DIFFUSE CEREBRAL MICROINFARCTION DISRUPTS NEUROVASCULAR FUNCTION AND REVEALS SEX-DEPENDENT VULNERABILITY

Cerebral microinfarcts are small ischemic lesions caused by microvascular occlusions and highly prevalent in the aging brain. Microinfarcts are present in both cognitively impaired and unimpaired individuals and strongly associated with vascular cognitive impairment (VCI) and dementia. Microinfarct burden is further linked to vascular dysfunction, neuroinflammation, and cognitive impairment, suggesting additive contributions to neurodegeneration. This study aimed to investigate the pathophysiological consequences of diffuse microvascular occlusion. Male and female C57BL/6 mice were systemically transduced with the encoded calcium indicator GCaMP6s via intravenous AAV.PHP.eB.Syn.GCaMP6s delivery. Diffuse cerebral microinfarcts were induced by injecting red fluorescent 45µm microspheres into the internal carotid artery, producing lesions reminiscent of human small vessel disease. Behavioural tasks, retinal angiography and transcranial imaging of resting state, visual-stimulation evoked activity and blood flow were recorded longitudinally in awake, headfixed mice. Widefield calcium imaging revealed marked impairments in evoked neuronal responses and resting-state functional connectivity, accompanied by deficits in sensorimotor and cognitive behaviors, with females exhibiting greater susceptibility to microsphere-induced dysfunction. Laser speckle contrast imaging demonstrated blood flow rerouting through collateral vessels, while longitudinal imaging revealed progressive microemboli migration. Retinal angiography identified transient increases in venous diameter and tortuosity 2 days post-induction (DPI). Light-sheet fluorescence microscopy confirmed widespread cortical microsphere distribution persisting at 14 DPI. These findings establish a robust model of cerebral microinfarction that recapitulates key features of VCI. The results highlight acute vascular and neuronal consequences of diffuse microvascular occlusion, sex-dependent vulnerability, and provide a foundation for mechanistic studies of microinfarct-driven neurodegeneration.