Phosphodiesterase-III Inhibitor Prevents Hemorrhagic Transformation Induced by Focal Cerebral Ischemia in Mice Treated with tPA

Abstract

The purpose of the present study was to investigate whether cilostazol, a phosphodiesterase-III inhibitor and antiplatelet drug, would prevent tPA-associated hemorrhagic transformation. Mice subjected to 6-h middle cerebral artery occlusion were treated with delayed tPA alone at 6 h, with combined tPA plus cilostazol at 6 h, or with vehicle at 6 h. We used multiple imaging (electron microscopy, spectroscopy), histological and neurobehavioral measures to assess the effects of the treatment at 18 h and 7 days after the reperfusion. To further investigate the mechanism of cilostazol to beneficial effect, we also performed an in vitro study with tPA and a phosphodiesterase-III inhibitor in human brain microvascular endothelial cells, pericytes, and astrocytes. Combination therapy with tPA plus cilostazol prevented development of hemorrhagic transformation, reduced brain edema, prevented endothelial injury via reduction MMP-9 activity, and prevented the blood-brain barrier opening by inhibiting decreased claudin-5 expression. These changes significantly reduced the morbidity and mortality at 18 h and 7 days after the reperfusion. Also, the administration of both drugs prevented injury to brain human endothelial cells and human brain pericytes. The present study indicates that a phosphodiesterase-III inhibitor prevents the hemorrhagic transformation induced by focal cerebral ischemia in mice treated with tPA.

Cilostazol Ameliorates Warfarin-Induced Hemorrhagic Transformation After Cerebral Ischemia in Mice

“…We determined the optimal timing and route of cilostazol administration in a previous study using a tissue-type plasminogen activator-induced HT model. 12 We have also reported that a high dose of cilostazol (10 mg/kg, IP) suppressed infarct volume, 10 but a lower dose (3 mg/kg, IP) did not, 29 and we found similar results in the present study. However, swelling was exacerbated by warfarin administration, and this effect was suppressed by cilostazol (3 mg/kg, IP), resulting in the same severity of swelling as that seen in the vehicle group.…”

“…26 We and others have reported that cilostazol has protective effects on vascular endothelial cells 10,13,27 and that it suppresses the exacerbation of HT by tissue-type plasminogen activator. 12 In the present study, we obtained the following 4 results: (1) cilostazol (3 mg/kg, IP) prevented the exacerbation of HT caused by warfarin without affecting infarct volume; (2) survival rate was significantly higher in the combination therapy group than in the warfarin monotherapy group; (3) the mechanism whereby cilostazol prevented the exacerbation of HT might involve maintenance of the expression of tight junction proteins (claudin-5 and ZO-1) and VE-cadherin; and (4) combination therapy did not extend bleeding time.…”

“…This is in agreement with our previous study, where we found that the neurological deficit scores of mice with tissue-type plasminogen activatorinduced HT did not worsen and were not altered by cilostazol (3 mg/kg, IP). 12,29 Long-term studies may show greater intergroup differences in neurological deficit scores.…”

“…12 This finding suggested that MMP-9 was involved in BBB collapse, and that overexpression of MMP-2 or MMP-9 may exacerbate swelling and hemorrhage after brain injury, through the breakdown of collagen type IV in the vessel basement membrane. [30][31][32] We therefore investigated MMP-2 and MMP-9 expression levels; however, no drug-related changes in MMP-2 or MMP-9 protein levels were found ( Figure I in the online-only Data Supplement).…”

“…One of the characteristic features of cilostazol is its potential to protect the vascular endothelium. 10,[12][13][14] We previously demonstrated that cilostazol reduced HT after cerebral ischemia, via prevention of BBB disruption in mice. 10,12 In the present study, we extend this work to clarify the efficacy of cilostazol in preventing warfarin-induced HT after cerebral ischemia in a mouse model.…”