Hi guys,.
I have done MTT assays with different drugs with 1000 or 2000 cells plated in 96 well plates. When I obtained my results, the line on the graph of cell viability against drug concentration have relatively the same pattern in both 1000 and 2000 cells per well experiments. However, the IC50s were different. To me this makes sense, because I would expect that different cell densities would have different IC50s for the same line. Is this right?
Regards,
Abraham.
From observation from my lab this is the case, and it works for many different cancer cell lines and drugs. Furthermore IC50 strongly depends also on the time of incubation - how long (24,48, 72h) the cells are kept with the drug. The longer the time of incubation the lower the IC50. Theoretically. The best time to incubate the cells with the drug is the doubled time of they doubling time (eg. cells have doubling time 24h, so they should be incubated with the drug for 48h).
The cell density is a crucial factor for the cell survival after treatment with the same drug concentration. Lower cell density makes cells more susceptible to the drug - their survival/growth rate is smaller. That phenomenon is caused by lower concentration of growth factors produced by cells as well as by the fact that they are more exhibited to the drug (free spaces between cells).
Hi Agnieszka,
So does this support the theory that lower cell density would have a lower IC50? Thereby meaning, that IC50 can vary from publication to publication?
Thanks for your response.
From observation from my lab this is the case, and it works for many different cancer cell lines and drugs. Furthermore IC50 strongly depends also on the time of incubation - how long (24,48, 72h) the cells are kept with the drug. The longer the time of incubation the lower the IC50. Theoretically. The best time to incubate the cells with the drug is the doubled time of they doubling time (eg. cells have doubling time 24h, so they should be incubated with the drug for 48h).
- Badges
- Science topic
- Similar topics
- Mathematical Sciences
- Graphs