Functional recovery after spinal cord injury in mice through activation of microglia and dendritic cells after IL‐12 administration

Abstract We have previously reported that the transplantation of dendritic cells (DCs) brings about functional recovery after spinal cord injury in mice through the activation of endogenous microglia/macrophages and neural stem/progenitor cells. In this study, the effect of interleukin‐12 (IL‐12), which is secreted from DCs, was evaluated for the treatment of spinal cord injury in mice. Administration of IL‐12 into the injured site significantly increased the number of activated microglia/macrophages and DCs as well as the expression of brain‐derived neurotrophic factor surrounding the lesion site. Immunohistochemical analyses showed that de novo neurogenesis and remyelination were induced by IL‐12 treatment. Furthermore, an open field test using Basso‐Beattie‐Brenham scoring revealed a significant improvement of locomotor function in mice treated with IL‐12. These results suggest that IL‐12 administration into the injured spinal cord results in a functional recovery through the activation of microglia/macrophages and DCs. © 2008 Wiley‐Liss, Inc.