Spatial-Temporal Dynamics of Collective Chemosensing

Although chemosensing by individual cells is stochastic, multi-cellular organisms exhibit highly regulated response to stimulations. The key elements to understand orders in chemosensing are cellular communications and the existence of pacemakers. To study the collective behaviors in chemosensing induced by these two factors, we studied spatial-temporal calcium dynamics of fibroblast cells in response to ATP in microfluidic devices. We found gap junction communications led to faster, more synchronized, and correlated responses compared to isolated cells. We demonstrated the existence of pacemakers and how they dictated the initial responses in the presence of gap junctions. By further studying the calcium dynamics of cells embedded in a thin hydrogel film, where cellular communications were only through diffusing molecules, we conclude that gap junctions are essential to generate prompt, synchronized and highly correlated responses. In addition, both communication channels lead to calcium oscillations following the elevation by external ATP in high density cell colonies. While the calcium oscillations associated with gap junctions were transient, the calcium oscillations in the hydrogel persisted more than 10 minutes and demonstrated rich structures in the Fourier spectrum. Further study is needed to understand the ATP-triggered collective behavior within the hydrogel.View Large Image | View Hi-Res Image | Download PowerPoint Slide