSCs in the infarcted myocardium. MicroRNAs are short endogenous, conserved, non-coding RNAs and important regulators involved in numerous facets of cardiac pathophysiologic processes. There is an obvious involvement of microRNAs in almost every facet of putative repair mechanisms of MSC-based therapy in MI, such as stem cell differentiation, neovascularization, apoptosis, cardiac remodelling, cardiac contractility and arrhythmias, and others. It is proposed that therapeutic modulation of individual cardiovascular microRNA of MSCs, either mimicking or antagonizing microRNA actions, will hopefully enhance MSC therapeutic efficacy. In addition, MSCs may be manipulated to enhance functional microRNA expression or to inhibit aberrant microRNA levels in a paracrine manner. We hypothesize that microRNAs may be used as novel regulators in MSC-based therapy in MI and MSC transplantation by microRNA regulation may represent promising therapeutic strategy for MI patients in the future.     

Placenta-derived mesenchymal stem cells improve memory dysfunction in an Aβ1–42-infused mouse model of Alzheimer's disease

Mesenchymal stem cells (MSCs) promote functional recoveries in pathological experimental models of central nervous system (CNS) and are currently being tested in clinical trials for neurological disorders, but preventive mechanisms of placenta-derived MSCs (PD-MSCs) for Alzheimer''s disease are poorly understood. Herein, we investigated the inhibitory effect of PD-MSCs on neuronal cell death and memory impairment in Aβ_1–42-infused mice. After intracerebroventrical (ICV) infusion of Aβ_1–42 for 14 days, the cognitive function was assessed by the Morris water maze test and passive avoidance test. Our results showed that the transplantation of PD-MSCs into Aβ_1–42-infused mice significantly improved cognitive impairment, and behavioral changes attenuated the expression of APP, BACE1, and Aβ, as well as the activity of β-secretase and γ-secretase. In addition, the activation of glia cells and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were inhibited by the transplantation of PD-MSCs. Furthermore, we also found that PD-MSCs downregulated the release of inflammatory cytokines as well as prevented neuronal cell death and promoted neuronal cell differentiation from neuronal progenitor cells in Aβ_1–42-infused mice. These data indicate that PD-MSC mediates neuroprotection by regulating neuronal death, neurogenesis, glia cell activation in hippocampus, and altering cytokine expression, suggesting a close link between the therapeutic effects of MSCs and the damaged CNS in Alzheimer''s disease.     

Polydimethylsiloxane Films Modified with Chitosan/Pectin Multilayers as Scaffolds for Mesenchymal Stem Cells

Solid (smooth) and porous films of polydimethylsiloxane (PDMS) have been obtained; the effect of their structure on the adhesion of mesenchymal stem cells (MSCs) on their surface was found. It is shown that modification of these films with a (chitosan/pectin)₄ multilayer increased the efficiency of viable cell adhesion. A (3-aminopropyl)triethoxysilane–glutaraldehyde system was used to enhance the binding of the polysaccharide layer to the hydrophobic surface of PDMS. It was found that MSCs formed a monolayer culture of the fibroblast-like cells with high viability on porous PDMS modified with (chitosan/pectin)₄.     

Mesenchymal stem cells conditioned with glucose depletion augments their ability to repair-infarcted myocardium

Mesenchymal stem cells (MSCs) are an attractive candidate for autologous cell therapy, but their ability to repair damaged myocardium is severely compromised with advanced age. Development of viable autologous cell therapy for treatment of heart failure in the elderly requires the need to address MSC ageing. In this study, MSCs from young (2 months) and aged (24 months) C57BL/6 mice were characterized for gene expression of IGF‐1, FGF‐2, VEGF, SIRT‐1, AKT, p16^INK4a, p21 and p53 along with measurements of population doubling (PD), superoxide dismutase (SOD) activity and apoptosis. Aged MSCs displayed senescent features compared with cells isolated from young animals and therefore were pre‐conditioned with glucose depletion to enhance age affected function. Pre‐conditioning of aged MSCs led to an increase in expression of IGF‐1, AKT and SIRT‐1 concomitant with enhanced viability, proliferation and delayed senescence. To determine the myocardial repair capability of pre‐conditioned aged MSCs, myocardial infarction (MI) was induced in 24 months old C57BL/6 wild type mice and GFP expressing untreated and pre‐conditioned aged MSCs were transplanted. Hearts transplanted with pre‐conditioned aged MSCs showed increased expression of paracrine factors, such as IGF‐1, FGF‐2, VEGF and SDF‐1α. This was associated with significantly improved cardiac performance as measured by dp/dt_max, dp/dt_min, LVEDP and LVDP, declined left ventricle (LV) fibrosis and apoptosis as measured by Masson's Trichrome and TUNEL assays, respectively, after 30 days of transplantation. In conclusion, pre‐conditioning of aged MSCs with glucose depletion can enhance proliferation, delay senescence and restore the ability of aged cells to repair senescent infarcted myocardium.     

