title: Large-scale reconstitution of a retina-to-brain pathway in adult rats using gene therapy and bridging grafts: An anatomical and behavioral analysis.
abstract: Peripheral nerve (PN) grafts can be used to bridge tissue defects in the CNS. Using a PN-to-optic nerve (ON) graft model, we combined gene therapy with pharmacotherapy to promote the long-distance regeneration of injured adult retinal ganglion cells (RGCs). Autologous sciatic nerve was sutured onto the transected ON and the distal end immediately inserted into contralateral superior colliculus (SC). Control rats received intraocular injections of saline or adeno-associated virus (AAV) encoding GFP. In experimental groups, three bi-cistronic AAV vectors encoding ciliary neurotrophic factor (CNTF) were injected into different regions of the grafted eye. Each vector encoded a different fluorescent reporter to assess retinotopic order in the regenerate projection. To encourage sprouting/synaptogenesis, after 6 weeks some AAV-CNTF injected rats received an intravitreal injection of recombinant brain-derived neurotrophic factor (rBDNF) or AAV-BDNF. Four months after surgery, cholera toxin B was used to visualize regenerate RGC axons. RGC viability and axonal regrowth into SC were significantly greater in AAV-CNTF groups. In some cases, near the insertion site, regenerate axonal density resembled retinal terminal densities seen in normal SC. Complex arbors were seen in superficial but not deep SC layers and many terminals were immunopositive for presynaptic proteins vGlut2 and SV2. There was improvement in visual function via the grafted eye with significantly greater pupillary constriction in both AAV-CNTF+BDNF groups. In both control and AAV-CNTF+rBDNF groups the extent of light avoidance correlated with the maximal distance of axonal penetration into superficial SC. Despite the robust regrowth of RGC axons back into the SC, axons originating from different parts of the retina were intermixed at the PN graft/host SC interface, indicating that there remained a lack of order in this extensive regenerate projection.
authors.affiliation: Department of Ophthalmology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.
authors.forename: Si-Wei
authors.initials: SW
authors.lastname: You
authors.affiliation: Laboratory for Transplantation and Regenerative Medicine, Dept. of Obstetrics and Gynecology, Sahlgrenska Academy, University of Gothenburg, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Hellström
authors.affiliation: School of Anatomy, Physiology and Human Biology, The University of Western Australia, Australia.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Pollett
authors.affiliation: School of Anatomy, Physiology and Human Biology, The University of Western Australia, Australia.
authors.forename: Chrisna
authors.initials: C
authors.lastname: LeVaillant
authors.affiliation: School of Anatomy, Physiology and Human Biology, The University of Western Australia, Australia.
authors.forename: Colette
authors.initials: C
authors.lastname: Moses
authors.affiliation: Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Australia.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Rigby
authors.affiliation: School of Animal Biology, The University of Western Australia, Australia.
authors.forename: Marissa
authors.initials: M
authors.lastname: Penrose
authors.affiliation: School of Animal Biology, The University of Western Australia, Australia; Western Australian Neuroscience Research Institute, Australia.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Rodger
authors.affiliation: School of Anatomy, Physiology and Human Biology, The University of Western Australia, Australia; Western Australian Neuroscience Research Institute, Australia. Electronic address: alan.harvey@uwa.edu.au.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Harvey
mesh_terms: D000818:Animals; D001369:Axons / Q000187:drug effects; D001522:Behavior, Animal; D001921:Brain / Q000033:anatomy & histology*; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology; D020934:