Antagonism of sphingosine 1-phosphate receptor-2 enhances migration of neural progenitor cells toward an area of brain.

BACKGROUND AND PURPOSE: We have previously shown that the sphingosine 1-phosphate (S1P)/S1P receptor-1 (S1P(1)R) axis contributes to the migration of transplanted neural progenitor cells (NPCs) toward areas of spinal cord injury. In the current study, we examined a strategy to increase endogenous NPC migration toward the injured central nervous system to modify S1PR.

METHODS: S1P concentration in the ischemic brain was measured in a mouse thrombosis model of the middle cerebral artery. NPC migration in vitro was assessed by a Boyden chamber assay. Endogenous NPC migration toward the insult was evaluated after ventricular administration of the S1P(2)R antagonist JTE-013.

RESULTS: The concentration of S1P in the brain was increased after ischemia and was maximal 14 days after the insult. The increase in S1P in the infarcted brain was primarily caused by accumulation of microglia at the insult. Mouse NPCs mainly expressed S1P(1)R and S1P(2)R as S1PRs, and S1P significantly induced the migration of NPCs in vitro through activation of S1P(1)R. However, an S1P(1)R agonist failed to have any synergistic effect on S1P-mediated NPC migration, whereas pharmacologic or genetic inhibition of S1P(2)R by JTE-013 or short hairpin RNA expression enhanced S1P-mediated NPC migration but did not affect proliferation and differentiation. Interestingly, administration of JTE-013 into a brain ventricle significantly enhanced endogenous NPC migration toward the area of ischemia.

CONCLUSIONS: Our findings suggest that S1P is a chemoattractant for NPCs released from an infarcted area and regulation of S1P(2)R function further enhances the migration of NPCs toward a brain infarction.