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Abstract Studying and quantifying the mechanics of blood clots is essential to better diagnosis and prognosis of, as well as therapy for, thromboembolic pathologies such as strokes, heart attacks, and pulmonary embolisms. Unfortunately, mechanically testing blood clots is complicated by their softness and fragility, thus making the use of classic mounting techniques, such as clamping, challenging. This is particularly true for mechanical testing under large deformation. Here, we describe protocols for creating in vitro blood clots and securely mounting these samples on mechanical test equipment. To this end, we line 3D‐printed molds with a hook‐and‐loop fabric that, after coagulation, provides a secure interface between the sample and device mount. In summary, our molding and mounting protocols are ideal for performing large‐deformation mechanical testing, with samples that can withstand substantial deformation without delaminating from the apparatus. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Cube‐shaped blood clot preparation Basic Protocol 2: Sheet‐shaped blood clot preparation
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Mechanical properties of clot made from human and bovine whole blood differ significantly
Thromboembolism – that is, clot formation and the subsequent fragmentation of clot – is a leading cause of death worldwide. Clots’ mechanical properties are critical determinants of both the embolization process and the pathophysiological consequences thereof. Thus, understanding and quantifying the mechanical properties of clots is important to our ability to treat and prevent thromboembolic disease. However, assessing these properties from in vivo clots is experimentally challenging. Therefore, we and others have turned to studying in vitro clot mimics instead. Unfortunately, there are significant discrepancies in the reported properties of these clot mimics, which have been hypothesized to arise from differences in experimental techniques and blood sources. The goal of our current work is therefore to compare the mechanical behavior of clots made from the two most common sources, human and bovine blood, using the same experimental techniques. To this end, we tested clots under pure shear with and without initial cracks, under cyclic loading, and under stress relaxation. Based on these data, we computed and compared stiffness, strength, work-to-rupture, fracture toughness, relaxation time constants, and prestrain. While clots from both sources behaved qualitatively similarly, they differed quantitatively in almost every metric. We also correlated each mechanical metric to measures of blood composition. Thereby, we traced this inter-species variability in clot mechanics back to significant differences in hematocrit, but not platelet count. Thus, our work suggests that the results of past studies that have used bovine blood to make in vitro mimics – without adjusting blood composition – should be interpreted carefully. Future studies about the mechanical properties of blood clots should focus on human blood alone.
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- Award ID(s):
- 2105175
- PAR ID:
- 10517632
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Journal of the Mechanical Behavior of Biomedical Materials
- Volume:
- 154
- Issue:
- C
- ISSN:
- 1751-6161
- Page Range / eLocation ID:
- 106508
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.jmbbm.2024.106508
