Human iPSC-Derived Neurons and Organoids for Studying Cortical Development, Synapses, and Synaptopathies

Background: Human cerebral cortex is a complex brain structure associated with many human-specific behaviors and disorders. Many genes important for the development and wiring of this structure have been found mutated in the individuals with autism spectrum disorders (ASDs). It has previously demonstrated that cerebral organoids generated from induced pluripotent stem cells recapitulate many important aspects of human cortical development. The main issue, however, has been reduced reproducibility and impaired functional maturation of neurons in these structures.

Results: To improve experimental reproducibility and neuronal maturation, we developed a new method enabling generation of three-dimensional cortical organoids from single induced pluripotent stem cell (iPSC-) derived neural rosettes – neural tube-like structures in vitro. We demonstrate that single-rosette-derived cortical organoids grow large in suspension culture, reaching 4-5 mm in diameter by 4 months while maintaining a single internal lumen, and consist of different types of neuronal cells, including cortical neural progenitors, deep and superficial cortical excitatory neurons, inhibitory neurons, and different glial cells, organized around the lumen. Using slice patch-clamp electrophysiology, we also show that many neurons in slices from single-rosette-derived cortical organoids fire repetitive action potentials, receive excitatory and inhibitory synaptic inputs, exhibit typical pyramidal-like morphologies, and have dendritic spines.

Conclusions: Our results indicate that human cortical organoids generated from single iPSC-derived neural rosettes could be useful for studying and modeling human cortical development in health and disease.