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Updated: Mar 22, 2026
Microfluidics in Assessing Platelet Function
Published on: November 8, 2024
Endothelial, platelet, and macrophage microparticle levels do not change acutely following transcatheter aortic valve
Julio F Marchini1,2, Ayumi Aurea Miyakawa3, Flavio Tarasoutchi4
1Laboratory of Genetics and Molecular Cardiology, Heart Institute, University of São Paulo Medical School, São Paulo, SP, Brazil. jfmarchini@usp.br.
Background:
Patients with severe aortic stenosis have increased levels of prothrombotic and proinflammatory microparticles (MP), and MPs actively regulate pathological processes that lead to atherothrombotic cardiovascular events. Shear stress is a validated stimulus of MP production, and abnormal shear stress in aortic stenosis increases MP release in ex-vivo studies. We hypothesized that in patients with severe aortic stenosis, percutaneous replacement of the aortic valve (TAVR) would reduce abnormal shear stress and would decrease levels of circulating MPs.
Findings:
The experimental protocol utilized flow cytometry (FC) and nanoparticle tracking analysis (NTA) to quantify circulating plasma MP levels in aortic stenosis patients at baseline and 5 days after TAVR. The baseline and 5 day MP counts measured by FC were 6.10⋅10(5) ± 1.21⋅10(5) MP/μL and 5.74⋅10(5) ± 9.54⋅10(4) MP/μL, respectively (p = 0.91). The baseline and 5 day MP counts measured by NTA were 9.29⋅10(13) ± 1.66⋅10(13) MP/μL and 3.95⋅10(14) ± 3.11⋅10(14) MP/μL, respectively (p = 0.91). When MPs were stratified by cell source, there was no difference in pre/post TAVR endothelial, platelet, or leukocyte MP levels.
Conclusion:
Levels of circulating MPs do not change acutely following TAVR therapy for aortic stenosis. Trial registered at clinicaltrials.gov NCT02193035 on July 11, 2014.
Insights
Percutaneous aortic valve replacement (TAVR) did not acutely alter circulating microparticle (MP) levels in patients with severe aortic stenosis. This suggests TAVR does not immediately impact the prothrombotic and proinflammatory state associated with this condition.
Area of Science:
- Cardiovascular Medicine
- Hematology
- Biomaterials Science
Background:
- Severe aortic stenosis is linked to elevated prothrombotic and proinflammatory microparticles (MPs).
- Abnormal shear stress in aortic stenosis stimulates MP production, contributing to atherothrombotic events.
Purpose of the Study:
- To investigate the effect of transcatheter aortic valve replacement (TAVR) on circulating microparticle levels in severe aortic stenosis patients.
- To determine if TAVR reduces abnormal shear stress and consequently decreases MP levels.
Main Methods:
- Quantification of circulating plasma microparticle (MP) levels using flow cytometry (FC) and nanoparticle tracking analysis (NTA).
- MP levels were measured at baseline and 5 days post-TAVR in patients with severe aortic stenosis.
Main Results:
- No significant acute change in overall circulating MP levels was observed 5 days after TAVR (p = 0.91 for both FC and NTA).
- Stratification by cell source revealed no significant differences in pre/post-TAVR endothelial, platelet, or leukocyte MP levels.
Conclusions:
- Circulating microparticle levels do not acutely change following TAVR for aortic stenosis.
- The prothrombotic and proinflammatory state associated with aortic stenosis may not be immediately resolved by TAVR.
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