sphingosine-1-phosphate and Ischemia

The damage of the endothelial glycocalyx as a consequence of ischemia and/or reperfusion injury (IRI) following kidney transplantation has come at the spotlight of research due to potential associations with delayed graft function, acute rejection as well as long-term allograft dysfunction. The disintegration of the endothelial glycocalyx induced by IRI is the crucial event which exposes the denuded endothelial cells to further inflammatory and oxidative damage. The aim of our review is to present the currently available data regarding complex links between shedding of the glycocalyx components, like syndecan-1, hyaluronan, heparan sulphate, and CD44 with the activation of intricate immune system responses, including toll-like receptors, cytokines and pro-inflammatory transcription factors. Evidence on modes of protection of the endothelial glycocalyx and subsequently maintenance of endothelial permeability as well as novel nephroprotective molecules such as sphingosine-1 phosphate (S1P), are also depicted. Although advances in technology are making the visualization and the analysis of the endothelial glycocalyx possible, currently available evidence is mostly experimental. Ongoing progress in understanding the complex impact of IRI on the endothelial glycocalyx, opens up a new era of research in the field of organ transplantation and clinical studies are of utmost importance for the future.

Topics: Endothelium; Glycocalyx; Heparitin Sulfate; Humans; Hyaluronic Acid; Ischemia; Kidney; Kidney Transplantation; Lysophospholipids; Reperfusion Injury; Sphingosine

Ischemia and reperfusion injury is a complex hemodynamic pathological phenomenon that engages the metabolic to inflammatory machinery in development of disease conditions like heart failure, stroke and acute kidney failure. Target specific therapeutic approaches for ischemia reperfusion injury remains critical despite the extensive studies contributing to the understanding of its pathogenesis. Ischemic or pharmacological conditionings have been long established manipulations to harness the endogenous protective mechanisms against ischemia reperfusion injury that fostered the development of potential therapeutic targets such as sphingolipids signaling. Sphingosine 1-phosphate has been emerged as a crucial metabolite of sphingolipids to regulate the cell survival, vascular integrity and inflammatory cascades in ischemia reperfusion injury. Sphingosine 1-phosphate signaling process has been implicated to downgrade the mitochondrial dysfunction, apoptotic assembly along with upregulation of RISK and SAFE pro-survival pathways. It also regulates the endothelial dysfunction and immune cells behavior to control the vascular permeability and immune cells infiltration at ischemia reperfusion injury site. Targeting the signaling of this single moiety holds the vast potential to extensively influence the detrimental signaling of ischemia reperfusion injury. This review highlights the role and significance of S1P signaling that can be therapeutically exploit to treat ischemia reperfusion injury mediated pathological conditions in different organs.

Topics: Animals; Brain; Humans; Ischemia; Kidney; Lysophospholipids; Reperfusion Injury; Signal Transduction; Sphingosine

The plasma lysophospholipid mediator sphingosine-1-phosphate (S1P) is produced exclusively by sphingosine kinase (SPHK) 1 and SPHK2 in vivo, and plays diverse biological and pathophysiological roles by acting largely through three members of the G protein-coupled S1P receptors, S1P1, S1P2 and S1P3. S1P1 expressed on endothelial cells mediates embryonic vascular maturation and maintains vascular integrity by contributing to eNOS activation, inhibiting vascular permeability and inducing endothelial cell chemotaxis via Gi-coupled mechanisms. By contrast, S1P2, is expressed in high levels on vascular smooth muscle cells (VSMCs) and certain types of tumor cells, inhibiting Rac and cell migration via a G(12/13)-and Rho-dependent mechanism. In rat neointimal VSMCs, S1P1 is upregulated to mediate local production of platelet-derived growth factor, which is a key player in vascular remodeling. S1P3 expressed on endothelial cells also mediates chemotaxis toward S1P and vasorelaxation via NO production in certain vascular bed, playing protective roles for vascular integrity. S1P3 expressed on VSMCs and cardiac sinoatrial node cells mediates vasopressor and negative chronotropic effect, respectively. In addition, S1P3, together with S1P2 and SPHK1, is suggested to play a protective role against acute myocardial ischemia. However, our recent work indicates that overexpressed SPHK1 is involved in cardiomyocyte degeneration and fibrosis in vivo, in part through S1P activation of the S1P3 signaling. We also demonstrated that exogenously administered S1P accelerates neovascularization and blood flow recovery in ischemic limbs, suggesting its usefulness for angiogenic therapy. These results provide evidence for S1P receptor subtype-specific pharmacological intervention as a novel therapeutic approach to cardiovascular diseases and cancer.

