Fig. 7

Transplantation of human iPSC-RPE cells into murine eyes. a–h Injection of pigmented human iPSC-RPE cells into the subretinal space of albino mouse eyes. In the examples illustrated, injections were performed at P14. a Posterior segment of a whole eye, 28 days after injection, showing evidence of pigment. b–d Thick retinal cryosection, 28 days after injection, labeled with anti-RHO (b) and phalloidin (c), shown under phase contrast (d). e Merge of RHO and actin labeling, together with phase contrast imaging. RHO labels ROSs, as well as phagosomes in the RPE (yellow arrows in b; inner retina is lower left). Phalloidin labeling of f-actin delineates the apical RPE. Pigmentation in the RPE cells is evident by the phase-contrast imaging. Pigmented RPE cells are therefore evident in the RPE layer, adjacent to the labeled ROSs, and contain ROS phagosomes. f–h Retinal semi-thin sections from a P40 noninjected albino mouse (control) (f), and from albino mice fixed 28 days (g) or 205 days (h) after injection. Boxed regions in the lower panels are shown at higher magnification in the upper panels. iPSC-RPE cells are identifiable by the presence of melanosomes in the apical processes (red arrows in g), adjacent to the tips of the POSs, in addition to the cell body. Pigmented iPSC-RPE cells (red arrows in h) remain integrated in the retina, 200 days post injection. i–k Injection of pigmented human iPSC-RPE cells into the subretinal space of Mertk ^–/– mouse eyes. In the examples illustrated, injections were performed at P10, and retinas were examined 27 days after injection, at P37. i Fluorescence micrograph of retinal section labeled with anti-RHO (green) and phalloidin (red). Nuclei were counterstained with DAPI. Yellow arrows in an enlarged region (upper) indicate RHO-positive phagosomes in transplanted iPSC-RPE cells. j Micrograph of toluidine blue-stained semi-thin section (yellow arrows indicate ROS phagosomes). k Quantification of photoreceptor nuclei in semi-thin sections of the central retina. For the data illustrated, injections were made with PBS (control) or iPSC-RPE cells (p = 0.0001) at P10, and sections were obtained 27 days later, at P37. For reference, the central region of a 1–2-month-old WT retina contains ~ 10 rows of photoreceptor nuclei (e.g., f). Scale bars: b–e, 5 μm; f–h, 20 μm; i, j, 10 μm. iPSC induced pluripotent stem cell, ONL outer nuclear layer, POS photoreceptor (rod and cone) outer segment, RHO rhodopsin, RPE retinal pigment epithelium