Abstract
Purpose: :
CFH-deficient (cfh-/-) mice exhibit significantly increased levels of C3 and C3b deposition around Bruch's membrane and reduced visual acuity compared with age-matched controls. We tested to what extent AAV-mediated CFH gene therapy would reduce or halt the progression of the cfh-/- eye phenotype and if it would reduce the effects of experimentally induced CNV in the wild-type retina.
Methods: :
AAV2/7-EGFP vector was delivered subretinally to determine dose selection and transduction efficiency. 1 µl of AAV2/7-CFH vector was delivered subretinally into young (prophylactic) and aged (therapeutic) cfh-/- mice and age-matched controls. 1 µl of AAV2/7-CFH vector was also delivered to CNVinduced wild-type mice (preventive treatment). Treated cfh-/- and control eyes were harvested for histochemical analysis at 1,4 and 8 months after intervention, and treated CNV-induced eyes were imaged in vivo using fluorescein angiography 10 days after photocoagulation, followed by histochemical processing.
Results: :
Immunohistochemistry showed consistent CFH expression in the outer segments and RPE and reduced deposition of C3 and C3b in treated eyes of cfh-/- mice at all time points after intervention. Prophylactic treatment exhibited significant reductions of C3 and C3b deposition, while the therapeutic effect on reversal or halting of the progression of the cfh-/- eye phenotype in aged CFH-deficient mice was less pronounced. Fluorescein angiography showed significant reduction of leakage. Immunohistochemical analysis revealed C3b and MAC related C5 expression colocalized with RPE melanin pigmentation around CNV lesions in un-treated retinae, while C3 and C3b deposition and lesion size was significantly reduced in photocoagulated retinae with preventive AAV-CFH treatment.
Conclusions: :
AAV-mediated delivery of the CFH gene to the subretinal space of cfh-/- mice improved on some of the characteristic pathological features associated with the disease phenotype in this mouse model of retinal degeneration. In particular, it significantly reduced deposition of uncleaved and active forms of C3 around Bruch's membrane in the CFH-deficient mouse model thus restoring control of the alternative pathway activation. It also significantly reduced the effects of experimentally induced CNV in the wild-type mouse.
Keywords: gene transfer/gene therapy • retinal pigment epithelium • retinal degenerations: hereditary