Development Of Microstereolithography And Photopolymerisable Polymers for Peripheral Nerve Repair

The human peripheral nervous system has a limited ability for self-repair however trauma often results in life-long debilitation. Due to the prevalence of dislocation it is preferred that the two severed nerve ends are approximated via direct suturing or for larger injury gaps an autograft or alternatively an NGC can be implanted. NGC’s are nerve entubulation devices designed to not only act as a guide and modulator for the regenerating nerve however improved device design and manufacturing methods are required to match the efficacy of autograft and achieve clinical acceptance. Additive manufacturing is a rapidly emerging research and commercial production method for producing highly resolved polymeric structures such as NGC’s whilst allowing the incorporation of intralumenary features, rapid production rates, economic material usage and patient device specificity. The aim of the present study was to design and fabricate NGC devices utilising a bespoke laser-sourced microstereolithography system and microwave synthesised, degradable photopolymerisable liquid pre-polymers. The suitability of the structuring system and materials in this function where assessed by the fabrication of well-defined structures and using in vitro cell culture and an in vivo PNI model to confirm biocompatibility. Commercially derived materials were used in order to establish the system, with more biologically relevant degradable materials also being developed. The use of in-vitro neuronal and explant DRG cell culture with cell viability assaying and confocal microscopy confirmed a positive cellular interaction in both commercial and custom synthesised materials. Results from the PNI animal implantation model produced promising preliminary regeneration and re-innervation results in comparison to graft repair. The adaptability of the technique and materials developed in this work allowed their use for producing other biomedical devices for bone grafts and for fabrication of a highly resolved regeneration device for the central nervous system. This work establishes the applicability of this technique and the materials used for the fabrication of simple and advanced intralumenary feature containing NGC’s but also for a wide range of other biomedical and non-biomedical applications that require highly defined structures that are geometrically complex structures and devices.