Comparison of cell proliferation and toxicity assays using two cationic liposomes

The present study compares different cytotoxicity and cell proliferation assays including cell morphology, mitochondrial activity, DNA synthesis, and cell viability and toxicity assays. CaSki cells were exposed to two cationic liposomal preparations containing dimethyldioctadecyl-ammonium bromide (DDAB), dioleoylphosphatidylethanolamine (DOPE) and a commercial transfection-reagent DOTAP (N[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium-methylsulfat e). The results provided by these assays were similar. However, the lactate dehydrogenase assay was more sensitive in measuring early damages of cell membranes than the Trypan blue assay. Also, cell morphology showed early toxic changes, such as cytoplasmic vacuolization and cell shrinking, and it should be included with such toxicity evaluations. DDAB:DOPE was more toxic than DOTAP. The cells treated with DOTAP at 10 microM were surviving as well as the control cells, while DOTAP at 40 uM and DDAB:DOPE at 10 microM had slight toxic effects on CaSki cells. The most toxic effects were seen in CaSki cells after treatment with DDAB:DOPE at 40 microM.