Background Exosomes play an important role in intercellular signaling and exert regulatory function by carrying bioactive molecules. This study investigated the cardioprotective capabilities of exosomes derived from mesenchymal stem cells (MSC) overexpressing GATA-4 (MSCGATA-4) and its underlying mechanisms through delivering miroRNAs (miRs) to regulate the target proteins in recipient cells. Methods and Results Exosomes were isolated and purified from MSCGATA-4 (ExoGATA-4) and control MSCs (ExoNull). Cell injury was investigated in primary cultured rat neonatal cardiomyocytes (CM) and in the rat heart. Exosomes contributed to increased CM survival, reduced CM apoptosis, and preserved mitochondrial membrane potential in CM cultured under a hypoxic environment. Direct intramyocardial transplantation of exosomes at the border of an ischemic region following ligation of the left anterior descending coronary artery significantly restored cardiac contractile function and reduced infarct size. Real-time PCR revealed that several anti-apoptotic miRs were highly expressed in ExoGATA-4. Rapid internalization of ExoGATA-4 by CM was documented using time-lapse imaging. Subsequent expression of these miRs, particularly miR-19a was higher in CM and in the myocardium treated with ExoGATA-4 compared to those treated with ExoNull. The enhanced protective effects observed in CM were diminished by inhibition of miR-19a. The expression level of PTEN, a predicted target of miR-19a, was reduced in CM treated with ExoGATA-4, which resulted in the activation of the Akt and ERK signaling pathways. Conclusions ExoGATA-4 transferred miRs into damaged CM, triggering activation of the cell survival signaling pathway.

Zerumbone (ZER), a sesquiterpene from the edible plantZingiber zerumbet Smith, has recently been found to suppress tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Epstein-Barr virus activation in a potent manner. In the present study, we evaluated the antiinflammatory and chemopreventive potentials of ZER in a variety of cell culture experiments. ZER effectively suppressed TPA-induced superoxide anion generation from both NADPH oxidase in dimethylsulfoxide-differentiated HL-60 human acute promyelocytic leukemia cells and xanthine oxidase in AS52 Chinese hamster ovary cells. The combined lipopolysaccharide-and interferon-γ-stimulated protein expressions of inducible nitric oxide synthase and cyclooxygenase (COX)-2, together with the release of tumor necrosis factor-α, in RAW 264.7 mouse macrophages were also markedly diminished. These suppressive events were accompanied with a combined decrease in the medium concentrations of nitrite and prostaglandin E 2 , while the expression level of COX-1 was unchanged. ZER inhibited the proliferation of human colonic adenocarcinoma cell lines (LS174T, LS180, COLO205, and COLO320DM) in a dose-dependent manner, while the growth of normal human dermal (2F0-C25) and colon (CCD-18 Co) fibroblasts was less affected. It also induced apoptosis in COLO205 cells, as detected by dysfunction of the mitochondria transmembrane, Annexin V-detected translocation of phosphatidylserine, and chromatin condensation. Intriguingly, α-humulene, a structural analog lacking only the carbonyl Abbreviations: AP, allopurinol; COX, cyclooxygenase; DMEM, Dulbecco's modified Eagle medium; DMSO, dimethylsulfoxide; DPI, diphenyleneiodonium; EBV, Epstein-Barr virus; FBS, fetal bovine serum; FITC, fluorescence isothiocyanate; HUM, α-humulene; IFN, interferon; iNOS, inducible NO; synthase; IR, inhibitory rate; LPS, lipopolysaccharide; MEM, minimum essential medium; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; NF-ΦB, nuclear factor-kappaB; NO, nitric oxide; NO 2 -, nitrite; O 2 -, superoxide anion; PBS, phosphate-buffered saline; PG, prostaglandin; PI, propiodium iodide; PS, phosphatidylserine; TNF, tumor necrosis factor; TPA, 12-O-tetradecanoylphorbol-13-acetate; XO, xanthine oxidase; ZER, zerumbone.© Oxford University Press 795 group in ZER, was virtually inactive in all experiments conducted, indicating that the α,β-unsaturated carbonyl group in ZER may play some pivotal roles in interactions with unidentified target molecule(s). Taken together, our results indicate that ZER is a food phytochemical that has distinct potentials for use in anti-inflammation, chemoprevention, and chemotherapy strategies.

