Figure 5.

Effect of MMF on photoreceptor structure at P22 in rd10 and rd1 mice. (A) Quantification of the average number of ONL cell body rows in rd10 and rd1 mice show progressive decline over P8-19 and P13-P35, respectively. Wild-type c57 mice had stable ONL cell body counts at P22 and P35. Compared with naïve animals, treatment with MMF beginning at P8 (MMFP8) in rd1 mice or P12 (MMFP12) in rd10 mice showed significant preservation of ONL cell body rows at P15 (n = 8 and 3, P < 0.0001) and P22 (n = 11 and 7, P < 0.0001), respectively. However, there was no difference between MMFP12-treated and naïve rd10 mice at P27 (n = 6 and 4, P = 0.44) or P35 (n = 3 and 3, P = 0.97). (B) IHC at P22 of MMFP12-treated rd10 mice showed normal appearance of photoreceptor structure similar to c57 naïve mice as visualized with DAPI stain and immunolabeling for visual arrestin 1:50 (red) and cone arrestin 1:30,000 (white). Naïve rd10 mice had severely thinned ONL layer and disorganized cone and rod outer segments. A spider plot of the average number of ONL cell body rows, quantified by DAPI staining, per degrees of horizontal eccentricity from the optic nerve showed that MMFP12-treated rd10 mice (n = 10) had significantly greater ONL rows than naïve rd10 mice (n = 11) at −70° (P = 0.02), −50° (P = 0.02), −30° (P = 0.05), −10° (P = 0.02), +10° (P = 0.005), +30° (P = 0.002), +50° (P = 0.02), and +70 degrees (P = 0.01). There was no difference in ONL cell body rows between MMFP12-treated rd10 mice, MMFP12-treated c57 mice (n = 5), or naïve c57 mice (n = 4). (C) Cone arrestin 1:1000 whole retinal flat mount IHC also showed that MMFP12-treated rd10 mice had normal-appearing cone tips as compared with degenerated shortened cone tips in naïve rd10 mice. The rd10 mice treated with MMFP12 (n = 4) had significantly greater cone tip counts than naïve rd10 mice (n = 4), P < 0.0001), but still less than that of c57 mice (n = 4, P = 0.03). INL, inner nuclear layer; ns, non-significant; ^*P ≤ 0.05.