Long-term imaging of cultured cells requires controlled environmental conditions. Continuous perfusion of the medium allows maintaining cells under optimal physiological conditions, with constant nutrient supply and controlled pH environment while avoiding cell debris accumulation.
Medium flow in a continuous way and generating minimal shear stress for cells can be achieved through perfusion systems, which allow a flowing medium through positive pressure (pressure controllers) or through negative pressure (vacuum through syringe pumps). Additional components in a perfusion system allow to ensure a highly controlled flow rate through flow sensors, and the possibility to perform fast-medium switches (for instance, when sequential drug injection is required).
To be maintained under continuous medium flow, cells can be cultured in commercially available flow chambers, commercially available microfluidic devices, or homemade chambers. Perfusion systems can be coupled to temperature controllers for a fully controlled environment during live-cell imaging.
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