Astrogliosis across models: 3D printing and in vivo implantation

• Autor(a) principal: Cruz, Elisa Marozzi [UNIFESP]
• Data de Publicação: 2024
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: https://hdl.handle.net/11600/71625
• topic: Astrogliosis; 3D bioprinting; Neurogenesis; Traumatic Brain Injury; Astrogliose; Impressão 3D; Neurogênese; Lesão traumática cerebral

Brain injuries are a significant public health issue due to their personal and socioeconomic impacts. The recovery of affected individuals is reduced because the neurogenic potential of the adult Central Nervous System (CNS) is limited. Therefore, identifying potential targets for the recovery and regeneration of injured nervous tissue is necessary. In this scenario, non-neuronal cells, such as astrocytes, present a promising alternative for the treatment of brain injuries. Astrocytes are glial cells in the CNS that perform various functions in neural homeostasis and pathology. CNS injuries induce astrocyte activation, initiating a process known as astrogliosis, leading to changes in astrocyte morphology, gene expression, and functions. Populations of reactive astrocytes can dedifferentiate, acquiring a neural stem cell phenotype with the potential to generate new neurons. In vitro studies of neuron co-culture with astrocytes show that astrocytes are important for neuronal maturation and survival. Cell cultures have traditionally been performed in a two-dimensional (2D) environment, but three-dimensional (3D) cultures are recognised to offer an environment with structural and biomechanical characteristics that mimic natural tissue. In the last decade, 3D printing has become an important tool in the fabrication of 3D constructs composed of bioinks to encapsulate living cells, better mimicking the natural microenvironment. This study aimed to evaluate the neurogenic potential of primary murine cortical astrocytes in 3D constructs generated by extrusion bioprinting and to assess the neurotrophic support provided by these cells to neurons derived from H9 cells. Additionally, the effect of astrocytes on brain injury healing was evaluated by implanting 3D constructs generated by microfluidics into the cortex of mice subjected to a traumatic brain injury model. The results indicate that, under specific signalling influence, bioprinted astrocytes express SOX2, indicating the acquisition of a less differentiated phenotype. The cultivation of dedifferentiated astrocytes in the presence of neurotrophic factors causes the appearance of cells positive for TUJ1 and MAP2 with characteristic neuronal morphology, earlier than in the control group. In 2D cultures, when cultivated in the presence of astrocytes, neural progenitor cells derived from H9 cells (neural progenitors, NPCs) show accelerated maturation and acquisition of cortical layer neuron identity, concomitant with the decrease in the neurogenic potential of NPCs compared to the control group. In 3D constructs fabricated by microfluidics, astrocytes seem to increase NPC survival, which could be implanted into xiii the cortex of mice after traumatic brain injury induction. Animals implanted with astrocyte and NPC co-culture constructs showed significantly smaller glial scars on the brain surface, as well as a reduction in the total lesion area. In conclusion, the results presented in this thesis indicate the importance of astrocytes for maintaining neuronal health and supporting maturation in 2D and 3D neuronal cultures, as well as their therapeutic potential, both in activating the neurogenic potential of the adult CNS through their reactive response and in their role in healing injuries in vivo models of traumatic brain injury.