Endothelial differentiation of bone marrow mesenchyme stem cells applicable to hypoxia and increased migration through Akt and NF\u03baB signals

Cheng Liu,Chia-Ching Wu,Ping-Chia Li,An-Ly Tsai,Chia-Wei Huang

doi:10.1186/s13287-017-0470-0

Abstract

BackgroundBone marrow mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) are used to repair hypoxic or ischemic tissue. However, the underlining mechanism of resistance in the hypoxic microenvironment and the efficacy of migration to the injured tissue are still unknown. The current study aims to understand the hypoxia resistance and migration ability of MSCs during differentiation toward endothelial lineages by biochemical and mechanical stimuli.MethodMSCs were harvested from the bone marrow of 6–8-week-old Sprague–Dawley rats. The endothelial growth medium (EGM) was added to MSCs for 3 days to initiate endothelial differentiation. Laminar shear stress was used as the fluid mechanical stimulation.ResultsApplication of EGM facilitated the early endothelial lineage cells (eELCs) to express EPC markers. When treating the hypoxic mimetic desferrioxamine, both MSCs and eELCs showed resistance to hypoxia as compared with the occurrence of apoptosis in rat fibroblasts. The eELCs under hypoxia increased the wound closure and C-X-C chemokine receptor type 4 (CXCR4) gene expression. Although the shear stress promoted eELC maturation and aligned cells parallel to the flow direction, their migration ability was not superior to that of eELCs either under normoxia or hypoxia. The eELCs showed higher protein expressions of CXCR4, phosphorylated Akt (pAkt), and endogenous NFκB and IκBα than MSCs under both normoxia and hypoxia conditions. The potential migratory signals were discovered by inhibiting either Akt or NFκB using specific inhibitors and revealed decreases of wound closure and transmigration ability in eELCs.ConclusionThe Akt and NFκB pathways are important to regulate the early endothelial differentiation and its migratory ability under a hypoxic microenvironment.

Highlights

Bone marrow mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) are used to repair hypoxic or ischemic tissue
Cleaved PARP was observed and confirmed the hypoxia-induced cell apoptosis in fibroblasts, but not in either MSCs or endothelial lineage cells (eELCs) (Fig. 1d). These results suggest that MSCs are resisted to the hypoxic microenvironments and the early differentiation of endothelial lineage cells (ELCs) endures in DFO treatment
DFO is on the List of Essential Medicines as announced by the World Health Organization to demonstrate its safety and importance in medications, especially for treating acute iron poisoning in small children. eELC induction and preconditioning to DFO can provide a novel and convenientto-clinics therapeutic strategy to increase the function of MSCs

Summary

Introduction

Bone marrow mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) are used to repair hypoxic or ischemic tissue. The underlining mechanism of resistance in the hypoxic microenvironment and the efficacy of migration to the injured tissue are still unknown. The current study aims to understand the hypoxia resistance and migration ability of MSCs during differentiation toward endothelial lineages by biochemical and mechanical stimuli. The injured tissues produce cytokines and chemokines to recruit stem or progenitor cells for repairing the damaged sites. Cell apoptosis under hypoxia is regulated by mitogenactivated protein kinase (MAPK), nuclear factor-κB (NFκB), phosphatidylinositol 3-kinase (PI3K)/Akt, or the release of cytochrome C to activate the apoptotic. Hypoxia regulates hypoxia inducible factor-1 (HIF-1) activity via PI3K/Akt or MAPK signaling in an oxygen-independent manner. The interaction and crosstalk of HIF-1 and NFκB signals are important for immune responses, inflammation, and anti-apoptosis [16]

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Conclusion