Breast is really best

Posted on December 14, 2011

Breast FeedingFor the first time, embryonic-like stem cells have been discovered in an adult. Perhaps not surprisingly, they were found in breast milk which is about as closely associated with embryonic cells as you can get without being the embryo or the pregnant mother. If they live up to their potential we may have one day soon a source of stem cells for medical therapy which do not involve destroying any embryos at all.

English: Embryonic Stem Cells. Image shows hESCs.

It was back in 2008 when Peter Hartman at the University of Western Australia and his collegues announced they had discovered stem cells in breast milk and now, crucially, those cells have been turned into the sort that represent all three of the embryonic germ-plasm layers: the endoderm, the mesoderm and the ectoderm. The existence of all three of these layers is a defining property of embryonic stem cells (ESCs) and is what makes them so medically valuable.

“They can become bone cells, joint cells, pancreatic cells that produce their own insulin, liver cells that produce albumin and neuronal cells,” said Foteini Hassiotou, a member of Hartman’s team and leader of the most recent work. The cells also express most of the protein markers expected in ESCs.

“What is really amazing,” Hassiotou added, “is that these cells can be obtained in quite large amounts in breast milk.” She says that the stem cells make up about two percent of the cells found in breast milk although the number varies according to how long the woman has been producing milk and how full her breasts are.

Many other researchers are sceptical though. The real test will come when these cells are injected into mice to see if they form teratomas (tumours containing tissue or structures derived from all three of the germ layers).

English: Diagram to show how embryonic stem ce...“Perhaps there are some mammary gland stem cells that can be coaxed to have a broader potential,” said Robin Lovell-Badge of the UK’s National Institute for Medical Research based in London, “but I very much doubt that embryonic-like cells normally exist in the breast.”

Embryonic stem cells have previously been found in the amniotic fluid that surrounds the developing embryo and in the umbilical cord, but never before in adults. Other forms of stem cells do exist in adults, such as those that can develop into blood cells or turn into bone. Such cells though cannot generate anything like as many cell types as ESCs are capable of. Even if the cells turn out not to be ESCs, they still provide a potential medical resource for regenerative medicine for the mother should she develop some disease later in life. Perhaps the most interesting question, though, is what function these cells have in the normal development of the child as it grows.