Polydopamine and dopamine interfere with tetrazolium-based cytotoxicity assays and produce exaggerated cytocompatibility inferences

Polydopamine (PDA) and dopamine (DA) can spontaneously reduce MTT reagent to formazan, resulting in incorrect cell-viability inferences. The non-redox Trypan Blue exclusion assay provides a more reliable estimate of cell viability with PDA and DA.

Effect of lead on proliferation, oxidative stress and genotoxic damage of 3T3-L1 fibroblasts

Lead (Pb) is an environmental and industrial contaminant that still represents a public health problem. In this paper, we investigated the effect of Pb on proliferation, lipid peroxidation and the number of micronucleated cells in exponentially growing 3T3-L1 fibroblasts, a cell line previously used to evaluate different environmental contaminants. We found that Pb (10 μM or higher) was able to inhibit proliferation of exponentially growing cells after 24-h treatment, which was evaluated by the MTT assay and cell counting in Neubauer chamber, but cell survival was not affected according to the trypan blue exclusion assay. On the other hand, Pb was able to increase lipid peroxidation and the number of micronucleated cells, which are indicative of oxidative stress and genotoxic damage respectively. We also found that removal of Pb after 24-h treatment allowed cells to recover proliferation. Our results indicate that Pb was able to induce oxidative stress and genotoxicity in this cell line under standardized conditions, which supports the involvement of Pb in similar effects observed in human exposed to this heavy metal. In addition, Pb inhibits proliferation of exponentially growing fibroblasts but cells resume proliferation after removal of this metal, which suggests that it is important to move away Pb-exposed individuals from the source of contamination.

Effects of curcumin and luteolin on viability and cell death induction in NFS-60 cell line

Inducing cell death in tumor cells has been recognized as a promising strategy in curing tumors. Parallely, natural products, especially those with long-known usage in folk medicine, are gaining demanding and extensive clinical interests. Aiming to contribute to overall knowledge of curcumin and luteolin antitumour potentials, we analyzed their effects on cell death induction in NFS-60 cell line, using Trypan blue exclusion assay and TransDetect® Anenexin V-EGFP/PI assay. Results show that both tested agents induce cell death, especially in higher applied concentrations, but further investigations are needed to elucidate the mechanisms behind it.

Clarification of the Phenotypic Characteristics and Anti-Tumor Activity of Hedyotis diffusa

Hedyotis diffusa Willd. (Rubiaceae) is an important folk herb used to prevent and cure hepatitis and liver cancer in Taiwan. For differentiation of H. diffusa from counterfeits, macroscopic and microscopic characters of H. diffusa, H. corymbosa and H. tenelliflora were examined in this study. According to Trypan blue exclusion assay and Western blot analysis, H. diffusa had a significant inhibition of cell growth and induction of cell apoptosis in COLO 205 (colon cancer), Hep 3B (hepatocellular carcinoma) and H460 (lung cancer) cell lines. This study also used high-performance liquid chromatography (HPLC) to determine the quality control of H. diffusa. The HPLC data showed that ursolic and oleanolic acid are the components of the H. diffusa, consisting of approximately 4.66–4.80% and 1.86–1.96%, respectively. Our study also demonstrated that ursolic acid has significant anti-tumor activity in COLO 205, Hep 3B and H460 cancer cells.