Examining Cytoskeletal Organization and Cell Morphology on P(MEO2MA-co-OEGMA) Thermoresponsive Biomaterials of Variable Lower Critical Solution Temperature

Thermoresponsive polymer (TRP) substrates as in vitro cell culture platforms have recently gained popularity due to their ability to release cells from the growth substrate without biochemical enzymes and while maintaining cell-cell and cell-matrix interactions. Cells grown on TRPs are released from their culture surface by a simple change in temperature below the lower critical solution temperature (LCST) of the polymer.  P(MEO2MA-co-OEGMA) substrates offer a unique advantage over PNIPAM, the gold standard: the ability to tune the LCST.  In this work, we investigate cell growth on four P(MEO₂MA-co-OEGMA) substrates of varying LCST using immunofluorescence and confocal microscopy.  The effects of tunable LCST on cell adhesion was also investigated using contact angle as a proxy for cellular adhesion.  Specifically, we quantified the equilibrium spreading coefficient of P(MEO₂MA-co-OEGMA) thermobrushes with aqueous LCSTs of 28, 31, 34, and 37°C as a function of temperature and examined cell height and cytoskeletal organization over the course of 48 hours.  Results show that surface hydrophobicity increases as LCST decreases, with LCST of 28^oC being the most hydrophobic surface.  Phase contrast microscopy images revealed an increase in cell adhesion as a function of LCST, with the most hydrophobic surface (28^oC) promoting cell spreading comparable to a TCP control. Cell height also varied with changing LCST. In conclusion, thermoresponsive brushes synthesized from random copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (MEO₂MA) and oligo(ethylene glycol) methacrylate (OEGMA) (P(MEO₂MA-co-OEGMA)) that exhibit variable aqueous LCST values can be used to promote cell adhesion in tissue engineering applications.