Background: Exosomes are nanovesicles released by cells
that can be detected in blood. Exosomes contain several
molecules, such as cytokines that have potential utility
as disease biomarkers. The aim of the present work is to
compare six different commercial kits suitable for the
clinical laboratory in relation to the efficiency and purity
of exosome isolation, and their effect in subsequent
cytokines analysis.
Methods: Serum exosomes were obtained from 10
volunteers
using six commercial kits: exoEasy, ExoQuick,
Exo-spin, ME kit, ExoQuick Plus and Exo-Flow. Exosome
concentrations and size distributions were quantified by
nanoparticle tracking analysis. Exosome markers CD63,
CD9 and TSG101 were determined by Western blot. ApoB
and albumin were measured using nephelometry. S100A9,
CXCL5 and CXCL12 were measured using a Luminex assay.
Results: The concentration of particles obtained between
different kits varied by a factor of 100. There was no correlation
in particle concentrations extracted between
different kits, except between ExoQuick and Exo-Flow.
The highest exosome purity was achieved with ExoQuick
Plus and exoEasy, while the lowest were achieved with
ME and ExoQuick. Albumin was present in all exosome
extracts analyzed and ApoB in all except those extracted
with Exo-Flow and ME. Cytokine detection varied depending
on the purification kit used and there was no correlation
in cytokine concentrations between samples obtained
with different kits.
Conclusions: Both the sample and the type of commercial
kit used affect the efficiency and purity of exosome isolation.
In addition, the exosome purification method deeply
affects the capability to detect and quantify cytokines