Vascular thrombosis is a major underlying factor in many cardiovascular, neurovascular, and related disorders, and is a significant post-surgical complication. Current imaging modalities used to assess thrombotic events present challenges because they primarily visualize the lack of blood flow rather than detailed information about a thrombus directly, and they cannot distinguish between newly formed and aged blood clots. Our team has previously demonstrated that high affinity and high specificity RNA aptamers can be generated against a number of coagulation proteins including thrombin and factor IXa. In addition, our team has demonstrated that aptamer-antidote pairs can be used as rapid binding-rapid reversal probes for real time detection of thrombi. The studies proposed in this application integrate aptamer-antidote pairs with sensitive total-body positron emission tomography (PET) imaging to develop a new approach in the way patients with thrombotic events can be stratified and subsequently treated. This proposal represents the convergence of multidisciplinary domains of expertise to explore a new team direction that will have a major impact on the field through the following Specific Aims: (1) Develop and evaluate aptamer-antidote pairs to perform rapid imaging of thrombi in mouse models for molecular thrombus profiling in vivo, and (2) Assess efficiency of radiolabeled aptamers for total-body PET in nonhuman primates. Preliminary results have demonstrated that aptamers can rapidly bind thrombin on active thrombi in vivo and that the antidotes can reverse such binding in under 5 minutes.
In Specific Aim 1, we will further develop this technology by conducting studies in mice with aptamer-antidote pairs generated to thrombin, von Willebrand Factor, and platelet protein GPIIb/IIIa individually and combined. Findings will be adapted in Specific Aim 2 to the translational rhesus monkey model system using total-body PET that has demonstrated outstanding sensitivity. These investigations propose a new strategy to address characterization of thrombi in vivo and include a multidisciplinary translational team with expertise in nucleic acid biochemistry, combinatorial chemistry, antithrombotic agents, novel diagnostic imaging tools and methods, and a nonhuman primate model system of profound translational importance.
The studies proposed are focused on the assessment of thrombi in vivo using rapid binding-rapid reversal aptamer-antidote technology in animal models, and a total-body positron emission tomography (PET) imaging approach. The overriding objective is to address current roadblocks to personalized care by providing new ways to stratify risk and characterize thrombotic events in patients across all age groups.
