Transplantation of genetically modified oligodendrocyte progenitor cells (OPCs) into a mouse model of MS improves remyelination, new research has demonstrated. The researchers used CRISPR in human embryonic stem cell-derived OPCs to delete neuropilin 1, a receptor for SEMA3A that is highly expressed in demyelinated lesions in people with MS and is chemorepulsive to OPCs. Transplantation of the modified OPCs enhanced remyelination in the mice, providing proof of concept for OPC transplantation as a potential therapeutic strategy for MS.