The brain possesses extraordinary connectivity of neural networks. This complexity is evident at multiple levels of structural and functional hierarchy, including microcircuits dominated by neuronal clusters, and larger distinctive regions of grey matter interconnected by white matter axon tracts. Prior in vitro models of 3D brain-like tissues have not recapitulated this complexity and sustained functions to provide a route to mechanistic studies.  Usually, such systems are based on spontaneous cell assembly and network formation or random cell seeding in 3D polymer scaffolds. Spontaneous cell assembly allows for the natural reproduction of the extracellular space and cell-cell interactions, while creating a 3D environment. However, due to the very high cell density these cultures suffer from poor reproducibility and frequently form necrotic cores, even if cultured in spinning flask bioreactors. Moreover, random cell seeding inside the scaffolds  does not reflect cellular arrangements in neural tissue, where axonal tracts form bundles and neuronal bodies are clustered (gray/white matter). Further, the majority of other models are rodent-based. Recent advances with pluripotent stem cell-based approaches have generated human cerebral tissue models for neurodevelopmental disorders.

 

In contrast to the above systems, we have recently developed brain-like tissues that replicate some fundamental features of the brain, such as structure (e.g., grey and white-matter compartmentalization and inter-connected neural networks) and function (electrophysiological responses, responses to drugs, responses to mechanical damage as in traumatic brain injury). This brain tissue model demonstrates in vivo-like sustained viability and injury responses to mechanical perturbations. The 3D brain-like tissue model allows outcome assessments to be made in real-time and non-destructively, and importantly is already sustainable for over 1 year.