Circulating Micro RNAs as Novel Disease Biomarkers: Can they be Applied in Daily Clinical Practice? An Update

MicroRNAs (miRNAs), a large family of short noncoding RNA sequences, modulate gene expression
and regulate a wide range of biological processes as cell differentiation, proliferation and
development, cell-to-cell communication, cell metabolism and apoptosis. There is evidence that
miRNAs may have a role in molecular mechanisms linked to cellular pathways of certain diseases, as
viral infections, cancer, diabetes and cardiovascular disease. miRNAs are contained in tissue cells but
they are also detectable in extracellular sites, as plasma and other body fluids so they may be
identified and quantified in the circulating blood by several techniques. The potential of circulating
miRNAs as stable blood-based biomarkers for some diseases is described in this updated review.
There are currently no circulating miRNAs that are validated as biomarkers for routinary use in daily
clinical practice; lack of significant comparative studies between miRNAs and disease common
biomarkers and high detection costs are the main limitations to use these nucleotides in daily clinical
practice. In the near future, larger, comparative, long-term and randomized controlled trials must be
undertaken to validate these disease biomarkers.