A Study of the Cytogenetics of the Human Cell Strain WI-38

Cultures of the human diploid cell strain WI-38 were subcultivated under conditions which would meet the requirements proposed for the use of this strain as a substrate for the preparation of viral vaccines and would be in keeping with efficient production procedures. For chromosomal analysis, the cultures were combined in three groups at low, intermediate, and high passage levels, the latter being beyond those recommended for vaccine production. At all passage numbers, the incidence of aneuploid cells was low and constant up to those passages where the finite life span was approached and the population doubling time became markedly prolonged. At all passage levels, the incidence of gaps was higher than that of breaks but there was no significant increase of either of these abnormalities with continuous subcultivation. Among structural abnormalities dicentrics, despiralizations and deletions predominated. A significant increase in polyploidy occurred in the highest passage numbers, although the ratio of polyploidy to endoreduplication was constant throughout the series. Neither heteroploid transformation nor nonrandom chromosomal aberrations were observed. Nor was there correlation between observed aberrations and their location on the chromosomes. The incidence of hypodiploidy was lower than reported by other investigators. At the cellular level, no morphological changes could be associated with the distribution of chromosomal aberrations.