PROJECT SUMMARY Parkinson's disease (PD) is one of the most prevalent neurodegenerative disorders, affecting nearly one million people in the United States as of 2020. The core etiopathology comprises intracellular accumulation of Lewy body-like α-synuclein (α-syn), followed by progressive loss of motor-controlling midbrain dopaminergic (mDA) neurons in the substantia nigra pars compacta. There is growing evidence that the dysfunction of the cerebral vasculature called the blood-brain barrier (BBB) is involved in PD progression and, more importantly, implicated in altered drug efficacy. PD patients suffer from a wide spectrum of clinical syndromes such as movement disorders/parkinsonism, dementia, and autonomic nervous system dysfunction. Current standards-of-care are not curative and focus on symptom management. Thus, a treatment option that can modify the disease pathology is sorely needed. One of the major challenges in developing such a therapy is the absence of an experimental model recapitulating human PD pathology, which is needed for quick and reliable screening of candidate therapies prior to clinical evaluation. Even though recent advances in human induced pluripotent stem cell (hiPSC) technology makes it possible to derive mDA neurons of PD patients, current 2D culture models do not recapitulate the native microenvironment around the neurovascular unit and thus cannot model the pathophysiology of late-onset human PD, which is induced by accumulated aberrant α-syn aggregation. To this end, we will develop and validate an advanced high-throughput in vitro human PD model that reflects pathological vascular and tissue changes observed in the brains of PD patients. Specifically, we will engineer and optimize a multi-well microfluidic tissue on-a-chip platform integrated with vascular perfusion and a blue light module to reconstruct the complex microenvironment at the interface of the human neurovascular unit and parenchyma tissue in human brains (Aim 1). We will then induce the core etiopathology of brain-borne α-syn aggregation in the PD patient-derived mDA neurons using our novel light-inducible pathogenic protein aggregation system (i.e., optogenetics-assisted alpha-synuclein aggregation induction system, OASIS) and α-syn preformed fibrils (Aim 2.1). In parallel, we will investigate the effect of blood-borne pathogenic α-syn aggregates, observed in patients, on PD progression in our model (Aim 2.2). We will validate our newly engineered human PD model by its comparison to clinical observations, including α-syn accumulation, neuroinflammation, progressive neuronal death, and pathological changes of the BBB. Finally, we will demonstrate that our PD model can serve as a testbed to evaluate the delivery efficiency and therapeutic efficacy of highly versatile drug-loaded delivery platforms (i.e., human ferritin nanocages) (Aim 3). If successful, the developed platform will ultimately allow us to build patient-specific disease models instrumen...