Microvascular structure after embolic focal cerebral ischemia in the rat

Objectives: We analyze morphological alterations of cerebral neovascularization after stroke using a new 3D imaging software program. Methods: Male Wistar rats underwent unilateral embolic middle cerebral artery occlusion (MCAo) by a single fibrin rich clot. Subjects were sacrificed from 1 to 28 days post infarct. Vessel perimeters were measured on coronal sections stained with endothelial cell-specific antibody to von Willebrand's factor. Vessel segment lengths, diameters and number of vessels were analyzed on cerebral microvessels perfused with FITC-dextran 14 days after ischemia using LSCM and a 3-D vessel quantification program. Results: The mean number of microvessels with enlarged perimeters significantly increased in the ipsilateral cortex at day 7 when compared to the contralateral cortex (29.7 +/- 14.7 vs. 3.7 +/- 2.5, P<0.05). Subsequently, differences in the number of microvessels with enlarged perimeters decreased on days 14 and 28. Fourteen days post-MCA occlusion, microvessel segment length (15.0 vs. 26.0 mum, P<0.05) and diameter (3.14 vs. 3.75 Rm, P<0.05) significantly decreased in the ipsilateral hemisphere when compared to the contralateral hemisphere, respectively. Furthermore, the mean total number of these smaller microvessels increased in the ipsilateral hemisphere (57.33 +/- 14.5 vs. 32.22 +/- 11.7, P<0.05). Conclusions: Focal cerebral ischemia induces morphological changes (early dilated microvessels followed by decreased microvessel segment length and diameter) that are consistent with newly generated microvessels. (C) 2003 Elsevier Science B.V. All rights reserved.