| Abstract: |
Progressive tissue decay at the lesion site is the pathologic hallmark of spinal cord (SC) injury. Identifying the stages of pathology progression is crucial in developing strategies for repair. In transected rat SC, the onset of decay can be prevented by radiation delivered before intrinsic repair is aborted-2-3 wks postinjury (PI)-thereby, structural and functional repair is facilitated (PNAS(1996)93:111791; BR(2001)904:199). Our focus now is on contusion injury that is similar to the human SC injury. Here we examine the progression of events at the lesion site after contusion in adult rat SC. A moderate (12.5mm drop) contusion in rat SC was performed with an NYU weight-drop device.)The lesion site was analyzed at 0,1,4,6,8,11,14,19,21,28,34,40,50 & 57 days PI by routine histology and by immunohistochemistry for VCAM-1 to pinpoint the onset of chronic inflammation by activated blood-cord barrier endothelia. Data show that apart from the swelling and related compression and rupture of intact tissue, which develop by the 4th day PI, the progression of events after contusion are similar to those in transection injury1; i.e., intrinsic repair proceeds through the 2nd wk PI whereas the onset of decay occurs early at the 3rd wk PI.)Similar results were obtained in our longitudinal in vivo MRI study (SNA (2001)27:2118). The swelling seems to be detrimental in the SC fate as at first the lesion (hemorrhage) is confined to the SC center while the dorsal/ventral white matter is intact. Our data suggest a window of opportunity for preventing the onset of decay also exists in contusion injury provided that prior decompression is performed. |
