Quality Assessment and Comparison of Plasma-Derived Extracellular Vesicles Separated by Three Commercial Kits for Prostate Cancer Diagnosis.
Introduction
Current standard biomarkers in clinic are not specific enough for prostate cancer (PCa) diagnosis. Extracellular vesicles (EVs) are nano-scale vesicles released by most mammalian cells. EVs are promising biomarker source for PCa liquid biopsy due to its minimal invasive approach, rich information and improved accuracy compared to the clinical standard prostate-specific antigen (PSA). However, current EV separation methods cannot separate pure EVs and the quality characteristics from these methods remain largely unknown. In this study, we evaluated the quality characteristics of human plasma-derived EVs by comparing three clinical suitable separation kits.


Methods
We combined EV separation by commercial kits with magnetic beads capture and flow cytometry analysis, and compared three kits including ExoQuick Ultra based on precipitation and qEV35 and qEV70 based on size exclusion chromatography (SEC).


Results
Our results indicated that two SEC kits provided higher EV purity and lower protein contamination compared to ExoQuick Ultra precipitation and that qEV35 demonstrated a higher EV yield but lower EV purity compared to qEV70. Particle number correlated very well particularly with CD9/81/63 positive EVs for all three kits, which confirms that particle number can be used as the estimate for EV amount. At last, we found that several EV metrics including total EVs and PSA-specific EVs could not differentiate PCa patients from health controls.


Conclusion
We provided a systematic workflow for the comparison of three separation kits as well as a general analysis process in clinical laboratories for EV-based cancer diagnosis. Better EV-associated cancer biomarkers need to be explored in the future study with a larger cohort.
['Pang|Bairen|B|0000-0002-4664-7593', 'Zhu|Ying|Y|0000-0002-8840-176X', 'Ni|Jie|J|', 'Ruan|Juanfang|J|0000-0001-8994-5235', 'Thompson|James|J|', 'Malouf|David|D|', 'Bucci|Joseph|J|', 'Graham|Peter|P|0000-0002-4957-4895', 'Li|Yong|Y|']
D002850:Chromatography, Gel D000067128:Extracellular Vesicles D006801:Humans D018189:Immunomagnetic Separation D008297:Male D010949:Plasma D011471:Prostatic Neoplasms
extracellular vesicles separation prostate cancer immunomagnetic beads lipoprotein protein biomarker