Anti-inflammatory, antithrombotic, and neuroprotective effects of activated protein C in a murine model of focal ischemic stroke

Background-Activated protein C (APC) contributes to systemic anticoagulant and anti-inflammatory activities. APC may reduce organ damage by inhibiting thrombin generation and leukocyte activation. Neutrophils and cerebrovascu lar thrombosis contribute to ischemic neuronal injury, suggesting that APC may be a potential protective agent for stroke. Methods and Results-We examined the effects of APC in a murine model of foc al ischemia. After middle cerebral artery occlusion/reperfusion, the averag e survival time in controls was 13.6 hours. Animals that received purified human plasma-derived APC 2 mg/kg IV either 15 minutes before or 10 minutes after stroke induction survived 24 hours and were killed for neuropathologi cal analysis. APC 2 mg/kg given before or after onset of ischemia restored cerebral blood flow, reduced brain infarct volume (59% to 69%; P<0.003) and brain edema (50% to 61%; P<0.05), eliminated brain infiltration with neutr ophils, and reduced the number of fibrin-positive cerebral vessels by 57% ( P<0.05) and 25% (nonsignificant), respectively. The neuroprotective effect of APC was dose-dependent and associated with significant inhibition of ICA M-1 expression on ischemic cerebral blood vessels (eg, 61% inhibition with 2 mg/kg APC). Intracerebral bleeding was not observed with APC. Conclusions-APC exerts anti-inflammatory, antithrombotic, and neuroprotecti ve effects in stroke. Central effects of APC are likely to be related to im proved maintenance of the blood-brain barrier to neutrophils and to reduced microvascular obstructions and fibrin deposition.