Fig 1: The 2A7 antibody detects aSyn expression in neural precursors and neurons. (A) The 2A7 antibody detects higher aSyn protein levels in neurons (TUBB3+) compared to non-neuronal cells (TUBB3-) in hiPSC-derived cortical organoids. Left: Histograms of intracellular aSyn staining of hiPSC-derived cortical organoid cells. Right: Comparison of mean fluorescence intensities (MFI) of intracellular aSyn staining in TUBB3+ and TUBB3- organoid cells. Error bars represent standard deviations. Four independent staining experiments were performed. (B) Intracellular aSyn staining with the 2A7 antibody in the midbrain and cortical neural precursor cells (NPCs) revealed a more robust detection of an aSyn protein increase in NPC from patients with Parkinson's disease having SNCA locus duplication (Dupl 1, 2, and 3 lines) compared to control NPC (Ctrl 1 and 2 lines). Histograms (“midbrain NPCs” and “cortical NPCs”) and quantified mean fluorescence intensities (MFI, right to each histogram) are shown. Normalized MFI values for each staining were calculated as a difference between MFI of antibody staining and of isotype control staining (Iso). (C) The 2A7 antibody detects a significant increase of aSyn expression in hiPSC-derived midbrain dopaminergic neurons from SNCA locus duplication in patients with Parkinson's disease (SNCA dupl) compared to control (ctrl) using immunocytochemistry. Left: Representative images of ctrl (Ctrl 1 line) and SNCA dupl hiPSC-derived (Dupl 1 line) midbrain dopaminergic neurons stained for aSyn (green) with 2A7 antibody, tubulin ß3 (Tuj 1; white), and DAPI (blue). Right: Quantification of mean gray values of the 2A7 aSyn staining of ctrl and SNCA dupl midbrain dopaminergic neurons. Error bars represent standard deviations. Five independent measurements were performed. **p < 0.01, one-way ANOVA.