Second of Four Featured Abstract at ISEV 2020 Virtual Annual Meeting (July 20-22) Describes Initial Results of Efforts to Develop Reference Intervals for Extracellular Vesicles (EVs) in Human Plasma by Flow Cytometry

On Monday, June 20, in the second of four Featured Abstracts being presented by junior investigators during the ISEV 2020 Virtual Annual Meeting (July 20-22) (, Bo Li (photo), PhD, from the Department of Laboratory Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China (People’s Republic), presented her group’s abstract (FA04) “Towards Reference Intervals of Extracellular Vesicles in Human Plasma by Flow Cytometry.” In her introduction, Dr. Li noted that, although flow cytometers with submicrometer sensitivity can characterize single extracellular vesicles (EVs) in clinical samples, there is no consensus about the concentrations of EVs in plasma from healthy humans. To determine cut-off values for diagnoses, reference intervals of EVs in plasma are needed, Dr. Li asserted. To establish such reference intervals, Dr. Li said there are four requirements. First, a significant number of healthy donors should be included. Secondly, the presence of non-EV particles, residual platelets, lipoproteins, and hemolysis should be quantified. Thirdly, a clinically applicable protocol to avoid swarm detection should be established in advance. And lastly, flow cytometry signals should be in SI units. Dr. Li said that the long-term aim of this study is to determine reference intervals of EV concentrations in human plasma within known dynamic ranges of the detectors. In the experimental work to establish a clinical reference, Dr. Li and colleagues first collected blood from 224 healthy volunteers and prepared platelet-free plasma. Then, they performed quality-control measurements including residual platelet count, serum index, and lipid spectrum. They also determined that a protocol of 31-fold to 10(3) dilution is safe to prevent swarm detection in plasma from healthy donors.
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