Enhanced methodology for analysis cytotoxicity of ruthenium dendrimers

Resistance of cancer cells to chemotherapy is one of the major causes of treatment failure and poor patient survival. Reduced cellular response to drugs can result from their genetic diversity, acquired mutations of drug targets, epigenetic modifications and many others. Metallodendrimers, in particular, ruthenium dendrimers of the first and second generation are promising novel anticancer drug carriers, as their usage can result in increased drug concentration in tumour tissue and reduced toxicity in healthy tissues. However the conventional, biological methods do not provide sufficient knowledge about cytotoxicity of these compounds. Therefore in the paper we propose an efficient, multimodal methodology for cytotoxicity studies at cellular level. It combines the conventional flow cytometry method (Annexin V-FITC assay), which provides global/statistical information about a cell culture, and digital holographic microscopy (DHM) allowing for continuous quantitative monitoring of cells behaviour and identifying cells with non-standard behaviour. The results reveal that tested ruthenium metallodendrimers have a strong impact on apoptotic and necrotic death of both human alveolar epithelial cell line A549 and Chinese hamster ovary cell line CHO-K1. We also have shown that DHM enables detection of the individual, drug resistance cells, through real-time monitoring of a single cell. We believe that the methodology proposed is a necessary supplement to conventional approach for studying drug cytotoxicity, which will help, in the near future, to overcome the problem of cellular resistance to anticancer therapies.