Contactless Electrical Impedance Spectroscopy (EIS) platform to monitor changes in cell morphology

Abstract: Simple, rapid assays of cellular responses to small molecule treatments are required to increase the efficiency of pre-clinical drug testing in in vitro models. Furthermore, the integration of widespread genomic sequencing into the NHS necessitates the development of technologies for the rapid and robust assay of genetic variants of unclear pathogenic significance, in order for accurate diagnostics and precision medicine to be achieved. Current assays often depend on expensive, time- and labour-intensive high-content imaging methods for detection of morphological changes. We present recent progress in development of a totally contactless electrical impedance spectroscopy (EIS) platform to detect changes in cell morphology in adherent cell cultures. This represents a simple, effective, low-cost method for genetic and drug testing in vitro. Our bespoke resonance impedance system consists of 8 22.1mm diameter electrodes on printed circuit board, and an 8-way plate system linked to a computer, which we have previously shown to be effective in detecting cytotoxic changes in endothelial cells induced by sodium butyrate1. We have now applied this system to successfully define impedance spectra of two adherent mammalian retinal cell lines, each in two different morphological states induced by specific changes to culture conditions. Cells were cultured in standard 12-well tissue culture plates, and half of these wells were subjected to serum starvation to induce morphological changes. At the time of assay, plates were simply placed on top of the electrode array and impedance measured across a range of frequencies from 200 – 2000kHz. Characteristic impedance spectra were produced, allowing traces of specific cell changes to be characterised, such that similar changes can be rapidly identified when they occur in novel cultures. This represents a robust, simple, rapid non-invasive assay for cellular morphological changes resulting from a variety of stimuli, or induced genetic changes. Whilst high-throughput EIS systems have been developed previously2,3, a contactless high-throughput system is novel. This system can be useful for detection of cells of morphological interest in small molecule drug screening and reverse genetic siRNA or CRISPR/Cas screening.