Biophysical study of neuronal networks in midbrain organoids derived from Parkinson's disease patients

In vitro approaches to model human brain development and disease are an intense area of research. In the context of Parkinson's disease (PD), human midbrain organoids (hMOs) are significatively relevant, as they generate dopaminergic neurons, which are subject to degeneration. Here, we compare hMOs derived from healthy subjects with hMOs from patients carrying different PARK2 mutations. Our aim is to characterize the functionality of the neuronal network by means of calcium imaging and patch clamp. Combining two-photon microscopy with AM calcium dyes allows us to detect spontaneous neuronal activity both in healthy and diseased hMOs, based on the calcium transients evoked by action potentials (APs). Futhermore, we describe the effects of several drugs on the spontaneous oscillations. Since calcium imaging has a limited temporal resolution, while patch clamp allows to record intracellular APs from single neurons, we applied this technique on slices of the hMOs. In addition, we adoperate multielectrode arrays (MEAs) to record extracellular field potentials generated by APs. This research, together with morphological results, suggests that PARK2 mutated midbrain organoids have the potential to explore different mechanisms underlying PD.