Related Experiment Video
Updated: Sep 12, 2025
11:30
Freeze-Fracture Electron Microscopy for Extracellular Vesicle Analysis
Published on: September 16, 2022
3.9K
Assessment of Vault Particles in Cancer Cell Line-Derived Extracellular Vesicle Preparations
Xinming Liu1, Zubair Ahmed Nizamudeen2, Christopher J Hill3
1School of Clinical Dentistry, The University of Sheffield, Sheffield, UK.
Journal of Extracellular Vesicles
|August 6, 2025
Summary
Vault RNA (vtRNA) and major vault protein (MVP) appear abundant in extracellular vesicle (EV) preparations but are often not membrane-enclosed. This suggests they may be co-purified contaminants rather than true EV cargo.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Extracellular vesicles (EVs) are increasingly recognized for their role in intercellular communication.
- EVs are known to carry diverse molecular cargo, including proteins and nucleic acids.
- Vault particles and their components have been frequently reported as EV cargo in scientific literature.
Purpose of the Study:
- To investigate the association of vault RNA (vtRNA) and major vault protein (MVP) with extracellular vesicles (EVs).
- To determine whether vtRNA and MVP are truly enclosed within EVs or are co-purified contaminants.
- To clarify the topological relationship between vault components and EVs.
Main Methods:
- Differential centrifugation (DC) for EV enrichment.
- Quantitative PCR (qPCR) to measure vtRNA levels.
- Western blotting to detect MVP.
- RNase and proteinase treatments to assess membrane protection.
- Cryo-transmission electron microscopy (cryo-TEM) for particle visualization.
- Size exclusion chromatography (SEC) for EV and contaminant separation.
- Immunocapture techniques for EV isolation.
Main Results:
- vtRNA and MVP were highly abundant in EV pellets obtained by differential centrifugation (DC).
- RNase and proteinase treatments indicated that most vtRNA and MVP were not protected within an EV membrane.
- Vault-like particles were observed in 100k DC pellets via cryo-TEM.
- SEC showed co-elution of EV markers and vault proteins.
- Immunocapture of EVs from ultracentrifugation pellets co-purified MVP, but direct immunocapture from conditioned medium did not.
Conclusions:
- The abundance of vtRNA and MVP in EV preparations does not confirm them as EV cargo.
- Most detected vtRNA and MVP are likely not enclosed within EVs, suggesting co-purification.
- Distinguishing EV-associated contaminants from true EV cargo requires careful topological analysis.
- This study emphasizes the need for rigorous validation of EV cargo.
