Three-dimensional scaffolds as platforms for development of cell-based strategies for central nervous system rescue and repair

The mammalian central nervous system (CNS) has limited intrinsic repair mechanisms. Damage or trauma to the CNS causes a loss of cells, causing motor and cognitive impairments. Cell transplantation strategies have made great advances in the last few decades and have been essential in the field of regenerative medicine. Recently, biomaterials in conjunction with stem cells have been used to supplement therapeutic strategies. The objective of this project was using an interdisciplinary approach combining polymers, three-dimensional (3D) scaffolds and stem cells to provide a platform for enhancing cell proliferation and differentiation for future cell transplantation strategies. Poly (ε-caprolactone) (PCL) is a synthetic polymer that can be used to fabricate microfibers using a microfluidic technique. Adult rat hippocampal progenitor cells (AHPCs) were used to examine the ability of 3D microfibrous scaffolds to support the growth, proliferation and differentiation of cells in vitro. In contrast to conventional two-dimensional (2D) surfaces, our group revealed that PCL microfibers significantly increased proliferation and glial differentiation of AHPCs, demonstrating the importance of topographic cues on cellular behavior. Alternatively, we demonstrated the ability to encapsulate AHPCs within a hydrogel opposed to seeding cells onto a polymer surface. Encapsulation and recovery of AHPCs from alginate hydrogels demonstrated an increase in proliferation and neuronal differentiation, suggesting that fibrous hydrogels may mimic the natural microenvironment present in vivo and modulate cell behavior. To implement cell-based biomaterial strategies, we chose zebrafish (Danio rerio) as our model because they are optically transparent as larvae, enabling transplantation studies to be followed in vivo. First, we developed an efficient method to dissociate neural tissue from embryonic zebrafish brains in order to isolate neurons, with the ultimate goal of using these cells in conjunction with biomaterials to investigate novel therapeutic strategies. Second, we provided preliminary evidence on using zebrafish as a system to investigate biomaterial- based strategies. This work has provided evidence using a combinatorial approach of biomaterials and stem cells to promote cell proliferation and differentiation without the use of chemicals. Biomaterials provide a permissive environment leading to enhanced cell proliferation and differentiation, which may lead to the development of efficacious cell-based therapies