A library of tunable poly(ethylene glycol)/poly(L-lysine) hydrogels to investigate the material cues that influence neural stem cell differentiation.

Neural stem cells (NSCs) have the potential to replace the major cell types of the central nervous system (CNS) and may be important in therapies for injuries to and diseases of the CNS. However, for such treatments to be safe and successful, NSCs must survive and differentiate appropriately following transplantation. A number of polymer scaffolds have shown promise in improving the survival and promoting the differentiation of NSCs. To capitalize on the interaction between scaffolds and NSCs, we need to determine the fundamental material properties that influence NSC behavior. To investigate the role of material properties on NSCs, we synthesized a library of 52 hydrogels composed of poly(ethylene glycol) and poly(L-lysine) (PLL). This library of hydrogels allows independent variation of chemical and mechanical properties across a wide range of values. By culturing NSCs on this library, we have identified a subset of gels that promotes NSC migration and a further subset that promotes NSC differentiation. By combining the material properties of these subsets with the cell behavior, we determined that mechanical properties play a critical role in NSC behavior with elastic moduli promoting NSC migration and neuronal differentiation. Amine concentration is less critical, but PLL molecular weight also plays a role in NSC differentiation.