Figure 7.

Ultrastructural analysis of patient-derived iNs. (A–D) Representative electron micrographs showing somata and proximal dendrites of two iPSC-derived controls (Ctrls 1 and 18; A and C), and Patient 1 (B) and Patient 18 (D) iNs (highlighted in red). [A(i and ii) and C(i and ii)] High magnification images of the boxed regions in A and C, respectively. Asterisks indicate lysosomes in control iNs. [B(i and ii) and D(i and ii)] High magnification images of the boxed regions in B and D, respectively. Note the abundance of lysomes in Patient 1 (B) and Patient 18 (D) iN somata compared to control iNs. Asterisks indicate lysosomes with dense concentric lamellae, a number sign (#) points to irregular shaped lysosomes filled with heterogeneous material and lipid droplets, and arrows point to small round-shaped lysosomes filled with electron-dense material. (E) Large lysosome in a control iN. Note the homogenous and round structure of the organelle. (F) Lysosomes (Lys) in the iN soma of Patient 1. (G) Lysosomes with heterogeneous material and lipid droplets in the iN soma of Patient 18. Note the irregular shape of lysosomes filled with concentric lamellae. (H, left) Lysosomal areas in iNs from four control subjects [n = 2 independent iPSC-derived iN subclones for Ctrl 1 (-c1/c2) and Ctrl 18 (-c1/c2) and one subclone from two independent hESC-derived iNs (ESC_Ctrl 1 and 2)] and two patients [n = 2 independent iPSC-derived iN subclones per each subject (Patient 1−c1/c2 and Patient 18-c1/c2)]. Data are presented as medians with 95% confidence intervals (CIs). (H, right) Pooled area of lysosomes for control and patient samples (n_control = 2429 lysosomes from six samples; n_patient = 2918 lysosomes from four samples; P < 0.001, Mann–Whitney’s U-test). Data are presented as medians with 95% CIs. (I, left) Density of lysosomes in iNs from four control subjects [n = 2 independent iPSC-derived iN subclones for Ctrl 1 (-c1/c2) and Ctrl 18 (-c1/c2) and one subclone from two independent hESC-derived iNs (ESC_Ctrl 1-c1 and ESC_Ctrl 2-c1) and two patients (n = 2 independent iPSC-derived iN subclones per each subject (Patient 1-c1/c2 and Patient 18-c1/c2)]. Data are presented as medians with 95% CIs. (I, right) Pooled densities of lysosomes in control and patient samples (n_control = 58 cells from six samples; n_patient = 29 cells from four samples; P = 0.702, Mann–Whitney’s U-test). Data are presented as medians with 95% CIs. Lys = lysosome, Ctrl = control; Pat = patient; ns = not significant, *** P < 0.001. Scale bars = 5 µm (A–D), 500 nm (Ai–Di, Aii–Dii, G), 200 nm (E and F).