Hypoxia and low-dose inflammatory stimulus synergistically enhance bone marrow mesenchymal stem cell migration

Objectives: Cell migration is necessary for numerous physiological cell processes. Although either inflammatory or hypoxic stimuli of certain dose and duration have positive influence on cell migration, their combination has not been shown to result in a synergistic effect. Materials and methods: In this study, we investigated combined effects of hypoxia and low-dose inflammatory stimulus (one-tenth of that of a previously used concentration) on migration of human bone marrow-derived mesenchymal stem cells (BMMSCs). Results: Our results from real-time PCR, Western blot analysis and an immunofluorescence assay, showed that dual stimulation up-regulated CXCR4 expression. Based on tablet scratch experimentation and transwell assay, the dual stimuli exhibited greater positive effects on cell migration than a single inflammatory or hypoxic stimulus. When effects of various pre-treatments on cell proliferation, differentiation and immunosuppression were screened, cells subjected to the hypoxic stimulus or dual stimuli had increased cell proliferation, while short-term inflammatory stimulus and/or hypoxic stimulus had no negative effect on cell differentiation and immunosuppression. Conclusions: These findings suggest that the combination of hypoxia and low-dose inflammatory stimuli enhances the potential of BMMSCs to migrate, thus identifying cell pre-treatment conditions that could enhance future stem cell- based therapeutics.