Review of the growth characteristics of cystic fibrosis and normal human diploid fibroblasts in vitro.

The growth kinetics of human diploid skin fibroblasts derived from cystic fibrosis 
(CF) homozygotes, CF heterozygotes and normal individuals was determined. The population 
doubling times increased with time in culture, and no difference was 
observed between the 3 genotypes tested. The cell cycle times remained 
constant through the 10th subculture, while the growth fraction, or fraction 
of cells in the cell cycle, decreased with culture time; however, 
changes in the growth fraction and population doubling time appear to 
be related to cellular senescence in vitro rather than to cystic 
fibrosis. 