Thrombospondin 2 (TSP2) can inhibit angiogenesis in vitro by limiting proliferation and inducing apoptosis of endothelial cells (ECs). TSP2 can also modulate the extracellular levels of gelatinases (matrix metalloproteases, MMPs) and potentially influence the remodeling of the extracellular matrix (ECM). Here, we tested the hypothesis that by regulating MMPs, TSP2 could alter EC-ECM interactions. By using a three-dimensional angiogenesis assay, we show that TSP2, but not TSP1, limited angiogenesis by decreasing gelatinolytic activity in situ. Furthermore, TSP2-null fibroblast-derived ECM, which contains irregular collagen fibrils, was more permissive for EC migration. Investigation of the role of TSP2 in physiological angiogenesis in vivo, using excision of the left femoral artery in both TSP2-null and wild-type mice, revealed that TSP2-null mice displayed accelerated recovery of blood flow. This increase was attributable, in part, to an enhanced arterial network in TSP2-null muscles of the upper limb. Angiogenesis in the lower limb was also increased and was associated with increased MMP-9 deposition and gelatinolytic activity. The observed changes correlated with the temporal expression of TSP2 in the ischemic muscle of wild-type mice. Taken together, our observations implicate the matrix-modulating activity of TSP2 as a mechanism by which physiological angiogenesis is inhibited. The thrombospondins (TSPs) are a small family of five, secreted, modular glycoproteins (TSPs 1 to 5), with diverse functions.1,2 TSP1 and TSP2 share a high degree of similarity and are thought to constitute a subfamily. TSP1 has been extensively studied and has been shown to be synthesized by a variety of cells and to interact with a number of receptors such as CD36, CD47, GPIIb/IIIa, heparan sulfate proteoglycan, low-density lipoprotein receptor-related protein (LRP), and several integrins.3 TSP2, has not been extensively studied, but because of its similarity to TSP1 it is believed that it can bind to the same receptors. 4,5 In fact, CD36, heparan sulfate proteoglycan, LRP, and ␣ V ␤3 have been shown to be receptors for TSP2. 6,7 TSPs have also been shown to interact with several extracellular matrix (ECM) proteins including collagen, fibrinogen, and fibronectin. 2,8 Recently, the very low-density lipoprotein receptor was shown to be a receptor for TSP1 and TSP2, and their interaction was shown to inhibit the division of microvascular endothelial cells (ECs). 9TSP1 was identified as the first endogenous inhibitor of angiogenesis.10 The anti-angiogenic activities of TSP1 and TSP2 have been the focus of rigorous investigation and numerous studies have implicated both proteins in the regulation of tumor angiogenesis.3,11-13 TSP1 and TSP2 have also been shown to have broad anti-angiogenic activities in in vivo and in vitro assays, and a down-regulation of TSP1 synthesis has been implicated in a number of pathological conditions that involve increased angiogenesis. Like TSP1, TSP2 can directly influence ECs by inhibiting basic fibroblast...

The exploitation of low-cost, stable, and highly active electrocatalysts based on earth-abundant metals for hydrogen evolution reaction (HER) is crucial for developing renewable energy techniques. In this work, we report a facile synthesis strategy for in-situ fabrication of 3D hierarchically porous Ni3S2 films on a nanoporous copper substrate (Ni3S2@NPC) by unusual galvanic replacement reaction in the Ethaline-based deep eutectic solvent (DES) under a normal atmosphere. The self-supported nanoporous Ni3S2@NPC electrode is binder-free and exhibits good structural integrity with high conductivity. A mild evolution of bulk gas bubbles (H2-O2 gas mixture) is proved to drive an in-situ structure rearrangement process of the Ni3S2@NPC and results in substantial increases in the HER activity. The activated Ni3S2@NPC (a-Ni3S2@NPC) electrode can serve as a highly efficient and stable electrocatalyst for the HER in water over a wide pH range. Significantly, it displays high-performance HER catalytic activity in acidic media with robust durability over 111 h and functions well under alkaline and neutral conditions. Such a superior catalytic performance of the a-Ni3S2@NPC is mainly due to the unique hierarchically nanoporous architectures and the synergetic effects in it caused by the restructuring NPC skeletons and active components. Our work offers a generic strategy for design and fabrication of many other self-supported transition metal sulfide and phosphide based HER electrocatalysts, and uncovers a new O2-induced electrochemical self-activation mechanism for improving the activity of catalysts.

