T-Regulatory Cells Confer Increased Myelination and Stem Cell Activity after Stroke-Induced White Matter Injury

Stroke-induced hypoxia causes oligodendrocyte death due to inflammation, lack of oxygen and exacerbation of cell death. Bone marrow-derived stem cells (BMSCs) possess an endogenous population of T-regulatory cells (T(regs)) which reduce secretion of pro-inflammatory cytokines that lead to secondary cell death. Here, we hypothesize that oligodendrocyte progenitor cells (OPCs) cultured with BMSCs containing their native T(reg) population show greater cell viability, less pro-inflammatory cytokine secretion and greater myelin production after exposure to oxygen-glucose deprivation and reoxygenation (OGD/R) than OPCs cultured without T(regs). OPCs were cultured and then exposed to OGD/R. BMSCs with or without T(regs) were added to the co-culture immediately after ischemia. The T(regs) were depleted by running the BMSCs through a column containing a magnetic substrate. Fibroblast growth factor beta (FGF-β) and interleukin 6 (IL-6) ELISAs determined BMSC activity levels. Immunohistochemistry assessed OPC differentiation. OPCs cultured with BMSCs containing their endogenous T(regs) showed increased myelin production compared to the BMSCs with depleted T(regs). IL-6 and FGF-β were increased in the group cultured with T(regs). Collectively, these results suggest that BMSCs containing T(regs) are more therapeutically active, and that T(regs) have beneficial effects on OPCs subjected to ischemia. T(regs) play an important role in stem cell therapy and can potentially treat white matter injury post-stroke.