Quantitation of exosomes and their microRNA cargos in frozen human milk

Researchers at the University of Nebraska-Lincoln assessed feasibility of analyzing exosomes and microRNA cargos in frozen human milk as a prerequisite for epidemiological studies of milk exosomes. They collected milk from 5 mother-preterm infant dyads at 3 time points during postnatal hospital care for storage at −80 °C. They purified the exosomes by ultracentrifugation, probed marker proteins using immunoblots, assessed size and counts with a nanoparticle tracker, and quantified 3 microRNAs with quantitative PCR. Positive exosome marker proteins were detectable; β-casein was the only detectable contaminant. Exosome count and size trended to decrease from early to late samples (count, 2.3 × 109 ± 3.8 × 109 to 5.6 × 108 ± 9.7 × 108 exosomes/mL; size, 117 ± 25 to 92 ± 16 nm). Two microRNAs were detectable in early samples only; cycle threshold values equaled 28.7 ± 0.7 for miR-30d-5p and miR-125a-5p; miR-423-5p was not detectable. The researchers conclude that the analysis of exosomes and quantification of microRNAs is feasible in human milk previously stored at −80 °C.

Change in cycle threshold (Ct) values of miR-30d-5p and miR-125a-5p in previously frozen milk from 5 mother-preterm infant dyads during hospitalization


Each participant is represented by a different line. miR-30d-5p is shown in black and squares; miR125a-5p is shown in red and circles.

Wang H, Wu D, Sukreet S, Delaney A, Belfort M, Zempleni J. (2022) Quantitation of Exosomes and Their MicroRNA Cargos in Frozen Human Milk. JPGN Reports [Epub ahead of print]. [article]

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