Design of the Hydrophobic Core of Self-Assembling EF-C Peptide Fibrils for Enhanced Neural Regeneration

Neural cells have limited self-repair ability, and the therapeutic approaches for treating nerve injuries rely heavily on surgery. Hindered by the lack of donor tissues and the complex neural environment, it is of great interest to develop biomaterials to support neural regeneration. Self-assembling peptides with fibrous structures that mimic the extracellular matrix have become potential therapeutic agents for neural regeneration. Previously, we identified peptide sequences derived from enhancing factor-C (EF-C), which are neurotrophic without additional supplements or growth factors. Here, a library of nine EF-C variants is designed by varying the hydrophobic core of the peptide backbone since a detailed understanding of how hydrophobic interactions impact self-assembly and, subsequently, bioactivity is lacking. The physicochemical properties, including binding affinity, secondary structure, and assembled morphologies, of these variants are thoroughly analyzed. To obtain information at the molecular level, computer simulations based on AlphaFold 3 models are used to investigate the stability of EF-C peptide fibrils and their assembly. Our simulations provide theoretical insights that explain the differential assembly and stability of EF-C variants. In addition, the EF-C variants are tested for bioactivity in a human neuroblastoma cell line (SH-SY5Y) to establish the structure-property relationship. The structure-forming EF-C variants facilitated cell viability and differentiation of SH-SY5Y. The combination of experimental and computational approaches paves the way for the design of novel peptide sequences for neural regeneration.