Activation of autophagy by FOXO3 regulates redox homeostasis during osteogenic differentiation

Bone remodeling is a continuous physiological process that requires constant generation of new osteoblasts from mesenchymal stem cells (MSCs). Differentiation of MSCs to osteoblast requires a metabolic switch from glycolysis to increased mitochondrial respiration to ensure the sufficient energy supply to complete this process. As a consequence of this increased mitochondrial metabolism, the levels of endogenous reactive oxygen species (ROS) rise. In the current study we analyzed the role of forkhead box O3 (FOXO3) in the control of ROS levels in human MSCs (hMSCs) during osteogenic differentiation. Treatment of hMSCs with H₂O₂ induced FOXO3 phosphorylation at Ser294 and nuclear translocation. This ROS-mediated activation of FOXO3 was dependent on mitogen-activated protein kinase 8 (MAPK8/JNK) activity. Upon FOXO3 downregulation, osteoblastic differentiation was impaired and hMSCs lost their ability to control elevated ROS levels. Our results also demonstrate that in response to elevated ROS levels, FOXO3 induces autophagy in hMSCs. In line with this, impairment of autophagy by autophagy-related 7 (ATG7) knockdown resulted in a reduced capacity of hMSCs to regulate elevated ROS levels, together with a reduced osteoblast differentiation. Taken together our findings are consistent with a model where in hMSCs, FOXO3 is required to induce autophagy and thereby reduce elevated ROS levels resulting from the increased mitochondrial respiration during osteoblast differentiation. These new molecular insights provide an important contribution to our better understanding of bone physiology.     

Autocrine fibroblast growth factor 2‐mediated interactions between human mesenchymal stem cells and the extracellular matrix under varying oxygen tension

Human mesenchymal stromal or stem cells (hMSCs) are being investigated for cell therapy in a wide range of diseases. MSCs are a potent source of trophic factors and actively remodel their immediate microenvironment through the secretion of bioactive factors in response to external stimuli such as oxygen tension. In this study, we examined the hypothesis that hypoxia influences hMSC properties in part through the regulation of extracellular milieu characterized by the extracellular matrix (ECM) matrices and the associated fibroblast growth factor‐2 (FGF‐2). The decellularized ECM matrices derived from hMSC culture under both hypoxic (e.g., 2% O₂) and the standard culture (e.g., 20% O₂) conditions have different binding capacities to the cell‐secreted and exogenenous FGF‐2. The reduced hMSC proliferation in the presence of FGF‐2 inhibitor and the differential capacity of the decellularized ECM matrices in regulating hMSC osteogeneic and adipogenic differentiation suggest an important role of the endogenous FGF‐2 in sustaining hMSC proliferation and regulating hMSC fate. Additionally, the combination of the ECM adhesion and hypoxic culture preserved hMSC viability under serum withdrawal. Together, the results suggest the synergistic effect of hypoxia and the ECM matrices in sustaining hMSC ex vivo expansion and preserving their multi‐potentiality and viability under nutrient depletion. The results have important implication in optimizing hMSC expansion and delivery strategies to obtain hMSCs in sufficient quantity with required potency and to enhance survival and function upon transplantation. J. Cell. Biochem. 114: 716–727, 2013. © 2012 Wiley Periodicals, Inc.     

