Novel thin-walled nerve conduit with microgrooved surface patterns for enhanced peripheral nerve repair

Abstract

Randomly aligned nerve cells in vitro on conventional culture substrata do not represent the complex neuronal network in vivo and neurites growing in uncontrolled manner may form neuroma. It is of great importance to mimic the organised growth pattern of nerve cells in the study of peripheral nerve repair. The aim of this work was to modify and optimize the photolithographic technique in creating a reusable template in the form of a silicon wafer that could be used to produce contact guidance on biodegradable polymer surface for the orientated growth of nerve cells. Micro-grooves (approximately 3 μm in depth) were etched into the silicon template using KOH at increased temperature. The originality of this work lies in the low cost and high efficiency method in producing microgrooves on the surface of biodegradable ultra-thin polymer substrates (50-100 μm), which can be readily rolled up to form clinically implantable nerve conduits. The design of a pattern with small ridge width (i.e., 5 μm) and bigger groove width (i.e., 20 μm) favored the alignment of cells along the grooves rather than on the ridges of the patterns, which minimized the effect of cross growing of neurites between adjacent grooves. Effectively, enhanced nerve regeneration could be anticipated from these patterned conduits.

Polymer Scaffolds with Preferential Parallel Grooves Enhance Nerve Regeneration

“…Control films were also prepared on a smooth silicone substrate, whereby the flat uppermost surface of the film resulted in a micropitted conformation. 5 …”

“…4 We have previously reported that ultrathin PCL films and PCL/PLA blended films with a micropitted surface are able to support the attachment and growth of the NG108-15 neuronal cell line and Schwann cells. 5 Schwann cells are key players in nerve regeneration through delivery of neurotrophic factors and extracellular matrix proteins; however, the absence of Schwann cells in a nerve gap has led to much current work being focused on the use of stem cells to deliver this. We have previously demonstrated that PCL films can support adipose-derived stem cells (ASCs), differentiated to a Schwann cell-like phenotype (dASC), as a potential tissue-engineered route to nerve repair.…”

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

“…In particular, textures can be used to control optical properties, [35] to tailor how liquid spread on surfaces or flow within channels, [36,37] and to influence how cells grow and nerves regenerate. [38][39][40] The fabrication of fibers with sub-micrometer textures that could exhibit such advanced…”

Bioactive Nanomaterials for Neural Engineering

“…Cells are distinctly responsive to every cue in their environment including surface topography, stiffness, and interacting fi ber diameter and change their behavior accordingly (Georges and Janmey 2005 ;Pedersen and Swartz 2005 ;Khatiwala et al 2006 ;Curtis and Riehle 2001 ). Grooves, micro-and nanofi bers, gels, and fi lms have been studied in order to promote and direct neuronal outgrowth and enhance neuronal attachment (Xie et al 2010 ;Sun et al 2010 ;Mobasseri et al 2013 ;Daud et al 2012 ;Bell and Haycock 2012 ). Instead of using hollow guidance tubes that lacks physical properties of the native nerve structure, studies have focused on developing materials that guide the axons to the distal site of the injury.…”