Quantitative analyses of changes in intracellular calcium ion concentrations under flow-induced mechanical stimuli utilising a microchip

The authors use quantitative engineering methods to investigate changes in intracellular calcium ion concentrations ([Ca²⁺]i) under various flow-induced shear stresses utilising a microchip. MG-63 cells were seeded onto microchannels in a chip made of polydimethylsiloxane. A commercially available gear pump was utilised to induce and control the shear stress for up to 20 min. The temperature was maintained at 35±1°C using a computer-controlled heating jacket. Five types of flow patterns, each of which consisted of equal stimulation and rest intervals (50, 100, 150 and 200 s for stimulation, rest and steady flow) were tested. Each interval produced different patterns indicating the [Ca²⁺]i. Various engineering parameters were extracted from the [Ca²⁺]i signals recorded from a single cell after filtering to reduce background noise, including the peak to peak interval, trends in the changes of the peak values based on an exponential function and the ratio of stimulation energy to [Ca²⁺]i. The results indicate that this protocol can be used to analyse [Ca²⁺]i and related cellular responses to shearing stresses.