Equivalence of in vitro blood clot mechanical properties using different anticoagulants

The mechanical properties of blood clots are critical both to normal clot function and in thromboembolic diseases. Thus, assessing these properties is critical to our understanding of clot (patho-)physiology. Because in vivo clot assessment is practically difficult, we and others have resorted to studying clots in vitro. One unanswered question about these in vitro studies has been whether results are sensitive to the choice of anticoagulant. Therefore, the objective of our work is to determine whether the most common anticoagulants, acid citrate dextrose (ACD) and sodium citrate (SC), yield mechanically similar results during in vitro clot experimentation. To this end, we collected blood from nine healthy donors, with varying sexes and ages, and clotted samples from the same subjects either with ACD or SC. We then tested those samples in vitro to determine their tangent modulus (stiffness), fracture toughness, strength, and work-to-rupture. To evaluate the impact of anticoagulant choice on in vitro clot mechanics, we calculated Cohen's d effect sizes for each metric and compared them to previously reported biological variation. Notably, the magnitude of these anticoagulant-related differences is smaller than previously observed biological variation by sex in a similar population and under similar in vitro conditions. This provides a quantitative sense of their relative impact, indicating that anticoagulant choice contributes less variability than underlying biological factors in vitro blood clot mechanics studies.