Goat milk: Non-invasive source for mammary epithelial cell isolation and in vitro culture

Mammary epithelial cells (MECs) used to study mammary gland function in vitro are typically isolated from mammary tissue. Breast milk offers an alternative source of MECs to replace mammary gland tissue. This study aimed to isolate and culture MECs from goat milk. Samples of fresh goat milk were collected from early and late-lactating Saanen goats. Samples were subjected to isolation, culture and characterization for putative MECs. The cells adhered to the culture dishes 1 day after isolation and displayed a monolayer pattern, epithelial-like cobblestone morphology, and formed alveoli-like structures that are typical of MECs. We identified the epithelial origin of the isolated cell by staining with antibodies against cytokeratin 8, 18 and alkaline phosphatase. Moreover, some of the isolated cells expressed the stem cell marker stage-specific embryonic antigen-4. The transcription of Capra hircus β-casein (CNS2) gene, a candidate gene for analysis of lactational function, was detected in MECs after induced differentiation. In addition, green fluorescence protein (GFP)-expressing cells could be generated from goat milk-derived MECs. This study demonstrated that goat MECs can be easily isolated from milk samples collected from early and late-lactating goats. Our MECs model could be an effective model for in vitro studies of milk synthesis and gene targeting in the goat mammary gland. Isolation of MECs from goat milk rather than mammary tissue improves animal welfare and can be used as a replacement for the animal in future studies.