Review: Milk Small Extracellular Vesicles for Use in the Delivery of Therapeutics.

Small extracellular vesicles (sEVs, "exosomes") in milk have attracted considerable attention for use in delivering therapeutics to diseased tissues because of the following qualities. The production of milk sEVs is scalable, e.g., more than 1021 sEVs may be obtained annually from a single cow. Milk EVs protect their cargo against degradation in the gastrointestinal tract and during industrial processing. Milk sEVs and their cargo are absorbed following oral administration and they cross barriers such as intestinal mucosa, placenta and the blood-brain barrier in humans, pigs, and mice. Milk sEVs do no alter variables of liver and kidney function, or hematology, and do not elicit immune responses in humans, rats, and mice. Protocols are available for loading milk sEVs with therapeutic cargo, and a cell line is available for assessing effects of milk sEV modifications on drug delivery. Future research will need to assess and optimize sEV shelf-life and storage and effects of milk sEV modifications on the delivery of therapeutic cargo to diseased tissues.