Figure 9: Transplantation of Cre+ photoreceptor precursors leads to widespread expression of floxed reporters in host cells.

(a), box (25–75% percentile) and whiskers (_min/max) plot showing median (line) number of reporter-labelled photoreceptors in adult dTomatofloxed host retinae following transplantation. **P<0.01 2-way ANOVA. N.B. all controls (uninjected, PBS-injected and final wash) were highly significantly different from both Cre⁺/GFP⁺ and TdTom⁺ populations but are not denoted on graph for clarity). (b–d), confocal projection images showing retinal sections after sub-retinal injection of (b) ShH10.CMV.iCre (5 × 10¹² viral particles per ml⁻¹), (c) uninjected, (d) PBS-injected, or (e) mice injected with final wash from cell preparation. (f), confocal projection images of GFP⁺ (green) and tdTomato⁺ (red) cells within the floxed tdTomato host retinae following transplantation of Crx.GFP⁺/Cre⁺ donor cells. Note that there are significantly higher numbers of tdTomato⁺ cells than GFP⁺ cells. Inset, example of a GFP⁺, tdTomato⁺ cells, surrounded by GFP⁻/tdTomato⁺ cells. (g), Immunostaining for CRE (grey) shows robust protein expression in donor cells in SRS and some weaker expression in reporter-labelled cells within host retina. (h), some cells in the SRS cell mass were tdTomato⁺ (arrow), indicating the potential for bidirectional material transfer. For panels (f) and (g), images from top to bottom show individual and/or combined channels for the same region of interest. (i), tdTomato⁺ cells were present in areas where donor cell masses were present but no GFP⁺ cells within the underlying host ONL. (j), few, if any, GFP⁺ or tdTomato⁺ cells were seen in retinae where donor cell mass had been rejected (N=2 retinae). Scale bars 10 μm.