A QUANTITATIVE SPATIAL-ANALYSIS OF THE BLOOD SPINAL-CORD BARRIER .2. PERMEABILITY AFTER INTRASPINAL FETAL TRANSPLANTATION

In previous experiments we utilized quantitative autoradiography to te mporally describe vascular permeability of a radiolabeled vascular tra cer following spinal contusion injury in the rat. In the present repor t we compare these findings with permeability assessments following fe tal grafting in the contused rat spinal cord. At 10 days postinjury, E mbryonic Day 14 spinal tissue was grafted into the lesioned spinal cor d of Sprague-Dawley rats. At 7, 14, and 28 days postgrafting the alpha -aminoisobutyric acid (AIB) technique was used to assess blood-to-tiss ue transfer rates in graft and host tissue over several segments of th e injured spinal cord, Regional changes in permeability were assessed using four distinct image analysis techniques. Using these methods, we have previously shown that contusion injury alone results in a chroni c relapse in vascular permeability. The present data indicate that fet al transplants at 7 days postgrafting have AIB transfer rates that are significantly above uninjured control levels and are similar in magni tude to neighboring host spinal tissue. In addition, permeability in 1 4- and 28-day intraspinal grafts decreased relative to that of the 7-d ay transplant group, but remained significantly elevated at and rostra l to the injury epicenter. Alternately, graft and host tissue in regio ns caudal to the injury epicenter (e.g., T-10-L(2)) acquired a functio nal barrier to AIB as early as 14 days posttransplantation. These expe riments suggest that graft development occurs in a different manner or at a different rate in segments of the injured spinal cord rostral an d caudal to the injury site. Additionally, it appears that vascular pe rmeability of the injured spinal cord can be influenced by the process of intraspinal transplantation. (C) 1996 Academic Press, Inc.