Characterization of a new mouse line triggering transient oligodendrocyte progenitor depletion.

Oligodendrocyte progenitor cells (OPC) are the main proliferative cells in the healthy adult brain. They produce new myelinating oligodendrocytes to ensure physiological myelin remodeling and regeneration after various pathological insults. Growing evidence suggests that OPC have other functions. Here, we aimed to develop an experimental model that allows the specific ablation of OPC at the adult stage to unravel possible new functions. We generated a transgenic mouse expressing a floxed human diphtheria toxin receptor under the control of the PDGFRa promoter, crossed with an Olig2Cre mouse to limit the recombination to the oligodendrocyte lineage in the central nervous system. We determined a diphtheria toxin dose to substantially decrease OPC density in the cortex and the corpus callosum without triggering side toxicity after a few daily injections. OPC density was normalized 7 days post-treatment, showing high repopulation capacity from few surviving OPC. We took advantage of this strong but transient depletion to show that OPC loss was associated with behavioral impairment, which was restored by OPC recovery, as well as disruption of the excitation/inhibition balance in the sensorimotor cortex, reinforcing the hypothesis of a neuromodulatory role of OPC in the adult brain.