Ion exchange membranes with high ionic conductivity and selectivity are indispensable for the operation of neutral aqueous organic redox flow batteries (NAORFBs). While ion exchange membranes based on microphase separation can enhance conductivity by enlarging the ionic cluster size, this can also lead to a considerable rise in the permeability of the active materials in NAORFBs. In this study, a series of anion exchange membranes were developed through the introduction of flexible segments into the polymer backbone. Atomic force microscopy analysis confirmed that the developed membranes exhibited similar ionic cluster sizes, while the conductivity increased significantly with the incorporation of flexible monomers. The optimal membrane (QPFEI-0.75) exhibits Cl-conductivity in excess of 30 mS cm-1 at room temperature. Combined with the Donnan effect, the permeability of TMAP-TEMPO in QPFEI-0.75 was determined to be 8.56 x 10-11 cm2 s-1, which confirms that the membrane has an excellent conductivity as well as a low permeation rate of the active materials. Upon assembling QPFEI-0.75 into a battery, it was observed that the battery exhibited remarkable stability, undergoing over 1000 complete charge and discharge cycles at 140 mA cm-2 without notable capacity degradation. Moreover, the energy efficiency of the battery remained consistently high at 62 % throughout the entire process. The findings substantiate the potential of the developed membranes in NAORFBs.

Advanced energy storage technologies are widely needed to efficiently utilize renewable energies such as solar and wind energy and satisfy burgeoning clean energy needs while mitigating the environmental impact of fossil fuels[1-4].Aqueous organic redox flow batteries(AORFBs)have drawn substantial attention in this area because of their decoupled energy and power,excellent scalability,and use of highly structurally tunable organic redox active species[5].As a result,a wide range of organic and organometallic redox active species have been extensively applied in acidic,neutral,and alkaline AORFBs[6].Compared to AORFBs,which operate under highly corrosive acidic or basic conditions and exhibit side reactions such as hydrogen and oxygen evolution,pH-neutral AORFBs are noncorrosive,safer,and exhibit high cycling stability due to the absence of these reactions[7].

Graphite felt is commonly used in redox flow batteries, but the low specific surface area and poor catalytic activity cause unsatisfactory mass transfer and reaction kinetics. Here, nitrogen‐doped vertical graphene is in‐situ grown on graphite felt via a metal‐free chemical vapor deposition method, which exhibits a high specific surface area and remarkable catalytic activity due to abundant exposed high‐density sharp graphene edges and nitrogen doping. Multiphysical simulations reveal that the vertical‐standing nanostructure promotes the accessibility of vanadium ions to electrode/electrolyte interfaces, effectively decreasing the mass transport resistance of active species. Density functional theory calculation evidence shows that nitrogen doping aids in the improvement of catalytic activity via boosting vanadium ions’ adsorption and redox. Consequently, the nitrogen‐doped vertical graphene/graphite felt electrode shows an energy efficiency of 87.1% at 200 mA cm −2 , significantly higher than that of pristine (65.9%) and air‐oxidize (73.1%) electrodes, an energy efficiency over 80.2% at 300 mA cm −2 during 1500 cycles, and a high‐peak power density of 1308.56 mW cm −2 , which are superior to previously reported carbon nanomaterial decorated electrodes for flow batteries. Significantly, the synthesis process only involves gas‐phase reactions without metal catalysts to avoid hydrogen evolution reactions. This work provides an exciting pathway for developing high‐performance electrodes for flow batteries.

One essential element of redox flow batteries (RFBs) is the flow field. Certain dead zones that cause local overpotentials and side effects are present in all conventional designs. To lessen the detrimental effects, a dead-zone-compensated design of flow field optimization is proposed. The proposed architecture allows for the detection of dead zones and their compensation on existing flow fields. Higher reactant concentrations and uniformity factors can be revealed in the 3D multiphysical simulation. The experiments also demonstrate that at an energy efficiency (EE) of 80%, the maximum current density of the novel flow field is 205 mA cm-2, which is much higher than the values for the previous ones (165 mA cm-2) and typical serpentine flow field (153 mA cm-2). Extensions of the design have successfully increased system EE (2.7 to 4.3%) for a variety of flow patterns. As a result, the proposed design is demonstrated to be a general method to support the functionality and application of RFBs.

