Cumulative labelling with thymidine analogues when the steady-state assumption is violated.

We present modelling results that examine the consequences of implementing cumulative labelling with thymidine analogues, to estimate the cell cycle time and growth fraction of dividing cells, when the steady-state assumption is violated. We fix the value of the cell cycle time a priori and examine whether cumulative labelling can reproduce this value. We find that the cumulative labelling technique systematically overestimates the growth fraction and cell cycle time in non-steady cell populations. Our results suggest an explanation for discrepancies in experimental measurements of oligodendrocyte precursor cell properties using cumulative labelling. These results also emphasise the utility of using computational models to determine what violating the assumptions of experimental techniques would look like in the laboratory before experiments are undertaken.