Prophylactic administration of NAC prevents severe TTP signs in mice. (A) Adamts13^−/− mice (control n = 11; NAC treatment n = 12) were injected with 800 mg/kg NAC (open blue circles) or equal volumes of saline for control (solid red circles) 15 minutes prior to rVWF injection. (B-D) At baseline and 24 hours after rVWF injection, platelet count (B), hemoglobin level (C), and LDH activity level (D) were determined. (E) H&E staining was performed on myocardial tissue sections from control mice (top panel) and mice with prophylactic NAC administration (bottom panel). Arrows indicate sites of myocardial necrosis. Scale bars indicate 50 μm. (F) VWF multimer composition was analyzed, and representative images of VWF multimeric profiles from a control mouse and an NAC-treated mouse are shown. (G) Percentage of HMW VWF multimers was quantified using densitometry. Statistical significance is indicated with asterisks: *P < .05, **P < .01, ***P < .001.