The Experimental Study Of The Chemotactic Effect Of The Chemokine SDF-1

Objective To investigate the possible chemotactic effect of SDF-1αon theprimary MSCs(Mesenchymal Stem Cells), astrocytes, microglial cells andneutrophils in vitro and in vivo for an exploration of possibility and mechanismof cell migration in brain injury.Methods 48-well microchemotaxis chamber was used to test the chemotacticeffect of SDF-1αon MSCs, astrocytes, N9 cells and neutrophils. In vitro,thecells were added to the upper well of the chamber separated by a polycarbonatefilter with defined pores. The lower well was filled with SDF-1αin ascendingconcentrations. Migrated cells were counted and the migration index wascalculated to show the difference of migration under the conditions with orwithout the existence of SDF-1α. The expression of CXCR4 gene in microglialcells was assayed by RT-PCR. In vivo, CTO-labeled MSCs, neutrophils and N9cells were injected into the tail vein of the rats which served as the middlecerebral artery occlusion model. The labeled cells were observed in the cerebralsections of the injured region as shown by fluorescence microscopy. Anti-CXCR4antibodies were used for inhibition studies.Results In vitro,the migration indexes of MSCs, N9 cells and neutrophils butnot the primary astrocytes were significantly higher in the SDF-1αtreatedgroups as compared with the non-SDF-1αtreated groups . The CXCR4 antibodyblocking significantly impaired the SDF-1αchemotaxis.RT-PCR revealed thatCXCR4 gene expressed obviously in N9 cells. In vivo, much more MSCs, N9 cellsand neutrophils migrated to the injuried region in the grafted groups than theother two groups. The CXCR4 antibody significantly impaired the migration ofMSCs, N9 cells and neutrophils.Conclusion Our results demonstrated that,by its combination with receptors,SDF-1αplayed a significant chemotactic role on the migration of MSCs, N9cells and neutrophils but not the primary astrocytes through the receptor CXCR4.This indicates a possible role of SDF-1αon the targeting and location ofgrafted MSCs, N9 cells or inflammatory cells by the increased secretion ofSDF-1αin injured brain.