Neuronal cultures are widely used in neuroscience research. However, the randomness of circuits in conventional cultures prevents accurate in vitro modeling of cortical development and of the pathogenesis of neurological and psychiatric disorders. A basic feature of cortical circuits that is not captured in standard cultures of dissociated cortical cells is directional connectivity. In this work, a polydimethylsiloxane (PDMS)-based device that achieves directional connectivity between micro 3D cultures is demonstrated. The device consists of through-holes for micro three-dimensional (μ3D) clusters of cortical cells connected by microtrenches for axon and dendrite guidance. The design of the trenches relies in part on the concept of axonal edge guidance, as well as on the novel concept of specific dendrite targeting. This replicates dominant excitatory connectivity in the cortex, enables the guidance of the axon after it forms a synapse in passing (an “en passant” synapse), and ensures that directional selectivity is preserved over the lifetime of the culture. The directionality of connections was verified morphologically and functionally. Connections were dependent on glutamatergic synapses. The design of this device has the potential to serve as a building block for the reconstruction of more complex cortical circuits in vitro.

神经元培养广泛应用于神经科学研究。然而，传统培养物中回路的随机性阻碍了皮质发育以及神经和精神疾病发病机制的准确体外建模。分离皮质细胞的标准培养物中未捕获的皮质回路的一个基本特征是定向连接。在这项工作中，展示了一种基于聚二甲基硅氧烷 (PDMS) 的设备，可实现微型 3D 培养物之间的定向连接。该装置由用于微型三维 (μ3D) 皮质细胞簇的通孔组成，这些通孔通过微沟槽连接，用于轴突和树突的引导。沟槽的设计部分依赖于轴突边缘引导的概念，以及特定树突靶向的新颖概念。这复制了皮层中的主要兴奋性连接，使得轴突在形成传递突触（“经过”突触）后能够进行引导，并确保在培养物的整个生命周期中保留方向选择性。连接的方向性在形态和功能上得到了验证。连接依赖于谷氨酸突触。该设备的设计有潜力作为体外重建更复杂的皮层回路的构建模块。