Previously, we showed that extracellular matrices (ECMs), produced ex vivo by various types of stromal cells, direct bone marrow mesenchymal stem cells (BM-MSCs) in a tissue-specific manner and recapitulate physio-logic changes characteristic of the aging microenvironment. In particular, BM-MSCs obtained from elderly donors and cultured on ECM produced by young BM stromal cells showed improved quantity, quality and osteogenic differentiation. In the present study, we searched for matrix components that are required for a functional BM-MSC niche by comparing ECMs produced by BM stromal cells from "young" (<= 25 y/o) versus "elderly" (>= 60 y/o) donors. With increasing donor age, ECM fibrillar organization and mechanical integrity deteriorated, along with the ability to promote BM-MSC proliferation and responsiveness to growth factors. Proteomic analyses revealed that the matricellular protein, Cyr61/CCN1, was present in young, but undetect-able in elderly, BM-ECM. To assess the role of Cyr61 in the BM-MSC niche, we used genetic methods to down-regulate the incorporation of Cyr61 during production of young ECM and up-regulate its incorporation in elderly ECM. The results showed that Cyr61-depleted young ECM lost the ability to promote BM-MSC pro-liferation and growth factor responsiveness. However, up-regulating the incorporation of Cyr61 during synthe-sis of elderly ECM restored its ability to support BM-MSC responsiveness to osteogenic factors such as BMP-2 and IGF-1. We next examined aging bone and compared bone mineral density and Cyr61 content of L4-L5 vertebral bodies in "young" (9-11 m/o) and "elderly" (21-33 m/o) mice. Our analyses showed that low bone mineral density was associated with decreased amounts of Cyr61 in osseous tissue of elderly versus young mice. Our results strongly demonstrate a novel role for ECM-bound Cyr61 in the BM-MSC niche, where it is responsible for retention of BM-MSC proliferation and growth factor responsiveness, while depletion of Cyr61 from the BM niche contributes to an aging-related dysregulation of BM-MSCs. Our results also suggest new potential therapeutic targets for treating age-related bone loss by restoring specific ECM components to the stem cell niche. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Islet transplantation in man is limited by multiple factors including islet availability, islet cell damage caused by collagenase during isolation, maintenance of islet function between isolation and transplantation, and allograft rejection. In this study, we describe a new approach for preparing islets that enhances islet function in vitro and reduces immunogenicity. The approach involves culture on native decellularized 3D bone marrow-derived extracellular matrix (3D-ECM), which contains many of the matrix components present in pancreas, prior to islet transplantation. Compared to islets cultured on tissue culture plastic (TCP), islets cultured on 3D-ECM exhibited greater attachment, higher survival rate, increased insulin content, and enhanced glucose-stimulated insulin secretion. In addition, culture of islets on 3D-ECM promoted recovery of vascular endothelial cells within the islets and restored basement membrane-related proteins (eg, fibronectin and collagen type VI). More interestingly, culture on 3D-ECM also selectively decontaminated islets of "passenger" cells (co-isolated with the islets) and restored basement membrane-associated type VI collagen, which were associated with an attenuation in islet immunogenicity. These results demonstrate that this novel approach has promise for overcoming two major issues in human islet transplantation: (a) poor yield of islets from donated pancreas tissue and (b) the need for life-long immunosuppression.

