Mammary epithelial cells: Exploring the possibility of developing mammary organoids, artificial mammary glands, and mammary cell lines

The mammary gland is a specific mammalian organ that synthesizes biological fluids required for young offspring. Milk is actively synthesized from this gland via mammary epithelial cells (MECs). In addition, breast cancer is the most commonly diagnosed cancer worldwide. The role of MEC as an in vitro model has been accepted to understand the mechanisms of milk synthesis and the biological mechanisms of breast cancer. This review aimed to determine the advantages of using MECs from two different sources: mammary tissue and fresh milk. MECs from mammary tissue contain stem cells that can be reconstituted to the mammary gland. The major MEC population from fresh milk is the epithelial progenitor. Because the in vitro MEC culture can synthesize major milk components; our first hypothesis is that the MEC culture can be enriched and used as a bioreactor to produce artificial milk components. We extended the protein-producing capacity of the MEC culture to pharmaceutical target proteins. This hypothesis based on the presence of intact posttranslation processes in MECs. Studies on breast cancer biology and the development of target cancer therapies require appropriate mammary cell lines. Therefore, this review provides information on the development of mammary cell lines using MECs from animals. We focused on the senescence and transformation of MECs from various mammalian species. These contemporary perspectives are essential for future research to enhance the well-being of the livestock, provide a choice for recombinant proteins, and refine our understanding of breast cancer.