Hidden Shifts in Breast Cells: Why Some Mothers Struggle to Breastfeed

Scientists have identified the genes behind the mammary gland’s dramatic shifts during pregnancy, breastfeeding, and its return to a resting state, using mice as a model (1^✔ ✔Trusted Source
Study of breast cell changes in motherhood provides clues to breastfeeding difficulties

Go to source). The work produced the most detailed gene expression atlas yet of the gland’s adult developmental cycle. The findings represent the most comprehensive atlas of genetic expression ever produced for the adult mammary gland’s developmental cycle, published today in Nucleic Acids Research.

Understanding the Mammary Gland’s Cellular Makeup

The mammary gland is made up of different cell types, each with a different function—such as fat cells that provide structural support, and basal cells that are crucial for milk ejection.

The team analyzed the cellular composition of the mammary gland at ten different time-points from before the first pregnancy, during pregnancy, during breastfeeding, and during involution, when the breast tissue is remodelled to its resting state. The mix of cell types changes dramatically through this cycle.

By measuring gene expression in the mammary gland across these time-points, the researchers were able to link specific genes to their functions at different stages of the developmental cycle.

“Our atlas is the most detailed to date, allowing us to see which genes are expressed in which cell types at each stage of the adult mammary gland cycle,” said Dr. Geula Hanin, first author from the University of Cambridge’s Department of Genetics.

New Clues to Breastfeeding Challenges

The team found that genes associated with breastfeeding disorders, such as insufficient milk supply, are active not only in milk-producing cells, but also in basal cells, which squeeze out milk as the infant suckles.

This suggests that, in some cases, breastfeeding issues may stem from mechanical problems rather than milk production, highlighting new cellular targets for investigation.

Genetic Links to Postpartum Breast Cancer

The study also revealed that genes linked to postpartum breast cancer become active immediately after weaning, across several cell types; including fat cells, which were previously overlooked as contributors to cancer risk after childbirth. This discovery opens new avenues for early detection and prevention strategies.

The researchers also studied ‘imprinted genes’—genes that are switched on or off depending on whether they are inherited from the mother or the father.

They identified 25 imprinted genes active in the adult mammary gland at precise times in the development cycle. These appear to orchestrate a finely tuned system that regulates milk production and breast tissue changes during motherhood.

Maternal and Infant Health Implications

Hanin noted: “We’ve found that genes associated with problems in milk production, often experienced by breastfeeding mothers, are acting in breast cells that weren’t previously considered relevant for milk production. We’ve found genes associated with postpartum breast cancer acting in cells that have been similarly overlooked.”

Breastfeeding influences lifelong health: breast-fed babies are less likely to develop obesity and diabetes. Yet one in twenty women face breastfeeding difficulties, an area that remains understudied in women’s health.

Postpartum breast cancer, occurring within five to ten years after childbirth, is associated with hormonal shifts and natural tissue remodelling during involution that may make the breast more vulnerable to malignancy.

“Breastfeeding is a fundamental process that’s common to all mammals; we wouldn’t have survived without it. I hope this work will lead to new ways to support mothers who have issues with breastfeeding, so they have a better chance of succeeding,” said Hanin.

Reference:

1. Study of breast cell changes in motherhood provides clues to breastfeeding difficulties - (https://www.cam.ac.uk/research/news/study-of-breast-cell-changes-in-motherhood-provides-clues-to-breastfeeding-difficulties)

Source-University of Cambridge