Assessment of Cytostretch - A Heart-On-Chip device. Experiments on Cardiomyocytes

Abstract

An organ-on-chip device, called Cytostretch (Philips NV), that is capable of mechanically stimulating cultured cells, is the subject of this study. The device comprises a microthin PolyDiMethylSiloxane membrane that is highly elastic, on which titanium nitride electrodes have been embedded. Its utility is projected in cardiac research to emulate the mechanically beating on the muscle cells (cardiomyocytes) of the beating heart and record the extracellular potentials simultaneously. The device is in its nascent state and requires validation through suitable experiments, for which a pneumatic apparatus was built. Following an overnight cyclic stretching, the membrane deforms permanently owing to hysteresis, which inhibits the formation of a uniform monolayer of cells on the membrane. There was a wide device-to-device variation in the noise levels at the electrodes in the MircoElectrode Array (MEA) recordings. Field potential recordings during spontaneous beating of cardiomyocytes cultured on the membrane were obtained successfully in the relaxed state of the membrane. The MEA recordings are however, accompanied by artefacts at the instance of stretching or relaxing the membrane which interfere with the field potential of the cardiomyocytes. The cardiomyocytes in the device died after their cyclic stretching, thought they were not detached from the membrane. In conclusion, the permanent deformation challenges the utility and re-usability of the device when uniform monolayer of cells is desired. Therefore, the mechanical properties of the membrane and metallic interconnect should be revised. The interference from the stretching artefacts hampers the quality of MEA recordings. The method of stretching needs revision to prevent damage to the cells and high frequency stretching artefacts. The susceptibility of the silicon chip toward optical noise during MEA recording omits the microscopic investigation together with MEA recording.