Isolation and culture of bovine mammary epithelial stem cells.

Bovine mammary epithelial stem cells (MESCs) are very important in agricultural production and bioengineering. In the present study, we compared different isolation and culture methods for MESCs and observed their growth and differentiation characteristics. MESCs have an extremely weak proliferation capacity, and it is very difficult to obtain and prolong subculture of a bovine mammary epithelial stem cell line. We obtained some multipotent MESC aggregates that looked like spherical colonies. These colonies were only derived from suspension culture and were induced to differentiate into epithelial-like cells, myoepithelial-like cells and secretory cells and to establish a ductal-like structure. In contrast, MESCs cultured in adherent culture displayed low morphogenetic competence and only differentiated into epithelial-like cells. MESCs are often identified by testing their differentiation in vivo; however, herein, we have demonstrated the in vitro differentiation potential of bovine MESCs. In our study, beta 1-integrin and alpha 6-integrin which are expressed by human epidermal stem cells, were found in bovine, which shows that bovine MESCs share the same molecular signature as human MESCs.