Abstract 187: Reversible Aptamer Inhibition of Von Willebrand Factor is a Potent Thrombolytic and Ameliorates Stroke Burden Following Vascular Injury Compared to Recombinant Tissue Plasminogen Activator

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Abstract

Introduction: While recombinant tissue plasminogen activator (rTPA) is the mainstay of ischemic stroke treatment, few patients are eligible for treatment, and recanalization is only seen in 25-50%. Von Willebrand Factor (VWF) inhibition may play a role in thrombolysis.

Hypothesis: VWF inhibition with an RNA aptamer lyses arterial thrombus and decreases ischemic injury. Furthermore, aptamer reversal with an antidote oligonucleotide ameliorates intracranial hemorrhage (ICH).

Methods: Adult wild-type (C57BL/6J) mice were anesthetized, and the right carotid artery was exposed. Baseline carotid flow was obtained using a Doppler flow probe, and thrombotic occlusion was induced with a ferric chloride patch. After clot stabilization, mice were administered vehicle (platelet binding buffer, n=11), no infusion (n=8), rTPA (n=5) or VWF aptamer (n=5). Carotid flow was monitored for an additional 100 minutes. In a second cohort of mice, a 6-0 nylon suture was advanced within the carotid artery to generate vascular injury and ICH. Mice were given vehicle (n=16), rTPA (n=11), VWF aptamer (n=9) or aptamer/antidote (n=8). An MRI was obtained after 90 minutes to assess stroke and ICH volumes.

Results: VWF aptamer successfully restored carotid blood flow 45 minutes following carotid occlusion (Figure 1) compared to controls (p<0.01*) and rTPA (p<0.05+). Stroke volume was significantly decreased in mice treated with VWF aptamer (23.03 ± 6.81 mm3) and aptamer/antidote (12.48 ± 5.68 mm3) compared to vehicle (45.25 ± 4.14 mm3, p<0.01). ICH volumes in mice treated with rTPA (2.64 ± 0.84 mm3) were trending higher than vehicle (1.51 ± 0.17 mm3), VWF aptamer (1.92 ± 0.22 mm3) or aptamer/antidote (1.31 ± 0.35 mm3).

Conclusions: Aptamer inhibition of VWF is a potent thrombolytic agent with greater efficacy compared to rTPA. VWF inhibition appears safe with a trend toward lower ICH volumes in animals treated with aptamer and aptamer/antidote compared to rTPA.

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