Essig F, Kollikowski AM, Müllges W, et al. - Researchers used a sampling and sample preparation protocol of local microcatheter aspiration from within the occluded vascular field (before recanalization) that is novel and efficient for measuring local concentrations. In acute ischemic stroke (IS), the efficacy of intravenous recombinant t-PA (rt-PA) is attributed to timely recanalization by clot fibrinolysis. Guidelines advocate rt-PA before mechanical thrombectomy (MT) because rt-PA may recanalize LVO earlier in large-vessel occlusion (LVO) stroke. Nevertheless, recanalization by rt-PA before MT occurs in only about 10% of cases. The data demonstrated that rt-PA acts beneficially on the ischemic microvascular even before recanalization despite occlusion. As per the data, local cerebral concentrations of exogenous rt-PA and endogenous t-PA (in patients not receiving rt-PA) are unknown.