Anisotropic 3D scaffolds for spinal cord regeneration ; Estruturas 3D anisotrópicas para regeneração da espinal medula

Spinal cord injuries pose major challenges to modern medicine due to the restricted capacity of the central nervous system to regenerate and the profound impact they have on patients' quality of life. Neural tissue engineering offers promising solutions, particularly through the development of three-dimensional (3D) scaffolds that serve as templates for tissue regeneration. Scaffolds possessing anisotropic characteristics, which mimic the inherent longitudinal alignment of nerve fibres in the spinal cord, have significant potential for restoring the structure and functionality of neural networks. This thesis examines the significance of scaffold anisotropy in the regeneration of neural tissue by studying the structural characteristics of scaffolds that possess axially aligned channels, pores, or fibres. The initial method utilised 3D printed moulds to fabricate a hydrogel-based multichannel 3D scaffold. The second method utilised directional freezing combined with cryopolymerization to create cryogels featuring longitudinal pores. Ultimately, an innovative automated microfabrication technique was employed to create magneto-responsive aligned fibres. The study examined how microarchitecture affects the behaviour of neural stem cells (NCS), specifically their viability, migration, and proliferation. Additionally, the study investigated how different scaffolds can promote neuronal differentiation and guide the growth of neurites. The various strategies were evaluated for their successes and limitations. The multichannel scaffolds offer precise structural control and easy fabrication but may pose challenges for irregular lesions. Importantly, they promoted unassisted cell adhesion, robust proliferation, and neuronal differentiation, fostering intricate neuronal networks with longitudinal neurite extension. The cryogels presented high deformability allowing injectability. Cryogels with longitudinal pores showed extensive cellular infiltration and migration, supporting neuronal differentiation and neurite extension ...