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Taurine is an abundant, β-amino acid with diverse cytoprotective activity. In some species, taurine is an essential nutrient but in man it is considered a semi-essential nutrient, although cells lacking taurine show major pathology. These findings have spurred interest in the potential use of taurine as a therapeutic agent. The discovery that taurine is an effective therapy against congestive heart failure led to the study of taurine as a therapeutic agent against other disease conditions. Today, taurine has been approved for the treatment of congestive heart failure in Japan and shows promise in the treatment of several other diseases. The present review summarizes studies supporting a role of taurine in the treatment of diseases of muscle, the central nervous system, and the cardiovascular system. In addition, taurine is extremely effective in the treatment of the mitochondrial disease, mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), and offers a new approach for the treatment of metabolic diseases, such as diabetes, and inflammatory diseases, such as arthritis. The review also addresses the functions of taurine (regulation of antioxidation, energy metabolism, gene expression, ER stress, neuromodulation, quality control and calcium homeostasis) underlying these therapeutic actions.

Abstract-Bone marrow (BM) is the major reservoir for endothelial progenitor cells (EPCs). Postnatal neovascularization depends on not only angiogenesis but also vasculogenesis, which is mediated through mobilization of EPCs from BM and their recruitment to the ischemic sites. Reactive oxygen species (ROS) derived from Nox2-based NADPH oxidase play an important role in postnatal neovascularization; however, their role in BM and EPC function is unknown. Here we show that hindlimb ischemia of mice significantly increases Nox2 expression and ROS production in BMmononuclear cells (BMCs), which is associated with an increase in circulating EPC-like cells. Mice lacking Nox2 show reduction of ischemia-induced flow recovery, ROS levels in BMCs, as well as EPC mobilization from BM. Transplantation of wild-type (WT)-BM into Nox2-deficient mice rescues the defective neovascularization, whereas WT mice transplanted with Nox2-deficient BM show reduced flow recovery and capillary density compared to WT-BM transplanted control. Intravenous infusion of WT-and Nox2-deficient BMCs into WT mice reveals that neovascularization and homing capacity are impaired in Nox2-deficient BMCs in vivo. In vitro, Nox2-deficient c-kit ϩ Lin Ϫ BM stem/progenitor cells show impaired chemotaxis and invasion as well as polarization of actins in response to stromal derived factor (SDF), which is associated with blunted SDF-1-mediated phosphorylation of Akt. In conclusion, Nox2-derived ROS in BM play a critical role in mobilization, homing, and angiogenic capacity of EPCs and BM stem/progenitor cells, thereby promoting revascularization of ischemic tissue. Thus, NADPH oxidase in BM and EPCs is potential therapeutic targets for promoting neovascularization in ischemic cardiovascular diseases. (Circ Res. 2008;103:212-220.)

Abstract-We previously found that angiotensin II-induced hypertension increases vascular extracellular superoxide dismutase (ecSOD), and proposed that this is a compensatory mechanism that blunts the hypertensive response and preserves endothelium-dependent vasodilatation. To test this hypothesis, we studied ecSOD-deficient mice. ecSODand C57Blk/6 mice had similar blood pressure at baseline; however, the hypertension caused by angiotensin II was greater in ecSOD Ϫ/Ϫ compared with wild-type mice (168 versus 147 mm Hg, respectively; PϽ0.01). In keeping with this, angiotensin II increased superoxide and reduced endothelium-dependent vasodilatation in small mesenteric arterioles to a greater extent in ecSOD Ϫ/Ϫ than in wild-type mice. In contrast to these findings in resistance vessels, angiotensin II paradoxically improved endothelium-dependent vasodilatation, reduced intracellular and extracellular superoxide, and increased NO production in aortas of ecSOD Ϫ/Ϫ mice. Whereas aortic expression of endothelial NO synthase, Cu/ZnSOD, and MnSOD were not altered in ecSOD Ϫ/Ϫ mice, the activity of Cu/ZnSOD was increased by 80% after angiotensin II infusion. This was associated with a concomitant increase in expression of the copper chaperone for Cu/ZnSOD in the aorta but not in the mesenteric arteries. Moreover, the angiotensin II-induced increase in aortic reduced nicotinamide-adenine dinucleotide phosphate oxidase activity was diminished in ecSOD Ϫ/Ϫ mice as compared with controls. Thus, during angiotensin II infusion, ecSOD reduces hypertension, minimizes vascular superoxide production, and preserves endothelial function in resistance arterioles. We also identified novel compensatory mechanisms involving upregulation of copper chaperone for Cu/ZnSOD, increased Cu/ZnSOD activity, and decreased reduced nicotinamide-adenine dinucleotide phosphate oxidase activity in larger vessels. These compensatory mechanisms preserve large vessel function when ecSOD is absent in hypertension. , which, in turn, leads to inactivation of NO-altering endothelium-dependent vasodilatation. 1 In some models, such as angiotensin II-induced hypertension and in the spontaneously hypertensive rat, membrane-targeted forms of superoxide dismutase (SOD) and SOD mimetics lower blood pressure suggesting that the oxidative inactivation of NO contributes to blood pressure elevation. 2-4 Increased production of O 2 ⅐Ϫ in kidneys and circumventricular organs of the central nervous system also contributes to the hypertension caused by angiotensin II. 5,6 A major antioxidant mechanism against O 2 ⅐Ϫ is the SODs, including the cytosolic Cu/ZnSOD (SOD1), the mitochondrial MnSOD (SOD2), and the extracellular superoxide dismutase (ecSOD or SOD3). 7 In most tissues, ecSOD is present in small amounts, however, in vascular tissues ecSOD represents 30% to 50% of total SOD. 8 We have shown previously that angiotensin II increases ecSOD expression in mice and human vascular smooth muscle cells. 9 One consequence of this increase in ecSOD might be a blunting of hypert...

