Smart thermoresponsive coatings and surfaces for tissue engineering: switching cell-material boundaries

The smart thermoresponsive coatings and surfaces that have been explicitly designed for cell culture are mostly based on poly( N -isopropylacrylamide) (PNIPAAm). This polymer is characterized by a sudden precipitation on heating, switching from a hydrophilic to a hydrophobic state. Mammalian cells cultured on such thermoresponsive substrates can be recovered as confluent cell sheets, while keeping the newly deposited extracellular matrix intact, simply by lowering the temperature and thereby avoiding the use of deleterious proteases. Thermoresponsive materials and surfaces are powerful tools for creating tissue-like constructs that imitate native tissue geometry and mimic its spatial cellular organization. Here we review and compare the most representative methods of producing thermoresponsive substrates for cell sheet engineering.