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. 2023 Oct 8;24(19):14999. doi: 10.3390/ijms241914999

Figure 1.

Figure 1

Cell viability and growth of multicellular spheroids depend on the pulse duration at 20 Hz. HCT 116-GFP spheroids were treated with 500 unipolar pulses lasting 0 (Control), 2, 4, 6, 8, and 10 nanoseconds (ns) delivered at a pulse repetition rate of 20 Hz with a 100 kV/cm electric field. After exposure, spheroids were incubated in culture medium containing 1 µM PI during wide-field fluorescence video microscopy over a period of 5 days. (A) Representative micrographs of spheroids with dead cells, which internalized propidium iodide (PI) exhibiting a red fluorescence and viable cells, constitutively expressing the green fluorescence protein (GFP) exhibiting the green fluorescence 24 h post nPEF exposure. Scale bar: 300 µm. (B) Cell death reflected by PI uptake mean fluorescence intensities (A.U.) plotted as a function of time (h). N = 1 experiment, n = 6 spheroids per condition. (C) Growth curves plotted from GFP fluorescence area (A.U.) as a function of time (h). N = 3 experiments, n = 6 spheroids per condition. Data are reported as mean ± standard error mean. Two-way ANOVA *** p < 0.001.