Nerve Growth Factor‐Binding Engineered Silk Films Promote Neuronal Attachment and Neurite Outgrowth

• Published in: Advanced functional materials Vol. 32; no. 45
• Main Authors: Baker, Lizzy A., Xu, Lingling, Badichi Akher, Farideh, Robertson, Madelaine K., Pugsley‐DeBruyn, Lauren, Ma, Chloe Xiaoyi, Liu, Xiang‐Qin, Frampton, John P., Rainey, Jan K.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.11.2022
• Subjects: Biomedical materials; Growth factors; Kinases; Materials science; Mechanical properties; nerve growth factors; Nerves; neurons; Proteins; scaffolds; Sequestering; Signaling; Silk; spider silk; Spiders
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202205178

Spider silks have outstanding potential as biomaterials due to their sought‐after mechanical properties and low immunogenicity. The toughest spider silk is aciniform silk, which is used by spiders to wrap prey and produce egg sacs. A variety of recombinant aciniform silk constructs are now been developed, including hybrid silks with domains from multiple spider silk proteins fused together. In this study, an engineered aciniform silk construct, termed NBSilk, fused both N‐ and C‐terminally to heptapeptide motifs that bind the neurotrophic factor and nerve growth factor‐β (NGF) is introduced. NBSilk is shown to be amenable to casting into robust films that remain intact while sequestering and maintaining bioactive NGF at the film surface for at least 7 days. These films support cell survival while enhancing differentiation and neurite density and outgrowth in neuron‐like PC12 cells, with elevation of signaling through both the mitogen‐activated protein kinase (MAPK) and protein kinase B (AKT) signaling pathways. Strikingly, preloading of NBSilk films with NGF enhances neuritogenesis even over conditions where cells are grown with NGF supplementation in the culture medium. NBSilk scaffolds, thus, warrant future development and evaluation as biomaterials for nerve regeneration. A recombinant spider silk fusion protein with the capability to bind to nerve growth factor (NGF) is introduced. Casting of films capable of sequestering NGF is shown. The functionality of these engineered silk films in supporting neuronal cell survival and neuritogenesis is demonstrated, with no need for addition of NGF to the cell culture medium for films pre‐loaded with NGF.