The SDF-1/CXCR4 Signaling Pathway Directs the Migration of Systemically Transplanted Bone Marrow Mesenchymal Stem Cells Towards the Lesion Site in a Rat Model of Spinal Cord Injury

It has been observed that bone marrow-derived mesenchymal stem cells (MSCs) migrate towards the injured spinal cord and promote functional recovery when systemically transplanted into the traumatized spinal cord. However, the mechanisms underlying their migration to the spinal cord remain poorly understood. In this study, we systemically transplanted GFP- and luciferase-expressing MSCs into rat models of spinal cord injury and examined the role of the stromal cell-derived factor 1 (SDF-1)/CXCR4 axis in regulating the migration of transplanted MSCs to the spinal cord. After intravenous injection, MSCs migrated to the injured spinal cord where the expression of SDF-1 was increased. Spinal cord recruitment of MSCs was blocked by pre-incubation with an inhibitor of CXCR4. Their presence correlated with morphological and functional recovery. In vitro, SDF-1 or cerebrospinal fluid (CSF) collected from SCI rats promoted a dose-dependent migration of MSCs in culture, which was blocked by an inhibitor of CXCR4 or SDF-1 antibody. The study suggests that SDF-1/CXCR4 interactions recruit exogenous MSCs to injured spinal cord tissues and may enhance neural regeneration. Modulation of the homing capacity may be instrumental in harnessing the therapeutic potential of MSCs.