Topics: Animals; Cardiovascular System; Humans; Ischemia; Lysophospholipids; Muscle, Smooth; Receptors, Lysosphingolipid; Signal Transduction; Sphingosine

Considerable attention has focused on identifying mediators of neovascularization at sites of growth and abnormal tissue development. By contrast, mediators of angiogenesis at sites of injury and wound repair are not well defined but factors generated during blood coagulation (haemostasis) are attractive candidates. In addition to proteins generated, activated and released during the activation of clotting cascades, platelet-derived lipid mediators are now known to play a key role in many aspects of the angiogenic response. The first indication of lipid mediator involvement in angiogenesis was the discovery that lysophosphatidate (LPA), phosphatidic acid (PA) and sphingosine 1-phosphate (SPP) are high affinity agonists for G-protein coupled EDG (endothelial differentiation gene) receptors. The prototype for this family, EDG-1, was cloned from genes expressed when endothelial cells were activated to assume an angiogenic phenotype in vitro. The subsequent finding that SPP is a high affinity ligand for EDG-1 led Spiegel, Hla and associates (Lee et al., Science 1998;279:1552-1555) to hypothesize that platelet-released phospholipids play an important role in angiogenesis. These investigators and others demonstrated that SPP, LPA and phosphatidate (PA) induce many important endothelial cell responses associated with angiogenesis, including liberation of endothelial cells from established monolayers, chemotactic migration, proliferation, adherens junction assembly and morphogenesis into capillary-like structures. Although these studies indicated the potential involvement of platelet-derived phospholipids in angiogenesis, their physiological importance was not established. However, recent work demonstrates that >80% of the potent endothelial cell chemoattractive activity generated in human serum during clotting--an activity necessary for optimal angiogenesis--results from platelet-derived SPP. Other factors released from platelets during clotting, including LPA and PA, exert profound effects on endothelial cells that contribute unique aspects to the angiogenic response. These combined studies establish that SPP and other platelet-derived lipid mediators provide a novel link between haemostasis and angiogenesis.

Topics: Apoptosis; Blood Platelets; Chemotaxis; Endothelium, Vascular; Growth Substances; Hemostasis; Humans; Ischemia; Lysophospholipids; Neovascularization, Physiologic; Phospholipids; Phosphotransferases (Alcohol Group Acceptor); Signal Transduction; Sphingosine; Wound Healing

Sphingosine 1-phosphate (S1P) and S1P receptors (S1PR) regulate many cellular processes, including lymphocyte migration and endothelial barrier function. As neutrophils are major mediators of inflammation, their transendothelial migration may be the target of therapeutic approaches to inflammatory conditions such as ischaemia-reperfusion injury (IRI). The aim of this project was to assess whether these therapeutic effects are mediated by S1P acting on neutrophils directly or indirectly through the endothelial cells. First, our murine model of peritoneum cell recruitment demonstrated the ability of S1P to reduce CXCL8-mediated neutrophil recruitment. Mechanistic in vitro studies revealed that S1P signals in neutrophils mainly through the S1PR1 and 4 receptors and induces phosphorylation of ERK1/2; however, this had no effect on neutrophil transmigration and adhesion. S1P treatment of endothelial cells significantly reduced TNF-α-induced neutrophil adhesion under flow (

Topics: Animals; Endothelial Cells; Immunologic Factors; Ischemia; Lysophospholipids; Mice; Receptors, Lysosphingolipid; Reperfusion; Sphingosine; Sphingosine-1-Phosphate Receptors

