Objective: 1. To identify a cohort of genetically confirmed SCA12 patients of Indian origin, derive iPSCs, progenitor cells and neurons from peripheral blood samples

2. To understand the cellular and molecular attributes of SCA12

Background: SCA12 is rare, with unique prevalence in the India, specifically Agarwal’s from North India. Features of cerebellar, pyramidal and extrapyramidal weakness including poor coordination and movement, dysfunction of gait, tremor at the onset, truncal instability, difficulties with speech, walking, fine motor skills, swallowing, and vision and cognitive deficits. An expansion mutation in PPP2R2B may influence and alter PP2A activity, implicated in multiple cellular functions.

Method: Blood sample were collected from SCA12 patients. Clinical examination, neuroimaging, and sample collection for the study was carried out after informed consent. The PBMC isolation after collection by density gradient separation technique and cryopreserved. iPSCs have been generated using standard published protocols, expanded and characterized for pluripotent markers/tested for genetic abnormalities. All newly reprogrammed iPSCs lines confirmed to have normal karyotypes and pass a battery of characterization tests.  iPSCs are first patterned towards forebrain Neural Stem Cells (NSCs) and further differentiated into neurons.

Results: Human iPSC were successfully reprogrammed using a least invasive method -peripheral blood and cryopreserved for future HTS. Differentiation into progenitor cells and neurons was done and confirmed using immunophenotyping. Further analysis is ongoing. Our preliminary data reveals altered response to mGluR receptor agonist such as DHPG suggestive of increased susceptibility to glutamate toxicity and further cell death.

Conclusion: Availability of human SCA12 iPSC opens up access to specific cell types of the brain in a powerful and unprecedented manner. This allows analysis across scales from molecules to cells, tissue, organ and the organism. Cellular basis of cognitive symptoms in SCA12 patients can be followed up in parallel using this in vitro system. Preliminary results reveal that glutamate induced neurotoxicity and mGluR signalling maybe implicated in forebrain neuronal cell death in SCA12 patients. This paves the path forward for cell specific targeted drug discovery using human cells.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/ipsc-based-modeling-of-sca12-for-targeted-therapeutic-screening/