The Polyunsaturated Fatty Acid Profile of Extracellular Vesicles in Human Milk

Abstract

Abstract Objectives Mammalian cells produce extracellular vesicles that function in intercellular communication. There is very little known about the structure of extracellular vesicles that are present in human milk. This research aimed to characterize the fatty acid composition of extracellular vesicles in human milk relative to the whole milk. Methods Mothers (n = 35) provided milk two weeks postpartum and the samples were frozen. Samples were thawed and de-fatted before extracellular vesicles were isolated using a precipitation reagent. The whole milk and corresponding samples of extracellular vesicles were analyzed for total fatty acid composition by liquid chromatography-coupled mass spectrometry. Results Docosahexaenoic (22:6n-3) acid (r,2 = 0.54; P < 0.001) and eicosapentaenoic (20:5n-3) acid (r,2 = 0.62; P < 0.001) content in extracellular vesicles from milk and in the whole milk were highly correlated. Other individual fatty acids (16:0, 18:0, 18:1, 18:2n-6, 18:3n-3, 20:4n-6) and total saturated, unsaturated, and polyunsaturated fatty acids were not significantly correlated in extracellular vesicles from milk and in the whole milk. The content of docosahexaenoic acid and eicosapentaenoic acid were enriched 1.5-fold in the whole milk relative to extracellular vesicles from milk. Linoleic (18:2n-6) acid and alpha-linolenic (18:3n-3) acid were enriched 3- and 2-fold respectively in extracellular vesicles from milk relative to the whole milk. Conclusions Extracellular vesicles in milk are enriched in essential fatty acid precursors (18:2n-6, 18:3n-3) and the whole milk is enriched in long-chain omega-3 products (22:6n-3, 20:5n-3). Polyunsaturated fatty acids are partitioned in human milk extracellular vesicles in a discriminate manner. Funding Sources The research was supported by the NIH and University institutional funds.