Abstract 522: VWF Inhibition by an RNA Aptamer Improves Functional Outcome Compared to rTPA in Ferric Chloride-induced Carotid Artery Thrombosis in Mice

Objective: To compare the functional effects of von Willebrand Factor (VWF) inhibition by RNA aptamer (T79) vs rTPA utilizing in vivo arterial thrombosis in mice. Approach and Results: We previously demonstrated that inhibition of VWF by a targeted RNA aptamer (T79) both prevents thrombosis and thrombolyses stabilized clots in a murine model of ferric chloride (FeCl 3 )-induced vascular injury suggesting a pivotal role for VWF in the pro-thrombotic and anti-thrombotic milieu. We hypothesized that T79 treatment, which demonstrated no hemorrhagic complications and greater re-perfusion compared to rTPA, would result in improved behavioral outcome with 7 day survival after vascular injury. Baseline locomotor testing in an open field was performed on both male and female, 8-16 week old, wild-type C57BL/6J mice. Occlusive arterial thrombus formation was induced by a 3 minute exposure to 10% FeCl 3 on the right common carotid monitored by Doppler flow and time to occlusion (blood flow of 0 ml/min) was measured. Twenty minutes after thrombus stabilization either T79 (0.1 mg/kg or 0.5 mg/kg bolus), rTPA (10 mg/kg 45 min infusion) or saline vehicle (45 min infusion) was introduced via a saphenous catheter. Animals were recovered and locomotor testing was repeated 48 hours and 7 days after injury with baseline set as 100%. All groups including vehicle control resulted in a statistically significant decrease in distance traveled (meters) and speed (meters/sec) at 48 hours after injury. At 7 days, 0.1 mg/kg T79 increased 29.89% from 48 hours, 0.5 mg/kg T79 increased 22.50% from 48 hours but rTPA treatment showed no significant improvement (2.79% increase) (n=4, p<0.001). In addition, 0.1 mg/kg and 0.5 mg/kg T79 resulted in a 28.46% and 22.44% increase in speed, respectively, at 7 days compared to 48 hours whereas rTPA did not (2.94% increase) (n=4, p<0.001). Interestingly, males scored lower on most behavioral parameters at 48 hours, but recovered to the same level as females by 7 days. No significant differences in time to occlusion or baseline locomotor testing were observed in any group. Conclusion: Inhibition of VWF by T79 aptamer markedly improves behavioral outcomes compared to rTPA after survival carotid artery occlusion following ferric chloride-induced injury in mice.