I am currently performing a kill curve with HEK-293 and OE-33 cells and geneticin.

I followed the same protocol for both cell lines:

48 well plate. 8 diff concentrations (0 µg/ml -> 1000 µg/ml), 6 replicates per concentration. Seeded at 0,03x10^6 cells per well. Medium change every 2-3 days.

To the date I have performed 2 counts. Unexpectedly, I have observed that at higher Gen. concentrations the total cell number is much higher than at lower concentrations. The percentage of live cells is, as expected, progressively lower with increasing concentrations and time in culture.

I am just curious as to what could be the reason for the higher number of total cells at much higher Geneticin concentrations (ex: 3,9x10^5 at 50 µg/ml vs. 2.2 x10^6 at 1000 µg/ml)

Thanks in advance