title: Comparison of serum exosome isolation methods for microRNA profiling.
abstract: OBJECTIVE
  Exosomes are small membrane bound vesicles secreted by most cell types. Exosomes contain various functional proteins, mRNAs and microRNAs (miRNAs) that could be used for diagnostic and therapeutic purposes. Currently, a standard method for serum exosome isolation is differential ultracentrifugation, but a search for alternative, less time-consuming and labour extensive exosomal isolation method for use in clinical settings is ongoing. The effect of serum exosome isolation method on obtained miRNA profile is not yet clear. The aim of this study was to determine to which extent selected exosome isolation methods influence the serum exosomal miRNA profile.
  
  
  METHODS
  Exosomes were isolated from blood serum of healthy individuals by ultracentrifugation and ExoQuick Precipitation methods. The expression profile of 375 miRNAs was determined by real time PCR using Exiqon miRCURY LNA™ microRNA Human panel I assays.
  
  
  RESULTS
  Although a strong correlation of exosomal miRNA profiles was observed between the two isolation methods, distinct clusters of miRNA levels between the used methods were identified. The detected levels of two miRNAs, miR-92a and miR-486-5p, were significantly influenced by the exosome isolation method used.
  
  
  CONCLUSIONS
  Both exosome isolation methods are suitable for serum exosomal miRNA profiling. Differences found in miRNA patterns between the two methods indicate that the observed exosomal miRNA profile is slightly affected by the extracellular vesicle isolation method.
authors.affiliation: Competence Centre on Reproductive Medicine and Biology, Tiigi 61b, 50410 Tartu, Estonia; Department of Obstetrics and Gynecology, University of Tartu, L. Puusepa 8, 51014 Tartu, Estonia. Electronic address: kadri.vaidla@gmail.com.
authors.forename: Kadri
authors.initials: K
authors.lastname: Rekker
authors.affiliation: Competence Centre on Reproductive Medicine and Biology, Tiigi 61b, 50410 Tartu, Estonia; Department of Obstetrics and Gynecology, University of Tartu, L. Puusepa 8, 51014 Tartu, Estonia; Institute of Bio- and Translational Medicine, University of Tartu, Ravila 19, 50411 Tartu, Estonia.
authors.forename: Merli
authors.initials: M
authors.lastname: Saare
authors.affiliation: Competence Centre on Reproductive Medicine and Biology, Tiigi 61b, 50410 Tartu, Estonia.
authors.forename: Anne Mari
authors.initials: AM
authors.lastname: Roost
authors.affiliation: HansaBioMed Ltd, Akadeemia tee 15, 12618 Tallinn, Estonia.
authors.forename: Anna-Liisa
authors.initials: AL
authors.lastname: Kubo
authors.affiliation: HansaBioMed Ltd, Akadeemia tee 15, 12618 Tallinn, Estonia.
authors.forename: Natasa
authors.initials: N
authors.lastname: Zarovni
authors.affiliation: HansaBioMed Ltd, Akadeemia tee 15, 12618 Tallinn, Estonia.
authors.forename: Antonio
authors.initials: A
authors.lastname: Chiesi
authors.affiliation: Competence Centre on Reproductive Medicine and Biology, Tiigi 61b, 50410 Tartu, Estonia; Department of Obstetrics and Gynecology, University of Tartu, L. Puusepa 8, 51014 Tartu, Estonia; Institute of Bio- and Translational Medicine, University of Tartu, Ravila 19, 50411 Tartu, Estonia.
authors.forename: Andres
authors.initials: A
authors.lastname: Salumets
authors.affiliation: Competence Centre on Reproductive Medicine and Biology, Tiigi 61b, 50410 Tartu, Estonia; Department of Obstetrics and Gynecology, University of Tartu, L. Puusepa 8, 51014 Tartu, Estonia.
authors.forename: Maire
authors.initials: M
authors.lastname: Peters
mesh_terms: D055354:Exosomes / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D012016:Reference Values; D014461:Ultracentrifugation
chemical_list: D035683:MicroRNAs
keywords: EQ; ExoQuick; ExoQuick Precipitation Solution; Exosomes; Extracellular vesicles; UC; Ultracentrifugation; miRNA; ultracentrifugation