The treatment of ischemic stroke remains a daunting task as few therapeutic strategies have proven to be effective. Systemic thrombolysis with intravenous tissue plasminogen activator (tPA) remains the only proven treatment to improve clinical outcome of patients with acute ischemic stroke. But because of an increased risk of hemorrhage beyond 4.5 hours after onset of stroke, only certain stroke patients (1-2%) can benefit from tPA treatment.