(294c) Engineered Matrices with Dynamic Crosslinks Support the Culture of Human Neural Progenitor Cells

Human induced pluripotent stem cells (hiPSCs) have emerged as a promising in vitro model system for studying neurodevelopment. However, current models are limited in their ability to efficiently incorporate extracellular matrix-derived biochemical and biomechanical cues. Here, we present the development of a three-dimensional (3D) biomaterials platform which supports the culture and expansion of hiPSC-derived neural progenitor cells (hNPCs) and is suitable for probing biomechanical properties of the neural microenvironment. These recombinant materials are composed of an aldehyde-modified hyaluronic acid and a hydrazine-modified elastin-like protein, the mixture of which is named HELP (hyaluronic acid/elastin-like protein) hydrogels. The hydrogel crosslinks are formed through dynamic covalent bonds, which allow the material to be adaptable to cell-imposed forces. The hydrogel stiffness is controlled by altering the total number of crosslinks, while the hydrogel stress relaxation rate is controlled by altering the kinetics of crosslink dynamics, achieving mechanical properties that more closely resemble the stiffness and stress relaxation rates of native brain tissue. Independently, the biochemical properties can be customized by altering the amino acid sequence within the elastin-like protein. We demonstrate that these dynamically-crosslinked HELP hydrogels facilitate gel remodeling, which is required for hNPC viability. After 7 days in culture, the hNPCs remain proliferative and continue to express stemness markers. Furthermore, by tuning the rate of stress relaxation, we find that cell spreading and neurite extension are enhanced in hNPCs cultured in gels with faster stress relaxation. Taken together, these results highlight the importance of biomechanical signaling cues and the potential for engineered biomaterials to advance current models of neurodevelopment by incorporating such design parameters.