Exosomes isolated from two different cell lines using three different isolation techniques show variation in physical and molecular characteristics

Abstract

Exosomes are the nanoscopic lipid bi-layered extracellular vesicles with the potential to be utilized as targeted therapeutics. In our investigation, we compared three major exosome isolation techniques that were Total Exosome Isolation reagent (TEI), Protein organic solvent precipitation (PROSPR) and differential ultracentrifugation (UC) based on the biophysical and physicochemical characteristics of exosomes isolated from COLO 205 and MCF-7 cancer cell's conditioned media with an aim to select a suitable method for translational studies. 3D image analysis and particle size distribution of exosomes from their HRTEM images depicted the morphological differences. Molecular and analytical characterization of exosomes using western blotting, Raman and ATR-FTIR spectroscopy and the multivariate analysis on the spectral data obtained, assessed for better molecular specifications and purity of particle. TEI method isolated exosomes with higher exosomal yield, purity, and recovery directly translatable into drug delivery and targeted therapeutics whereas ultracentrifuge had good recovery of particle morphology but showed particle aggregation and yielded exosomes with smaller mean size. PROSPR technique isolated a mixture of EVs, showed lower protein recovery in PAGE and western blotting but higher spectroscopic protein to lipid ratio and distinguishable EV population in multivariate analysis compared to exosomes isolated by TEI and UC. This comparative study should help in choosing a specific exosome isolation technique required for the objective of downstream applications.