Collateral growth and angiogenesis around cortical stroke

Background and Purpose-We tested the hypothesis that there are significant long-term local vascular changes after ministroke that could form a basis f or functional recovery. Methods-A 6- to 8-mm cranial window was opened over the barrel cortex, whic h was identified by an intrinsic optical signal during mechanical stimulati on of the whiskers in anesthetized female Wistar rats. Branches of the midd le cerebral artery (MCA) to this region were ligated. Fluorescein isothiocy anate (FITC) transits were recorded by videomicroscopy in each rat just bef ore, immediately after, and 30 days after ligation. Changes in surface vess els and parenchymal perfusion were measured. In similarly prepared rats, an giogenesis was identified by 5-bromo-2-deoxyuridine labeling and immunohist ochemistry for the integrin family member alpha (v)beta (3). Results-The intrinsic optical signal disappeared immediately after MCA liga tions. FITC injection just after ligation demonstrated 3 concentric regions : 1 region of unchanged perfusion, surrounding I region of reduced perfusio n (the ischemic border) surrounding a central core with little observable p erfusion. At 30 days, the following had taken place: (1) diameters and leng ths of surface collaterals in the ischemic border had grown significantly, but no new surface vessels were detected, (2) FITC entered occluded MCA seg ments, (3) arteriocapillary latencies in the ischemic border were shortened compared with latencies just after ligation, and (4) small infarcts were v irtually identical to the poorly perfused core. Angiogenesis was confined t o the ischemic border. Conclusions-Arteriolar collateral growth and new capillaries support restor ed perfusion in the ischemic border after ministroke and could support long -term functional recovery.