Direct Induction of Neural Stem Cells from Somatic Cells

Neural stem cells are a promising source for cell therapy in spinal cord injury. However, the preparation of human neural stem cells from induced pluripotent stem cells is time consuming, and the preparation of a patient's own neural stem cells within the subacute phase after spinal cord injury is impossible. The authors succeeded in inducing self-renewing and tripotent neural stem cells directly from mouse and human fibroblasts using Oct4, Sox2, Klf4, and cMyc without clonal isolation of the induced pluripotent stem cells. These directly induced cells, which bypassed complete reprogramming into induced pluripotent stem cells, rapidly differentiated into their progenies, compared with similar cells that differentiated from induced pluripotent stem cells. For future cell-based therapy, induced neural stem cells, which are reprogrammed by neural stem cell-specific transcriptional factors and are identical to those in vivo, should be established.