The use of microRNA mimics to increase microRNA levels in the developing organs of newborn mice.

The use of microRNA antimiRs which deplete microRNA pools is a well-established and successful intervention in both in vivo and in vitro settings, where the goal is to reduce the abundance of selected microRNA species. However, whilst efforts to increase the abundance of selected microRNA species in vitro have found widespread success in cell culture, delivering functional microRNA to the organs of living, intact experimental animals remains problematic.

The objective of this study was to examine the efficacy of delivery of commercially-available microRNA mimics that are marketed for in vitro and in vivo use to multiple organs of the laboratory mouse, following parenteral administration in various protocols over the first 14 days of post-natal life. The data presented indicate that parenteral administration of a microRNA mimic is largely inefficient, with moderate delivery of a miR-497a-5p mimic noted in the liver, but not the kidneys, lungs, heart, or brain.