Tissue-type plasminogen activator crosses the intact blood-brain barrier by low-density lipoprotein receptor-related protein-mediated transcytosis.

Accumulating evidence demonstrates a critical involvement of tissue-type plasminogen activator (tPA) in pathological and physiological brain conditions. Determining whether and how vascular tPA can cross the blood-brain barrier (BBB) to enter the brain is thus important, not only during stroke but also in physiological conditions.