Abstract-Vascular endothelial growth factor (VEGF) binding induces phosphorylation of VEGF receptor (VEGFR)2 in tyrosine, which is followed by disruption of VE-cadherin-mediated cell-cell contacts of endothelial cells (ECs), thereby stimulating EC proliferation and migration to promote angiogenesis. Tyrosine phosphorylation events are controlled by the balance of activation of protein tyrosine kinases and protein tyrosine phosphatases (PTPs). Little is known about the role of endogenous PTPs in VEGF signaling in ECs. In this study, we found that PTP1B expression and activity are markedly increased in mice hindlimb ischemia model of angiogenesis. In ECs, overexpression of PTP1B, but not catalytically inactive mutant PTP1B-C/S, inhibits VEGF-induced phosphorylation of VEGFR2 and extracellular signal-regulated kinase 1/2, as well as EC proliferation, whereas knockdown of PTP1B by small interfering RNA enhances these responses, suggesting that PTP1B negatively regulates VEGFR2 signaling in ECs. VEGF-induced p38 mitogen-activated protein kinase phosphorylation and EC migration are not affected by PTP1B overexpression or knockdown. In vivo dephosphorylation and cotransfection assays reveal that PTP1B binds to VEGFR2 cytoplasmic domain in vivo and directly dephosphorylates activated VEGFR2 immunoprecipitates from human umbilical vein endothelial cells. Overexpression of PTP1B stabilizes VE-cadherin-mediated cell-cell adhesions by reducing VE-cadherin tyrosine phosphorylation, whereas PTP1B small interfering RNA causes opposite effects with increasing endothelial permeability, as measured by transendothelial electric resistance. In summary, PTP1B negatively regulates VEGFR2 receptor activation via binding to the VEGFR2, as well as stabilizes cell-cell adhesions through reducing tyrosine phosphorylation of VE-cadherin. Induction of PTP1B by hindlimb ischemia may represent an important counterregulatory mechanism that blunts overactivation of VEGFR2 during angiogenesis in vivo. (Circ Res. 2008;102:1182-1191.)Key Words: protein tyrosine phosphatase 1B Ⅲ vascular endothelial growth factor Ⅲ endothelial cell Ⅲ cell-cell adhesions Ⅲ angiogenesis

Background and Objective. Exosomes secreted from mesenchymal stem cells (MSC) have demonstrated cardioprotective effects. This study examined the role of exosomes derived from MSC overexpressing CXCR4 for recovery of cardiac functions after myocardial infarction (MI). Methods. In vitro, exosomes from MSC transduced with lentiviral CXCR4 (ExoCR4) encoding a silencing sequence or null vector were isolated and characterized by transmission electron microscopy and dynamic light scattering. Gene expression was then analyzed by qPCR and Western blotting. Cytoprotective effects on cardiomyocytes were evaluated and effects of exosomes on angiogenesis analyzed. In vivo, an exosome-pretreated MSC-sheet was implanted into a region of scarred myocardium in a rat MI model. Angiogenesis, infarct size, and cardiac functions were then analyzed. Results. In vitro, ExoCR4 significantly upregulated IGF-1α and pAkt levels and downregulated active caspase 3 level in cardiomyocytes. ExoCR4 also enhanced VEGF expression and vessel formation. However, effects of ExoCR4 were abolished by an Akt inhibitor or CXCR4 knockdown. In vivo, ExoCR4 treated MSC-sheet implantation promoted cardiac functional restoration by increasing angiogenesis, reducing infarct size, and improving cardiac remodeling. Conclusions. This study reveals a novel role of exosomes derived from MSCCR4 and highlights a new mechanism of intercellular mediation of stem cells for MI treatment.