Therapeutic administration of plasminogen activator inhibitor-1 prevents hypoxic-ischemic brain injury in newborns.

Author(s): Yang D, Nemkul N, Shereen A, Jone A, Dunn RS, Lawrence DA, Lindquist D, Kuan CY

Affiliation(s): Division of Developmental Biology and Division of Neurology, Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.

Publication date & source: 2009-07-08, J Neurosci., 29(27):8669-74.

Publication type: Comparative Study; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Disruption of the integrity of the blood-brain barrier (BBB) is an important mechanism of cerebrovascular diseases, including neonatal cerebral hypoxia-ischemia (HI). Although both tissue-type plasminogen activator (tPA) and matrix metalloproteinase-9 (MMP-9) can produce BBB damage, their relationship in neonatal cerebral HI is unclear. Here we use a rodent model to test whether the plasminogen activator (PA) system is critical for MMP-9 activation and HI-induced brain injury in newborns. To test this hypothesis, we examined the therapeutic effect of intracerebroventricular injection of plasminogen activator inhibitor-1 (PAI-1) in rat pups subjected to unilateral carotid artery occlusion and systemic hypoxia. We found that the injection of PAI-1 greatly reduced the activity of both tPA and urokinase-type plasminogen activator after HI. It also blocked HI-induced MMP-9 activation and BBB permeability at 24 h of recovery. Furthermore, magnetic resonance imaging and histological analysis showed the PAI-1 treatment reduced brain edema, axonal degeneration, and cortical cell death at 24-48 h of recovery. Finally, the PAI-1 therapy provided a dose-dependent decrease of brain tissue loss at 7 d of recovery, with the therapeutic window at 4 h after the HI insult. Together, these results suggest that the brain PA system plays a pivotal role in neonatal cerebral HI and may be a promising therapeutic target in infants suffering hypoxic-ischemic encephalopathy.