Distinguishing heat-treated dead cells from viable cells using frequency dependence of electrical impedance

Abstract

BACKGROUND: There is currently no methodology for evaluating the accuracy of ablation in ablation therapy, and thus normal cells in the surrounding area can be damaged, possibly leading to complications. OBJECTIVE: The aim of this study was to distinguish heat-treated dead cells from viable cells using the electrical impedance-to-frequency ratio as an evaluation index. METHODS: Rat heart striated myocytes were cultured in a monolayer on collagen-coated microelectrodes placed in the center of an electrode-loaded chamber. The cells in the chamber were killed by heat treatment for 5 minutes at 50 °C, and the frequency response of the cell impedance was measured before and after heat treatment. The frequency of the input current was varied from 10 to 100 kHz. The measured electrical impedance at each frequency was divided by the value at 100 kHz, and we refer to the resulting values as the impedance ratio. RESULTS: The impedance ratio was high at low frequencies and low at high frequencies. Furthermore, the impedance ratio was lower at lower frequencies after heat treatment than before heat treatment. CONCLUSIONS: The electrical impedance ratio can be used to distinguish viable and dead cells after heat treatment.