Exosomes Derived from Colostrum and Mature Human Breast Milk Protect Against Experimental Necrotizing Enterocolitis

Background: Human breast milk-derived exosomes can protect intestinal organoids from the injury caused by lipopolysaccharide (LPS). The aim of the current study is to further investigate the effects of the exosomes derived from different periods of lactation on the intestinal injury caused by experimental necrotizing enterocolitis (NEC).

Methods: Colostrum and mature breast milk samples from healthy lactating mothers were collected. Exosomes were isolated using serial ultracentrifugation and filtration and characterized (transmission electron microscopy and western blot). NEC was induced in C57/BL6 mice by hypoxia, gavage of feeding of formula and LPS administration between postnatal days 5 and 9. Breastfed pups were controls (n=12), whereas NEC groups received daily gavage feeding of formula with added phosphate buffered saline (PBS; n=10), colostrum exosomes (0.1μg/μl; n=11), or mature breast milk exosomes (0.1μg/μl; n=11). The distal ileum was examined for NEC histology, inflammatory cytokines (IL-6 and TNF- α), epithelial proliferation (PCNA) and intestinal regeneration marker (Lgr5 and Olmf4) expression.

Results: Compared to NEC groups, both colostrum and mature breast milk exosomes significantly decreased NEC incidence (p < 0.05), improved intestinal injury (Figure A-B), reduced intestinal inflammation (Figure C), and enhanced both enterocyte proliferation (Figure D) and intestinal regeneration (Figure D). Furthermore, compared to mature breast milk exosomes, colostrum exosomes appear to be more effective at enhancing enterocyte proliferation and intestinal regeneration.

Conclusion: Human breast milk-derived exosomes were able to decrease the incidence and severity of experimental NEC. Colostrum exosomes induce greater intestinal regeneration compared to mature breast milk exosomes.