Lateral trapezoid microfluidic platform for investigating mechanotransduction of cells to spatial shear stress gradients

Microfluidic platforms enable the influence of a variety of chemical and physical gradients on single or multiple cells to be examined and monitored in real-time. Research into chemical gradients has been more prevalent in literature; however, with the interest in mechanotransduction, research investigating the influence of physical gradients, such as force from shear stress, are appearing. Shear stress studies, to date have been focused on using parallel plate flow chambers, or shear stress gradients spanning the length of the microchannel. In this paper, we designed a Trapezoid microchannel, which enables production of a unique lateral spatial shear stress gradient, in order to examine the responses it evokes in cells, using microscopy. We investigated the effect of a lateral spatial shear stress gradient on intracellular calcium signalling in HEK-293-TRPV4 cells. The Trapezoid microchannel was designed to produce a spatial shear stress gradient, spanning the width of the microchannel. Additionally, we investigated the effect of temporal shear stress using the microfluidic platform, to further examine the complexity of the transduction of shear stress forces, which mimic pathological and physiological conditions into cellular signalling. We show that the temporal pattern of shear stress, modulated intracellular calcium signalling, with slower response times (responding to stimulus and reaching maximum Calcium influx), compared to those observed in the absence of temporal shear stress. Our experiments highlight the importance of considering the nature of shear stress under physiological and pathological conditions - with microfluidic platforms providing a useful means to do so.