(497e) Electrospinning Biodegradable “Smart” Substrates for Harvest of Intact Mammalian Cell Sheets

Poly(N-isopropyl acrylamide), or pNIPAM, is a ?smart? polymer that responds to slight temperature changes near physiologically relevant temperatures. When pNIPAM is tethered to a surface at cell culture temperature (37 °C), the polymer is relatively hydrophobic, and mammalian cells will readily attach and proliferate on the polymer surface. When the temperature is shifted to ~25 °C, the polymer becomes hydrophilic and swells on the surface, causing the cells to spontaneously detach. PNIPAM has been deposited onto surfaces using a variety of techniques for mammalian cell culture applications. However, it has been reported to take up to 2 hours for a cell sheet to fully detach from these pNIPAM surfaces. The long response is most likely due to the limited access of water to the underlying pNIPAM film, resulting in slow swelling of the film at room temperature. In order to overcome this problem, a highly porous surface which allows for water to be exposed to the polymer faster is required. In this work, fiber mats were created by electrospinning nano- and microscale pNIPAM fibers. The fibrous electrospun pNIPAM mats (espNIPAM) were seeded with several mammalian cell types (bovine aortic endothelial cells, EMT6 tumor cells, and MC-3T3 osteoblasts) and incubated at 37 °C, under normal cell culture conditions, to allow the cells to reach confluence. Due to the hydrophilic nature of the polymer at low temperatures and the high porous character of the mats, when the temperature was changed to ~25 °C, the mats quickly transitioned. The transition resulted in a detached cell sheet within five minutes of exposure to the low temperature. We found that espNIPAM mats greatly improve the rate of cell detachment from the substrate. In addition, we find that the cells align with the fibers within the mat, therefore providing a system where directed cell alignment can also be observed.