# Impact of Holder Pasteurization on Extracellular Vesicles and Immunoregulatory MicroRNAs in Human Breast Milk

## TL;DR

This study examines how Holder pasteurization affects microRNAs and extracellular vesicles in breast milk, which are important for infant development and immunity.

## Contribution

The study reveals specific changes in exosomal miRNA expression and EV morphology due to Holder pasteurization.

## Key findings

- Pasteurization altered exosome morphology, reducing particle size and increasing protein concentration.
- Eight out of 13 exosomal miRNAs showed significantly decreased expression after pasteurization.
- miRNA profiles in fat and serum fractions were largely unaffected by pasteurization.

## Abstract

Human breast milk contains bioactive molecules, including
microRNAs
(miRNAs) that regulate neonatal development and immunity. Pasteurization
ensures microbiological safety in milk banks, but its effects on milk-derived
miRNAs remain unclear. This study evaluated the impact of Holder pasteurization
(62.5 °C, 30 min) on extracellular vesicle (EVs) morphology and
immunoregulatory miRNA expression in exosome, fat, and serum fractions
from six donor samples. EVs were characterized by transmission electron
microscopy, dynamic light scattering, nanoparticle tracking analysis,
and protein quantification. Thirteen miRNAs were analyzed by RT-qPCR.
Pasteurization caused morphological alterations in exosomes, reducing
particle size and increasing protein concentration, while total particle
number remained stable. Expression of eight out of 13 exosomal miRNAs
significantly decreased (p ≤ 0.05), whereas
miRNA profiles in fat and serum fractions were largely preserved.