Abstract 11490: The Role of Breast Milk Extracellular Vesicles on Endothelial Dysfunction

Introduction: Breast milk has abundant extracellular vesicles (EVs), which have strong anti-inflammatory properties. EVs are not degraded in the stomach, thus, orally administered milk exosomes are absorbed into the intestine and then disseminated to other organs via circulation. Circulating milk EVs in the blood have a high chance of interacting with endothelium, however, the impact of milk exosomes on the endothelial cells has not been examined. Endothelial dysfunction is a hallmark of cardiovascular diseases induced by the inflammatory process. In this study, we have tested if orally administered human breast milk EVs (bEVs) can improve endothelial dysfunction in obese mice. Hypothesis: Oral administration of bEVs restores the endothelial function in high fat diet-induced obese mice Methods: Breast milk was obtained from healthy mothers with normal pre-pregnancy BMI who delivered a baby within the past 30 days (n=24). bEVs were isolated by ultracentrifugation, and the presence of exosomes was confirmed with the expression of CD9, CD81, CD63, and TSG101. C57BL/6J male mice were fed a 60% high-fat diet for 16 weeks, then bEVs were administered weekly via oral gavage for six weeks (3μg of EVs/g). The same amount of PBS was administered to obese and chow diet-fed mice. Glucose tolerance test and insulin tolerance test were performed before and after treatment. Endothelial cell-dependent vasorelaxation was measured in the 1 st branches of mesenteric arteries. Results: Oral administration of bEVs for 6-weeks did not change body weight in obese mice. Glucose tolerance and insulin tolerance were not also affected. However, the fasting blood glucose level was significantly reduced (p=0.0012, n=5-7) in bEV-treated obese mice. In mesenteric arteries, acetylcholine-induced relaxation was significantly improved (p<0.001) in bEV-treated obese mice compared with the PBS-treated obese mice. Conclusions: Oral administration of bEVs improved the endothelial cell function in obese mice, although the metabolic parameters were not changed. Further investigation will be followed to understand how bEVs improve the impaired endothelial cell-dependent vasorelaxation.