Photoreceptor Differentiation following Transplantation of Allogeneic Retinal Progenitor Cells to the Dystrophic Rhodopsin Pro347Leu Transgenic Pig
Figure 6
Expression of ROM-1 within rosettes of the graft. Recipient was 6 weeks of age at time of transplantation and experiment terminated 5 weeks later. Immunohistochemical labeling for rod outer segment marker-1. Panels in the left column of Figures (a, d, g) show endogenous GFP transgene expression (green) of donor cells, panels in the central column (b, e, h) show ROM-1 expression (red), and panels in the right column (c, f, i) show the merged images comprised of the 2 preceding panels of the same row. (a) The widespread GFP expression within the graft is periodically interrupted by rounded lacunae (arrows), where (b) ROM-1 labeling can be found. Merged image (c) shows that regions of ROM-1 labeling are encircled by inwardly directed straight processes, thereby indicating that ROM-1 corresponds to the core region of the rosettes, which is the predicted location for rod outer segments in this type of structure. These findings are corroborated by examination of another rosette (d) in which there is a greater number of GFP+ cells with photoreceptor morphology, the processes of which are directed inward toward a small central core. (e) ROM-1 labeling (arrows) predominantly localizes to the core region of the rosette. (g–i) Examination of the same rosette at higher power allows visualization of the limit of GFP expression (arrows) within some of the processes of donor-derived photoreceptor-like cells, in juxtaposition to the adjacent localization of ROM-1 labeling.
