Desynchronization rate in cell populations: Mathematical modeling and experimental data

We characterize the kinetics of two cancer cell lines: IGROV1 (ovarian carc inoma) and MOLT4 (leukemia). By means of flow cytometry, we selected two po pulations from exponentially growing in vitro cell lines, depending on the cells' DNA synthesis activity during a preceding labeling period. For these populations we determined the time course of the percentages of cells in d ifferent phases of the cycles, sampling every 3 hr for 60 hr. Initially, se mi-synchronous populations quickly converged to a stable age distribution, which is typical of the cell line (at equilibrium); this desynchronization reflects the intercell variability in cell cycle duration. By matching thes e experimental observations to mathematical modelling, we related the conve rgence rate toward the asymptotic distribution (R) and the period of the ph ase-percentage oscillations (T), to the mean cell cycle duration and its co efficient of variation. We give two formulas involving the above-mentioned parameters. Since T and R can be drawn by fitting our data to an asymptotic formula obtained from the model, we can estimate the other two kinetic par ameters. IGROV1 cells have a shorter mean cell cycle time, but higher inter cell variability than the leukemia line, which takes longer to lose synchro ny. (C) 2001 Academic Press.