Biomedical scientists at The University of Western Australia published a study combining nanoscale imaging, stable isotope tracing, and single-cell analysis to reveal the structural and metabolic complexity of living cells inside human milk.
Imaging Human Milk Cells at the Nanoscale
Human milk functions as a complex biological ecosystem populated by diverse living cells, yet researchers have historically known relatively little about the specific jobs those cells perform. To look closer, biomedical scientists at The University of Western Australia examined major cell populations using an advanced multimodal imaging platform. Combining these methods provides a way to connect cell structure with function.
The research team combined confocal and electron microscopy with nanoscale secondary ion mass spectrometry, known as NanoSIMS. This setup allowed investigators to map individual cells, aligning measurements to study milk-producing lactocytes alongside immune cells such as neutrophils, macrophages, and dendritic cells. Dr Kai Chen, from UWA’s School of Biomedical Sciences, noted that the approach provided a new way to explore the biology of human milk compared to traditional methods.
With our new approach, we can look inside individual cells at the nanoscale and begin to understand how their structure, chemical composition and metabolism are connected.
Qiongxiang (Lynn) Lin, PhD candidate and lead author, via The University of Western Australia
Tracing Nutrients Inside Individual Cells
By using stable isotope tracing to track where sugar (glucose) ended up, the research team found that macrophages showed carbon being turned into fat droplets inside them, indicating those cells were switching on genes involved in handling fat.
When the investigators tracked protein building blocks using amino acids, milk-making cells known as lactocytes proved especially busy, producing milk, releasing protein, and using energy and fat. Integrating these imaging results with single-cell RNA sequencing helped connect how specific cell structures matched up with their nutrient use.
🍼Scientists reveal hidden world of living cells in human milk uncovering new insights into how the cells are structured, what they contain and how they use nutrients. 🤱 @UWAresearch @uwa_chlrt https://t.co/Qb71Ms8g4x
Neutrophils Store Sulphur and Iron to Protect Babies
The structural survey also uncovered high levels of sulphur and iron stored within immune cells called neutrophils. Professor Donna Geddes, director of UWA’s Centre for Human Lactation Research and Translation, highlighted the relevance of these immune cells to infection protection, noting that these elements contribute to the killing of bacteria and help protect babies from infection.
Investigators emphasize that the framework establishes a research platform rather than a clinical test. Future investigations aim to determine whether conditions such as gestational diabetes alter the metabolic characteristics of human milk cells.
We are particularly interested in understanding whether conditions such as gestational diabetes alter the cellular and metabolic characteristics of human milk.
Associate Professor K. Swaminathan Iyer, Director of the ARC Training Centre for Biomedical Analysis, via The University of Western Australia