Mammary stem cells have myoepithelial cell properties.

Abstract:: Contractile myoepithelial cells dominate the basal layer of the mammary epithelium and are considered to be differentiated cells. However, we observe that up to 54% of single basal cells can form colonies when seeded into adherent culture in the presence of agents that disrupt actin-myosin interactions, and on average, 65% of the single-cell-derived basal colonies can repopulate a mammary gland when transplanted in vivo. This indicates that a high proportion of basal myoepithelial cells can give rise to a mammary repopulating unit (MRU). We demonstrate that myoepithelial cells, flow-sorted using two independent myoepithelial-specific reporter strategies, have MRU capacity. Using an inducible lineage-tracing approach we follow the progeny of myoepithelial cells that express α-smooth muscle actin and show that they function as long-lived lineage-restricted stem cells in the virgin state and during pregnancy.

Authors:: MD Prater, V Petit, I Alasdair Russell, RR Giraddi, M Shehata, S Menon, R Schulte, I Kalajzic, N Rath, MF Olson, D Metzger, MM Faraldo, M-A Deugnier, MA Glukhova, J Stingl

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