Expression of CXCR4 and CXCR7 receptors in bone marrow mesenchymal stem cells and role of these receptors in bone repair

Abstract

Objective To investigate the function of CXCR4 and CXCR7 receptors expressed in bone marrow mesenchymal stem cells (BMSCs) membrane surface in process of cell migration,in order to provide a theoretical basis for bone trauma repair.Methods C57BL/6 mice were selected to collect BMSCs of second passage after using the adherence culture method.Expressions of CXCR4 and CXCR7 receptors on BMSCs membrane surface were detected using immunofluorescent staining and flow cytometry.In CXCL12-induced chemotaxis of BMSCs,the assay was divided into control group (cells were seeded in serum-free medium),CXCL12 group and (cells were seeded in serum-free medium containing CXCL12),and CXCR4-blocked group (cells were seeded in serum-free medium containing CXCL12 after the blockade of CXCR4).Migration of BMSCs was qualified and used to determine the chemotaxis role of CXCR4 and CXCR7.After the blockade of CXCR4,expression of CXCR7 was detected using the Western blot method.Results lmmunofluorescence showed overexpressions of CXCR4 and CXCR7 receptors on BMSCs membrane surface.Flow cytometry showed the positive rate of CXCR4 and CXCR7 on BMSCs membrane surface was 96.4％ and 97.3％ respectively.Cell migration assay showed amount of MBSCs migration was the highest in CXCL12 group,relative higher in CXCR4-blocked group and the lowest in control group (P ＜ 0.01).In CXCR4-blocked group,expression of CXCR7 increased.Conclusion CXCR4 and CXCR7 Receptors are expressed in BMSCs membrane surface,but CXCR4 play the major role in CXCL12-induced BMSCs migration to traumatic bone wounds. Key words: Wounds and injuries; Mesenchymal stem cells; Autoreceptors