Identification of Novel Growth Factor Conjugated Nanofibers for Stimulation of Neuronal Growth.

Growth factors (GF) fulfil essential functions during organ development and regeneration. In tissue regeneration, evidence suggests that the combined application of several GFs is more efficient compared to their individual application. Single or multiple GFs are often applied to animal models of organ regeneration through release by hydrogels. Such hydrogels are often formed by self-assembling peptides (SAPs) spontaneously polymerizing into peptide nanofiber (PNF) networks. In this study, we established PNFs by conjugating an SAP backbone (KIKIQIN) with bioactive peptide sequences derived from two GFs, FGF2 and IGF1. This resulted in the GF-mimicking fusion peptides FGF2-SAP and IGF1-SAP, respectively. In these PNFs, both GFs were stably incorporated rather than released as in the case of PNF-derived hydrogels. When individually added to culture medium, FGF1-SAP and IGF1-SAP stimulated the growth of mouse primary hippocampal neurons. Notably, their growth-stimulating potential exceeded neuronal growth achieved with the SAP backbone or the GF peptides alone. Finally, combinations of FGF2-SAP, IGF1-SAP, and the SAP backbone were tested, which formed FGF2 and IGF1 presenting PNFs. Indeed, specific GF-SAP combinations resulted in elevated numbers of surviving neurons compared to individual application. In summary, in this study, we identified novel GF-SAP hybrid nanofibers capable of stimulating cellular growth. Such nanofibers, enabling stable and simultaneous presentation of multiple GFs, might be well suited for tissue regeneration in vivo.