Microfluidic Approach for Modeling Coupled Circadian Clock.

In mammals, it is believed that the intercellular coupling mechanism between neurons in the suprachiasmatic nucleus (SCN) confers circadian robustness and distinguishes the central clock from peripheral circadian oscillators. Current in vitro culturing methods mainly work with Petri dishes to study intercellular coupling by exogenous factors and invariably cause perturbations, such as simple exchanges of media. Here, a microfluidic device is designed to quantitatively study the intercellular coupling mechanism of circadian clock at the single-cell level and to demonstrate that the vasoactive intestinal peptide (VIP)-induced coupling in clock mutant Cry1-/- mouse adult fibroblasts (MAF), which are engineered to express the VIP receptor (i.e., VPAC2), is sufficient to synchronize, and maintain, robust circadian oscillations. This method provides a proof-of-concept strategy to reconstitute the intercellular coupling system of the central clock using uncoupled, single mouse adult fibroblast (MAF) cells in vitro and to mimic SCN slice cultures ex vivo and mouse behavior in vivo phenotypically. Such a versatile microfluidic platform may greatly facilitate the studies of intercellular regulation networks and provide new insights into the coupling mechanisms of the circadian clock.