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Mitchell JL, Dunster JL, Kriek N, Unsworth AJ, Sage T, Mohammed YMM, De Simone I, Taylor KA, Bye AP, Ólafsson G, Brunton M, Mark S, Dymott LD, Whyte A, Ruparelia N, Mckenna C, Gibbins JM, Jones CI. The rate of platelet activation determines thrombus size and structure at arterial shear. J Thromb Haemost 2023:S1538-7836(23)00333-1. [PMID: 37085037 DOI: 10.1016/j.jtha.2023.03.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 03/02/2023] [Accepted: 03/28/2023] [Indexed: 04/23/2023]
Abstract
BACKGROUND The response of platelets to activating stimuli and pharmaceutical agents varies greatly within the normal population. Current platelet function tests measure endpoint levels of platelet activation without taking the speed at which platelets activate into account, potentially missing vital metrics to characterise platelet reactivity. OBJECTIVES To identify variability, to agonist and between individuals, in platelet activation kinetics and assess the impact of this on thrombus formation. METHODS We have developed a bespoke real-time flow cytometry assay and analysis package that measures the rate of platelet activation over time using two parameters of platelet activation, fibrinogen binding and P-selectin exposure. RESULTS The rate of platelet activation varied considerably within the normal population but did not correlate with maximal platelet activation, demonstrating that platelet activation rate is a separate and novel metric to describe platelet reactivity. The relative rate of platelet response between agonists was strongly correlated, suggesting a central control mechanism regulates the rate of platelet response to all agonists. CONCLUSIONS For the first time, we have shown that platelet response rate corresponds to thrombus size and structure, where faster responders form larger, more densely packed thrombi at arterial, but crucially not venous shear. We have demonstrated that the rate of platelet activation is an important metric in stratifying individual platelet responses and will provide a novel focus for the design and development of anti-platelet therapy, targeting high shear thrombosis without exacerbating bleeding at low shear.
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Affiliation(s)
- Joanne L Mitchell
- School of Biological Sciences, University of Reading, UK; Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, UK
| | | | - Neline Kriek
- School of Biological Sciences, University of Reading, UK
| | | | - Tanya Sage
- School of Biological Sciences, University of Reading, UK
| | | | | | - Kirk A Taylor
- School of Biological Sciences, University of Reading, UK
| | - Alexander P Bye
- Molecular and Clinical Sciences Research Institute, St George's University, Cranmer Terrace, London, UK
| | - Geir Ólafsson
- Bristol Composites Institute, Faculty of Civil, Aerospace and Mechanical Engineering, University of Bristol, UK
| | - Mark Brunton
- University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Sharon Mark
- University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Leanne D Dymott
- University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Abigail Whyte
- University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Neil Ruparelia
- School of Biological Sciences, University of Reading, UK; University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Charlie Mckenna
- University Department of Cardiology, Royal Berkshire Hospital, UK
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Dunster JL, Mitchell JL, Mohammed YMM, Taylor KA, Gibbins JM, Jones CI. Kinetx: A Combined Flow Cytometry Assay and Analysis Software Framework to Quantitatively Measure and Categorize Platelet Activation in Real-time. J Vis Exp 2021. [PMID: 34694288 DOI: 10.3791/62947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Platelets react rapidly to vascular injury and undergo activation in response to a range of stimuli to limit blood loss. Many platelet function tests measure endpoint responses after a defined time period and not the rate of platelet activation. However, the rate at which platelets convert extracellular stimuli into a functional response is an essential factor in determining how efficiently they can respond to injury, bind to a forming thrombus, and signal to recruit other platelets. This paper describes a flow cytometry-based platelet function assay that enables simultaneous data acquisition and sample stimulation and utilizes newly developed bespoke open-source software (Kinetx) to enable quantitative kinetic measurements of platelet granule release, fibrinogen binding, and intracellular calcium flux. Kinetix was developed in R so that users can alter parameters such as degree of smoothing, identification of outlying data points, or time scales. To aid users unfamiliar with the R environment, Kinetix analysis of data can be performed by a single command. Together, this allows real-time platelet activation metrics, such as rate, acceleration, time to peak-rate, time to peak-calcium, and qualitative shape changes, to be accurately and reproducibly measured and categorized. Kinetic measurements of platelet activation give a unique insight into platelets' behavior during the first stages of activation and may provide a method of predicting the recruitment of platelets into a forming thrombus.
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Affiliation(s)
| | - Jo L Mitchell
- ICMR, School of Biological Sciences, University of Reading; Institute of Cardiovascular Sciences, University of Birmingham
| | | | - Kirk A Taylor
- ICMR, School of Biological Sciences, University of Reading
| | | | - Chris I Jones
- ICMR, School of Biological Sciences, University of Reading;
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