Neural stem cells of Parkinson's disease patients exhibit aberrant mitochondrial morphology and functionality

Emerging evidence suggest that Parkinson's disease (PD), besides being an age-associated disorder, might also have a neurodevelopment component. Disruption of mitochondrial homeostasis has been highlighted as a crucial cofactor in its etiology. Here, we show that PD patient-specific human neuroepithelial stem cells (NESCs) carrying the LRRK2-G2019S mutation recapitulate key mitochondrial defects previously described only in differentiated dopaminergic neurons. By combining high-content imaging approaches, 3D image analysis, and functional mitochondrial readouts we show that LRRK2-G2019S mutation caused aberrations in mitochondrial morphology and functionality compared to isogenic controls. LRRK2-G2019S NESCs displayed an increased number of mitochondria compared to isogenic control lines. However, these mitochondria were more fragmented and exhibited decreased membrane potential. Coherently, the release of total and mitochondrial redox oxidative species increased in LRRK2-G2019S NESC compared to controls. Functional alterations in LRRK2-G2019S cultures were also accompanied by a reduced mitophagic clearance via lysosomes. These findings support the hypothesis that preceding mitochondrial developmental defects contribute to the manifestation of the PD pathology later in life. Overall design: Single-cell RNA-Sequencing experiments were performed on a total of 8 samples. These correspond to 4 time-points (Day 0, 10, 14 and 42). The time-point at 0 days refers to NESCs. The other time-points refer to Dopaminergic differentiation. Two cell-lines were analysed for each time-point: LRRK2-WT and LRRK2-G2019S.