Nonalcoholic fatty liver (NAFL) is emerging as a leading risk factor of hepatic ischemia/reperfusion (I/R) injury lacking of effective therapy. Lipid dyshomeostasis has been implicated in the hepatopathy of NAFL. Herein, we investigate the bioactive lipids that critically regulate I/R injury in NAFL.. Lipidomics were performed to identify dysregulated lipids in mouse and human NAFL with I/R injury. The alteration of corresponding lipid-metabolizing genes was examined. The effects of the dysregulated lipid metabolism on I/R injury in NAFL were evaluated in mice and primary hepatocytes.. Sphingolipid metabolic pathways responsible for the generation of sphingosine-1-phosphate (S1P) were uncovered to be substantially activated by I/R in mouse NAFL. Sphingosine kinase 1 (Sphk1) was found to be essential for hepatic S1P generation in response to I/R in hepatocytes of NAFL mice. Sphk1 knockdown inhibited the hepatic S1P rise while accumulating ceramides in hepatocytes of NAFL mice, leading to aggressive hepatic I/R injury with upregulation of oxidative stress and increase of reactive oxygen species (ROS). In contrast, administration of exogenous S1P protected hepatocytes of NAFL mice from hepatic I/R injury. Clinical study revealed a significant activation of S1P generation by I/R in liver specimens of NAFL patients. In vitro studies on the L02 human hepatocytes consolidated that inhibiting the generation of S1P by knocking down SPHK1 exaggerated I/R-induced damage and oxidative stress in human hepatocytes of NAFL.. Generation of S1P by SPHK1 is important for protecting NAFL from I/R injury, which may serve as therapeutic targets for hepatic I/R injury in NAFL.

Topics: Animals; Hepatocytes; Humans; Ischemia; Lysophospholipids; Mice; Non-alcoholic Fatty Liver Disease; Phosphotransferases (Alcohol Group Acceptor); Reactive Oxygen Species; Reperfusion Injury; Signal Transduction; Sphingosine

Berberine exerts neuroprotective and modulates hypoxia inducible factor-1-alpha (HIF-1[Formula: see text]. Based on the role of HIF-1[Formula: see text] in hypoxia preconditioning and association between HIF-1[Formula: see text] and sphingosine-1-phosphate (S1P), we hypothesized that berberine preconditioning (BP) would ameliorate the cerebral injury induced by ischemia through activating the system of HIF-1[Formula: see text] and S1P. Adult male rats with middle cerebral artery occlusion (MCAO) and rat primary cortical neurons treated with oxygen and glucose deprivation (OGD) with BP at 24[Formula: see text]h (40[Formula: see text]mg/kg) and 2[Formula: see text]h (10[Formula: see text][Formula: see text]mol/L), respectively, were used to determine the neuroprotective effects. The HIF-1[Formula: see text] accumulation, and S1P metabolism were assayed in the berberine-preconditioned neurons, and the HIF-1[Formula: see text]-mediated transcriptional modulation of sphingosine kinases (Sphk) 1 and 2 was analyzed using chromatin immunoprecipitation and real-time polymerase chain reaction. BP significantly prevented cerebral ischemic injury in the MCAO rats at 24[Formula: see text]h and 72[Formula: see text]h following ischemia/reperfusion. In OGD-treated neurons, BP enhanced HIF-1[Formula: see text] accumulation with activation of PI3K/Akt, and induced S1P production by activating Sphk2 via the promotion of HIF-1[Formula: see text]-mediated Sphk2 transcription. In conclusion, BP activated endogenous neuroprotective mechanisms associated with the S1P/HIF-1 pathway and helped protect neuronal cells against hypoxia/ischemia.

Topics: Animals; Berberine; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Ischemia; Lysophospholipids; Male; Neurons; Neuroprotective Agents; Phosphotransferases (Alcohol Group Acceptor); Rats; Rats, Sprague-Dawley; Sphingosine

Steatosis is a risk factor in partial hepatectomy (PH) under ischaemia-reperfusion (I/R), which is commonly applied in clinical practice to reduce bleeding. Nutritional support strategies, as well as the role of peripheral adipose tissue as energy source for liver regeneration, remain poorly investigated.. To investigate whether the administration of either glucose or a lipid emulsion could protect steatotic and non-steatotic livers against damage and regenerative failure in an experimental model of PH under I/R. The relevance of peripheral adipose tissue in liver regeneration following surgery is studied.. Steatotic and non-steatotic rat livers were subjected to surgery and the effects of either glucose or lipid treatment on damage and regeneration, and part of the underlying mechanisms, were investigated.. In non-steatotic livers, treatment with lipids or glucose provided the same protection against damage, regeneration failure and ATP drop. Adipose tissue was not required to regenerate non-steatotic livers. In the presence of hepatic steatosis, lipid treatment, but not glucose, protected against damage and regenerative failure by induction of cell cycle, maintenance of ATP levels and elevation of sphingosine-1-phosphate/ceramide ratio and phospholipid levels. Peripheral adipose tissue was required for regenerating the steatotic liver but it was not used as an energy source.. Lipid treatment in non-steatotic livers provides the same protection as that afforded by glucose in conditions of PH under I/R, whereas the treatment with lipids is preferable to reduce the injurious effects of liver surgery in the presence of steatosis.

