Hypothetic Interindividual and Interspecies Relevance of microRNAs Released in Body Fluids.

MicroRNAs may not only be relevant within the organism, but microRNAs released in body fluids might affect other individuals and hypothetically also other species. Such interindividual and cross-species activity of microRNAs appears to be very interesting, but these actions are largely hypothetic at present warranting extensive experimental validation. Food-derived microRNAs might extend the relevance of food for epigenetic regulation; however, the efficient gastrointestinal transfer of microRNAs needs to be demonstrated. We have raised the hypothesis that the nonprotein coding "dark matter" of the genome containing microRNA genes might be relevant in the regulation of interindividual and interspecies epigenetic communication.