The Median Eminence, A New Oligodendrogenic Niche in the Adult Mouse Brain

The subventricular zone (SVZ) of the lateral ventricles and the subgranular zone (SGZ) of the dentate gyrus in the hippocampus are known as neurogenic niches. We show that the median eminence (ME) of the hypothalamus comprises BrdU+ newly proliferating cells co-expressing NG2 (oligodendrocyte progenitors) and RIP (pre-myelinating oligodendrocytes), suggesting their differentiation toward mature oligodendrocytes (OLs). ME cells can generate neurospheres (NS) in vitro, which differentiate mostly to OLs compared with SVZ-NS that typically generate neurons. Interestingly, this population of oligodendrocyte progenitors is increased in the ME from experimental autoimmune encephalomyelitis (EAE)-affected mice. Notably, the thrombospondin 1 (TSP1) expressed by astrocytes, acts as negative regulator of oligodendrogenesis in vitro and is downregulated in the ME of EAE mice. Importantly, transplanted ME-NS preferentially differentiate to MBP+ OLs compared with SVZ-NS in Shiverer mice. Hence, discovering the ME as a new site for myelin-producing cells has a great importance for advising future therapy for demyelinating diseases and spinal cord injury. [Display omitted] •Median eminence of the hypothalamus contains proliferating OPCs•The number of OPCs in the median eminence is increased under demyelination•Median eminence cells generate neurospheres in vitro•Thrombospondin 1 inhibits oligodendrocyte differentiation of median eminence cells Zilkha-Falb and colleagues show an enrichment of BrdU+ NG2+ cells in the median eminence (ME) of EAE mice. ME cells generate neurospheres differentiating to MBP+ OLs after transplantation to the LV of Shi mice. TSP1 inhibits oligodendrocyte differentiation of ME cells, corroborating its decreased expression in the ME of EAE mice. These findings suggest the ME as oligodendrogenic niche to increase OPCs under demyelination.