Thrombolysis with
tissue plasminogen activator (tPA) is the only FDA-approved
therapy for
acute ischemic stroke. However, hemorrhagic transformation, neurotoxicity, and a short treatment time window comprise major limitations for
thrombolytic therapy. The purpose of the present study was to investigate whether
fasudil, a
Rho kinase (ROCK) inhibitor, would prevent tPA-associated hemorrhagic transformation and extend the reperfusion window in an experimental
stroke model in mice. Mice subjected to 6-h
middle cerebral artery occlusion were treated with delayed tPA alone, with combined tPA plus
fasudil, or with a vehicle. We used histological and neurobehavioral measures to assess the effects of the treatment at 18 h and 7 days after the reperfusion. To investigate the mechanism of
fasudil's beneficial effects further, we also performed an in vitro study with tPA and
fasudil in human brain microvascular endothelial cells. Combination
therapy with tPA plus
fasudil prevented the development of hemorrhagic transformation, but did not reduce the
infarct volumes. These changes significantly reduced mortality and increased locomotor activity at 7 days after the reperfusion. Furthermore, the administration of both drugs prevented injury to the human brain endothelial cells via the reduction of
matrix metalloproteinase-9 (MMP-9) activity. These findings indicate that
fasudil prevents the hemorrhagic transformation induced by focal
cerebral ischemia in mice treated with tPA, at least in part, by inhibiting the increased activity of MMP-9 in endothelial cells.