Methods for Eluting Intact Extracellular Vesicles From Aptamer-Based Affinity Chromatography: A Critical Evaluation Based on Downstream Applications

Abstract

Extracellular vesicles (EVs) are nanosized vesicles released by cells, containing molecular cargo such as proteins and nucleic acids. EVs offer promising avenues for the detection of biomarkers of disease and are excellent candidates for drug delivery and therapeutics. Although EVs can be obtained from biological fluids, it is challenging to obtain intact EVs from complex fluids and there is no universally accepted standard method of isolating EVs. When affinity chromatography-based isolation is used to isolate EVs from complex biofluids, there exist multiple ways to elute intact EVs from capture. This review aims to identify effective EV elution methods for preserving EV integrity and bioactivity after capture on aptamer-functionalized substrates, addressing the requirements of various downstream applications. We hypothesize that when used for elution, different materials and techniques influence the characteristics of EVs, such as their molecular content and bioactivity. The elution reagent and technique must be selected for the intended application for isolated EVs. However, currently, there is no agreement on the optimal elution method for EVs. This literature review aims to evaluate the different methods used to elute intact EVs from capture with regards to the downstream applications of isolated EVs. Based on the results of our analysis of recent literatures, the two elution reagents that are optimal for general purposes of the eluted intact EVs are deoxyribonuclease I and complementary oligonucleotides, as they both preserve EV characteristics that are required for molecular analysis and bioactivity, such as maintained morphology and protein profiles.