Aims: 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.
Methods and results: 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.
Conclusion: 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.