Tracing Cellular Origin of Human Exosomes Using Multiplex Proximity Extension Assays

Area of Science:

• Biochemistry
• Molecular Biology
• Biotechnology

Background:

• Extracellular vesicles (EVs), including exosomes and microvesicles, are released by cells and found in body fluids.
• Their variable composition makes them promising biomarkers, but identifying their cellular origin is crucial for advancing research.
• Current methods for EV characterization are limited in specificity and sensitivity.

Purpose of the Study:

• To develop and validate a method for identifying the cellular origin of extracellular vesicles (EVs) based on their protein profiles.
• To discover distinct protein signatures of EVs from different cell types and body fluids.
• To assess the utility of multiplex proximity extension assays (PEA) for EV biomarker discovery.

Main Methods:

• Multiplex proximity extension assays (PEA) were employed to analyze the protein profiles of exosomes from seven cell lines and two body fluids.
• Protein patterns were analyzed using principal component analysis (PCA).
• EV protein profiles were compared with their originating cell lines to identify source-specific markers.

Main Results:

• PEA successfully identified the cellular origin of exosomes with high specificity and sensitivity.
• Human milk EVs and prostasomes clustered with breast and prostate cell lines, respectively.
• Distinct protein markers were identified for milk exosomes (CXCL5, MIA, KLK6) and prostasomes (NKX31, GSTP1, SRC).

Conclusions:

• PEA is a powerful tool for screening protein expression in extracellular vesicles (EVs).
• This method enables the identification of the cell source of EVs, crucial for understanding their function and origin.
• The distinct protein signatures discovered can facilitate the identification of novel EV biomarkers for diseases such as cancer and inflammation.