Electroporation of a Bladder Cancer Cell Line in Presence of Calcium: Efficacy Dependence on Electric Field Strength and Calcium Concentration

Electroporation in presence of calcium has been recently demonstrated to be capable of inducing cell death, suggesting that calcium might be used as an alternative to bleomycin in the palliative treatment of tumors via electrochemotherapy. In this work, SW780 bladder cancer cells were exposed to eight, 99 ?s long, 1 Hz repetition rate pulses with variable electric field (0.2 to 1.6 kV/cm) in presence of calcium (0, 1, 3, 5 mM), and cell viability was evaluated by means of MTS assay at 1, 4, 8, 22 and 24 hours after electroporation. A mathematical fitting analysis of the experimental data was then carried out to estimate the electric field amplitudes leading to a desired percentage of cell death at different calcium concentrations. The results here presented confirm previous in vitro findings on calcium electroporation, and highlighted that the presence of extracellular calcium allows to employ lower electric field amplitudes to induce cancer cell death with respect those required in the case of treatments with electric pulses alone. The procedure here adopted can be tailored to different cell types to identify the optimum combinations of electrical conditions and calcium concentrations that maximize cell killing, and can also provide information to optimize application of calcium electroporation in vivo. The activity here presented was carried out at the University of Copenhagen, Herlev Hospital, Department of Oncology, in the framework of a short term scientific mission funded by the Cost Action TD1104, and included in a recently accepted publication in PlosOne.