Fractionated radiation facilitates repair and functional motor recovery after spinal cord transection in rat

Previous studies suggest that motor recovery does not occur after spinal co rd injury because reactive glia abort the natural repair processes. 4 perma nent wound gap is left in the cord and the brain-cord circuitry consequentl y remains broken. Single-dose x-irradiation destroys reactive glia at the d amage site in transected adult rat spinal cord. The wound then heals natura lly, and a partially functional brain-cord circuitry is reconstructed. Tint ing is crucial; cell ablation is beneficial only within the third week afte r injury. Data presented here point to the possibility of translating these observations into a clinical therapy for preventing the paralysis followin g spinal cord injury in the human. The lesion site (at low thoracic level) in severed adult rat spinal cord was treated daily, over the third week pos tinjury, with protocols of fractionated radiation similar to those for trea ting human spinal cord tumors. This resulted, as with the single-dose proto col, in wound healing and restoration of some hindquarter motor function, i n addition, the beneficial outcome was augmented. Of the restored hindlimb motor functions, weight-support and posture in stance was the only obvious one. Recovery of this motor function was partial to substantial and its inc idence was 100% instead of about 50% obtained with the single-dose treatmen t. None of the hindlimbs, however, regained frequent stepping or any weight -bearing locomotion. These data indicate that the therapeutic outcome may b e further augmented by tuning the radiation parameters within the critical time-window after injury. These data also indicate that dose-fractionation is an effective strategy and better than the single-dose treatment for targ eting of reactive cells that abort the natural repair, suggesting that radi ation therapy could be developed into a therapeutic procedure for repairing injured spinal cord. (C) 2001 Elsevier Science B.V. All rights reserved.