IMMORTAL, DEVELOPMENTALLY ARRESTED HUMAN FETAL KIDNEY-CELL LINES CREATED BY RETROVIRAL EXPRESSION OF HUMAN PAPILLOMA-VIRUS E6 AND E7

Aims: For studies of kidney organogenesis, clonal human fetal kidney ( HFK) cell lines that represent various stages of kidney epithelial dev elopment would provide valuable tools for in vitro approaches to kidne y cell differentiation. Methods: Cell cultures from the cortices of 12 - to 16-week HFKs were immortalized by retroviral expression of human papilloma virus (HPV) E6/E7 genes, and clonal isolates were characteri zed with regard to morphology, expression of molecular markers, growth on different matrices, and their ability to differentiate further in vitro. Results: Three immortal, clonal cell lines displayed homogeneou s but distinct morphologies in vitro, ranging from mesenchymal to epit helial. Northern blotting with stage-specific markers allowed us to as sign particular cell lines to discrete stages in kidney cell different iation. These results were confirmed by assessing cell growth on type- I collagen versus Matrigel matrices. We have also demonstrated that fo r one of the cell lines fetal calf serum contains a differentiation fa ctor that induced morphological differentiation and enhanced expressio n of epithelial-specific genes. Conclusion: Immortalization by HPV-E6/ E7 expression preserved important phenotypic characteristics of fetal kidney cells. The creation of these lines provides useful tools for in vitro approaches to kidney growth and development.