Activated T cells induce proliferation of oligodendrocyte progenitor cells via release of vascular endothelial cell growth factor‐A

Neuroinflammatory diseases such as multiple sclerosis are characterized by infiltration of lymphocytes into the central nervous system followed by demyelination and axonal degeneration. While evidence suggests that activated T lymphocytes induce neurotoxicity and impair function of neural stem cells, the effect of T cells on oligodendrocyte progenitor cells (OPCs) is still uncertain, partly due to the difficulty in obtaining human OPCs. Here we studied the effect of activated T cells on OPCs using OPCs derived from human hematopoietic stem cells or from human fetal brain. OPCs were exposed to supernatants (sups) from activated T cells. Cell proliferation was determined by EdU incorporation and CellQuanti‐Blue assays. Surprisingly, we found that sups from activated T cells induced OPC proliferation by regulating cell cycle progression. Vascular endothelial growth factor A (VEGF‐A) transcripts were increased in T cells after activation. Immunodepletion of VEGF‐A from activated T cell sups significantly attenuated its effect on OPC proliferation. Furthermore, VEGF receptor 2 (VEGFR2) was expressed on OPCs and its inhibition also attenuated activated T cell‐induced OPC proliferation. Thus, activated T cells have a trophic role by promoting OPC proliferation via the VEGFR2 pathway.