Mammary Epithelial Stem Cells: Our Current Understanding
- Cite this article as:
- Chepko, G. & Smith, G.H. J Mammary Gland Biol Neoplasia (1999) 4: 35. doi:10.1023/A:1018752519356
It has recently been shown that the progeny froma single cell may comprise the epithelial population ofa fully developed lactating mammary outgrowth in mice.Serial transplantation of epithelial fragments from this clonally derived gland demonstratesthat the subsequently generated outgrowths are alsocomprised of progeny from the original antecedent.Similarly, genetic analysis of contiguous portions of individual human mammary ducts within the samebreast indicates their clonal derivation. Theseobservations support the concept that multipotenttissue-specific epithelial stem cells are present amongthe parenchymal cells of the mammary gland. Here,we present the developing evidence for the presence ofstem cells in virtually every renewing mammalian tissueas well as some classically considered to consist only of differentiated cells. Further, wereview the present morphologic and biologic evidence forstem cells and lineage-limited progenitor cells in humanand rodent mammary epithelium. Although a number of selective markers are known for variouslineage-limited hematopoietic cells and their progeny,our understanding of the biology of the precursor cellsfor mammary epithelium is just beginning. Our purpose here is to develop further interest in theclarification of these issues in the biology of themammary gland.