Immortalized epithelial cells derived from human colon biopsies express stem cell markers and differentiate in vitro.

Abstract

Long-term propagation of human colonic epithelial cells (HCEC) of adult origin has been a challenge; currently used HCEC lines are of malignant origin and/or contain multiple cytogenetic changes. We sought to immortalize human colon biopsy-derived cells expressing stem cell markers and retaining multilineage epithelial differentiation capability. We isolated and cultured cells from biopsy samples of 2 patients undergoing routine screening colonoscopy. Cells were immortalized by expression of the nononcogenic proteins cyclin-dependent kinase 4 (Cdk4) and the catalytic component of human telomerase (hTERT) and maintained for more than 1 year in culture. The actively proliferating HCECs expressed the mesenchymal markers vimentin and alpha-smooth muscle actin. Upon growth arrest, cells assumed a cuboidal shape, decreased their mesenchymal features, and expressed markers of colonic epithelial cells such as cytokeratin 18, zonula occludens-1, mucins-1 and -2, antigen A33, and dipeptidyl peptidase 4. Immortalized cells expressed stem cell markers that included LGR5, BMI1, CD29, and CD44. When placed in Matrigel in the absence of a mesenchymal feeder layer, individual cells divided and formed self-organizing, cyst-like structures; a subset of cells exhibited mucin-2 or polarized villin staining. We established immortalized HCECs that are capable of self-renewal and multilineage differentiation. These cells should serve as valuable reagents for studying colon stem cell biology, differentiation, and pathogenesis.