Morphological Analysis of Human Milk Membrane Enclosed Structures Reveals Diverse Cells and Cell-like Milk Fat Globules

AbstractOver the past decade, the cellular content of human milk has been a focus in lactation research due to the benefit a potential non-invasive stem cell compartment could provide either to the infant or for therapeutic applications. Despite an increase in the number of studies in this field, fundamental knowledge in regard to milk cell identification and characterisation is still lacking. In this project, we investigated the nature, morphology and content of membrane enclosed structures (MESs) and explored different methods to enrich human milk cells (HMCs) whilst reducing milk fat globule (MFG) content. Using both flow cytometry and immunofluorescence imaging, we confirmed previous reports and showed that nucleated HMCs make up a minority of milk-isolated MESs and are indistinguishable from MFGs without the use of a nuclear stain. HMC heterogeneity was demonstrated by differential uptake of nuclear stains Hoechst 33258 and DRAQ5 ™ using a novel technique of imaging milk MESs (by embedding them in agar), that enabled examination of both extracellular and intracellular markers. We found that MESs often contain multiple lipid droplets of various sizes and for the first time report that late post-partum human milk contains se cretory luminal binucleated cells found across a number of participants. After investigation of different techniques, we found that viably freezing milk cells is an easy and effective method to substantially reduce MFG content of samples. Alternative...

Source: Journal of Mammary Gland Biology and Neoplasia - January 4, 2021 Category: Cancer & Oncology Source Type: research