Preparation of electrospun chitosan fibres for Schwann cell-guided axonal growth

Abstract

Schwann cell-seeded guidance channels have been exploited to bridge and guide axonal re-growth across gaps in lesioned nerves. Mis-orientation of Schwann cells in the channels can however distort axonal growth within the lesion. We therefore propose to orient the growth of Schwann cells on aligned nanofibers such that axonal growth can be guided along the designated direction towards the target. Chitosan was the choice scaffold material given its biocompatibility and the tunable susceptibility to biodegradation. To be suitable for electrospinning, chitosan was dissolved in trifluoroacetic acid/methylene chloride solution. By replacing the grounded plate collector of the conventional electrospinning setup with parallel collector plates placed 1.6 cm apart, the positively charged chitosan fibersbecame alternately attracted to the parallel plates and ended up uniaxially aligned as fiber suspension across the plates. Stability of the chitosan fibers in aqueous, physiological environment was achieved with the use of sodium carbonate to neutralize residual acidity in the chitosan fiber preparation. Schwann cells seeded onto these stabilized aligned chitosan nanofibers aligned uniaxially with the chitosan nanofibers. In addition, by seeding dissociated cells of dorsal root ganglia (DRG, E14/15 rats) onto the uniaxially aligned nanofibers, both neurons and Schwann cells were aligned with uniaxial arrangement of nanofibers, and the Schwann cells showed myelination ofthe axons. A model of the chitosan nerve conduit was constructed with a core nanofiberbundle, and seeding of Schwann cells. Thesein vitro results provide proof-of-principle for pursuing improvement in post-traumatic recovery from nerve injury with use of uniaxially aligned chitosan nanofibers in Schwann cell-seeded nerve guidance channels.