Labeling Extracellular Vesicles for Nanoscale Flow Cytometry.

Area of Science:

• Biotechnology
• Cell Biology
• Nanotechnology

Background:

• Extracellular vesicles (EVs) are crucial for intercellular communication, implicated in cancer and inflammation.
• Their potential as disease biomarkers and cell-free therapeutics necessitates advanced detection methods.
• High-resolution cytometry requires efficient and artifact-free fluorescent labeling of EVs.

Purpose of the Study:

• To identify an optimal fluorescent labeling strategy for individual extracellular vesicles (EVs).
• To evaluate various EV labeling methods using high-resolution nanoFACS.
• To establish a sensitive and specific assay for EV characterization.

Main Methods:

• Utilized nanoFACS, a high-resolution flow cytometry technique, to assess EV labeling.
• Compared lipid-, protein-, and RNA-based staining approaches for EV labeling.
• Developed a robust staining strategy using 5-(and-6)-Carboxyfluorescein Diacetate Succinimidyl Ester and size exclusion chromatography.

Main Results:

• Identified an amine-reactive fluorescent label (5-(and-6)-Carboxyfluorescein Diacetate Succinimidyl Ester) as a robust EV staining method.
• Demonstrated the effectiveness of size exclusion chromatography in removing unconjugated label, reducing artifacts.
• Showcased nanoFACS's capability to evaluate EV labeling sensitivity and specificity through combined light scattering and fluorescence measurements.

Conclusions:

• A novel, sensitive, and specific method for fluorescently labeling extracellular vesicles (EVs) was developed.
• This optimized labeling strategy, combined with nanoFACS, facilitates efficient EV characterization.
• The findings pave the way for advanced studies on EV roles in health and disease.