Label-free detection of ischemic effects on the cardiomyocytes by impedance spectroscopy

Abstract

Heart diseases represent a most common cause of death in industrialised countries. For this reason target identification and development of novel anti-target drugs are in the focus of pharmaceutical industry. Especially cardiac infarct is a topical field of research. A bottleneck in today’s long-duration and high-cost drug development is the lack of fast, label-free and cell-based high throughput/high content screening (HTS/HCS) assays for bridging the gap between cell-free screening and animal experiments. Here, we report for the first time an in vitro cardiac ischemic model, where pathological consequences of simulated cardiac infarct can be detected quantitatively by microelectrode array-based impedance spectroscopy. Through use of the contractile HL-1 cell line and defined ischemic conditions we were able to develop a standardised and reproducible pathologic model. We characterised and verified the HL-1 based ischemic model by apoptosis and proliferation assays as well as immunochemical analysis of cell-cell junctions. We showed that the observed cell and biomolecular effects correspond with results obtained by impedance spectroscopy. Functionality of the impedimetric assay was demonstrated by real-time detection of reduced pathological effects due to application of the selective Rac1 inhibitor NCS23766. Numerical analysis by means of an equivalent circuit allowed the quantification of changes in resistance and capacitance of the adherent cell layer after ischemic treatment and application of NSC23766 as drug model. Our findings provide a novel cell-based real-time screening system for testing drug candidates against cardiac infarct and its implications.