Figure 6. Sema4A gene transfer prevents photoreceptor degeneration in the retinas of Sema4A^−/− and Sema4A^F350C/F350C mice.

(a) Schematic diagram of the protocol: At 1 week of age, suspensions of lentiviral vectors expressing Sema4A^WT-FLAG or Sema4A^F350C-FLAG were injected into the subretinal space of Sema4A^−/− or Sema4A^F350C/F350C infant mice. Viral suspensions were injected into the right eye, while the left eye was used as a negative control (only eyelids were incised). At 4 weeks of age, their eye tissues were fixed and sectioned. (b) (Top) Haematoxylin and eosin (HE) staining of the retinal sections from each mouse. Scale bar, 50 μm. (Bottom) The serial sections from those of HE staining were examined by immunohistochemistry (IHC) using an anti-FLAG antibody. Scale bar, 50 μm. (c) Histogram showing the average number of photoreceptor cells (±s.e.m.; n=9–18) in retinas. *P<0.01 (Student’s t-test); NS, not significant. The number of row of photoreceptor cells was counted at three random points per retinal section in which Sema4A^WT-FLAG or Sema4A^F350C-FLAG was expressed in immunohistochemistry using an anti-FLAG antibody. (d) ERG responses to single flashes were recorded using Sema4A^−/− or Sema4A^F350C/F350C mice after Sema4A gene transfer. A suspension of lentiviral vectors expressing Sema4A^WT-FLAG was injected into the retinas of Sema4A^−/− or Sema4A^F350C/F350C mice at 1 week of age, and ERGs were recorded at 4 weeks of age. Viral suspensions were injected into the right eye, while the left eye was used as a negative control (only eyelids were incised).