Human Breast Milk Contains PLURIPOTENT Stem Cells!

Last September, during the Bi-Annual Meeting of the International Society for Research in HumanMilk and Lactation occurred in gorgeous Trieste, Italy one could hear a pin drop when Prof. FoteiniHassiotoupresented her and colleagues’ ground-breaking work on human stem cells in breastmilk.

Most of us are familiar with embryonic stem cell research as potentially revolutionary for regenerative medicine and human health. This is because during embryonic development, all of our adult tissues derive from three initial germ layers - the endoderm, the mesoderm, and the ectoderm. In this way embryonic stem cells are pluripotent, which means that the cells have the potential to develop into any of the ~200 cell types in our body.

However, significant controversy surrounds embryonic stem cell research, limiting research effort on this topic. Adult stem cells exist, but they are generally more limited in terms of the types of cells they can become- known as multipotent. Although the presence of adult stem cells had been known to occur in mammary tissue, the presence of stems cells in breast milk was established by Cregan and collegues in 2007. Their initial research suggested that these cells were multipotent and could develop into a limited number of subsequent cell types.  In 2010, the multipotent features of stem cells in breast milk were confirmed by researchers in India (Patki et al. in 2010).

art by Sarah Wray

Dr. Hassiotou and colleagues have now established that pluripotent stem cells are active in the lactating breast and can be non-invasively collected from breast milk (2012). Embryonic stem cells have a “core-circuitry of self-renewal” through the transcription of particular genes (OCT4, SOX2, NANOG, SSEA4, & three transcription factors (TFs)) (Hassiotou et al., 2012). Human breastmilk stem cells (hBSC) show similar patterns of gene activity that allow for the stem cells to replicate. Most excitingly, in vitroinvestigation of hBSC revealed that cells differentiated into cell types of all three germ layers, suggesting pluripotency. For example, hBSC can become neural cells and cells that express insulin, including many others!

Hormonal cues during pregnancy and lactation seemingly activate the stem cells within the mammary gland- hBSC were not found in the breasts of women who were non-pregnant or non-lactating.

In general, discussion of stem cells usually turns to regenerative medicine. Proponents for developing stem cell therapies hypothesize that stem cells could be used to treat patients with Type I diabetics whose islet cells in the pancreas no longer produce insulin. However, from a developmental biological perspective, I am most intrigued about what these hBSC may do when ingested by the infant. Hassiotou and colleagues suggest that hBSC may behave similarly to immunofactors in the infant, crossing into the infant’s bloodstream and playing a role in tissue repair and development.

The discovery of pluripotent stem cells in human milk is a game changer, whether your perspective is regenerative medicine or developmental biology. Research on pluripotent stem cells can now potentially rely on hBSC collected non-invasively, reducing reliance on human embryonic stem cell research. Within the neonate, these stem cells ingested via breastmilk may contribute to developmental programming for health and metabolism later in life. We can further hypothesize that stem cells in breastmilk may be critically important for tissue development and repair in pre-term and NICU infants. Although there are only a handful of studies on this topic, the implications of this discovery can not be overstated. I know I am not alone among my colleagues in eagerly anticipating the next discoveries in human breastmilk stem cells.


Enjoyed this post? Check Out Top Ten Highlights from Mammals Suck, Year 1!

Citations

Cregan MD, Fan Y, Appelbee A, Brown ML, Klopcic B, Koppen J, Mitoulas LR, Piper KM, Choolani MA, Chong YS, Hartmann PE. 2007. Identification of nestin-positive putative mammary stem cells in human breastmilk. Cell Tissue Res. 329(1):129-36.

Hassiotou F, Beltran A, Chetwynd E, Stuebe AM, Twigger AJ, Metzger P, Trengove N, Lai CT, Filgueira L, Blancafort P, Hartmann PE. 2012. Breastmilk is a novel source of stem cells with multilineage differentiation potential. Stem Cells. 30(10):2164-74. doi: 10.1002/stem.1188.

Patki S, Kadam S, Chandra V, Bhonde R.  2010. Human breast milk is a rich source of multipotent mesenchymal stem cells. Hum Cell. 23(2):35-40.

A previous version of this post appeared in SPLASH! Milk Science Update