Spinal cord ependymal cells display neural stem cell properties in vitro and generate scar-forming astrocytes and remyelinating oligodendrocytes after injury. We report that ependymal cells are functionally heterogeneous and identify a small subpopulation (8% of ependymal cells and 0.1% of all cells in a spinal cord segment), which we denote ependymal A (EpA) cells, that accounts for the in vitro stem cell potential in the adult spinal cord. After spinal cord injury, EpA cells undergo self-renewing cell division as they give rise to differentiated progeny. Single-cell transcriptome analysis revealed a loss of ependymal cell gene expression programs as EpA cells gained signaling entropy and dedifferentiated to a stem-cell-like transcriptional state after an injury. We conclude that EpA cells are highly differentiated cells that can revert to a stem cell state and constitute a therapeutic target for spinal cord repair.