Comparison of the transcriptpmes of long-tern label retaining-cells and C cells microdissected from mammary epithelium: an initial study to character potential stem/progenitor cells

Authors: CHOUDHARY, RATAN - University Of Maryland; Li, Robert; Clover, Christina; Capuco, Anthony

Submitted to: Frontiers in Oncology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2013
Publication Date: 2/15/2013
Citation: Choudhary, R.K., Li, R.W., Clover, C.M., Capuco, A.V. 2013. Comparison of the transcriptpmes of long-tern label retaining-cells and C cells microdissected from mammary epithelium: an initial study to character potential stem/progenitor cells. Frontiers in Oncology. 3:21.

Interpretive Summary: Mammary stem cells (MaSC) account for the cell lineages of the mammary secretory tissue and provide for mammary growth, development and tissue maintenance. Attempts to characterize MaSC have utilized cell sorting techniques or the in vitro cultivation of cells from enzymatically dissociated tissue as means to obtain a population of cells that is enriched for MaSC. However, use of these approaches results in the loss of information regarding localization of MaSC within the mammary gland. Here we report the use of an alternative approach, laser microdissection, to excise presumptive MaSC and control cells from their locations in histological sections from calf mammary gland and to characterize the molecular properties of these cells. We conclude that MaSC are localized in the basal epithelial and display enriched expression of genes that are associated with stem cell attributes; whereas more committed progenitor cells are localized in the epithelium above the basal layer and express some genes that are associated with stem cell attributes along with genes that are indicative of cell differentiation. Our results also provide a molecular profile and novel candidate markers for bovine MaSC, confirmed by antibody-based histology. These results, generated for bovine mammary gland, have probable application to the study of MaSC in other species.

Technical Abstract: Mammary stem cells (MaSC) account for the cell lineage of mammary epithelia and provide for mammary growth, development and tissue homeostasis. The presence of MaSC was clearly demonstrated by the generation of an entire mammary gland from a single cell implanted into epithelium-ablated mammary fat pads of recipient mice. Attempts to evaluate the molecular character of MaSC have utilized fluorescence-activated cell sorting or the in vitro cultivation of cells from enzymatically dissociated tissue, as means to obtain a population of cells that is enriched for MaSC. However, utilization of these approaches necessitates the loss of histological information encoding the in vivo locale and function of MaSC and their more committed progenitor cell progeny. Here we report the use of an alternative approach, laser microdissection, to excise putative MaSC and control cells from their in situ locations in histological cryosections and to characterize the molecular properties of these cells. We identified potential MaSC in calves based upon their ability to retain bromodeoxyuridine-labeled DNA for an extended period. We then conclude that label retaining epithelial cells in the basal epithelial layer are MaSC, as these cells showed enriched expression of genes that are associated with stem cell attributes; whereas label retaining epithelial cells in suprabasal epithelial layers are progenitor cells, expressing some genes that are associated with stem cell attributes along with those indicative of cell differentiation. Our results also provide a molecular profile and novel candidate markers, confirmed by immunohistochemistry, for bovine MaSC, which have probable application to the study of MaSC in other species.