Abstract WMP116: Age-related Dysfunction In Leptomeningeal Collateral Remodeling After Ischemic Stroke

Introduction: The leptomeningeal collaterals (LMCs) are specialized brain surface arterioles that interconnect the major cerebral artery territories. Good outcome following ischemic stroke is highly correlated with high collateral number and function. Unfortunately, with aging and disease, the LMCs demonstrate impaired dilatory capacity, reduced vessel diameter, and even complete vessel loss (rarefaction). The present study examined the chronic remodeling capacity of LMCs following permanent stroke in young and aged mice. Methods: Young and aged C57BL6 mice (5 and 20 months) were subjected to permanent distal middle cerebral artery occlusion (pdMCAO). At 2 weeks or 3 months, LMCs were evaluated for inner diameter and VWF expression (% LMC coverage). We compared the LMCs feeding the occluded MCA territory (LMC ipsi) to the contralateral equivalent vessels (LMC contra). Diameter change is reported as fold change relative to the distal-most arteriole (DMA) associated with each LMC. Results: Young male mice demonstrated increased diameter of LMC ipsi relative to DMA at both 2 weeks (1.36 ± 0.075; n=24 vessels/4 mice, P Conclusions: Our data show lasting LMC remodeling in young stroke brain, consisting of increased LMC diameter and expression of VWF. With aging, LMC remodeling is transient and evidence of LMC rarefaction is apparent by 3 months.