Monitoring Changes in Morphological Parameters of Primary and Metastatic Melanoma Cell-Lines following Exposure to Taxol by Digital Holographic Microscopy

Fast determination of the sensitivity of cancer cells towards chemotherapeutic agents is of high importance for effective choice of the chemotherapeutic treatment. We suggest a new approach for monitoring various morphological parameters of the cancer cells to a chemotherapeutic agent, by using digital holographic microscopy (DHM). DHM or interferometric phase microscopy can be used to simultaneously record the quantitative spatial profiles of both the amplitude and the quantitative phase of mostly transparent biological samples. The quantitative phase profile is proportional, at each pixel, to the product of the cell thickness and its refractive index. The accuracy of this product is sub-nanometric. Thus, DHM provides label-free quantitative information on various conventional and new parameters related to the cell morphology and intracellular content.

We compared the morphological changes induced by taxol in a primary (WM-115) and metastatic (WM-266-4) melanoma cell lines isolated from the same patient. Dose dependent viability of both cell lines was determined following 48 hours exposure to taxol by XTT assay. Cell viability following exposure to 50nM taxol was determined by employing PI and YO-PRO®-1 probes, at shorter exposure periods of 1-6 hours. In parallel, we used DHM to measure the change in the morphological parameters of the two cell lines. The results indicate that melanoma cells that were exposed to taxol undergo morphological changes including in the area, thickness and dry mass of the cells. The original morphological parameters and their taxol-induced changes were different for the primary and metastatic cells.

These findings demonstrate the possibility of DHM to monitor differential sensitivity of primary and metastatic cell lines towards the toxicity of taxol, solely based on label-free, quantitative imaging.