Identification of mammary epithelial stem/progenitor cells in goat (Capra hircus)

Goats were among the first farm animals to be domesticated and today produce about 2 % of the world total amount of milk. Goat mammary gland epithelial cells have been used to establish primary cell lines and some permanent cells lines but to date there is no data on mammary stem cells in this species. The goat mammary gland stem cells (MaSCs) are interesting because of the low incidence of ruminant mammary gland neoplasias as well as from the economic point of view where stem cells could be used to manipulate and boost milk production. The objective of our study was to demonstrate that a subpopulation of MaSCs resides in the goat mammary gland. Mammary tissue from lactating Saanen goat (Capra hircus) was dissociated and processed to a single cell suspension. Using in vitro colony-forming (CFC) assay we demonstrated that there are distinct colony types with specific lineage marker expression. Using two different growth media we showed that the frequencies of caprine clonogenic progenitors differ according to growth conditions. Because of the lack of antibodies reacting whit goat epitopes, bulk fraction of goat epithelial cells was transplanted under the kidney capsule of NOD/SCID mice and formed organised bilayered structures. Our results indicate that there are MaSCs in caprine mammary gland and this in vivo assay represents a basis for subsequent studies using FACS and magnetic beads based strategies to further characterise the hierarchy of cells that comprise goat mammary gland.