Blake Holthaus – Biomedical Science

Project Title: VWF inhibition by an RNA aptamer (DTRI-031) in combination with rTPA increases thrombolytic efficacy compared to rTPA or aspirin in mouse, canine, and human blood

Project Mentor: Shahid Nimjee – Neurological Surgery

Abstract:

Acute ischemic stroke (AIS) is the leading cause of disability in the US. Although recombinant tissue plasminogen activator (rTPA) is the only approved AIS thrombolytic, treatment is limited by lack of reversibility and risk of hemorrhage. Von Willebrand Factor (VWF) is a glycoprotein involved in platelet activation and aggregation to mediate thrombosis in case of lethal injury. We have developed an RNA aptamer (DTRI-031) that inhibits VWF. We compared the thrombolytic efficacy of DTRI-031 to rTPA and aspirin utilizing an ex vivo Halo assay with whole blood from male and female, 15 month old wild-type C57BL/6J adult mice, 1 year old hounds, and healthy patients 40-60 years of age. Healthy patients The mean CLRmax of the control group (n=6) was 0.024 +/- 0.17 min-1. Addition of 250 nM DTRI-031 (n=8) or 0.7 nM rTPA (n=8) increased the CLRmax to 1.67 +/- 1.56 min-1 and 1.80 +/- 1.41 min-1 respectively (Fig 1A). Addition of 500 nM DTRI-031 and 0.7 rTPA (n=4) resulted in a synergistic effect of both compounds with a CLRmax of 10.15 +/- 2.4 min-1(p=.0003). Mice The CLRmax of the negative control (n=6) was 0.013 +/- 0.011 min-1. Addition of 250 nM DTRI-031 (n=6) increased the CLRmax to 1.19 +/- 1.27 min-1 (Fig 1B). Addition of 7 nM rTPA (n=6) increased the CLRmax to 0.13 +/- 0.13 min-1. The synergistic effect of DTRI-031+rTPA was seen at doses of 250 nM DTRI + 7 nM rTPA (n=4) with a CLRmax of 2.08 +/- 1.45 min-1 and 500 nM + 7 nM rTPA (n=6) with a CLRmax of 4.3 +/- 2.5 min-1compared to monotherapy (p<0.0001). Canine The CLRmax of the negative control (n=33) was 2.611 +/- 2.659 min-1. Addition of 250 nM DTRI-031 or 500 nM DTRI-031 and 0.7 rTPA (n=18) resulted in a synergistic effect of both compounds which were significantly greater than all monotherapies with a CLRmax of 13.52 +/- 8.985 min-1 and 9.152 +/- 6.943 min-1, respectively. DTRI-031 + rTPA significantly improves clot lysis rate compared to monotherapies in mouse, canine, and human blood.

 

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