Brain-on-a-chip integrated neuronal networks

The brain-on-a-chip technology aims to provide an efficient and economic in vitro platform for brain disease study. In the well-known literature on brain-on-a-chip systems, nonstructured surfaces were conventionally used for the cell attachment in a culture chamber, therefore the neuronal networks grown in these systems face limitations of forming comparable organisation as in vivo. Approaches to achieving suitable and functional biomaterials which can be developed as artificial scaffolds to emulate the extracellular environment in vitro have been made in the past decades, and are still of great research interests. The work described in this thesis focuses on the fabrication of artificial extracellular matrix (ECM) scaffoldswith submicrometer scale linear patternswithmicro/nanofabrication techniques, and subsequently the study of the influence of these scaffolds on the formation of the primary neuronal networks of the cortex of a rat’s brain. It was demonstrated in the thesis that the linear scaffolds provide topographical guidance for the orientation of the cell outgrowths, e.g. the neurites and the branches of the astroglia, resulting in a highly organized neuronal cell networks which show cell outgrowth aligned parallel with the direction of the linear pattern. The influence of the dimensional as well as mechanical properties of the scaffolds, for instance, the matrix compliance, on the morphology of the primary neuronal networks were investigated with an aim of realising a more in vivo comparable extracellular environment. In addition, an microfluidic actuator chip that is able to exert nanoscale mechanical stimuli on the cells cultured atop was developed as an attempt to study the effects of mechanical changes in the scaffolds on the dynamic activities within the primary neuronal networks, e.g. the cellular calcium ion transmission, which contributes in the neuroelectrophysiological behaviours. Experimental results show that the primary neuronal networks are influenced by the structural andmechanical properties of the artificial scaffolds, both morphologically and biochemically. The highly ordered neuronal networks achieved by introducing submicrometer linear scaffolds maybe an approach to realising the unique laminar and orientated organisation of the neurons in the cortex in vitro. The research performed in this thesis particularly takes into account the intrinsic composition of multitype cells in the primary cortical cell culture, which is complementary to the studies on simplified mono-type cell cultures and is believed to provide more understanding of the interaction between the biointerface and the complicated cell organisations. The experiments and results shown in this thesis improved our understanding of the effect of the linear nanopatterned artificial ECMscaffolds on the primary neuronal networks. Conclusions and recommendations based on the findings in this thesis are expected to be useful for further research on engineering a brain-on-a-chip: the establishment of a well-engineered cell culture and analysis platform for novel brain disease models and the better understanding of the cellular processes involved in the functions of the brain.