QUANTITATIVE-ANALYSIS OF VASCULARIZATION AND CYTOCHROME-OXIDASE FOLLOWING FETAL TRANSPLANTATION IN THE CONTUSED RAT SPINAL-CORD

In the normal adult central nervous system, a coupling between energy consumption and vascular density is well established. Likewise, the su rvival of fetal neural tissue grafts is highly dependent on the establ ishment of functional vascular integration with the host. However, to what degree graft vascularization and tissue metabolism influence the normal host response to traumatic injury has not been extensively stud ied. In the present report, embryonic day 14 fetal spinal cord suspens ion grafts were made into the lesion epicenter of subchronic (10 days) contusion-injured rats. Three months later, intraspinal transplants w ere analyzed using correlative cytochrome oxidase histochemistry and v ascular morphometric analysis. The same approaches were applied to the host spinal cord and injured, non-transplanted animals in order to de termine the ability of a graft to alter the level of post-injury vascu larization and/or metabolism. In general, graft vascular density was i ncreased over that measured in normal or injured gray matter. Vascular density in gray matter near the host/graft interface was markedly inc reased when compared to either gray matter of the same spinal level in injured non-grafted animals or normal control spinal gray matter. Vas cular changes were not noted in gray matter 3 mm distal to the lesion epicenter (rostral or caudal) in all groups analyzed. Cytochrome oxida se was up-regulated at this time in the graft and gray matter at the h ost/graft interfaces when compared to either gray matter of the same s pinal level in injured, non-grafted animals or that of uninjured contr ols. These data indicate that an intraspinal transplant placed into th e contused adult rat spinal cord reaches a metabolic capacity that is likely to be associated with high levels of oxidative metabolism in th e well-vascularized graft neuropil. In addition, transplantation chron ically alters vascularization and metabolic patterns of adjacent spina l gray matter following contusion injury. (C) 1996 Wiley-Liss, Inc.