Elucidating the Relation between Human Milk Fatty Acids, Extracellular Vesicles, and Infant Developmental Outcomes in the First Year of Life

For most infants, human milk is the recommended source of nutrition. Improved developmental outcomes have been reported in infants that consume human milk compared to infant formula. Essential fatty acids (EFAs) confer health benefits. However, EFAs cannot be synthesized by the body, and therefore must be consumed in diet. Extracellular vesicles (EVs) are nanoparticles containing a lipid bilayer membrane and are present in human milk. Methods of EV isolation such as ultracentrifugation (UC) may not be feasible for the study of EVs in human milk due to the need for large sample volume, which may not be available. The objectives of this research were therefore to investigate i) if the concentration of essential fatty acids in milk correlated to infant developmental outcomes reported by the Bayley Scales of Infant Development (BSID-III) and ii) if an EV isolation method using a precipitation method could be optimized for isolation of EVs in a low volume of human milk. Human milk samples were obtained two weeks post-partum (n=70), and corresponding developmental data was obtained. Total fatty acids from milk samples were quantified by Gas Chromatography-Mass Spectrometry (GC-MS). Electron microscopy, nanoparticle tracking analysis, and semi-quantitative antibody array were conducted to confirm isolation of human milk EVs. Count, size, protein content, and fatty acid quantification of EVs were also determined. Arachidonic acid was inversely correlated with cognitive development at 12 months of age (