ENDOGENOUS REPAIR AFTER SPINAL-CORD CONTUSION INJURIES IN THE RAT

Contusion injuries of the rat thoracic spinal cord were made using a s tandardized device developed for the Multicenter Animal Spinal Cord In jury Study (MASCIS). Lesions of different severity were studied for si gns of endogenous repair at times up to 6 weeks following injury. Cont usion injuries produced a typical picture of secondary damage resultin g in the destruction of the cord center and the chronic sparing of a p eripheral rim of fibers which varied in amount depending upon the inju ry magnitude. It was noted that the cavities often developed a dense c ellular matrix that became partially filled with nerve fibers and asso ciated Schwann cells. The amount of fiber and Schwann cell ingrowth wa s inversely related to the severity of injury and amount of peripheral fiber sparing. The source of the ingrowing fibers was not, determined , but many of them clearly originated in the dorsal roots. In addition to signs of regeneration, we noted evidence for the proliferation of cells located in the ependymal zone surrounding the central canal at e arly times following contusion injuries. These cells may contribute to the development of cellular trabeculae that provide a scaffolding wit hin the lesion cavity that provides the substrates for cellular infilt ration and regeneration of axons. Together, these observations suggest that the endogenous reparative response to spinal contusion injury is substantial. Understanding the regulation and restrictions on the rep air processes might lead to better ways in which to encourage spontane ous recovery after CNS injury. (C) 1997 Academic Press.