Hörberg Carl-Johan, Englund Johansson Ulrica, Johansson Fredrik, O'Carroll David
Department of Biology, Lund University, 223 62 Lund, Sweden
Department of Health and Caring Sciences, Linnaeus University, 391 82 Kalmar, Sweden.
eNeuro. 2022 Oct 10;9(5). doi: 10.1523/ENEURO.0143-22.2022.
Three-dimensional neuronal culture systems such as spheroids, organoids, and assembloids constitute a branch of neuronal tissue engineering that has improved our ability to model the human brain in the laboratory. However, the more elaborate the brain model, the more difficult it becomes to study functional properties such as electrical activity at the neuronal level, similar to the challenges of studying neurophysiology We describe a simple approach to generate self-assembled three-dimensional neuronal spheroid networks with defined human cell composition on microelectrode arrays. Such spheroid networks develop a highly three-dimensional morphology with cell clusters up to 60 µm in thickness and are interconnected by pronounced bundles of neuronal fibers and glial processes. We could reliably record from up to hundreds of neurons simultaneously per culture for ≤90 d. By quantifying the formation of these three-dimensional structures over time, while regularly monitoring electrical activity, we were able to establish a strong link between spheroid morphology and network activity. In particular, the formation of cell clusters accelerates formation and maturation of correlated network activity. Astrocytes both influence electrophysiological network activity as well as accelerate the transition from single cell layers to cluster formation. Higher concentrations of astrocytes also have a strong effect of modulating synchronized network activity. This approach thus represents a practical alternative to often complex and heterogeneous organoids, providing easy access to activity within a brain-like 3D environment.Neuronal "organoid" cultures with multiple cell types grown on elaborate three-dimensional scaffolds have become popular tools to generate brain-like properties but bring with them similar problems concerning access to physiological function as real brain tissue. Here, we developed a new approach to form simple brain-like spheroid networks from human neurons, but using the normal supporting cells of the brain, astrocytes, as the scaffold. By growing these cultures on conventional microelectrode arrays, we were able to observe development of complex patterns of electrical activity for months. Our results highlight how formation of three-dimensional structures accelerated the formation of synchronized neuronal network activity and provide a promising new simple model system for studying interactions between known human cell types .
三维神经元培养系统，如球体、类器官和组装体，构成了神经元组织工程的一个分支，它提高了我们在实验室中模拟人类大脑的能力。然而，大脑模型越精细，就越难以研究神经元水平的功能特性，如电活动，这与研究神经生理学所面临的挑战类似。我们描述了一种简单的方法，可在微电极阵列上生成具有明确人类细胞组成的自组装三维神经元球体网络。这种球体网络呈现出高度三维的形态，细胞簇厚度可达60微米，并通过明显的神经元纤维束和神经胶质突起相互连接。我们能够在每个培养物中可靠地同时记录多达数百个神经元，持续时间≤90天。通过随时间量化这些三维结构的形成，同时定期监测电活动，我们能够在球体形态和网络活动之间建立紧密联系。特别是，细胞簇的形成加速了相关网络活动的形成和成熟。星形胶质细胞既影响电生理网络活动，又加速从单细胞层到簇形成的转变。更高浓度的星形胶质细胞对调节同步网络活动也有很强的作用。因此，这种方法代表了一种实用的替代方案，可替代通常复杂且异质的类器官，提供了在类似大脑的三维环境中轻松获取活动的途径。在精心制作的三维支架上培养具有多种细胞类型的神经元“类器官”已成为产生类似大脑特性的流行工具，但与真实脑组织一样，在获取生理功能方面也存在类似问题。在这里，我们开发了一种新方法，利用大脑的正常支持细胞星形胶质细胞作为支架，从人类神经元形成简单的类似大脑的球体网络。通过在传统微电极阵列上培养这些培养物，我们能够观察到数月的复杂电活动模式的发展。我们的结果突出了三维结构的形成如何加速同步神经元网络活动的形成，并为研究已知人类细胞类型之间的相互作用提供了一个有前景的新的简单模型系统。
