A Simple, Cost-Effective Method to Improve Cell Viability in Microniche Culture Systems

Microfluidic networks are increasingly used to generate custom microenvironmental niches for cell culture and assays of cellular behavior. Perfusion systems are typically required to overcome diffusive limitations associated with culturing cells longer than a few hours when nutrient delivery, oxygen delivery and metabolic waste removal are required to maintain cell viability. In addition to the added complexity of experimental methods, perfusion systems can result in nonuniform nutrient delivery and subject cells to shear stresses, which may alter cell behavior and possibly cause cell death. In particular, when culturing cells within hydrogel scaffold-filled networks, as may be done in micro-tissue engineering, the need for perfusion culture also increases the likelihood of a destructive bubble entering the network. Moreover, analysis of micro-cultures frequently entails labelling with antibodies and/or fluorescent probes, which again requires controlled perfusion of the various reagents through the network. We have developed a simple technique to preserve cell viability and simplify labeling within microscale cultures without the need for perfusion. Instead of bonding a microfluidic network to glass, PDMS, or another impermeable substrate, the network is bonded to a semi-permeable microdialysis membrane, which allows free exchange of oxygen, proteins, nutrients, and waste between the microfluidic channels and culture media in static culture plates.