Mitochondrial Dysfunction and Neuronal Anomalies inPOLGMutant Midbrain Organoids

Abstract

Human pluripotent stem cell-derived midbrain organoids offer transformative potential for elucidating brain development, disease representation, and therapeutic innovations. We introduce a novel methodology to generate midbrain-specific organoids from both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). By employing tailored differentiation cues, notably dual-SMAD inhibition combined with FGF-8b and Sonic hedgehog agonist purmorphamine, we direct pluripotent stem cells towards a midbrain lineage. These organoids, growing beyond 2mm in diameter, house diverse neuroepithelial cell populations. Their midbrain character is affirmed by the pronounced expression of midbrain-specific markers and the absence of forebrain and hindbrain indicators. Critically, these organoids differentiate into dopaminergic neurons characteristic of the midbrain, displaying both morphological sophistication and electrophysiological vigor. Additionally, our experiments with POLG iPSC-derived midbrain organoids revealed a marked loss of dopaminergic neurons and diminished expression of genes governing mitochondrial pathways. This evidence underscores the model’s potential in simulating mitochondrial diseases and neurodegenerative conditions, notably Parkinson’s disease. Our protocol thus emerges as a pivotal instrument for crafting functionally adept, midbrain-centric organoids, paving avenues for advanced studies in midbrain evolution, disorders like Parkinson’s disease, and their interplay with mitochondrial dysfunction.

Nicotinamide Riboside Supplementation Ameliorates Mitochondrial Dysfunction and Neuronal Loss in POLG Mutant Midbrain Organoids

“…Our previous study (39), describes the generation of midbrain-specific organoids from both embryonic stem cells and iPSCs. This methodology produced organoids with midbrain characteristics via expression of midbrain markers, while largely excluding forebrain and hindbrain indicators.…”