Introduction Bone marrow-derived mesenchymal stem cells (BM-MSCs) for clinical use should not be grown in media containing fetal bovine serum (FBS), because of serum-related concerns over biosafety and batch-to-batch variability. Previously, we described the preparation and use of a cell-free native extracellular matrix (ECM) made by bone marrow cells (BM-ECM) which preserves stem cell properties and enhances proliferation. Here, we compare colony-forming ability and differentiation of MSCs cultured on BM-ECM with a commercially available matrix (CELLstart™) and tissue culture plastic (TCP) under serum-free conditions. Methods Primary MSCs from freshly isolated bone marrow-derived mononuclear cells or passaged MSCs (P1) were grown in serum-containing (SCM) or serum-free (SFM) media on BM-ECM, CELLstart™, or TCP substrates. Proliferation, cell composition (phenotype), colony-forming unit replication, and bone morphogenetic protein-2 (BMP-2) responsiveness were compared among cells maintained on the three substrates. Results Proliferation of primary BM-MSCs was significantly higher in SCM than SFM, irrespectively of culture substrate, suggesting that the expansion of these cells requires SCM. In contrast, passaged cells cultured on BM-ECM or CELLstart™ in SFM proliferated to nearly the same extent as cells in SCM. However, morphologically, those on BM-ECM were smaller and more aligned, slender, and long. Cells grown for 7 days on BM-ECM in SFM were 20–40 % more positive for MSC surface markers than cells cultured on CELLstart™. Cells cultured on TCP contained the smallest number of cells positive for MSC markers. MSC colony-forming ability in SFM, as measured by CFU-fibroblasts, was increased 10-, 9-, and 2-fold when P1 cells were cultured on BM-ECM, CELLstart™, and TCP, respectively. Significantly, CFU-adipocyte and -osteoblast replication of cells grown on BM-ECM was dramatically increased over those on CELLstart™ (2X) and TCP (4-7X). BM-MSCs, cultured in SFM and treated with BMP-2, retained their differentiation capacity better on BM-ECM than on either of the other two substrates. Conclusions Our findings indicate that BM-ECM provides a unique microenvironment that supports the colony-forming ability of MSCs in SFM and preserves their stem cell properties. The establishment of a robust culture system, combining native tissue-specific ECM and SFM, provides an avenue for preparing significant numbers of potent MSCs for cell-based therapies in patients.

The extracellular matrix (ECM) is a critical tissue component, providing structural support as well as important regulatory signaling cues to govern cellular growth, metabolism, and differentiation. The study of ECM proteins, however, is hampered by the low solubility of ECM components in common solubilizing reagents. ECM proteins are often not detected during proteomics analyses using unbiased approaches due to solubility issues and relatively low abundance compared to highly abundant cytoplasmic and mitochondrial proteins. Decellularization has become a common technique for ECM protein-enrichment and is frequently used in engineering studies. Solubilizing the ECM after decellularization for further proteomic examination has not been previously explored in depth. In this study, we describe testing of a series of protocols that enabled us to develop a novel optimized strategy for the enrichment and solubilization of ECM components. Following tissue decellularization, we use acid extraction and enzymatic deglycosylation to facilitate re-solubilization. The end result is the generation of three fractions for each sample: soluble components, cellular components, and an insoluble ECM fraction. These fractions, developed in mass spectrometry-compatible buffers, are amenable to proteomics analysis. The developed protocol allows identification (by mass spectrometry) and quantification (by mass spectrometry or immunoblotting) of ECM components in tissue samples.Biological significanceThe study of extracellular matrix (ECM) proteins in pathological and non-pathological conditions is often hampered by the low solubility of ECM components in common solubilizing reagents. Additionally, ECM proteins are often not detected during global proteomic analyses due to their relatively low abundance compared to highly abundant cytoplasmic and mitochondrial proteins. In this manuscript we describe testing of a series of protocols that enabled us to develop a final novel optimized strategy for the enrichment and solubilization of ECM components. The end result is the generation of three fractions for each sample: soluble components, cellular components, and an insoluble ECM fraction. By analysis of each independent fraction, differences in protein levels can be detected that in normal conditions would be masked. These fractions are amenable to mass spectrometry analysis to identify and quantify ECM components in tissue samples. The manuscript places a strong emphasis on the immediate practical relevance of the method, particularly when using mass spectrometry approaches; additionally, the optimized method was validated and compared to other methodologies described in the literature. (C) 2013 Elsevier B.V. All rights reserved.

