Fig. 6

Synapse formation between engrafted eye-wall c-kit⁺/SSEA1⁻ cell-derived photoreceptors and the bipolar cells of rd1 mice. Representative images of rd1 mice injected with c-kit⁺/SSEA1⁻ cells at 4 weeks (C, F) and 8 weeks (L, N) after transplantation and of age-matched control mice including wild-type (WT) mice (A, D) and rd1 mice injected with phosphate-buffered saline (PBS; B, E, K, M). WT mice expressed synaptophysin (Syn) and postsynaptic density-95 (PSD-95) in the OPL (D); the PBS control group showed much lower levels of these proteins (B, E, 4 weeks; K, M, 8 weeks). Syn-immunoreactive puncta were observed on the cell membrane of engrafted c-kit⁺/SSEA1⁻ cells at 4 weeks (C) and 8 weeks (L) post transplantation. PSD-95-positive postsynaptic terminals contacted incorporated donor cell-derived photoreceptors at 4 weeks (F) and 8 weeks (N) post transplantation. Representative western blot bands of Syn versus β-actin (G) and PSD-95 versus β-actin (H) at 4 weeks after transplantation. The blots were then quantitated for expression of Syn (I) and PSD-95 (J), corrected for β-actin, and plotted as the mean expression ± SD (n = 3 for each time point, *P < 0.05). DAPI 4′,6-diamidino-2-phenylindole, ONL outer nuclear layer, INL inner nuclear layer, GCL ganglion cell layer, QD quantum nanocrystal dot. Scale bars represent 10 μm (A1–A3, B1–B3, C1–C4, D1–D3, E1–E3, F1–F4, K1–K3, L1–L3, M1–M3, N1–N3) and 20 μm (A–F, K–N) (Color figure online)