microRNAs are small non-coding RNA molecules of 20-22 nucleotides in length having a major role in regulation of gene expression. microRNAs influence many cellular pathways and are involved in cell development and differentiation.
De-regulation of microRNA was found to be part of many pathologies and therefore microRNAs are considered to be important molecular candidates in both diagnostics and therapeutics for many clinical indications. There are around 2000 known microRNAs in humans, and more in other species, with great interspecies conservation and homology.
Endogenous microRNAs can serve as biomarkers since their de-regulation in many disease conditions can be detected due to their stability and technical ease of identification. Therapeutically, microRNAs hold a great promise due to their multi-path targeting. MicroRNAs can be inhibited (anti-miR molecules) or be replaced (miR mimetic) in the targeted tissue.