Goat mammary gland epithelial cells have been used to establish primary and permanent cell lines but to date there is no data on mammary stem cells in this species. The detection and characterization of goat mammary stem cells (gMaSCs) is an important task for a better understanding of the cyclic character of the mammary gland development which will also offer a potential for manipulation of lactation yield and persistency. The objective of the present study was to demonstrate that a subpopulation of MaSCs resides in the goat mammary gland. Mammary tissue from lactating Saanen goats (Capra hircus) was dissociated and processed to a single cell suspension. Using an in vitro colony-forming assay we demonstrated that distinct colony types, which expressed specific lineage markers, arose from unipotent progenitors. Using two different growth media we showed that the frequencies of caprine clonogenic progenitors differed according to growth conditions. Goat epithelial cells were transplanted under the kidney capsule of non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice where they formed organized bilayered structures. Our results indicate the presence of MaSCs in the caprine mammary gland. These data represent the first description of the tissue hierarchy of the goat mammary gland and demonstrate the regenerative potential of goat adult mammary stem cells.
The importance of pluripotent cells, which can differentiate in to different cell lineages and form an entire organism, is fundamental for understanding developmental biology including emerging diseases and offers potential for numerous applications in medicine and biotechnology. However, molecular mechanisms behind differentiation and de-differentiation (reprogramming) remain largely unknown. Until recently it was possible to obtain stem cells only from embryos in the early stages of development (embryonic stem cells - ESCs) or by using very inefficient and technically difficult method of somatic cell nuclear transfer (SCNT) that requires use of egg cells (oocytes). Both methods raised ethical concerns, especially when using human biological material. On the other hand, induced pluripotent stem cells (iPSCs) can be generated by direct reprogramming of differentiated adult somatic cells. iPSCs show similarities to ESCs and represent ethically acceptable and almost unlimited source of individuum-specific pluripotent cells. iPSCs are particularly important for development of regenerative medicine, disease modelling, drug development and testing, basic research, generation of transgenic animals, and for conservation of endangered species. However, before it is possible to exploit their potential in full, reprogramming processes should be investigated and understood in details and safe methods developed - that will enable production of genetically and epigenetically stable cells without tumorigenic potential. This article provides an overview of the field of iPSCs and addresses some of the latest achievements and applications of pluripotent cells in human and farm animals.