Immortalization of cells from brains derived from a strain (MSM/MSfB6C3F1) of wild mouse

Escape from cellular aging is the rate-limiting step of multistep carcinogenesis. While normal human cells invariably undergo cellular aging and almost never spontaneously immortalize, cells derived from rodents such as mice are relatively easily immortalized. In this experiment, we studied the immortalization patterns of cells obtained from brain tissues of an inbred strain (MSM/MSfB6C3F1) derived from wild mice. We established 12 cell strains derived from 12 mouse brains in order to investigate whether these cells show cellular aging in the same fashion as human cells or whether these cells are immortalized as easily as rodent cells reported previously. As a result, all cell strains were immortalized up to about 200 days in culture. One strain immortalized very early, in the first 50 days, four strains immortalized in the last 200 days, and the other seven strains became immortal between 150 and 200 days in culture. All immortalized cell strains showed varying amounts of chromosome abnormalities, numerically and structurally, but no specific changes related to immortalization were detected. Before immortalization, three types of cells, glial-like, polygonal flat-thin, and fibroblast-like cells, were observed in culture, but after immortalization most of the cultures became fibroblastic. From these results, we concluded that fibroblast-like cells derived from brains of these mice immortalized in like fashion to fibroblasts of other inbred mice.