Ribonucleic artefacts: are some extracellular RNA discoveries driven by cell culture medium components?
In a recently published study, Anna Krichevsky and colleagues raise the important question of whether results of in vitro extracellular RNA (exRNA) studies, including extracellular vesicle (EV) investigations, are confounded by the presence of RNA in cell culture medium components such as foetal bovine serum (FBS). The answer, according to their data, is a resounding "yes". Even after lengthy ultracentrifugation to remove bovine EVs from FBS, the majority of exRNA in FBS remained. Although technical factors may affect the degree of depletion, residual EVs and exRNA in FBS could influence the conclusions of in vitro studies: certainly, for secreted RNA, and possibly also for cell-associated RNA. In this commentary, we critically examine some of the literature in this field, including a recent study from some of the authors of this piece, in light of the Wei et al. study and explore how cell culture-derived RNAs may affect what we think we know about EV RNAs. These findings hold particular consequence as the field moves towards a deeper understanding of EV-RNA associations and potential functions.
Functional Genomics Unit, Institut Pasteur de Montevideo, Montevideo, Uruguay; Nuclear Research Center, Faculty of Science, Universidad de la República, Montevideo, Uruguay.
Juan Pablo
JP
Tosar
Functional Genomics Unit, Institut Pasteur de Montevideo, Montevideo, Uruguay; Department of Medicine, Faculty of Medicine, Universidad de la República, Montevideo, Uruguay.
Alfonso
A
Cayota
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health , Baltimore , MD , USA.
Erez
E
Eitan
Department of Pathology, The Johns Hopkins University School of Medicine , Baltimore , MD , USA.
Marc K
MK
Halushka
Department of Molecular and Comparative Pathobiology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Kenneth W
KW
Witwer
RNA; artefact; cell culture; contamination; exosomes; extracellular vesicles; microRNA; microvesicles; serum; ultracentrifugation