Electrospun Polycaprolactone Fibre Bundles for Tendon Regeneration

Electrospun Polycaprolactone Fibre Bundles for Tendon RegenerationL. A. Bosworth S. J. Eichhorn S. Downes 1. IntroductionThe high prevalence of pain caused by degenerating and ruptured tendons brought about by age and injury offer incentive for development of regenerated tendon tissue for implantation. It is important that the physical properties of the original tendon are determined to ensure replicated tissue is structurally indistinguishable. Biomimicry of the three-dimensional architecture of the extracellular matrix (ECM) is essential to aid cellular organisation and function.Tendons are predominantly comprised of aligned collagen type I fibres grouped into bundles, oriented parallel to the tendon axis to form an intricate hierarchical arrangement. Tendon cells are positioned in columns amongst these fibres and assist in ECM turnover.To best resemble tendon structure the artificial scaffold should ideally be composed of bundled fibre levels. 2. Materials and Method2.1 MaterialsThe chosen polymer was polycaprolactone (PCL) (Mw = 80 000). The polymeric solution used for electrospinning was obtained by dissolving polycaprolactone in acetone. Solution concentration was 10 % w/v.2.2 Electrospinning SetupThe polymeric solution was contained within a needle-tipped syringe. A flow rate of 0.1 ml/min was applied to the solution.The needle was further connected to a high voltage FC Series 120 Watt power supply from Glassman High Voltage. A voltage of 25 kV was applied to the polymeric solution.The grounded collector was a foil tin containing chilled distilled water with a depth of 1 cm. The tip to collector distance was 10 cm.The non-woven network of fibres formed on the water surface was drawn through the liquid reservoir with the aid of plastic tweezers and lifted off the water into air.A diagrammatic representation of the electrospinning setup is shown in Fig. 1.2.3 Fibre CharacterisationThe drawn fibres were sputter-coated with gold and their morphology analysed by scanning electron microscopy (SEM). Fig. 1 ??? Electrospinning setup with liquid reservoir as the grounded electrode3. Results and DiscussionDrawing of the fibrous network through the water caused elongation and fibre alignment. Lifting of this stretched network off the water surface led to the formation of three-dimensional fibre bundles (fig. 2). The average width of the fibre bundle was measured as 84.4 ??m (?? 1.74). The average diameter of the fibres encompassed within the fibre bundle was 800 nm (?? 0.33). The thickness of the PCL bundle as a whole is representative of a tendon tertiary fibre bundle, whose diameter range is 50 ??? 400 ??m [1]. Fig. 2 ??? Electrospun PCL fibre bundle4. ConclusionModification of the electrospinning setup has proven to be successful for the fabrication of uniaxial fibre bundles.Production of these bundles furthers the development of the scaffold structure, intended to replicate the bundle levels within the natural tendon tissue.[1] Screen, H.R.C., Lee, D.A., Bader, D.L., Shelton, J.C. Proc. Instn Mech. Engrs Vol.218 part H: J. Engineering in Medicine