Breast milk-derived exosomes promote intestinal epithelial cell growth

Background: Breast milk administration prevents necrotizing enterocolitis (NEC). However, the mechanism remains unclear. Exosomes are cell-derived vesicles highly present in human milk and regulate intercellular signaling, inflammation, and immune response. We hypothesized that milk-derived exosomes beneficially affect intestinal epithelial cells. Methods: Rat milk was collected, and exosomes were isolated using ExoQuick reagent and visualized by Nanoparticle Tracking Analysis. Protein was extracted from encapsulating exosomes, and concentration was measured. 2 x 10(4) intestinal epithelial cells (IEC-18) were treated for five hours with 0.5-mu g/mu l exosomes, an equal volume of exosome-free milk, or control solution (PBS). IEC-18 viability was measured using a colorimetric assay (MTT), and gene expression was analyzed by qRT-PCR. Data were compared using one-way ANOVA with Bonferroni post-test. Results: Rat milk was collected, and exosome isolation was confirmed. Compared to control, treatment with exosomes significantly increased IEC viability, proliferation, and stem cell activity (all p < 0.05). However, administration of exosome-free milk had less significant effects. Conclusions: Rat milk-derived exosomes promote IEC viability, enhance proliferation, and stimulate intestinal stem cell activity. These findings provide insight into the mechanism of action of breast milk in the intestines. Exosome administration is a promising prevention method for infants at risk of developing NEC when breastfeeding is not tolerated. (C) 2017 Elsevier Inc. All rights reserved.