Gateway- Human dopaminergic neurons and microglia midbrain organoid culture models for Parkinson’s disease pathogenesis and treatment

Parkinson's disease (PD), a slow and progressive degeneration of dopaminergic neurons, manifests with both motor and non-motor features, and is the second most common neurodegenerative disorder. The pathogenesis, onset, progression, and severity of PD are not yet clearly understood. The onset of PD occurs decades before the first symptoms appear, and patients with PD are prone to developing dementia. There have been an increased number of PD cases associated with coronavirus disease (COVID)-19. While the precise pathogenetic mechanisms remain unclear, the effect of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) on synaptic and neuronal degeneration has been implicated, potentially via neuroinflammation mediated by activation of microglia. Administration of the neurotoxin 1-methyl-4-phenylpyridinium (MPP+) induces experimental PD and can activate glial cells and mast cells to release neuroinflammatory mediators. The main treatment of PD is still replenishing dopamine in the brain. Effective treatments are lacking, partly due to the lack of an appropriate experimental model. Increasing evidence indicates that certain naturally occurring flavonoids have beneficial anti-inflammatory and neuroprotective actions, including in PD. Luteolin (tetraxydroxyflavone) was shown to protect rat PC12 neurons from MPP+-induced toxicity. A unique flavonoid is the hexamethoxyflavone nobiletin, which has been reported to improve motor and cognitive deficits in animal and _in vitro_ models of PD, potentially via inhibition of neuroinflammation. **Premise. Neuroinflammation is involved in PD pathogenesis and will be studied using a surrogate model of co-cultured human dopaminergic neurons and microglia. Specific Aims: 1.** Measure dopaminergic neuronal density and function before and after co-culture with stimulated microglial cells, an in vitro organoid system. **2.** Investigate the effect of MPP+ and SARS-CoV-2 recombinant spike (S) protein on dopaminergic neurons directly or via activation of microglia.**3.** Investigate the effect of nobiletin on dopaminergic neuronal integrity and microglia activation using optimal conditions from Aim 2. This project is highly innovative because it will study PD pathogenesis and treatment by using a novel surrogate system of co-cultured microglia activation on dopaminergic neuronal health following different toxic stimuli. The anticipated outcomes will identify novel targets to be used as a foundation for screening new effective treatments for PD starting with nobiletin, which makes the study significant. A pilot Phase I clinical study using nobiletin (500 mg/day for four months) in patients (n=20; 40-65 years of age) with early PD is targeted as the next step to this proposed study. Funded: Yes Funding source type: Local