Evaluation of MTT and Trypan Blue assays forradiation-induced cell viability test in HepG2 cells

Background: cell viability is an important factor in radiation therapy and thusis a method to quantify the effect of the therapy. materials and methods:the viability of human hepatoma (hepg2) cells exposed to radiation wasevaluated by both the mtt and trypan blue assays. the cells were seeded on96 well-plates at a density of 1 x 10^4 cells/well, incubated overnight, andirradiated with 1-100 gy. results: the cell viability was decreased in adose- and time- dependent manner when using the trypan blue assay, but nosignificant changes in the response to dose could be detected using the mttassay. it indicated that the mtt assay was not efficient at a cell density of1 x 10^4 cells/well on 96 well-plates to determine cell viability. subsequently,the relationship between cell viability and lower cell density (1 x 10^3, 3 x 10^3,and 5 x 10^3 cells/well) was investigated. a cell density of 1 x 10^3 was found tobe the most effective when using the mtt assay. results show that the celldensity is most important when using the mtt assay in 96 well-plates tofollow in radiation effects. furthermore, the radiation-induced cell viabilitydependent on cell density was confirmed by using the traditional clonogenicassay. conclusion: our results suggest that the mtt and trypan blue assaysare rapid methods to detect radiation-induced cell viability of hepg2 cells inabout 3 days as compared with 14 days of assay time in the clonogenic assay.to obtain accurate cell viability measures using both rapid assays, anincubation time of at least 3 days is needed a6er irradiation.