Cell-free circulating microRNAs are protected from degradation by their association
with either component of the RNAi machinery or vesicles. Although increasing evidences
shows that different types of vesicles are capable of transporting microRNAs, current
research mainly focuses on the characterization of exosomal microRNAs. Reason for
this is that exosomal-microRNAs are thought to directly participate in intercellular
communication. However, is yet unclear whether exosomal-microRNAs are also the most
reliable source for discovering disease-associated biomarker. In this study, the distribution
of circulating microRNAs associated to either the vesicular or non-vesicular fractions
of sera isolated from partially hepatectomized rats was measured. Here we show that
independently from their origin, levels of cell-free miR-122, miR-192, miR-194 and
Let-7a are upregulated two days after partial hepatectomy. The inflammation-associated
miR-150 and miR-155 are upregulated in the vesicular-fraction only, while the regeneration-associated
miR-21 and miR-33 are upregulated in the vesicular- and downregulated in the non-vesicular
fraction. Our study shows for the first time the modulation of microRNAs contained
in the non-vesicular fraction. Overall, these findings suggest that, in the search
for novel disease-associated biomarkers, the investigation of either vesicular or
non-vesicular microRNAs may be more informative compared to the analysis of microRNAs
isolated from unfractionated serum.
Corresponding author: Castoldi, Mirco
E-Mail:
mirco.castoldi@uni-duesseldorf.de
