The morphological variability of HeLa cells in vitro.

Puck and his colleagues (1956, 1957) classified tissue-cultured cells into 2 types, epithelioid (Ep) and fibroblast-like (Fb) cells, and reported that their morphological features were constant through many passages so that they could be supposed to be under genetic control. The HeLa strain derived from a human cervical carcinoma (Gey et al., 1952) is a typical cell line belonging to Ep-type of Puck. Observations on the stock culture of HeLa revealed a diversity of the cell shape inclusive of some of Fb-type. It gives rise to a question whether the transformation from Ep-type to Fb-type is possible. Vogt et al. (1958) reported that a mutant resistant to polio virus which occurred among HeLa cells had a morphology of fusiform and suggested the possibility mentioned above. In the previous report (Yamada et al., 1958), the changes in physiological activities of HeLa cells were pursued following their growth. It was observed that the endogenous respiration was most active in an early stage of cultivation and later the anaerobic glycolysis increased as the former decreased. The possibility was suggested that tissue culture might play the role of environmental factor to select cells with a high glycolytic activity. In order to better effectuate this selection, a culture of HeLa cells was exposed to a prolonged cultivation as will be described later. A new cell line obtained by the prolonged cultivation showed a high glycolytic activity and, at the same time, a special cell morphology of spindle-like or Fb-type, different from Ep-type representing the stock culture. The present paper deals with the process of the isolation of the variant, its morphological features and other properties. The morphological characters were durable, suggesting the genetic traits. The appearance of the new cell type was supposed, by scrutinizing the properties of the colonial clones, to be due to the spontaneous mutation and selection.