Nerve damage remains one of the most challenging problems in wound healing. The gold standard for nerve healing are autografts, the efficacy of this approach is limited due to the scarcity of donation sites which is especially pertinent for damage leaving large gaps in nervous tissue. There is a need for the development of more sophisticated solutions that can be applied to a wide variety of nerve regeneration cases. A recently published article in Acta Biomaterialia showcases a materials solution to facilitate peripheral nerve regeneration.
Recently published work by Wang et al features the creation of electroactive nanofibers. The fibres are based on a composite of Antheraea pernyi silk fibroin (ApF)/(Poly(L-lactic acid-co-caprolactone)) (PLCL) with the addition of reduced graphene oxide (RGO) by an in situ redox reaction to introduce electrical conductivity [Wang et al., Acta Biomaterialia (2019), doi: 10.1016/j.actbio.2018.11.032]
Figure 1 - Summary of the assessment of the nerve regeneration capability of the (ApF/(PLCL)-(RGO) nano-fibres. Culturing Schwann cells (peripheral nerve cells) and PC12 nerve cells on the fibres in vitro served to assess the potential for nerve regeneration. The transplantation of the fibres into the nerve gap in the axon encourages the migration and proliferation of Schwann Cells)The nanofibers’ potential for nerve regeneration was evaluated both in vivo by culturing cells onto the fibre and in vitro by transplantation of the fibres into gaps of the axons of nerves in rats. The inclusion of the RGO did not disrupt the structure of the nano-fibres and seemingly enhanced the mechanical properties and biocompatibility. In vitro analysis of the electrically stimulated fibres showed several cellular signs indicating nerve generating potential including gene expression and cell differentiation characteristic of nerve cells.
When implanted into 10mm rat sciatic nerve defects, the fibres supplemented with RGO showed myelination (the growth of a myelin sheath around a nerve cells to allow for faster signal transmission) and peripheral nerve cell migration that was comparable to results seen by using nerve autografts. Cross sections of the nerve tissue showed superior regeneration in fibres containing RGO suggesting that the electrical conductance facilitated better regeneration. The authors mention the physicochemical properties allow for better cell adhesion and protein adsorption. The benefits of electrical signals passing through the fibres is congruent with past research however, the mechanism by which electrical stimulation improves nerve regeneration still needs to be explored.
The implementation of RGO as an electroactive component of the nanofibers seemingly make the difference in the specialised regeneration of nerve tissue. Although the concept of bioelectricity and the presence of electric fields in living tissue has been known for decades, the implementation of biomaterials that capitalise on bioelectricity for tissue regeneration is still in its early stages. This study represents a promising effort to nerve regeneration without the need for autografts.