Effects of SDF-1α/CXCR4 on vascular smooth muscle cells and bone marrow mesenchymal cells in a rat carotid artery balloon injury model

Bone marrow mensenchyme cells (BMSCs) can differentiate into endothelial progenitor cells which then migrate to injured sites for the repair of neointima, and stromal cell-derived factor-1α (SDF-1α) can mediate the migration of CXCR4 expressing stem/progenitor cells to injured sites for pair. Protein and mRNA expression of SDF-1α and CXCR4 were determined by RT-PCR, Western blot and ELISA. Immediately after common carotid artery balloon injury, the mRNA expression of SDF-1α in vascular smooth muscle cells (VSMCs) first increased and then decreased 7 days later. VSMCs transfected with SDF-1α siRNA did not express SDF-1α mRNA, but after transfection with SDF-1α siRNA, the SDF-1α content in injured VSMCs gradually returned to the baseline level. Normal BMSCs rarely expressed CXCR4 mRNA, but the CXCR4 mRNA expression on BMSCs increased significantly 4 days after common carotid artery injury and was maintained. The migration of BMSCs after artery injury was enhanced when compared with normal BMSCs, but SDF-1α siRNA transfection of VSMCs and AMD3100 treatment remarkably decreased the chemotaxis of BMSCs to VSMCs and SDF-1α, respectively. We conclude that the SDF-1α/CXCR4 axis plays an important role in the migration of BMSCs after balloon injury and can ultimately cause abnormal proliferation of the intima.