Student award winner in the undergraduate's degree category for the Society for Biomaterials 35th Annual Meeting, Orlando, Florida, April 13-16, 2011. Neurite growth in PEG gels: effect of mechanical stiffness and laminin concentration.

Within a 3D environment, the chemical and mechanical properties of a scaffold can significantly influence nerve behavior. How these properties influence with nerve cells is important for optimizing neurite extension within a scaffold. The purpose of this study was to investigate the effect of low concentration poly(ethylene glycol) (PEG) with added laminin on 3D growth of dissociated dorsal root ganglia. Because of its high affinity for neurite adhesion and ability to promote extension, laminin was conjugated to the PEG chain, as well as mixed in the gel, at various concentrations to provide chemical cues. Gel stiffness, as determined by G*, significantly decreased with decreasing PEG concentration and with increasing laminin conjugate. Extension within the gels increased as the concentration of laminin increased with no difference between how laminin was presented (mixed or conjugated) to the cells. For example, in 3% PEG, extension increased from 92.29 ± 5.27 μm to 146.35 ± 13.12 μm as laminin conjugate concentration increased from plain to 100 μg/ml. Results indicated that the chemical properties of the scaffold influenced neurite growth more than the mechanical properties as laminin concentration had a greater impact on growth than the stiffness of the gel over the range studied. Neurite length as a function of scaffold stiffness and adhesion properties was also characterized and demonstrated a positive linear relationship between rate of neurite extension and laminin concentration. This study further demonstrates the importance of characterizing interactions between cell behavior and the chemical and mechanical environment.