ObjectiveUsing a mouse model, Iron Overload (IO) induced bone marrow microenvironment injury was investigated, focusing on the involvement of reactive oxygen species (ROS).MethodsMice were intraperitoneally injected with iron dextran (12.5, 25, or 50mg) every three days for two, four, and six week durations. Deferasirox(DFX)125mg/ml and N-acetyl-L-cysteine (NAC) 40mM were co-administered. Then, bone marrow derived mesenchymal stem cells (BM-MSCs) were isolated and assessed for proliferation and differentiation ability, as well as related gene changes. Immunohistochemical analysis assessed the expression of haematopoietic chemokines. Supporting functions of BM-MSCs were studied by co-culture system.ResultsIn IO condition (25mg/ml for 4 weeks), BM-MSCs exhibited proliferation deficiencies and unbalanced osteogenic/adipogenic differentiation. The IO BM-MSCs showed a longer double time (2.07±0.14 days) than control (1.03±0.07 days) (P<0.05). The immunohistochemical analysis demonstrated that chemokine stromal cell-derived factor-1, stem cell factor -1, and vascular endothelial growth factor-1 expression were decreased. The co-cultured system demonstrated that bone marrow mononuclear cells (BMMNCs) co-cultured with IO BM-MSCs had decreased colony forming unit (CFU) count (p<0.01), which indicates IO could lead to decreased hematopoietic supporting functions of BM-MSCs. This effect was associated with elevated phosphatidylinositol 3 kinase (PI3K) and reduced of Forkhead box protein O3 (FOXO3) mRNA expression, which could induce the generation of ROS. Results also demonstrated that NAC or DFX treatment could partially attenuate cell injury and inhibit signaling pathway striggered by IO.ConclusionThese results demonstrated that IO can impair the bone marrow microenvironment, including the quantity and quality of BM-MSCs.

Human MSCs constitutively expressed immunosuppressive levels of PGE, HGF and TGF-β. The proinflammatory cytokine IFN-γ exhibited synergistic effects with MSCs on immunosuppression, possibly by up-regulating PGE, HGF and TGF-β in MSCs and inducting MSCs expression of IDO, involved in tryptophan catabolism.

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