Development of a statistical model for cervical cancer cell death with irreversible electroporation in vitro

<div><p>Purpose</p><p>The aim of this study was to develop a statistical model for cell death by irreversible electroporation (IRE) and to show that the statistic model is more accurate than the electric field threshold model in the literature using cervical cancer cells in vitro.</p><p>Methods</p><p>HeLa cell line was cultured and treated with different IRE protocols in order to obtain data for modeling the statistical relationship between the cell death and pulse-setting parameters. In total, 340 in vitro experiments were performed with a commercial IRE pulse system, including a pulse generator and an electric cuvette. Trypan blue staining technique was used to evaluate cell death after 4 hours of incubation following IRE treatment. Peleg-Fermi model was used in the study to build the statistical relationship using the cell viability data obtained from the in vitro experiments. A finite element model of IRE for the electric field distribution was also built. Comparison of ablation zones between the statistical model and electric threshold model (drawn from the finite element model) was used to show the accuracy of the proposed statistical model in the description of the ablation zone and its applicability in different pulse-setting parameters.</p><p>Results</p><p>The statistical models describing the relationships between HeLa cell death and pulse length and the number of pulses, respectively, were built. The values of the curve fitting parameters were obtained using the Peleg-Fermi model for the treatment of cervical cancer with IRE. The difference in the ablation zone between the statistical model and the electric threshold model was also illustrated to show the accuracy of the proposed statistical model in the representation of ablation zone in IRE.</p><p>Conclusions</p><p>This study concluded that: (1) the proposed statistical model accurately described the ablation zone of IRE with cervical cancer cells, and was more accurate compared with the electric field model; (2) the proposed statistical model was able to estimate the value of electric field threshold for the computer simulation of IRE in the treatment of cervical cancer; and (3) the proposed statistical model was able to express the change in ablation zone with the change in pulse-setting parameters.</p></div

Dependence of E_c (‘◇’) and A (‘□’) on the pulse length.

<p>Dependence of E_c (‘◇’) and A (‘□’) on the pulse length.</p

Development of a statistical model for cervical cancer cell death with irreversible electroporation in vitro - Fig 9

<p>Viability plots for IRE in cervical tumor tissues for different IRE settings regarding to the number of pulses, the pulse strength, and the pulse length: a) 60, 1000 V, and 50 μs, b) 60, 2000 V, and 50 μs, c) 60, 3000 V, and 50 μs, d) 30, 2000 V, and, 50 μs, e) 60, 2000 V, and, 50 μs, f) 90, 2000 V, and 50 μs, g) 60, 2000 V, and 10 μs, h) 60, 2000 V, and 50 μs, and i) 60, 2000 V, and 100 μs, respectively.</p

Development of a statistical model for cervical cancer cell death with irreversible electroporation in vitro - Fig 5

<p>Cell viability dependence on the field strength and each of the four used pulse lengths (‘●’, ‘□’, ‘▽’ and ‘△’ represent 25, 50, 75, and 100 μs, respectively) for different number of pulses: a) 1, b) 10, c) 30, and d) 60, respectively.</p

Values of EFT for the cervical cancer under different pulse setting parameters.

<p>Values of EFT for the cervical cancer under different pulse setting parameters.</p

Curve fitting results for E_c(t) and A(t) at different numbers of pulses.

<p>Curve fitting results for E_c(t) and A(t) at different numbers of pulses.</p

Curve fitting results for E_c(n) and A(n) at different pulse lengths.

<p>Curve fitting results for E_c(n) and A(n) at different pulse lengths.</p

Schematic diagram of IRE experimental set-up and process.

<p>Schematic diagram of IRE experimental set-up and process.</p

Electric-field-dependent electrical conductivities of cervical cancer for four pulse lengths.

<p>Electric-field-dependent electrical conductivities of cervical cancer for four pulse lengths.</p

Development of a statistical model for cervical cancer cell death with irreversible electroporation in vitro - Fig 4

<p>Cell viability dependence on the field strength and each of the four used number of pulses (‘●’, ‘□’, ‘▽’ and ‘△’ represent 1, 10, 30, and 60 pulses, respectively) at different pulse lengths: a) 25 μs, b) 50 μs, c) 75 μs, and d) 100 μs, respectively.</p