May 22, 2015

By Medical Discovery News

While the benefits of breast feeding have been well-documented, scientists were surprised to learn of another one: breast milk contains a mother’s stem cells that become a part of different organs of the baby’s body.

Breast feeding protects infants against infections early in life and reduces their risk of juvenile diabetes, heart disease, and cancer as children. It also helps mothers lose weight after giving birth and lowers their risk of osteoporosis and uterine and ovarian cancer.

In addition, seven years ago scientists discovered the presence of mammary stem cells in breast milk. The mammary gland is unique in its ability to go through different stages in anticipation of producing milk, then a period of milk secretion followed by a return to the non-lactating state. All of this can occur as many times as necessary. This massive restructuring of the breast suggested the presence of stem cells.

Human breast milk contains about 14,000 cells in each milliliter. Most of these are the epithelial cells that are abundant in the breast and cells of the immune system. Some of the cells in breast milk had a molecule called nestin on the surface, which in adults is a marker for multipotent stem cells that can develop into many different types of cells, like those in the brain, pancreas, liver, skin, and bone marrow. When scientists transplanted a single nestin-positive stem cells into the fat pad of a grown mouse, it reconstituted a functional mammary gland. Scientists wondered if such cells were serving the same function in humans.

However, further research revealed quite a surprise. First, they genetically modified mice to produce a protein that makes the cells glow red under fluorescent light. Mothers with this new feature were given normal pups to nurse. When they were examined as adult mice, they had cells that glowed red like the mice they had nursed from in their blood, brain, thymus, pancreas, spleen, and kidneys. These cells became functional cells within these organs, so the ones in the brain behaved like neurons and those in the liver made albumin. Based on this experiment, breast milk stem cells travel into the baby’s blood and become functional parts of various organs, at least in mice.

In the laboratory, these stem cells have also shown the ability to differentiate into breast cells that produce milk in a petri dish, as well as bone cells, joint cells, brain cells, heart cells, liver cells, and pancreatic cells that synthesize insulin. In addition, this study may have also discovered a non-invasive, ethical, and sustainable source of multipotent stems.

We don’t yet fully understand the role of these cells in offspring, whether they maintain a tolerance for the mother’s milk, play a role in normal growth and development, or both. Until then, know that your mother is more a part of you than you ever realized.

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