Accelerating discovery: A novel flow cytometric method for detecting fibrin(ogen) amyloid microclots using long COVID as a model

• Published in: Heliyon 2023-09, Vol.9 (9), p.e19605-e19605, Article e19605
• Main Authors: Turner, Simone, Laubscher, Gert Jacobus, Khan, M Asad, Kell, Douglas B., Pretorius, Etheresia
• Format: Article
• Language: English
• Subjects: Amyloid microclots; Fluorescence; Imaging flow cytometry; Long COVID
• ISSN: 2405-8440; 2405-8440
• DOI: 10.1016/j.heliyon.2023.e19605

Long COVID has become a significant global health and economic burden, yet there are currently no established methods or diagnostic tools to identify which patients might benefit from specific treatments. One of the major pathophysiological factors contributing to Long COVID is the presence of hypercoagulability; this results in insoluble amyloid microclots that are resistant to fibrinolysis. Our previous research using fluorescence microscopy has demonstrated a significant amyloid microclot load in Long COVID patients. However, this approach lacked the elements of statistical robustness, objectivity, and rapid throughput. In the current study, we have used imaging flow cytometry for the first time to show a significantly increased concentration and size of these microclots. We identified notable variations in size and fluorescence between microclots in Long COVID and those of controls even using a 20× objective. By combining cell imaging and the high-event-rate and full-sample analysis nature of a conventional flow cytometer, imaging flow cytometry can eliminate erroneous results and increase accuracy in gating and analysis beyond what pure quantitative measurements from conventional flow cytometry can provide. Although imaging flow cytometry was used in our study, our results suggest that the signals indicating the presence of microclots should be easily detectable using a conventional flow cytometer. Flow cytometry is a more widely available technique than fluorescence microscopy and has been used in pathology laboratories for decades, rendering it a potentially more suitable and accessible method for detecting microclots in individuals suffering from Long COVID or conditions with similar pathology, such as myalgic encephalomyelitis. •Imaging flow cytometry utilizing a novel rapid flow cytometric detection method is a promising method for detecting amyloid fibrin(ogen) microclots in conditions associated with clotting pathology.•While this investigation represents a preliminary study, it lays the foundation for further research into the method's utility as a diagnostic tool for individuals with Long COVID.•Though challenging, future research can explore potential correlations between microclot detection and specific Long COVID symptoms and comorbidities, enhancing our understanding of the pathophysiology and tools to detect this condition.•The method's ability to evaluate amyloid microclot presence, concentration, and size offers valuable insights for c