Brain-derived neurotrophic factor (BDNF) increases in failing hearts, but BDNF roles in cardiac remodeling following myocardial infarction (MI) are unclear. Male BDNF(+/+) [wild-type (WT)] and BDNF(+/-) heterozygous (HET) mice at 6-9 mo of age were subjected to MI and evaluated at days 1, 3, 5, 7, or 28 post-MI. At day 28 post-MI, 76% of HET versus 40% of WT survived, whereas fractional shortening improved and neovascularization levels were reduced in the HET (all, P < 0.05). At day 1, post-MI, matrix metalloproteinase-9, and myeloperoxidase (MPO) increased in WT, but not in HET. Concomitantly, monocyte chemotactic protein-1 and -5 levels increased and vascular endothelial growth factor (VEGF)-A decreased in HET. Neutrophil infiltration peaked at days 1-3 in WT mice, and this increase was blunted in HET. To determine if MPO administration could rescue the HET phenotype, MPO was injected at 3 h post-MI. MPO restored VEGF-A levels without altering matrix metalloproteinase-9 or neutrophil content. In conclusion, reduced BDNF levels modulated the early inflammatory and neovascularization responses, leading to improved survival and reduced cardiac remodeling at day 28 post-MI. Thus reduced BDNF attenuates early inflammation following MI by modulating MPO and angiogenic response through VEGF-A.

Following myocardial infarction (MI), matrix metalloproteinase-9 (MMP-9) levels increase, and MMP-9 deletion improves post-MI remodeling of the left ventricle (LV). We provide here a technical report on plasma-analysis from wild type (WT) and MMP-9 null mice using fractionation and mass-spectrometry-based proteomics. MI was induced by coronary artery ligation in male WT and MMP-9 null mice (4–8 months old;n=3/genotype). Plasma was collected on days 0 (pre-) and 1 post-MI. Plasma proteins were fractionated and proteins in the lowest (fraction 1) and highest (fraction 12) molecular weight fractions were separated by 1-D SDS-PAGE, digested in-gel with trypsin and analyzed by HPLC-ESI-MS/MS on an Orbitrap Velos. We tried five different fractionation protocols, before reaching an optimized protocol that allowed us to identify over 100 proteins. Serum amyloid A substantially increased post-MI in both genotypes, while alpha-2 macroglobulin increased only in the null samples. In fraction 12, extracellular matrix proteins were observed only post-MI. Interestingly, fibronectin-1, a substrate of MMP-9, was identified at both day 0 and day 1 post-MI in the MMP-9 null mice but was only identified post-MI in the WT mice. In conclusion, plasma fractionation offers an improved depletion-free method to evaluate plasma changes following MI.

Post‐myocardial infarction (MI), proinflammatory macrophages secrete matrix metalloproteinase (MMP)‐9 to regulate the cardiac wound healing response. We hypothesized that overexpression of MMP‐9 in macrophages would amplify the inflammatory response to exacerbate left ventricular dysfunction post‐MI. Accordingly, we assessed function of the left ventricle (LV) in wild‐type mice (WT, n=16) and MMP‐9 macrophage‐specific transgenic mice (TG, n=28) at day 5 post‐MI. In response to similar infarct sizes of 49±2% for both WT and TG (p=0.9), LV ejection fraction was improved in the TG (25±2%) compared to the WT mice (18±2%; p<0.05). We also evaluated macrophage numbers by Mac‐3 and galectin‐3 levels and inflammatory cytokine gene expression. Despite a similar number of macrophages in both WT and TG, the expression of 23 inflammatory genes decreased in the infarct from the TG LV compared to WT LV (all p<0.05). Interestingly, SCYE1, a multifunctional cytokine involved in the regulation of inflammatory responses, was uniquely upregulated at baseline in TG (0.92±0.13 2−ΔCT units) compared to WT (0.52±0.07 units; p<0.05). SCYE1 levels decreased post‐MI in the TG (0.52±0.08 units) while WT levels doubled (1.02±0.16 units; p<0.05). The decrease in the TG levels of SCYE1 suggest that SCYE1 is a key MMP‐9 responsive regulator of the inflammatory response that follows MI.

