High-density lipoprotein and extracellular matrix promotes growth and plating efficiency of normal human mammary epithelial cells in serum-free medium.

A routine procedure has been developed for the establishment in culture of normal primary and secondary human mammary epithelial cells. The high (80-100%) rate of success resulted from the combined use of a serum-free medium supplemented with high-density lipoprotein (HDL) and of cell plating on a naturally produced extracellular matrix (ECM). Plating on ECM greatly improved cell attachment, plating efficiency and initial outgrowth. HDL supported epithelial cell proliferation and prevented their detachment and degeneration while the omission of serum prevented the growth of stromal fibroblasts. Under these conditions we obtained from each specimen, and regardless of the patient's age, pure and actively dividing epithelial cell cultures forming a tightly packed and non-overlapping cell monolayer covering the entire area of the culture dish. These epithelial cultures could be easily dissociated and subcultured at a split ratio of 1:10. The described procedure will promote studies on the role of hormones and growth factors in the proliferation and differentiation of human mammary epithelial cells and on the susceptibility of human breast epithelial cells to various transforming agents and anti-cancer treatments.