Identification of novel multipotent stem cells in mouse spinal cord following traumatic injury.

We showed that injury-induced multipotent stem cells (iSCs) emerge in the brain after stroke. These brain-derived iSCs (B-iSCs) can differentiate into various lineages, including neurons. This study aimed to determine whether similar stem cells can be induced even after non-ischemic injuries, such as trauma to the spinal cord. We characterized these cells, mainly focusing on their stemness, multipotency, and neuronal differentiation activities. Spinal cord injury was produced using forceps in adult mice. On day 3 after spinal cord injury, samples were obtained from the injured areas. Spinal cord sections were subjected to histological analyses. Cells were isolated and assessed for proliferative activities, immunohistochemistry, RT-PCR, FACS, and microarray analysis. Although nerve cell morphology was disrupted within the injured spinal cord, our histological observations revealed the presence of cells expressing stem cells, such as nestin and Sox2 in these areas. In addition, cells extracted from injured areas exhibited high proliferative abilities. These cells also expressed markers of both neural stem cells (e.g., nestin, Sox2) and multipotent stem cells (e.g., Sox2, c-myc, Klf4). They differentiated into adipocytes, osteocytes and chondrocytes, as well as neuronal cells. Microarray analysis further identified similar properties between spinal cord (SC)-derived iSCs and B-iSCs. However, SC-iSCs revealed specific genes related to the regulation of stemness and neurogenesis. We identified similar features related to multipotency in SC-iSCs compared to B-iSCs, including neuronal differentiation potential. Although the differences between SC-iSCs and B-iSCs remain largely undetermined, the present study shows that iSCs can develop even after non-ischemic injuries such as trauma. This phenomenon can occur outside the brain within the CNS.