Fig. 1

The differentiation of BCAS1(+) cells was affected by p-α-syn-immunoreactive inclusions in the frontal cortices of MSA brains. a Serial sections of brain tissues from the frontal cortices of an aged non-neurodegenerative disease control (upper) and an MSA patient (lower) which were immunostained with antibodies against BCAS1, MBP, p-α-syn, and NeuN. Scale bar = 100 μm. The regions marked by dotted squares are magnified in the right upper corners. The magnified images of BCAS1 staining show altered morphology of BCAS1(+) cells in the MSA case. Images of control and MSA cases are provided from case 21 and case 2 (Additional file 1: Table S1), respectively. b, e Quantification of BCAS1(+) cell counts (b), MBP(+) cell counts (c), p-α-syn(+) area (d), and NeuN(+) cell counts (e) in control and MSA brains. Mean ± SEM; control, N = 6, MSA, N = 9; Mann–Whitney, p** < 0.01, p*** < 0.001. f Illustration of oligodendroglial differentiation showing the morphological classification of early-stage and late-stage BCAS1(+) cells. g Immunostaining of an aged non-neurodegenerative disease control (case 21, Additional file 1: Table S1) with the anti-BCAS1 antibody showing representative images of early-stage (a, b) and late-stage (c, d) BCAS1(+) cells in the frontal cortex. Scale bar = 500 μm (low-power field, left) and 20 μm (high-power field, right). (H) Immunostaining of the serial sections from the frontal cortices of two different MSA cases (cases 1 and 2, Additional file 1: Table S1) showing the morphological variety of BCAS1(+) cells and their association with the density of the p-α-syn(+) area. Black arrowheads indicate late-stage BCAS1(+) cells, whereas white arrowheads indicate early-stage BCAS1(+) cells. Case 1 with sparse cortical p-α-syn pathology shows multi-processed mature BCAS1(+) cells. In contrast, case 2 with notable p-α-syn pathology shows round BCAS1(+) cells with few processes. Scale bar = 100 μm (low-power field, left and middle) and 20 μm (high-power field, right). (I) Linear regression analysis showing a negative correlation between the number of late-stage BCAS1(+) cells and the density of p-α-syn(+) in the frontal cortices of MSA patients (N = 9, Spearman r = − 0.8000, p = 0.0138)