Neuronal branching in stem cell models of mitochondrial and neurological diseases.

Neuronal branching, the extension and arborization of neurites, is critical for establishing and maintaining functional neural circuits. Emerging evidence suggests that mitochondria play an important role in regulating this process. In this review, we explore how the use of human induced pluripotent stem cell (iPSC)-derived neuronal models in two dimensions (2D) and three dimensions (3D) could help uncover possible mechanisms linking mitochondrial function and dysfunction to neuronal branching capacity. We highlight examples of iPSC-based models of mitochondrial and neurological diseases where aberrant neurite growth has been observed and discuss the potential therapeutic implications. Additionally, we review current methodologies for assessing neurite outgrowth in 2D and 3D neuronal models, addressing their strengths and limitations. Insights gained from these models emphasize the significance of mitochondrial health in neuronal branching and demonstrate the potential of iPSC-derived neurons and brain organoids for studying disrupted neuronal morphology. Harnessing these human stem cell models to devise phenotypic drug discovery platforms can eventually pave the way for innovative therapeutic interventions, particularly in the context of disorders with poorly understood genetic mechanisms and limited therapeutic options.