PHENOTYPIC CHARACTERIZATION OF COLLAGEN GEL EMBEDDED PRIMARY HUMAN BREAST EPITHELIAL-CELLS IN ATHYMIC NUDE-MICE

We have developed a method to characterize the phenotypes and tumorige nicity of dissociated human boast epithelial cells. The dissociated ce lls were first embedded in collagen gels and subsequently transplanted subcutaneously in vivo in athymic nude mice. The transplantation of d issociated epithelial cells from reduction mammoplasties, presumed to be normal, always resulted in normal histomorphology. Epithelial cells were arranged as short tubular structures consisting of lumina surrou nded by epithelial cells with an occasional more complex branching str ucture. These outgrowths were surrounded by intact basement membrane a nd were embedded in collagen gel that, at termination, contained colla genous stroma with fibroblasts and blood vessels. In contrast, transpl antation of dissociated breast epithelial cells from breast cancer spe cimens resulted in outgrowths with an invasive pattern infiltrating th e collagen gel as well as frank invasion into vascular space, nerves a nd muscles. These observations were made long before the subsequent pa lpable stage which resulted if left in the mouse for a long enough tim e. The dissociated human breast epithelial cells thus retained their i ntrinsic property to undergo morphogenesis to reflect their original p henotype when placed in a suitable environment, the collagen gel.