Topics: Adenosine Triphosphate; Analysis of Variance; Animals; Ceramides; Fatty Liver; Glucose; Hepatectomy; Ischemia; Lipids; Liver; Lysophospholipids; Rats; Regeneration; Reperfusion; Sphingosine

Therapeutic angiogenesis is a promising strategy for treating ischemia. The lysophospholipid mediator sphingosine-1-phosphate (S1P) acts on vascular endothelial cells to stimulate migration and tube formation, and plays the critical role in developmental angiogenesis. We developed poly(lactic-co-glycolic-acid) (PLGA)-based S1P-containing microparticles (PLGA-S1P), which are biodegradable and continuously release S1P, and studied the effects of PLGA-S1P on neovascularization in murine ischemic hindlimbs. Intramuscular injections of PLGA-S1P stimulated blood flow in C57BL/6 mice dose-dependently, with repeated administrations at a 3-day interval, rather than a single bolus or 6-day interval, over 28 days conferring the optimal stimulating effect. In Balb/c mice that exhibit limb necrosis and dysfunction due to retarded blood flow recovery, injections of PLGA-S1P stimulated blood flow with alleviation of limb necrosis and dysfunction. PLGA-S1P alone did not induce edema in ischemic limbs, and rather blocked vascular endothelial growth factor-induced edema. PLGA-S1P not only increased the microvessel densities in ischemic muscle, but promoted coverage of vessels with smooth muscle cells and pericytes, thus stabilizing vessels. PLGA-S1P stimulated Akt and ERK with increased phosphorylation of endothelial nitric oxide synthase in ischemic muscle. The effects of the nitric oxide synthase inhibitor, Nomega-nitro-L-arginine methylester, showed that PLGA-S1P-induced blood flow stimulation was partially dependent on nitric oxide. Injections of PLGA-S1P also increased the expression of angiogenic factors and the recruitment of CD45-, CD11b- and Gr-1-positive myeloid cells, which are implicated in post-ischemic angiogenesis, into ischemic muscle. These results indicate that PLGA-based, sustained local delivery of S1P is a potentially useful therapeutic modality for stimulating post-ischemic angiogenesis.

Topics: Animals; Delayed-Action Preparations; Disease Models, Animal; Extracellular Signal-Regulated MAP Kinases; Hindlimb; Ischemia; Lactic Acid; Lysophospholipids; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Transgenic; Microspheres; Neovascularization, Pathologic; Neovascularization, Physiologic; Nitric Oxide Synthase Type III; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Proto-Oncogene Proteins c-akt; Random Allocation; Regional Blood Flow; Sphingosine

Angiogenesis contributes to physiological and pathological conditions, including atherosclerosis. The Rap1 small G protein regulates vascular integrity and angiogenesis. However, little is known about the effectors of Rap1 involved in angiogenesis. It is not known whether afadin, an adherens junction protein that connects immunoglobulin-like adhesion molecule nectins to the actin cytoskeleton and binds activated Rap1, plays a role in angiogenesis.. We investigated the role of endothelial afadin in angiogenesis and attempted to clarify the underlying molecular mechanism.. Treatment of human umbilical vein endothelial cells (HUVECs) with vascular endothelial growth factor (VEGF) and sphingosine 1-phosphate (S1P) induced the activation of Rap1. Activated Rap1 regulated intracellular localization of afadin. Knockdown of Rap1 or afadin by small interfering RNA inhibited the VEGF- and S1P-induced capillary-like network formation, migration, and proliferation, and increased the serum deprivation-induced apoptosis of HUVECs. Knockdown of Rap1 or afadin decreased the accumulation of adherens and tight junction proteins to the cell-cell contact sites. Rap1 regulated the interaction between afadin and phosphatidylinositol 3-kinase (PI3K), recruitment of the afadin-PI3K complex to the leading edge, and the activation of Akt, indicating the involvement of Rap1 and afadin in the PI3K-Akt signaling pathway. Binding of afadin to Rap1 regulated the activity of Rap1 in a positive-feedback manner. In vivo, conditional deletion of afadin in mouse vascular endothelium using a Cre-loxP system impaired the VEGF- and S1P-induced angiogenesis.. These results demonstrate a novel molecular mechanism by which Rap1 and afadin regulate the VEGF- and S1P-induced angiogenesis.

