Fabrication of thermoresponsive surface for cell sheet harvest by photopolymerization

Our laboratory developed “cell sheet engineering”, which has been applied to regenerative medicine. However, the applications are restricted to the transplants of single-, double-, and triple-layered cell sheets, because of the poor supplies of nutrients and oxygen. To fabricate thicker and dense tissues in vitro, multi-layered cell sheets require to have capillary networks. Additionally, individual tissues found in animal body have individual specific micropatterns of cells for expressing their specific functions and characters. Therefore, we focus on micropatterned co-cultured cell sheets as one of the methods to fabricate thicker and more functional tissues. Polymerization of thermoresponsive polymer, poly(N-isopropylacrylamide) (PIPAAm), by electron beam irradiation has been used for fabrication of thermoresponsive surfaces on tissue culture polystyrene dishes. However, it is difficult to fabricate micropatterned surfaces of thermoresponsive polymer by electron beam irradiation. Therefore, we attempted to optimize photopolymerization condition of PIPAAm with a visible light photopolymerization initiator, water-soluble camphorquinone, as the fabrication method of thermoresponsive surface.