Scientists reveal hidden world of living cells in human milk

A groundbreaking study published in ACS Nano reveals the intricate cellular and metabolic makeup of human milk. Biomedical scientists from The University of Western Australia combined advanced nanoscale imaging, stable isotope tracing, and single-cell analysis to provide an unprecedented view of the diverse living cells within human milk.

Lead author Qiongxiang (Lynn) Lin explained that human milk is a complex biological system comprising various cell types, yet the functions of these cells remain largely unknown. By employing a novel approach that combines correlative imaging, metabolic tracing, and single-cell analysis, the researchers can now examine individual cells at the nanoscale, understanding how their structure, chemical composition, and metabolism are interconnected.

The study identified major cell populations in human milk, including lactocytes (milk-producing cells) and immune cells like neutrophils, macrophages, and dendritic cells. The researchers discovered that macrophages incorporated glucose into lipid droplets, while lactocytes exhibited active protein production and energy metabolism.

Neutrophils contained high levels of sulfur and iron, contributing to bacterial killing and infant infection protection. The team's findings demonstrate that human milk cells have distinct functions, optimizing milk composition and volume. Additionally, the study's integration of imaging, metabolic tracing, and single-cell analysis offers a new method for exploring human milk biology compared to traditional techniques.

This platform could be used to investigate variations in human milk cells between individuals, throughout lactation, and under different maternal health conditions, potentially enhancing our understanding of the biological roles of living cells in human milk and their significance for maternal and infant health.