Thermally drawn fibers as nerve guidance scaffolds

Abstract

Synthetic neural scaffolds hold promise to eventually replace nerve autografts for tissue repair following peripheral nerve injury. Despite substantial evidence for the influence of scaffold geometry and dimensions on the rate of axonal growth, systematic evaluation of these parameters remains a challenge due to limitations in materials processing. We have employed fiber drawing to engineer a wide spectrum of polymer-based neural scaffolds with varied geometries and core sizes. Using isolated whole dorsal root ganglia as an in vitro model system we have identified key features enhancing nerve growth within these fiber scaffolds. Our approach enabled straightforward integration of microscopic topography at the scale of nerve fascicles within the scaffold cores, which led to accelerated Schwann cell migration, as well as neurite growth and alignment. Our findings indicate that fiber drawing provides a scalable and versatile strategy for producing nerve guidance channels capable of controlling direction and accelerating the rate of axonal growth.

A wrappable microwire electrode for awake, chronic interfacing with small diameter autonomic peripheral nerves

“…Many groups have been developing more mechanically compliant microwires using various polymeric materials (Kolarcik et al 2015;Koppes et al 2016;Park et al 2017). This approach could be relevant to microwire interfacing groups to extend recording and potentially stimulation longevity.…”

Controlled Sub‐Micrometer Hierarchical Textures Engineered in Polymeric Fibers and Microchannels via Thermal Drawing

“…This supports the requirement for small groove sizes for beneficial effect on regenerative scaffold. [44] Furthermore, our process may be extended to a wide range of polymers, from transparent PC or PMMA to stretchable and even biodegradable materials. This range of properties can be exploited to better image the effect of texture on cell growth, to study the effect of the substrates' mechanical properties, or to exploit biodegradability during a regenerative process for nutrients delivery or self-degradation of a scaffold.…”

“…Any texture can be simply fabricated at the preform level (sub-millimeter scale), or imprinted onto a die for extrusion, but during the fiber pulling step a reflow of the desired pattern driven by surface tension (Laplace pressure) occurs, [41,42] resulting in the distortion of the initial shape at the fiber level below a certain feature size. Earlier work [43,44] has achieved the functionalization of thermally drawn fibers that integrated textures but with large sizes, typically around 30 micrometer, using polyetherimide (PEI), a thermoplastic with a very high mechanical strength that allows for a processing at high viscosity that can limit reflow at these dimensions. For many applications in optics, optoelectronics, microfluidics, biology or advanced textiles however, it is necessary to have smaller-sub-micrometer-patterns on the surface and within a variety of polymers, which display much weaker mechanical strengths such as polycarbonate (PC), poly(methyl methacrylate) (PMMA) or even soft elastomers such as the widely used poly(dimethylsiloxane) (PDMS).…”

Thermally drawn polycaprolactone fibres with customised cross sections

“…Surface features such as grooves in polymer and fibre scaffolds have already been demonstrated to have a strong influence on nerve cell regeneration 6 . Following our previous works on drawing soft polymer fibre materials 7 , here we report on the first time (to the best of our knowledge) successful drawing of solid-core and hollow-core PCL fibres with tailored cross sections using the well-established fibre drawing technique, used for making optical fibre, involving drawing in a furnace from a macroscale preform.…”