Adjuvant Treatment With a Glycoprotein IIb/IIIa Receptor Inhibitor Increases the Therapeutic Window for Low-Dose Tissue Plasminogen Activator Administration in a Rat Model of Embolic Stroke

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Abstract
Background— Platelet aggregation and fibrin deposition are key events leading to microvascular thrombosis and progressive impairment of downstream microvascular perfusion after stroke. We tested the hypothesis that inhibition of platelet function with a GP IIb/IIIa receptor antagonist would increase the efficacy and safety and increase the time window for thrombolytic therapy for stroke with full- and half-dose tissue plasminogen activator (tPA). Methods and Results— Rats were subjected to embolic middle cerebral artery occlusion. Four hours after ischemia, rats were treated with 7E3 F(ab′) 2 (6 mg/kg) in combination with tPA at doses of 10 and 5 mg/kg, tPA alone at a dose of 10 or 5 mg/kg, 7E3 F(ab′) 2 (6 mg/kg) alone, or saline. Combination treatment with 7E3 F(ab′) 2 and tPA (full- or half-dose) significantly ( P 2 or tPA (full- or half-dose) alone did not reduce infarct volume. Quantitative measurements of cerebral microvessels perfused by FITC-dextran revealed that combination treatment with 7E3 F(ab′) 2 and full-dose tPA significantly ( P 2 in combination with full-dose tPA significantly ( P Conclusions— Combination treatment with 7E3 F(ab′) 2 with full- and half-dose tPA at 4 hours after ischemia significantly reduces infarct volume and improves neurological outcome. Enhancement of patency and integrity of cerebral microvessels most likely contributes to the benefits observed with this combination therapy.