Photoreactive interpenetrating network of hyaluronic acid and Puramatrix as a selectively tunable scaffold for neurite growth.

The reconstruction of soft tissue, such as that which is found in the nervous system, is governed by the mechanical cues of the growth microenvironment. The complexity of the nervous system, particularly in cases of nerve repair and reconstruction, necessitates the development of facile high-throughput investigational tools. This study assesses the hypothesis that a mechanically tunable photoreactive interpenetrating network (IPN) of hyaluronic acid and Puramatrix can be manipulated in order to demonstrate that 3-D environmental stiffness influences neurite growth and proliferation. For these studies we employed photocrosslinkable glycidyl methacrylate hyaluronic acid (GMHA) and Puramatrix, a self-assembling peptide scaffold, leading to a structurally adjustable IPN system. Our in vitro model provides us with a simple, reproducible environment to generate different properties in a single specimen. Mechanically manipulated IPN systems with different degrees of methacrylation were fabricated using a dynamic mask projection photolithography apparatus and characterized. To gauge the impact of IPN stiffness on neurite outgrowth, dorsal root ganglia (DRG) explants were cultured in the hydrogels. We found that neurite outgrowth in 3-D was more likely to happen in an environment with a lesser degree of methacrylation, which corresponded to structures that were more compliant and more porous. Overall, tuning the mechanical behavior of our IPN systems led to statistically significant (p<0.05) differences in cellular growth and extension that warrants further investigations.