Can the outcomes of mesenchymal stem cell‐based therapy for myocardial infarction be improved? Providing weapons and armour to cells

Use of mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI) has been found to have infarct‐limiting effects in numerous experimental and clinical studies. However, recent meta‐analyses of randomized clinical trials on MSC‐based MI therapy have highlighted the need for improving its efficacy. There are two principal approaches for increasing therapeutic effect of MSCs: (i) preventing massive MSC death in ischaemic tissue and (ii) increasing production of cardioreparative growth factors and cytokines with transplanted MSCs. In this review, we aim to integrate our current understanding of genetic approaches that are used for modification of MSCs to enable their improved survival, engraftment, integration, proliferation and differentiation in the ischaemic heart. Genetic modification of MSCs resulting in increased secretion of paracrine factors has also been discussed. In addition, data on MSC preconditioning with physical, chemical and pharmacological factors prior to transplantation are summarized. MSC seeding on three‐dimensional polymeric scaffolds facilitates formation of both intercellular connections and contacts between cells and the extracellular matrix, thereby enhancing cell viability and function. Use of genetic and non‐genetic approaches to modify MSC function holds great promise for regenerative therapy of myocardial ischaemic injury.     

Ascorbic acid inhibits senescence in mesenchymal stem cells through ROS and AKT/mTOR signaling

Mesenchymal stem cell (MSC) aging seriously affects its function in stem cell transplantation for treatment. Extensive studies have focused on how to inhibit senescence in MSCs. However, the mechanism of senescence in MSC was not clear. In this study, we used d-galactose to induce MSC aging. Then we found that the number of aging cells was increased compared with untreated MSCs. We discovered that ascorbic acid could inhibit the production of reactive oxygen species (ROS) and activation of AKT/mTOR signaling in MSCs caused by d-galactose. Especially, when treated together with a ROS scavenger or AKT inhibitor, the senescent cells were obviously decreased in d-galactose-induced MSCs. Taken together, we identify that ascorbic acid owns the potential to inhibit the senescence of MSCs through ROS and Akt/mTOR signaling. Together, our data supports that ascorbic acid can be used to prevent MSCs from senescence, which can enhance the efficiency of stem cell transplantation in the clinic.     

A Plant-Derived Remedy for Repair of Infarcted Heart

Background

Myocardial infarction (MI) due to coronary artery disease remains one of the leading causes of premature death. Replacement of infarcted heart tissue with regenerating myocardium from endogenous progenitor pools or exogenously introduced stem cells remains a therapeutic ideal. Their impracticality mainly lies in their low efficiency in cardiogenic differentiation (CD). Our recent studies with an acute MI animal model have already demonstrated the therapeutic effect of the MeOH extract of Geum japonicum (EGJ), providing clear evidence of myocardial regeneration.

Methods and Findings

The present study further isolated the active component contained in EGJ using bioassay-guided isolation and investigated its efficacy in the treatment of infarcted heart in animal MI models. We demonstrated that substantial repair of infarcted heart in animal MI models by EGJ can be mimicked by the isolated candidate compound (cardiogenin) in MI animal models. Clear evidence of newly regenerated endogenous mesenchymal stem cells (MSCs) derived cardiomyocytes was observed throughout the infarct zone, accompanied by significantly improved functional performance of the heart. Transplantation of MSCs pretreated with EGJ or cardiogenin into a MI animal model also resulted in substantial regeneration of functional myocardium, implying that the activated MSCs carry all the necessary blueprints for myocardial regeneration. Signaling pathways specific to cell survival, CD identified in embryonic heart induction and angiogenesis were activated in both cardiogenin-treated MSCs and cardiogenin-induced regenerating myocardium.

Conclusions

This study has demonstrated the therapeutic effects of cardiogenin in infarcted heart repair, and identified the associated signalling pathways for effective cardiogenic differentiation of MSCs, cell survival and angiogenesis. These findings should enable new treatment strategies for MI to be developed immediately.     

Erythropoietin augments the efficacy of therapeutic angiogenesis induced by allogenic bone marrow stromal cells in a rat model of limb ischemia

Transplantation of adult marrow stromal cells (MSCs) has been developed as a new method of treating severe ischemia diseases by therapeutic angiogenesis. Erythropoietin (EPO) is capable of inducing angiogenesis and inhibiting MSCs apoptosis. The effect of EPO on the therapeutic potency of MSCs transplantation in a rat model of limb ischemia was investigated in the current study. The results indicate that the combined treatment with MSC transplantation and EPO infusion is superior to MSC transplantation alone in the treatment of limb ischemia. MSCs transplantation and EPO infusion could enhance the angiogenic effect of each other to achieve a better therapeutic effect. This combination therapy may become a more effective approach for ischemia diseases of the limbs.     

