Date of Award

Spring 5-2022

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Food Science

First Advisor

John Miklavcic, Ph.D.

Second Advisor

Lilian Were, Ph.D.

Third Advisor

Marco Bisoffi, Ph.D.

Abstract

Extracellular vesicles (EVs) are bioactive components of human milk that may impact functionality to regulate growth, cognitive development, metabolism, and immunity in newborns. The biogenesis of EVs and the mechanism by which EVs elicit biologic effects in vivo have not been characterized entirely. Gangliosides and fatty acids are integral in the formation, release, stability, and functionalities of EVs. Presumably, EV function is related to EV composition and lipids in EVs influence the bioavailability of EV cargo and downstream functions of EVs. The objective of this research was to characterize the fatty acid and ganglioside composition of EVs in human milk. Human milk (n=31) was obtained 2-4 weeks postpartum and EVs were isolated using a precipitation method. Gangliosides and fatty acids were extracted from the milk EVs using a modified Folch method. Relative (%w/w) fatty acids and ganglioside content was determined by GC-MS and HILIC-HPLC/MS-MS. The relative content of fatty acids and gangliosides within human milk EVs was assessed in relation to the relative content in the whole human milk. The EV isolation procedure yielded 2.08 x 1010 EV particles/mL of human milk and 4.71 (± 2.9) µg protein/µL of human milk. The relative content of 18:2, ω-6 fatty acids, and PUFAs were not correlated between human milk and human milk EVs (p >0.05). 22:6, 20:4, and 18:0 are enriched in EVs (1.5 – 2.5-fold); while 18:1 content is 50% lower in EVs than whole human milk. In contrast, 13/15 molecular species of GM3 and GD3 assessed were not positively correlated between human milk EVs and human milk. Total saturated species of GM3 are enriched 2-fold in human milk. GM3 d40:1, GM3 d34:1, and GD3 d36:1 are significantly enriched in human milk EVs. 18:2 and 20:4 contents are not correlated between human milk EVs and the whole human milk, indicating discriminate partitioning of lipids species containing these fatty acids into EVs in EV biogenesis, or the conversion of these fatty acids into mediators which aid in permeability of EVs and influence functionality. Further understanding of EV composition may offer insight into the roles of human milk EVs in infant growth and development.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Available for download on Sunday, April 21, 2024

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