Improving Multicolor Colocalization in Single-Vesicle Flow Cytometry with Vesicle Transit Time.

Area of Science:

• Biophysics
• Nanotechnology
• Biochemistry

Background:

• Extracellular vesicle (EV) immunophenotyping is crucial for understanding their biological roles.
• Accurate surface protein analysis of small EVs (30-40 nm) is challenging due to velocity variations in flow cytometry.
• Traditional cross-correlation analysis (Xcorr) can yield incorrect results for nanometer-sized vesicles.

Purpose of the Study:

• To introduce and validate an alternative cross-correlation analysis strategy (Scorr) for improved multicolor colocalization.
• To address the limitations of velocity distribution in flow-focused nanovesicles during immunophenotyping.
• To enhance the accuracy and efficiency of single-vesicle immunoprofiling.

Main Methods:

• Developed and implemented a novel cross-correlation analysis strategy (Scorr) utilizing particle transit time.
• Tested Scorr's performance using multicolor nanobeads and extracellular vesicles (EVs).
• Validated Scorr through experimental data and Monte Carlo simulations.

Main Results:

• Scorr significantly improved the efficiency and accuracy of multicolor colocalization compared to Xcorr.
• Monte Carlo simulations showed Scorr increased colocalized peaks by approximately 1.2-4.7 fold.
• Experimental results demonstrated a 1.3-2.5 fold increase for nanobeads and 1.2-2 fold for EVs.

Conclusions:

• Scorr offers a more reliable method for multicolor colocalization in single-vesicle immunoprofiling.
• The transit time-based approach effectively mitigates issues caused by particle velocity variations.
• This advancement facilitates more precise analysis of nanometer-sized vesicles and their surface proteins.