The role of ABCG2 in maintaining the viability and proliferative activity of bone marrow mesenchymal stem cells in hypoxia

Hypoxia (5% O₂) and the basic fibroblast growth factor (bFGF) were shown to reduce the doubling time of bone marrow mesenchymal stem cells (MSCs) in vitro, indicating an increase in cell proliferation. In addition, abcg2 expression at both the mRNA and protein levels increased in MSCs that were exposed to hypoxia and bFGF. The two factors acting together potentiated the effects of hypoxia in MSCs. Blocking the functional activity of ABCG2 led to a higher production of reactive oxygen species (ROS) in MSCs. Hypoxia and bFGF were tested for effects on the MSC protein profile. These findings, combined with the published data, implicate ABCG2 expression and function in maintaining the viability and proliferative activity of MSCs that are cultured in hypoxia, with ABCG2 playing a protective role.     

Effects of hepatocyte growth factor overexpressed bone marrow‐derived mesenchymal stem cells on prevention from left ventricular remodelling and functional improvement in infarcted rat hearts

Bone marrow‐derived mesenchymal stem cells (BM‐MSCs ) transplantation has been reported to be a promising therapy for myocardial infarction (MI). However, low survival rate of BM‐MSCs in infarcted heart is one of the major limitations for the perspective clinical application. In this study, we aimed to investigate the effect of hepatocyte growth factor (HGF) on left ventricular function improvement of HGF gene‐modified BM‐MSCs (HGF‐MSCs) after its delivery into the infarcted rat hearts. BM‐MSCs were isolated with fibroblast‐like morphology and expressed CD44+CD29+CD90+/CD34‐CD45‐CD31‐CD11a. After 5‐azacytidine induction in vitro, 20%–30% of the cells were positively stained for desmin, cardiac‐specific cardiac troponin I and connexin‐43. Histological staining revealed that 2 weeks after MI is an optimal time point with decreased neutrophil infiltration and increased vascular number. Minimal infarct size and best haemodynamic analysis were also observed after cell injection at 2 weeks compared with that of 1 h, 1 week or 4 weeks. Echocardiogram confirmed that transplantation with HGF‐MSCs significantly improved left ventricular function compared with other groups in rat MI models. MSCs and HGF‐MSCslabelled with DAPI were detected 4 weeks after MI in the infarcted area. Decreased infarcted scar area and increased angiogenesis formation could be found in HGF‐MSCs group than in other groups as demonstrated by hematoxylin and eosin (H&E) staining and factor VIII staining. These results indicate that HGF‐MSCs transplantation could enhance the contractile function and attenuate left ventricular remodelling efficiently in rats with MI. Copyright © 2012 John Wiley & Sons, Ltd.     

Differential Redox Regulation of Ca2+ Signaling and Viability in Normal and Malignant Prostate Cells

In prostate cancer, reactive oxygen species (ROS) are elevated and Ca²⁺ signaling is impaired. Thus, several novel therapeutic strategies have been developed to target altered ROS and Ca²⁺ signaling pathways in prostate cancer. Here, we investigate alterations of intracellular Ca²⁺ and inhibition of cell viability caused by ROS in primary human prostate epithelial cells (hPECs) from healthy tissue and prostate cancer cell lines (LNCaP, DU145, and PC3). In hPECs, LNCaP and DU145 H₂O₂ induces an initial Ca²⁺ increase, which in prostate cancer cells is blocked at high concentrations of H₂O₂. Upon depletion of intracellular Ca²⁺ stores, store-operated Ca²⁺ entry (SOCE) is activated. SOCE channels can be formed by hexameric Orai1 channels; however, Orai1 can form heteromultimers with its homolog, Orai3. Since the redox sensor of Orai1 (Cys-195) is absent in Orai3, the Orai1/Orai3 ratio in T cells determines the redox sensitivity of SOCE and cell viability. In prostate cancer cells, SOCE is blocked at lower concentrations of H₂O₂ compared with hPECs. An analysis of data from hPECs, LNCaP, DU145, and PC3, as well as previously published data from naive and effector T_H cells, demonstrates a strong correlation between the Orai1/Orai3 ratio and the SOCE redox sensitivity and cell viability. Therefore, our data support the concept that store-operated Ca²⁺ channels in hPECs and prostate cancer cells are heteromeric Orai1/Orai3 channels with an increased Orai1/Orai3 ratio in cells derived from prostate cancer tumors. In addition, ROS-induced alterations in Ca²⁺ signaling in prostate cancer cells may contribute to the higher sensitivity of these cells to ROS.