Autophagy dysfunction in iPSCs-derived neurons and midbrain organoids carrying a SNCA triplication.

Parkinson's disease (PD), characterized by α-Synuclein aggregation and dopaminergic neuronal loss, has no current cure. Autophagy is critical for α-Synuclein clearance, yet its real-time dynamics remain challenging to assess in human-relevant systems. Here, we used live-cell imaging to assess autophagy within human neuronal cultures and midbrain organoids (hMOs) derived from induced pluripotent stem cells (iPSCs) of PD patients carrying a triplication of the α-Synuclein gene (3xSNCA). Using the LC3-Rosella dual-fluorescent reporter, we quantified autolysosomes dynamics in real time. In 3xSNCA neuronal cultures, we detected early autophagy defects. In 3xSNCA hMOs, reduced autolysosome area, increased total and phosphorylated α-Synuclein (pS129), and decreased electrophysiological activity were observed at 50 days of differentiation (DoD). By 70 DoD, autophagy impairment became more pronounced, overlapping with dopaminergic neuron dysfunction. These findings support the use of human iPSCs-derived models to study autophagy dysfunction in PD and demonstrate a temporal correlation between impaired autophagy, α-Synuclein pathology and neuronal degeneration.