Hydrogel – Phosphate Glass Fibre Constructs For Neural Tissue Engineering Applications

Neural injuries, particularly spinal cord injuries, are considered critical global health priorities due to causing severe loss of function and disabilities that could last a lifetime. Besides restricted regeneration capacity of the axons in the central nervous system, following an injury with damaged integrity of axons, there are also other inhibitory factors like inflammation and the glial scar that restrict recovery. Although no valid therapies have been found effective for functional recovery; tissue engineering applications offer promising approaches to support axonal regeneration after such debilitating incidents. Utilising hydrogels as tissue constructs for the targeted injury sites can serve multifunctional purposes, from cell therapies to scaffolding to bridging the disconnected nerve stumps and carrying drugs and other bioactive molecules to mitigate local challenges. Current tissue engineering approaches are limited in CNS, because of either complexity of developed constructs or focusing on just nerves and continuity of axons so a tissue engineered construct that is while offering simple design also is presenting favourable outcomes for functional neural recovery is required. Thus, the development of a GelMA hydrogel-based, biocompatible, and biodegradable construct containing phosphate-based glass fibres (PGFs) within its physical form was investigated in this thesis aiming to provide a favourable environment to cells and provide directionality to axons with aligned glial cell growth. It has been hypothesised that having PGFs in the GelMA hydrogel platform can provide a physical cue for directional growth of glial cells, and GelMA can provide a supportive and permissive environment while offering its ability to serve as a cell and drug carrier. Two PGFs formulations with different metal oxides, Fe+3 and Ti+2, were assessed within GelMA, and their extensive physicochemical and mechanical characterisations were conducted with further n vitro and in vivo biocompatibility analyses. Moreover, in vitro 3D cell culture assessments were carried out with primary astrocytes to investigate the potential of GelMA-PGFs constructs to ameliorate glial scar formation and inflammation indirectly via upregulation of GFAP and IL6 after LPS induced reactivity in addition to the exploration of lithium introduction via loading into GelMA hydrogel have also investigated. The outputs of this thesis provide comprehensive characterisations of PGFs and GelMA hydrogels for utilisation in neural tissue engineering. Glial cells have shown significantly enhanced directional growth into GelMA-PGFs scaffolds than GelMA only hydrogel. Furthermore, while the presence of PGFs(Fe) in GelMA has led more decreasing GFAP expression levels, lithium has provided a protective effect to mitigate the early expression of IL6 with LPS induced reactive primary astrocytes