New window into women’s health uncovered as Cambridge researchers find breast milk contains live cells
Cambridge scientists have found that cells in human breast milk are alive, opening up a host of new avenues for research into women’s health.
It had been thought that cells in milk were dead or dying. But the new finding offers researchers the opportunity to study changes in mammary tissues during lactation and may also provide insight into a potential early indicator of future breast cancer development.
The study was led by researchers at the Wellcome-MRC Cambridge Stem Cell Institute (CSCI) and the Department of Pharmacology at the University of Cambridge.
They explored cellular changes in human mammary tissue in both lactating and non-lactating women to derive insights into the relationship between pregnancy, lactation, and breast cancer.
Dr Alecia-Jane Twigger, of CSCI, who led the study, said: “I believe that by studying human milk cells, we will be able to answer some of the most fundamental questions around mammary gland function such as: how is milk produced? Why do some women struggle to make milk and what strategies can be employed to improve breastfeeding outcomes for women?”
Voluntary breast milk samples were collected from lactating women along with samples of non-lactating breast tissue donated from women who elected to have aesthetic breast reduction surgery.
Single-cell RNA sequencing analysis was then use to compare the composition of the different mammary cells.
This identified distinctions between lactating and non-lactating human mammary glands.
“The first time Alecia told me that she found live cells in milk I was surprised and excited about the possibilities,” said Dr Walid Khaled, at CSCI and Cambridge’s Department of Pharmacology, who was also involved in the research. “We hope this finding will enable future studies into the early steps of breast cancer.”
Accessing breast tissue for study has relies on donors already undergoing surgery.
But breast milk samples are much easier to acquire, with midwives or women’s networks able to engage with donors.
While lactating women typically produce about 750-800ml of milk each day, Dr Twigger’s research requires only 50ml - and that amount can contain hundreds of thousands of cells for study.
Now that it is known such samples contain living and viable cells, researchers have the opportunity to capture dynamic cells in a non-invasive way.
Breast tissue changes during puberty, pregnancy, breastfeeding and aging. The new research, published in the journal Nature Communications,indicates how greater ease of access to live breast cells can enable further studies of women’s health.
The researchers report: “We found that human milk largely contains epithelial cells belonging to the luminal lineage and a repertoire of immune cells. Further transcriptomic analysis of the milk cells identified two distinct secretory cell types that shared similarities with luminal progenitors, but no populations comparable to hormone-responsive cells.
“Taken together, our data offers a reference map and a window into the cellular dynamics that occur during human lactation and may provide further insights on the interplay between pregnancy, lactation and breast cancer.”
They note: ”While mammary cells isolated from the milk do not directly contribute to breast cancer formation, they provide an opportunity to easily obtain and study human breast cells.”
The paper and its findings are part of the Human Breast Cell Atlas project funded by the MRC, and the research was funded by the MRC, BBSRC and Wellcome-MRC Cambridge Stem Cell Institute.
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