Human Blood Exosomes: Isolation and Characterization Methods, Variability, and the Need for Standardized Protocols-A...

Area of Science:

• Biochemistry and Molecular Biology
• Cell Biology
• Biotechnology

Background:

• Exosomes are bioactive extracellular vesicles crucial for intercellular communication and disease.
• Their complex structure poses challenges for standard analytical methods.
• Understanding exosome concentrations in healthy individuals is essential for baseline data.

Purpose of the Study:

• To review and summarize published exosome concentrations in human plasma, serum, and platelet-rich plasma from healthy individuals.
• To highlight methodological differences in exosome quantification.
• To identify factors influencing exosome yield and quality.

Main Methods:

• A comprehensive PubMed search was conducted for studies on exosome quantification in plasma, serum, and platelet-rich plasma.
• Studies excluded cancer and disease-related research.
• Eligible articles used particle-counting techniques like nanoparticle tracking analysis, flow cytometry, or tunable resistive pulse sensing.

Main Results:

• Twenty-two articles with 167 healthy donors were included.
• Reported exosome concentration ranges varied significantly across biofluids and quantification methods.
• Plasma: 4.50 × 10^8 to 6.70 × 10^11 particles/mL; Serum: 5.30 × 10^8 to 2.13 × 10^11 particles/mL; Platelet-rich plasma: 7.52 × 10^9 to 2.99 × 10^11 particles/mL.

Conclusions:

• High variability in isolation and quantification methods significantly impacts exosome quantity and quality.
• Exosome characteristics like cargo, purity, and integrity are critical for method development.
• Standardization of protocols is essential for advancing exosome research and clinical applications.