An Isogenic Collection of Pluripotent Stem Cell Lines With Elevated alpha-Synuclein Expression Validated for Neural Induction and Cortical Neuron Differentiation

alpha-Synuclein (alpha Syn) is a small, disordered protein that becomes aggregated in Lewy body diseases, such as Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Human induced pluripotent stem cells (hiPSCs) potentially provide a tractable disease model to monitor early molecular changes associated with PD/DLB. We and others have previously derived hiPSC lines from patients with duplication and triplication of the SNCA gene, encoding for alpha Syn. It is now recognised that to perform meaningful disease modelling with these hiPSC lines, it is critical to generate isogenic control cell lines that lack the disease causing mutations. In order to complement the existing and emerging hiPSC models for PD/DLB, we have generated an allelic series of alpha Syn over-expressing hESC lines on the same isogenic background. An unresolved question is whether pluripotent stem cell lines, with elevated levels of alpha Syn, can undergo efficient differentiation into dopaminergic and cortical neurons to model PD and DLB, respectively. We took advantage of our isogenic collection of hESC lines to determine if increased expression of alpha Syn affects neural induction and neuronal differentiation. Clonal hESC lines with significantly different levels of alpha Syn expression proliferated normally and maintained expression of pluripotent markers, such as OCT4. All cell lines efficiently produced PAX6(+) neuroectoderm and there was no correlation between alpha Syn expression and neural induction efficiency. Finally, global transcriptomic analysis of cortical differentiation of hESC lines with low or high levels of alpha Syn expression demonstrated robust and similar induction of cortical neuronal expression profiles. Gene expression differences observed were unrelated to neural induction and neuronal differentiation. We conclude that elevated expression of alpha Syn in human pluripotent stem cells does not adversely affect their neuronal differentiation potential and that collections of isogenic cell lines with differing levels of alpha Syn expression are valid and suitable models to investigate synucleinopathies.