CLONAL PROLIFERATION OF CULTURED NONMALIGNANT AND MALIGNANT HUMAN-BREAST EPITHELIA

Abstract

A method was developed for clonal growth of human mammary epithelial cells of nonmalignant and malignant origin. Plating efficiencies of 1-50% were obtained by seeding 2nd-passage mammary epithelial cells on fibroblast feeder layers in an enriched medium composed of various hormones and growth factors, as well as conditioned media from 3 specific human cell lines. Single mammary epithelial cells seeded sparsely onto the fibroblasts underwent at least 8 population doublings to form large, readily visible colonies. Optimal colony formation required feeder cells and the enriched medium. Epithelial colonies containing at least 16 cells were visible 5 days postseeding and these colonies continued to grow progressively. Plating efficiency and colony size were similar on UV-irradiated or nonirradiated fibroblasts. The number of colonies formed was proportional to the number of epithelial cells plated. The colonies were identified as epithelial by the presence of human mammary epithelial antigens.