Objective: To evaluate cellular pathogenesis in DA neuron function, and α-synuclein pathology using LRRK2-I1371V PD iPSC.

Background: It is reported for complex-neurodegenerative disorders like PD, ethnicity plays key role in etiology of disease-onset and prevalence. The heterogeneity of PD is major contributing factor to failure of disease modification trials, indicating need for more tailored therapeutic treatments. Clinical studies for LRRK2-mutation in Indian and Southeast Asian population for PD have shown I1371V-allele, but there are no studies on its association with ontogeny of DA neurons and α-synuclein pathology.

Method: iPSCs from PBMCs of PD-patient of East-Indian ethnicity carrying the I1371V mutation in LRRK2 gene and age and gender matched healthy control generated. iPSCs were characterized for self-renewal and pluripotency through FACS analysis, gene expression studies, differentiation to 3 derm lineages. DA neurons were differentiated from iPSCs and characterized by mRNA and protein level. Functional studies of intracellular Ca2+ response, vesicular dopamine release was measured through live-cell fluorescence imaging. Expression of α-synuclein oligomer, phosphorylated α-synuclein and synaptic density using PSD95 and synapsin was detected through immunofluorescence.

Results: iPSCs were derived from LRRK2 I1371V PD patient and healthy control PBMCs and DA neurons were differentiated from them. Each stage of ontogeny towards DA neurons showed compromise in key transcription factor expression and floorplate markers in PD cells. Neural progenitors from PD patient iPSCs showed compromised self-renewal capacity and migration property. Distinct functional impairment in intracellular Ca2+ response upon KCl stimulation and its corresponding vesicular dopamine release was observed. PD DA neurons showed distinct α-synuclein pathology such as higher α-synuclein oligomer and phosphorylated α-synuclein expression along with impaired synapse density.

Conclusion: Thus DA neurons mimicked the impairment in vesicular dopamine release as was detected in the PD patients. The PD DA neurons replicated PD pathology distinctly such as α-synuclein pathology and impaired intracellular Ca2+ response upon physiological stimulus. PD iPSCs thus can serve as a platform to replicate patient brain cell pathology and eventually used for drug screening and understanding key signalling pathways in disease pathology.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/evaluation-of-%ce%b1-synuclein-pathology-and-function-in-dopaminergic-neurons-derived-from-lrrk2-i1371v-pd-patient-ipscs/