Design of Potent and Controllable Anticoagulants Using DNA Aptamers and Nanostructures.

Abhijit Rangnekar,Bethany Goodfred,Yaroslava G Yingling,Thomas H Labean,Jessica A Nash

doi:10.3390/molecules21020202

Abhijit Rangnekar, Bethany Goodfred + Show 3 more

Open Access

https://doi.org/10.3390/molecules21020202

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Abstract

The regulation of thrombin activity offers an opportunity to regulate blood clotting because of the central role played by this molecule in the coagulation cascade. Thrombin-binding DNA aptamers have been used to inhibit thrombin activity. In the past, to address the low efficacy reported for these aptamers during clinical trials, multiple aptamers have been linked using DNA nanostructures. Here, we modify that strategy by linking multiple copies of various thrombin-binding aptamers using DNA weave tiles. The resulting constructs have very high anticoagulant activity in functional assays owing to their improved cooperative binding affinity to thrombin due to optimized spacing, orientation, and the high local concentration of aptamers. We also report the results of molecular dynamics simulations to gain insight into the solution conformations of the tiles. Moreover, by using DNA strand displacement, we were able to turn the coagulation cascade off and on as desired, thereby enabling significantly better control over blood coagulation.

Highlights

Thrombin is a crucial component of the blood coagulation cascade
We further demonstrated that thrombin-binding aptamers devoid of chemical modifications are much more stable in plasma when linked to weave tile compared to free aptamers [17]
When the aptamer pairs B-A and B-P were connected via a 20-nucleotide single-stranded DNA (ssDNA) linker, the resulting construct displayed much higher anticoagulant activity compared to free aptamers (Figure 3) which substantiates previously published results [3,17]

Summary

Introduction

Thrombin is a crucial component of the blood coagulation cascade. It catalyzes key reactions during coagulation, including conversion of Factor XI to XIa, Factor VIII to VIIIa, Factor V to Va and soluble fibrinogen to insoluble fibrin. Thrombin causes activation and aggregation of platelets during blood clot formation [1]. Regulation of thrombin activity via inhibition can play a crucial role in clinical conditions such as acute coronary syndrome, peripheral vascular disease and deep vein thrombosis, as well as arterial and venous thromboembolism [2]. The anion-binding exosite I helps in conversion of fibrinogen to fibrin and the heparin-binding exosite II plays a crucial role in platelet activation and aggregation during coagulation [1]. Nucleic acid aptamers are non-toxic and non-immunogenic and offer a safer alternative [2]

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Discussion

Conclusion