Neural Stem Cells Alleviate Inflammation via Neutralization of IFN-γ Negative Effect in Ischemic Stroke Model.

Inflammatory response generated by ischemic stroke commonly affects functional or structural recovery. The aim of this study was to examine the IFN-γ caused inflammatory effects on NSCs in vitro and in vivo. We found that IFN-γ did not affect NSCs proliferation but increased the SOD2 level of inflammatory oxidative stress in NSCs culturing. High dose IFN-γ (500 ng) injection aggravated the level of inflammation in the cerebral ischemic model but did not alter the repairing functions of the NSCs in vivo. NSCs based treatment, including the NSCs-IFN-γ combined treatment, significantly improved the ischemic microenvironment by decreasing CD4+, CD8+ T cells and microglia infiltration. Furthermore, anti-inflammatory cytokines IL-10 and TGF-β1 expression were increased in the NSCs and combined treatment groups, but the level of pro-inflammatory cytokines (IL-1 β, IL-6, IFN-γ, and TNF-α) were decreased. The IFN-γ/Stat1 signaling pathway was also activated. NSCs transplantation therefore promoted the neurological recovery of ischemic stroke rats mainly by altering the inflammatory microenvironment, neutralizing the negative effect of IFN-γ. In conclusion, in addition to promoting cell replacement or engraftment, the NSCs-based transplantation also enhanced the therapeutic effects of transplantation by optimizing its immune microenvironment of ischemic areas.