Table 1.

Topics for further study

Requirement	Comments and proposals
Proper normalizers for exogenous RNA experiments	Endogenous miRNAs that change with the circadian day, exercise, feeding, or drugs might be inappropriate. Synthetic spike-in(s)?
Development of tissue sensors	Extremely sensitive tissue sensors (as available in C. elegans [11]) could identify effects of low-level RNA transfer
Understanding of uptake mechanisms	Additional work on SIDT1, scavenger receptors, and other transmembrane proteins; further exploration of extracellular vesicles and viruses
Identification of conditions, treatments that facilitate RNA transfer	Examine samples from humans with gut permeability conditions: microbial and small RNA transfer? Are there dietary or medicinal substances with unappreciated effects on permeability?
Appreciation of human/model differences	Mice and humans: humans utilize a greater proportion of calcium absorbed in the upper small intestine [125]. Might there also be differences in nucleic acid uptake? Use of humanized mouse models [126]