<DEL CITE="MAILTO:SCH%C3%BCLKE-GERSTENFELD,%20MARKUS" DATETIME="2026-01-22T09:52"></DEL>MITOCHONDRIAL CALCIUM DYNAMICS IN HUMAN IPSC-DERIVED NEURAL PROGENITORS AS A MODEL FOR NEUROLOGICAL MTDNA DISORDERS

Mitochondrial disorders caused by mutations in MT-ATP6 are among the most severe mtDNA-related diseases, leading to maternally inherited Leigh syndrome (MILS) and Neuropathy Ataxia Retinitis Pigmentosa (NARP). Studying these rare conditions remains difficult. Patient-derived neuronal precursor cells (NPCs) have become a powerful model to investigate disease mechanisms and explore therapies as they directly represent the patients’ disease phenotype (Lorenz et al, 2017; Inak et al, 2021; Zink et al, 2025).
NPCs were generated from induced pluripotent stem cells (iPSCs) derived from patients carrying MT-ATP6 mutations (Zink et al, 2021, Haschke et al, 2023, Haschke et al, 2024). We assessed energy metabolism using luminescence-based assays and sub-cellular calcium dynamics through live-cell imaging with compartment-specific probes. This enabled us to simultaneously read out cytosolic and the intra-mitochondrial calcium transients in living cells.
High-content screening of >5,000 FDA-approved compounds previously identified Sildenafil as a candidate drug that was able to restore the mitochondrial membrane potential (MMP) in patient-derived NPCs (Lorenz et al, 2017). The translation into a clinical setting has since led to the treatment of six patients carrying MT-ATP6 mutations, with notable improvements in their clinical outcome (Zink et al, 2025). Building on these results, we now focus on dissecting mitochondrial energy production and calcium homeostasis in patient-derived NPCs. Our findings reveal distinct alterations in mitochondrial and cytosolic Ca²⁺ handling in patient-derived NPCs as compared to controls. These cellular phenotypes provide mechanistic insight into the pathophysiology and may develop novel readout paradigms that can be used for high content drug screening.