SDF-1α/CXCR4 signaling promotes capillary tube formation of human retinal vascular endothelial cells by activating ERK1/2 and PI3K pathways in vitro

The purpose of this study is to address the effect and mechanism of stromal cell-derived factor-1 (SDF-1)α/chemokine (C-X-C motif) receptor 4 (CXCR4) signaling on capillary tube formation of human retinal vascular endothelial cells (HRECs). The expression of CXCR4 in HRECs was quantified by reverse transcription (RT-PCR) and western blotting. The effects of SDF-1α/CXCR4 signaling in capillary tube formation and migration of HRECs was examined using three-dimensional Matrigel assay and wound scratching assay respectively in vitro. Cell proliferation of HRECs was examined using cell counting kit (CCK)-8 assay in the presence of different concentrations of SDF-1α protein. The effect of SDF-1α/CXCR4 signaling in HREC expression of VEGF, basic fibroblast growth factor (bFGF), IL-8 and intercellular cell adhesion molecule (ICAM)-1 was examined using RT-PCR and western blotting. RT-PCR and western blot analysis revealed CXCR4 was expressed in HRECs. The number of intact capillary tubes formed by HRECs in the presence of SDF-1α was markedly more compared with a PBS treated control group. However, it was reduced with treatment with an CXCR4 antagonist. Wound scratching assay showed a significant increase in the number of migrated HRECs under SDF-1α stimulation and the number was reduced with treatment with an CXCR4 antagonist. RT-PCR and western blotting showed that SDF-1α significantly promoted VEGF, bFGF, IL-8 and ICAM-1 expression in HRECs. The proliferation of HRECs in the presence of SDF-1α was promoted in a dosage-dependent manner. SDF-1α/CXCR4 signaling can increase HREC capillary tube formation through promoting HREC migration, proliferation and expression of VEGF, bFGF, IL-8 and ICAM-1.