Infection of the non-transfected SH-SY5Y cells with α-syn short amyloid fibrils and sub-passing over time. (A) Cells were infected with recombinant human FLAG-α-syn short fibrils. Cells were cultured on coverslips for each passage (p0 to p6). The deposition of exogenous short amyloid fibrils FLAG-α-syn (red) was detected by anti-FLAG antibody. Human endogenous α-syn detected by anti-human α-syn (C-20)-R antibody (green). The nuclei were stained with DAPI (blue). Bar, 12 μm. On the right p4, p5, and p6 zoomed images. Corrected total cell fluorescence (CTCF) from immunofluorescence imaging shows the induction of endogenous α-syn in SH (neuroblastoma SH-SY5Y cell line) infected with human α-syn short amyloid fibrils during the passages (bottom panel). The analysis was performed on at least 150 cells, n = 3, ***p < 0.005. Values are mean ± SD. (B) PCR analyses directed to α-syn using the total RNA extracted from non-transfected SH-SY5Y cells. Mix, RT-, S. Mix: negative controls, pET11A: positive control, SH-SF p6: SH-SY5Y cells passaged six times after exposure to short amyloid fibrils, SH: SH-SY5Y cells not treated with short amyloid fibrils. α-Syn was detected after 25 cycles and did not show any significant difference in transcripts before and after infection with short amyloid fibrils of recombinant α-syn.