Leveraging dynamic cell responses to design new protocols for pluripotency maintenance

Pluripotent stem cells have a high potential for research and development applications in biomedicine. They are unspecialized cells that can be indefinitely expanded retaining pluripotency or pushed into specific differentiated states by proper stimuli. Various protocols have been proposed to maintain mouse embryonic stem cells (mESCs) in the pluripotent state; state of the art cell culture protocols are based on serum-free media, and continuous provision of drugs inhibiting pathways associated to differentiation. We explore here the possibility to avoid continuous drug exposure. First, we employ an external feedback control microfluidics/microscopy platform to steer the expression of a pluripotency reporter. Control experiments show a significant delay in cell response to drugs; these dynamics are confirmed by flow-cytometry open-loop experiments. We then harness such delays to design novel culture protocols with limited cell exposure to small-molecule inhibitors; in so doing, we reduce cell exposure to drug, but we maintain pluripotency. Our results suggest new approaches to design cell culture protocols based on the quantitative analysis and control of cellular dynamics.