Throughout a person's life, the various tissues in his or her body will be replenished and repaired by drawing upon a reservoir of adult stem cells. As new cells replace old ones or are used to construct new tissue, the architecture of that specific tissue must be maintained. Otherwise, cancer or other diseases can arise. This process requires that lineage-specific progenitor cells or their differentiated progeny be able to reach their ultimate destination within the tissue. This task is particularly daunting for breast cell lineages because the mammary gland undergoes cyclical changes in its architectural structure, showing as much as a 10-fold expansion in preparation for lactation followed by return to normal size. During these cycles, the precise bi-layered branching organization throughout the gland, in which a layer of secretory luminal epithelial cells (LEPs) is surrounded by a layer of contractile myoepithelial cells (MEPs), must be maintained.
"We hypothesized that mammary epithelial cells possess lineage-specific intrinsic abilities to self-organize into domains of lineage specificity, which would help explain how, for instance, the mammary stem cell-enriched zone in the ducts is maintained separately from the rank-and-file LEPs and MEPs, and how LEPs and MEPs form and maintain bi-layers," LaBarge says. "The phenomenon of self-organization has not been well studied in humans, perhaps because of the challenges of working with primary materials and a paucity of tractable culture systems for maintaining cell types from normal adult tissues."
|Contact: Lynn Yarris|
DOE/Lawrence Berkeley National Laboratory