Evidence for stem cells in cultures of mouse prostate epithelial cells

BACKGROUND. Primary cultures of mouse prostatic epithelial cells were studied to identify cells having stem cell characteristics. METHODS. Culture conditions supporting the growth of mouse prostatic epithelial cells were identified. Immunostaining identified cells expressing cytokeratin 5 (K5), cytokeratin 8 (K8), and bcl-2. Cells with clonogenic capacity were identified by replating dissociated cells from primary colonies. RESULTS. Only 2-4% of prostatic epithelial cells that were plated formed colonies. Most cells cultured for 2-4 days expressed bcl-2, K5, and KS, After 6 days in culture, colonies had two distinct phenotypes, star- or disc-shaped. In colonies of both phenotypes, only a few cells expressed K5 and bcl-2, while all cells expressed K8. Upon replating, two-thirds of star-shaped colonies gave rise to a single colony; of 29 disc-shaped colonies, none gave rise to new colonies, CONCLUSIONS. Colonies deriving from putative prostatic epithelial stem cells are identified. These cells express K5 and bcl-2 and a-re clonogenic. (C) 2002 Wiley-Liss, Inc.