The Reliability of Plasma Exosome Concentrations in Healthy Male Individuals

Abstract

Exosomes are nanometer sized vesicles (30-100 nm), released from cells following the fusion of multivesicular bodies with the plasma membrane. Exosomes have a major role in intracellular communication, immune response modulation, physiological and pathological functions, and an important use in different drug therapies. Moreover, they have been identified as potential biomarkers and are involved in cancer and many other disease processes. Despite the developments in this area, no studies exist that assess the variability of plasma exosomes measures within and between subjects. The purpose of this study was to assess within and between day variability of plasma exosomes concentration in healthy individuals. Also, the stability of exosomes during freeze/thawing cycles was measured in this study. Eleven healthy men were assessed for reliability of exosome concentrations taken over the same sampling period, over 10 hours of a day and over five days. Exosomes were isolated by differential ultracentrifugation and characterized by their size distribution and morphology by electron microscopy and using the Nanosight tracking analysis respectively. Mean plasma exosome values were1.505-2.245 × 10^8/mL). Within day variability was not significantly different (P = 0.95), and between day variability was not significantly different (P = 0.42). The interclass correlation coefficients (ICC) of 0.80 for within sample showed good reliability; ICC of 0.84 for between day plasma exosomes concentrations showed good reliability, and the within day ICC of 0.70 showed a moderate reliability. There was no significant difference observed in using fresh or frozen plasma in exosome quantification or exosome concentration. The statistics show that there is little significant variability in plasma exosome concentrations taken over a single sampling period, over a day or between days, which is vital for plasma exosome studies.

Extracellular Vesicle Biomarkers Track Cognitive Changes Following Intranasal Insulin in Alzheimer’s Disease

“…We also found that, in placebo-assigned participants (Table 2 and Supplementary Figures 2 and 3), the concentration and phosphoprotein content of plasma neuronal-enriched EVs remained relatively stable over time, as previously shown for total plasma EVs [40], suggesting that circulating neuronal-enriched EVs in individual humans demonstrate a unique signature that remains stable over time. In addition, several studies have established the stability of EVs during storage and their resistance to a limited number of freeze-thaw cycles [41, 42], whereas EV phosphoproteins remain stable over 5 years in storage [43] suggesting that EV biomarkers may reflect the phosphoprotein status in their cells of origin even after years in storage. The presence of intracellular mediators that belong to a common cascade in different phosphorylated states raises the possibility that the status of signaling cascade in the parent cells may be interrogated using circulating EVs.…”

Extracellular Vesicles as Natural, Safe and Efficient Drug Delivery Systems

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Extracellular Vesicles for the Diagnosis of Cancers

“…Therefore, Abu-Seer evaluated the reliability of plasma EV testing. [218] In this experiment, EV reliability was evaluated in three aspects: 1) within-day reliability, which is to assess the repeatability of plasma-EV measurement results in one day at different points in time (i.e., 1, 2, 3, 4, 5, 6, 8, and 10 h); 2) between-day reliability, which is to assess the repeatability of plasma EV measurement results between multiple days (five times over five consecutive days); and 3) EV stability between freezing and fresh plasma samples. The measurements of EV concentrations and size distributions displayed good withinday reliability and between-day reliability.…”