IFNβ ameliorates delayed tPA-exacerbated brain injury and reduces mortality in ischemic stroke. (A) Adult male mice were subjected to 3-hour MCAO followed immediately by vehicle, tPA, or tPA plus IFNβ administration. At 20 hours postinjury, the ischemic brains were harvested and then subjected to TTC staining. Two representative TTC-stained brain samples of each group are shown, and the infarct volume of ischemic brains was measured (n = 10 per group). The survival rates of vehicle-, tPA-, and tPA plus IFNβ-treated MCAO mice were monitored up to day 7 postischemia (n = 10 per group). Aged male (B) and aged female (C) mice were subjected to 3-hour MCAO followed by vehicle, tPA, or tPA plus IFNβ administration. Mice were euthanized at 20 hours postinjury, and the harvested ischemic brains were subjected to TTC staining. Two representative TTC-stained brain samples of each group are shown, and the infarct volume of ischemic brains was measured (aged male mice: vehicle, n = 7; tPA, n = 8; tPA plus IFNβ, n = 10; aged female mice: vehicle, n = 9; tPA, n = 7; tPA plus IFNβ, n = 7). The mortality rate was also assessed (the numbers indicated on the figures represent the number of MCAO mice that died/the number of MCAO mice included in each group). *P < .05 by 1-way ANOVA (A [left],C) or log-rank test of Kaplan-Meier survival curve (A, right), **P < .01 by 1-way ANOVA (A [left]-B).