Beate Vestad1,2, Alicia Llorente3,4,5, Axl Neurauter5,6, Santosh Phuyal3,4,5, Bente Kierulf5,6, Peter Kierulf1,2, Tore Skotland3,4,5, Kirsten Sandvig3,4,5, Kari Bente Foss Haug1,2, Reidun Øvstebø1,2
1Regional Research Network on Extracellular Vesicles South‐Eastern Norway Regional Health Authority Norway
2The Blood Cell Research Group Department of Medical Biochemistry Oslo University Hospital Ullevål Oslo Norway
3Centre for Cancer Biomedicine, University of Oslo, Oslo, Norway
4Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital - The Norwegian Radium Hospital, Oslo, Norway
5Regional Research Network on Extracellular Vesicles, South-Eastern Norway Regional Health Authority, Norway
6Thermo Fisher Scientific, Life Sciences Solutions, Oslo, Norway
Tóm tắt
ABSTRACTCurrent methods for characterisation of extracellular vesicles (EVs) need further standardisation in order to obtain an acceptable level of data comparability. Size and concentration of EVs can be determined by nanoparticle tracking analysis (NTA). However, both the heterogeneity of EVs and the choice of instrument settings may cause an appreciable analytical variation. Intra‐assay (within‐day, n = 6) and inter‐assay (day‐to‐day, n = 6) variations (coefficient of variation, % CV) of different preparations of EVs and artificial vesicles or beads were determined using two NanoSight NS500 instruments, located at different laboratories. All analyses were performed by the same operator. The effect of applying identical software settings or instrument‐optimised settings for each sample type and instrument was also evaluated. Finally, the impact of different operators and the use of two different software versions were investigated. The intra‐assay CVs were 1–12% for both EVs and artificial samples, measured on the same instrument. The overall day‐to‐day variation was similar for both instruments, ranging from 2% to 25%. However, significantly different results were observed between the two instruments using identical software settings. The effect of applying instrument‐optimised settings reduced the mismatch between the instruments, resulting in little to no significant divergences. The impact of using different operators and software versions when analysing silica microspheres and microvesicles from monocytes using instrument‐optimised settings on the same instrument did not contribute to significant variation compared to the overall day‐to‐day variation of one operator. Performance differences between two similar NTA instruments may display significant divergences in size and concentration measurements when analysing EVs, depending on applied instrument settings and technical conditions. The importance of developing a streamlined and standardised execution of analysis, as well as monitoring longitudinal variation parameters on both biological and synthetic samples, should be highlighted.
