Transcriptome profiling of DA neurons, human midbrain-like organoids and prenatal midbrain

Recent advances in three dimensional (3D) culture systems have led to the generation of brain organoids that share resemblance to different parts of the human brains; however, a 3D organoid model of the midbrain that contains functional midbrain dopaminergic (mDA) neurons has not been reported. In this study, we develop a method to differentiate human PSCs into a large multicellular organoid-like structure that contains distinct layers of neuronal cells with a transcriptomic profile that resembles human prenatal midbrain. Importantly, we detected electrically active and functionally mature mDA neurons, and dopamine production in our 3D midbrain-like organoids (MLOs). In contrast to human mDA neurons generated using non-3D methods or in the MLOs generated from mouse embryonic stem cells, our human MLOs uniquely produced neuromelanin-like granules that were structurally similar to those isolated from human substantia nigra tissues. Thus our MLOs bearing features of the human midbrain may provide a novel tractable in vitro system to study the human midbrain and its related diseases.