The SDF-1/CXCR4 axis is involved in adipose-derived stem cell migration.

Abstract

Background: Intravenous injection of adipose-derived stem cells (ADSCs) can improve the urinary function of stress urinary incontinence (SUI) model rats and C-X-C chemokine receptor type 4 (CXCR4)-positive ADSCs are found in urethral tissues. The CXCR4 ligand stromal cell-derived factor-1 (SDF-1) is highly expressed in urinary incontinence model rats. In this study, we investigated the involvement of the SDF-1/CXCR4 axis in the homing of ADSCs.

Methods: ADSCs were isolated from rats and purified. The levels of CXCR4 and CXCR7 were determined by western blot analysis and immunofluorescence assays following stimulation with SDF-1. Hypoxia conditioning was performed to treat the cells in vitro, following which the messenger RNA (mRNA) and protein level of SDF-1, CXCR4, and CXCR7 were estimated.

Results: We found that CXCR4 and CXCR7 were expressed in ADSCs at passage zero (P0), P1, and P3, and the expression of both increased after SDF-1 stimulation. The level of expression of the mRNAs and proteins of SDF-1, CXCR4, and CXCR7 in ADSCs was higher after hypoxic conditioning. We then knocked down CXCR4 or CXCR7 using small interfering RNAs and found that the mRNA levels of CXCR4 and CXCR7 were considerably downregulated in the si-CXCR4/7-transfected cells. We also found that the SDF-1/CXCR4 axis was required for the migration of ADSCs. The phosphorylation levels of Janus kinase (JAK), protein kinase B (AKT), and extracellular regulated protein kinase significantly increased in SDF-1-stimulated ADSCs. However, the migration of ADSCs was suppressed when the corresponding specific inhibitors were used to block JAK and AKT signaling or silence CXCR4, whereas no significant change was observed in the migratory ability of ADSCs when the ERK pathway was blocked or CXCR7 was silenced.

Conclusions: The SDF-1/CXCR4 axis is involved in the migration of ADSCs and may play a role in the migrate of ADSCs in SUI.