White matter preservation after spinal cord injury in ICAM-1/P-selectin-deficient mice

We have previously demonstrated that mice deficient in ICAM-1 and P-selecti n (ICAM-1/PS-/-) have improved functional recovery after spinal cord injury (SCI), compared to injured controls. In this study the spinal cords from w ild-type and ICAM-1/PS-/- mice were evaluated histopathologically 14 days a fter severe compression-type SCI. Following injury there was an atrophy of the spinal cord. Significant sparing of total cross-sectional area was note d in ICAM-1/PS-/- mice compared to injured controls at the site of compress ion and in the distal peri-injury zone. Likewise, significant preservation of white matter area, as measured by Luxol staining, was found in mutant mi ce at the site of injury and in the proximal peri-injury zone. Gray matter damage was investigated by microtubule-associated protein 2 immunohistochem istry. Following severe SCI, a trend of gray matter sparing was noticed in ICAM-1/PS-/- animals. Quantitation of iba1 immunohistochemistry revealed th at microglial reaction was significantly suppressed in the mutant animals. Astroglial reaction, visualized by GFAP immunostaining, did not differ betw een groups. Our results indicate that ICAM-1 and P-selectin are involved in autodestructive events provoked by the initial injury but the precise unde rlying mechanisms remain obscure.