Flow cytometric assays to detect platelet activation and aggregation in device-implanted calves

Area of Science:

• Biomedical Engineering
• Immunology
• Hematology

Background:

• Cardiovascular device development necessitates large-animal models for blood biocompatibility assessment.
• Current assays for evaluating device biocompatibility in animal models are limited and do not fully leverage immunotechnological advancements.
• There is a need for more sensitive and informative assays to assess platelet activation and microaggregate formation in response to cardiovascular devices.

Purpose of the Study:

• To develop and validate novel flow cytometric techniques for measuring circulating activated bovine platelets and platelet microaggregates.
• To assess the utility of these new assays in monitoring platelet response during the implantation of ventricular-assist devices (VADs) in calves.
• To provide a more comprehensive understanding of blood-biomaterial interactions in cardiovascular device development.

Main Methods:

• Development of monoclonal antibodies (MAbs) targeting activated and quiescent bovine platelets.
• Application of flow cytometry to analyze whole blood samples stimulated with PMA or ADP.
• In vivo monitoring of five calves implanted with nonpulsatile VADs using the developed flow cytometric assays.

Main Results:

• Selected MAbs successfully detected activated bovine platelets and platelet microaggregates in vitro.
• VAD implantation in calves led to increased circulating activated platelets and microaggregates.
• Temporal analysis showed correlations between platelet activation percentages detected by different MAbs and between platelet activation and microaggregate formation.

Conclusions:

• The developed flow cytometric methods offer sensitive measurement of circulating activated bovine platelets and microaggregates.
• These novel assays can provide valuable data for the assessment of cardiovascular device biocompatibility.
• The findings support the use of these advanced techniques in the development and evaluation of future cardiovascular device designs.