Event Abstract Back to Event Multifactorial approaches for cell phenotype maintenance and function Christina Ryan1, 2, Diana Gaspar1, 2, Manus J. Biggs2, Abhay Pandit2 and Dimitrios I. Zeugolis1, 2 1 National University of Ireland, Galway (NUIG), Regenerative, Modular & Developmental Engineering Laboratory (REMODEL), Ireland 2 University of Ireland Galway (NUI Galway), Centre for Research in Medical Devices (CÚRAM), Ireland Introduction: Cell-based therapies require removal of cells from their optimal in vivo tissue context and propagation in vitro to attain suitable number. However, bereft of their optimal tissue niche, cells lose their phenotype and with it their function and therapeutic potential. Biophysical signals, such as surface topography and substrate stiffness, and biochemical signals, such as collagen I coating, have been shown to maintain permanently differentiated cell phenotype and to precisely regulate stem cell lineage commitment[1],[2]. Herein, we developed and characterised substrates of variable rigidity and constant topographical features to offer control over cellular functions during ex vivo expansion. Materials and Methods: PDMS substrates with varying ratios of monomer to curing agent (0:1, 1:1, 5:1) were fabricated based on established protocols. Grooved substrates were created using a silinated wafer with groove dimensions of 2µm x 2µm x 2µm; planar control groups were created using flat glass. The aforementioned PDMS solutions were poured onto the wafer/glass, cured at 200 ºC and treated with oxygen plasma. Substrates were then investigated with/without collagen I coating at 1 mg/ml. Atomic force microscopy (AFM) and optical profilometry were used to assess the topographical features of the substrates. Dynamic mechanical analysis (DMA) was used to determine the mechanical properties of the substrates. The simultaneous effect of surface topography / substrate rigidity on cell phenotype and function was assessed using human permanently differentiated cells (tenocytes) and stem cells (human bone marrow stem cells) and various morphometric and gene / protein assays. Results and Discussion: Conclusion: Preliminary in vitro data indicate that surface topography and substrate stiffness play crucial role in maintaining cell phenotype and the prevention of phenotypic drift in vitro. The research has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 263289 (Green Nano Mesh).