Following myocardial infarction (MI), activated macrophages infiltrate into the necrotic myocardium as part of a robust pro-inflammatory response and secrete matrix metalloproteinase-9 (MMP-9). Macrophage activation, in turn, modulates the fibrotic response, in part by stimulating fibroblast extracellular matrix (ECM) synthesis. We hypothesized that overexpression of human MMP-9 in mouse macrophages would amplify the inflammatory and fibrotic responses to exacerbate left ventricular dysfunction. Unexpectedly, at day 5 post-MI, ejection fraction was improved in transgenic (TG) mice (25±2%) compared to the wild type (WT) mice (18±2%; p<0.05). By gene expression profiling, 23 of 84 inflammatory genes were decreased in the left ventricle infarct (LVI) region from the TG compared to WT mice (all p<0.05). Concomitantly, TG macrophages isolated from the LVI, as well as TG peritoneal macrophages stimulated with LPS, showed decreased inflammatory marker expression compared to WT macrophages. In agreement with attenuated inflammation, only 7 of 84 cell adhesion and ECM genes were increased in the TG LVI compared to WT LVI, while 43 genes were decreased (all p<0.05). These results reveal a novel role for macrophage-derived MMP-9 in blunting the inflammatory response and limiting ECM synthesis to improve left ventricular function post-MI.

We evaluated the left ventricle (LV) response to hypoxia by comparing male Sprague Dawley rats exposed for 7 days to normoxia (control; n =18), chronic sustained hypoxia (CSH; n =12) and chronic intermittent hypoxia (CIH; n =12). Out of the 168 inflammatory, extracellular matrix and adhesion molecule genes evaluated, Ltb , Cdh4 , Col5a1 , Ecm1 , MMP-11 and TIMP-2 increased in the LV (range: 87–138%), whereas Tnfrsf1a decreased 27%, indicating an increase in inflammatory status with CSH (all P <0.05). CIH decreased Ltb , Spp1 and Ccl5 levels, indicating reduced inflammatory status. While Laminin β2 gene levels increased 123%, MMP-9 and fibronectin gene levels both decreased 74% in CIH (all P <0.05). Right ventricle/body weight ratios increased in CSH (1.1±0.1 g g −1 ) compared with control (0.7±0.1 g g −1 ) and CIH (0.8±0.1 g g −1 ; both P <0.05). Lung to body weight increased in CSH, while LV/body weight ratios were similar among all three groups. With CIH, myocyte cross sectional areas increased 25% and perivascular fibrosis increased 100% (both P <0.05). Gene changes were independent of global changes and were validated by protein levels. MMP-9 protein levels decreased 94% and fibronectin protein levels decreased 42% in CIH (both P <0.05). Consistent with a decreased inflammatory status, HIF-2α and eNOS protein levels were 36% and 44% decreased, respectively, in CIH (both P <0.05). In conclusion, our results indicate that following 7 days of hypoxia, inflammation increases in response to CSH and decreases in response to CIH. This report is the first to demonstrate specific and differential changes seen in the LV during chronic sustained and CIH.

AIMS Age-related diastolic dysfunction has been attributed to an increased passive stiffness, which is regulated by extracellular matrix (ECM). We recently showed that matrix metalloproteinase (MMP)-9, an ECM mediator, increases in the left ventricle (LV) with age. The aim of this study, accordingly, was to determine the role of MMP-9 in cardiac ageing. METHODS AND RESULTS We compared LV function in young (6-9 months), middle-aged (12-15 months), old (18-24 months) and senescent (26-34 months) wild-type (WT) and MMP-9 null mice (n ≥ 12/group). All groups had similar fractional shortenings and aortic peak velocities, indicating that systolic function was not altered by ageing or MMP-9 deletion. The mitral ratios of early to late diastolic filling velocities were reduced in old and senescent WT compared with young controls, and this reduction was attenuated in MMP-9 null mice. Concomitantly, the increase in LV collagen content was reduced in MMP-9 null mice (n = 5-6/group). To dissect the mechanisms of these changes, we evaluated the mRNA expression levels of 84 ECM and adhesion molecules by real-time qPCR (n = 6/group). The expression of pro-fibrotic periostin and connective tissue growth factor (CTGF) increased with senescence, as did transforming growth factor-β (TGF-β)-induced protein levels and Smad signalling, and these increases were blunted by MMP-9 deletion. In senescence, MMP-9 deletion also resulted in a compensatory increase in MMP-8. CONCLUSION MMP-9 deletion attenuates the age-related decline in diastolic function, in part by reducing TGF-β signalling-induced periostin and CTGF expression and increasing MMP-8 expression to regulate myocardial collagen turnover and deposition.