Injury-and ischemia-induced angiogenesis is critical for tissue repair and requires nitric oxide (NO) derived from endothelial nitric oxide synthase (eNOS). We present evidence that NO induces angiogenesis by modulating the level of the angiogenesis inhibitor thrombospondin 2 (TSP2). TSP2 levels were higher than WT in eNOS KO tissues in hind-limb ischemia and cutaneous wounds. In vitro studies confirmed that NO represses TSP2 promoter activity. Moreover, double-eNOS/TSP2 KO mice were generated and found to rescue the phenotype of eNOS KO mice. Studies in mice with knock-in constitutively active or inactive eNOS on the Akt-1 KO background showed that eNOS activity correlates with TSP2 levels. Our observations of NO-mediated regulation of angiogenesis via the suppression of TSP2 expression provide a description of improved eNOS KO phenotype by means other than restoring NO signaling.wound healing | extracellular matrix | Akt | matrix metalloproteinases E ndothelial nitric oxide synthase (eNOS) and its bioactive product nitric oxide (NO) are well-established proangiogenic molecules. Endothelial-derived NO is crucial for maintenance of proper vasodilatory tone and regulation of an antiproliferative and antiapoptotic state for endothelial cells (ECs) and has essential roles in physiological angiogenesis (1-3). Pharmacological inhibition or genetic disruption of eNOS limited angiogenesis during tissue repair, resulting in delayed wound closure (2, 4). Addition of NO donors to wounds enhanced angiogenesis and accelerated healing (5-7). eNOS KO mice recovered poorly from hind-limb ischemia as a consequence of decreased angiogenesis (3,8). These mice also displayed accelerated atherosclerosis, neointimal thickening postinjury, and hypertension (1, 9). Taken together, these observations highlight the ability of eNOS-derived NO to influence vascular function.Thrombospondins (TSPs) are a small family of antiangiogenic matricellular proteins (10). TSPs enhance clearance of matrix metalloproteinase (MMP)-2 and MMP-9 (11-13) and interact with cell-surface receptors, including α v β 3 , very low density lipoprotein receptor (VLDLR), CD36, and CD47, to inhibit angiogenesis (14). Further, ultrastructural studies demonstrated that TSP2 influences ECM assembly (15, 16). TSP2 KO mice displayed improved recovery of blood flow following ischemia (17), altered foreign body response (18,19), and accelerated wound healing (16,20,21). In contrast, TSP1 KO mice displayed delayed healing because of insufficient stimulation of inflammation (13). Consistent with these observations, the expression of TSP1 and TSP2 in tissue repair was associated with the inflammatory and repair phases, respectively (13, 16). Recently, several studies linked components of the Akt-eNOS cascade with TSPs. Specifically, TSP1 has been described to blunt the ability of NO to activate soluble guanyl cyclase (sGC) (22, 23) through interactions with CD36 and CD47 during ischemia. TSP1 has also been described to diminish eNOS activity by blocking phosphorylation at S117...

(PB) S U M M A R Y Thrombospondin-2 (TSP2) is an inhibitor of angiogenesis with pro-apoptotic and anti-proliferative effects on endothelial cells. Mice deficient in this matricellular protein display improved recovery from ischemia and accelerated wound healing associated with alterations in angiogenesis and extracellular matrix remodeling. In this study, we probed the function of TSP2 by performing a detailed analysis of dermal wounds and woundderived fibroblasts. Specifically, we analyzed incisional wounds by tensiometry and found no differences in strength recovery between wild-type and TSP2-null mice. In addition, analysis of full-thickness excisional wounds by terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate nick-end labeling stain and MIB-5 immunohistochemistry revealed similar numbers of apoptotic and proliferating cells, respectively. In contrast, the levels of matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitors of metalloproteinase (TIMP)-1, TIMP-2, and soluble vascular endothelial growth factor were increased in wounds of TSP2-null mice. Evaluation of the ability of TSP2-null wound fibroblasts to contract collagen gels revealed that it was compromised, even though TSP2-null wounds displayed normal myofibroblast content. Therefore, we conclude that the lack of TSP2 leads to aberrant extracellular matrix remodeling, increased neovascularization, and reduced contraction due in part to elevated levels of MMP-2 and MMP-9. These observations provide in vivo supporting evidence for a newly proposed function of TSP2 as a modulator of extracellular matrix remodeling. (J Histochem Cytochem 57:301-313, 2009)

Self-supported porous Ni–Mo alloy microsphere (Ni–Mo MS) films are fabricated in ethaline via a facile, one-step electrodeposition approach, which can act as highly efficient and durable bifunctional catalysts for both the HER and OER in 1.0 M KOH.