  Cell-free translational strategies are needed to accelerate the repair of
mineralised tissues, particularly large bone defects, using minimally invasive
approaches. Regenerative bone scaffolds should ideally mimic aspects of the
tissue's ECM over multiple length scales and enable surgical handling and
fixation during implantation in vivo. Leveraging the knowledge gained with
bioactive self-assembling peptides (SAPs) and SAP-enriched electrospun fibres,
we presented a cell free approach for promoting mineralisation via apatite
deposition and crystal growth, in vitro, of SAP-enriched nonwoven scaffolds.
The nonwoven scaffold was made by electrospinning poly(epsilon-caprolactone)
(PCL) in the presence of either peptide P11-4 (Ac-QQRFEWEFEQQ-Am) or P11-8
(Ac-QQRFOWOFEQQ-Am), in light of the polymer's fibre forming capability and its
hydrolytic degradability as well as the well-known apatite nucleating
capability of SAPs. The 11-residue family of peptides (P11-X) has the ability
to self-assemble into beta-sheet ordered structures at the nano-scale and to
generate hydrogels at the macroscopic scale, some of which are capable of
promoting biomineralisation due to their apatite-nucleating capability. Both
variants of SAP-enriched nonwoven used in this study were proven to be
biocompatible with murine fibroblasts and supported nucleation and growth of
apatite minerals in simulated body fluid (SBF) in vitro. The fibrous nonwoven
provided a structurally robust scaffold, with the capability to control SAP
release behaviour. Up to 75% of P11-4 and 45% of P11-8 were retained in the
fibres after 7-day incubation in aqueous solution at pH 7.4. The encapsulation
of SAP in a nonwoven system with apatite-forming as well as localised and
long-term SAP delivery capabilities is appealing as a potential means of
achieving cost-effective bone repair therapy for critical size defects.
