Proteomic Toolbox To Standardize the Separation of Extracellular Vesicles and Lipoprotein Particles

Area of Science:

• Biochemistry and Molecular Biology
• Nanotechnology and Biomaterials

Background:

• Extracellular vesicles (EVs) and lipoprotein particles (LPs) in circulation hold significant diagnostic and prognostic potential.
• Their similar physical properties (size, density) challenge traditional separation methods, hindering unambiguous functional studies.
• Standardized, high-resolution protocols are needed for EV isolation, alongside methods to quantify lipoprotein contamination.

Purpose of the Study:

• To develop and validate a mass spectrometry-based proteomic toolbox for evaluating EV and LP separation protocols.
• To quantitatively assess the efficiency of various affinity chromatography resins in depleting LPs from EV samples.
• To determine the suitability of different separation techniques for obtaining lipoprotein-free EVs.

Main Methods:

• Generation of 15N-labeled internal standards for quantifying EV-specific proteins, apolipoproteins (in LPs), and major serum proteins.
• Utilized multiple reaction monitoring (MRM) assays with these standards to evaluate five different chromatography resins (SEC, Heparin, LPS, HBCD, ConA Sepharose).
• Incorporated dynamic light scattering (DLS) to assess EV aggregation, a factor influencing separation efficiency.

Main Results:

• None of the evaluated individual separation protocols achieved complete removal of LPs from EV samples.
• Affinity chromatography resins showed varying efficiencies, and EV aggregation complicated assessment.
• Combining protocols was explored but presented challenges with low EV yield.

Conclusions:

• The developed proteomic toolbox provides a robust quantitative method for evaluating EV separation protocols.
• Current individual separation methods are insufficient for producing lipoprotein-free EVs.
• Further optimization and potentially combined strategies are necessary for high-purity EV isolation, highlighting the utility of the proteomic toolbox for future research.