The effects of cell culture parameters on cell release kinetics from thermoresponsive surfaces.

The thermoresponsive properties of poly(N-isopropyl acrylamide) (pNIPAM) have led to its wide use in bioengineering applications, including the reversible adhesion of mammalian cells. The groups performing this research have used different solutions to initiate cell release and have varied the temperature of the solution during detachment. To our knowledge, there has been no direct correlation between the solution identity or temperature on the efficiency of cell release from pNIPAM films. In this work, we present a study of the effect of the solution type and temperature used to initiate detachment on the time required to achieve 100% detachment of bovine aortic endothelial cells (BAECs) from pNIPAM. The pNIPAM films used in this work were obtained using a novel technique using a spin-coated solution containing pNIPAM (spNIPAM). We found that the fastest, most reliable release of cells occurred below the LCST of the polymer at 4 degrees C in serum free media (SFM). As it is sometimes desirable to stop cell metabolism at the time of detachment (e.g., to "freeze" protein expression prior to subsequent analysis), the use of extremely cold SFM would be ideal in such cases.