Topics: Animals; Apoptosis; Cell Movement; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Endothelial Cells; Hindlimb; Humans; Intercellular Junctions; Ischemia; Lysophospholipids; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microfilament Proteins; Muscle, Skeletal; Neovascularization, Physiologic; Phosphatidylinositol 3-Kinases; Protein Transport; Proto-Oncogene Proteins c-akt; rac1 GTP-Binding Protein; rap1 GTP-Binding Proteins; Rats; Recombinant Fusion Proteins; Retinal Neovascularization; RNA Interference; Signal Transduction; Sphingosine; Time Factors; Vascular Endothelial Growth Factor A

We previously reported a novel technology for the engineering of a capillary network using an optical lithographic technique. To apply this technology to the therapy of ischemic diseases, we tested human omental microvascular endothelial cells (HOMECs) as an autologous cell source and decellularized human amniotic membranes (DC-AMs) as a pathogen-free and low immunogenic transplantation scaffold.. Human umbilical vein endothelial cells were aligned on a patterned glass substrate and formed a capillary structure when transferred onto an amniotic membrane (AM). In contrast, HOMECs were scattered and did not form a capillary structure on AMs. Treatment of HOMECs with sphingosine 1-phosphate (S1P) inhibited HOMEC migration and enabled HOMEC formation of a capillary structure on AMs. Using quantitative RT-PCR and Western blot analyses, we demonstrated that the main S1P receptor in HOMECs is S1P(2), which is lacking in human umbilical vein endothelial cells, and that inhibition of cell migration by S1P is mediated through an S1P(2)-Rho-Rho-associated kinase signaling pathway. Implantation of capillaries engineered on DC-AMs into a hindlimb ischemic nude mouse model significantly increased blood perfusion compared with controls.. A capillary network consisting of HOMECs on DC-AMs can be engineered ex vivo using printing technology and S1P treatment. This method for regeneration of a capillary network may have therapeutic potential for ischemic diseases.

Topics: Adipose Tissue; Amnion; Animals; Blotting, Western; Cell Movement; Cells, Cultured; Disease Models, Animal; Endothelial Cells; Hindlimb; Humans; Ischemia; Lysophospholipids; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Microvessels; Muscle, Skeletal; Neovascularization, Physiologic; Omentum; Protein Kinase Inhibitors; Receptors, Lysosphingolipid; Regional Blood Flow; Reverse Transcriptase Polymerase Chain Reaction; rho GTP-Binding Proteins; rho-Associated Kinases; Signal Transduction; Sphingosine; Sphingosine-1-Phosphate Receptors; Tissue Engineering; Tissue Scaffolds; Transplantation, Autologous

Liver failure due to ischemia and reperfusion (IR) and subsequent acute kidney injury are significant clinical problems. We showed previously that liver IR selectively reduced plasma sphinganine-1-phosphate levels without affecting sphingosine-1-phosphate (S1P) levels. Furthermore, exogenous sphinganine-1-phosphate protected against both liver and kidney injury induced by liver IR. In this study, we elucidated the signaling mechanisms of sphinganine-1-phosphate-mediated renal and hepatic protection. A selective S1P(1) receptor antagonist blocked the hepatic and renal protective effects of sphinganine-1-phosphate, whereas a selective S1P(2) or S1P(3) receptor antagonist was without effect. Moreover, a selective S1P(1) receptor agonist, SEW-2871, provided similar degree of liver and kidney protection compared with sphinganine-1-phosphate. Furthermore, in vivo gene knockdown of S1P(1) receptors with small interfering RNA abolished the hepatic and renal protective effects of sphinganine-1-phosphate. In contrast to sphinganine-1-phosphate, S1P's hepatic protection was enhanced with an S1P(3) receptor antagonist. Inhibition of extracellular signal-regulated kinase, Akt or pertussis toxin-sensitive G-proteins blocked sphinganine-1-phosphate-mediated liver and kidney protection in vivo. Taken together, our results show that sphinganine-1-phosphate provided renal and hepatic protection after liver IR injury in mice through selective activation of S1P(1) receptors and pertussis toxin-sensitive G-proteins with subsequent activation of ERK and Akt.

