Automated Microfluidic System for Dynamic Stimulation and Tracking of Single Cells

Dynamic
environments determine cell fate decisions and function.
Understanding the relationship between extrinsic signals on cellular
responses and cell fate requires the ability to dynamically change
environmental inputs in vitro, while continuously observing individual
cells over extended periods of time. This is challenging for nonadherent
cells, such as hematopoietic stem and progenitor cells, because media
flow displaces and disturbs such cells, preventing culture and tracking
of single cells. Here, we present a programmable microfluidic system
designed for the long-term culture and time-lapse imaging of nonadherent
cells in dynamically changing cell culture conditions without losing
track of individual cells. The dynamic, valve-controlled design permits
targeted seeding of cells in up to 48 independently controlled culture
chambers, each providing sufficient space for long-term cell colony
expansion. Diffusion-based media exchange occurs rapidly and minimizes
displacement of cells and eliminates shear stress. The chip was successfully
tested with long-term culture and tracking of primary hematopoietic
stem and progenitor cells, and murine embryonic stem cells. This system
will have important applications to analyze dynamic signaling inputs
controlling fate choices.