Topics: Acute Kidney Injury; Animals; Extracellular Signal-Regulated MAP Kinases; Ischemia; Kidney; Liver; Liver Diseases; Lysophospholipids; Male; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinases; Oxadiazoles; Proto-Oncogene Proteins c-akt; Receptors, Lysosphingolipid; Reperfusion Injury; Signal Transduction; Sphingosine; Thiophenes

Sphingosine-1-phosphate (S1P) is a bioactive lipid molecule that stimulates endothelial cell migration, proliferation, and survival in vitro, and tumor angiogenesis in vivo. In this study, we used a humanized monoclonal antibody (sonepcizumab) that selectively binds S1P to investigate its role in retinal and choroidal neovascularization (NV). Intraocular injection of sonepcizumab significantly reduced macrophage influx into ischemic retina and strongly suppressed retinal NV in mice with oxygen-induced ischemic retinopathy. In mice with laser-induced rupture sites in Bruch's membrane, intraocular injection of sonepcizumab significantly reduced the area of choroidal NV and concomitantly reduced fluorescein leakage from the remaining choroidal NV. Four weeks after intraocular injection of up to 1.8 mg of the sonepcizumab in non-human primates, electroretinograms and fluorescein angiograms were normal, and light microscopy of ocular sections showed no evidence of structural damage. These data show for the first time that S1P stimulates both choroidal and retinal NV and suggest that sonepcizumab could be considered for evaluation in patients with choroidal or retinal NV.

Topics: Animals; Antibodies, Monoclonal; Choroidal Neovascularization; Female; Humans; Ischemia; Lysophospholipids; Macaca fascicularis; Macrophages; Male; Mice; Mice, Inbred C57BL; Retinal Neovascularization; Retinal Vessels; Sphingosine

The lysophospholipid mediator sphingosine-1-phosphate (S1P) acts on vascular endothelial cells to stimulate migration, proliferation, and capillary-like tube formation in vitro. It is unknown whether S1P stimulates in vivo angiogenesis induced under tissue ischaemia. We investigated the effects of both exogenously and endogenously overproduced S1P on post-ischaemic angiogenesis in murine hindlimbs.. The effects of locally injected S1P on blood flow recovery, angiogenesis, and vascular permeability in mouse ischaemic hindlimbs that underwent femoral arteriectomy were assessed by a laser Doppler blood flow (LDBF) analysis, anti-CD31 immunohistochemistry, and Miles assay, respectively, and compared with those induced by fibroblast growth factor (FGF)-2. Blood flow recovery and angiogenesis in sphingosine kinase 1-transgenic mice that overproduce S1P endogenously were also assessed and compared with wild-type mice. The LDBF analysis showed that daily intramuscular administration of S1P dose-dependently stimulated blood flow recovery, resulting in up to twice as much blood flow when compared with vehicle control, which was accompanied by 1.7-fold increase in the capillary density. The optimal S1P effects were comparable with those obtained with FGF-2. S1P injection did not increase vascular permeability. The post-ischaemic blood flow recovery and angiogenesis were accelerated in sphingosine kinase 1-transgenic mice, which showed 40-fold higher sphingosine kinase activity and 1.8-fold higher S1P content in skeletal muscle than in wild-type (WT) mice, without an increase in the vascular permeability when compared with WT mice.. These results indicate that either local exogenous S1P administration or endogenous S1P overproduction promotes post-ischaemic angiogenesis and blood flow recovery. These observations suggest potential therapeutic usefulness of S1P for tissue ischaemia.

Topics: Angiogenesis Inducing Agents; Animals; Blood Flow Velocity; Capillaries; Capillary Permeability; Disease Models, Animal; Fibroblast Growth Factor 2; Hindlimb; Immunohistochemistry; Ischemia; Laser-Doppler Flowmetry; Lysophospholipids; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Muscle, Skeletal; Neovascularization, Physiologic; Phosphotransferases (Alcohol Group Acceptor); Platelet Endothelial Cell Adhesion Molecule-1; Regional Blood Flow; Sphingosine; Time Factors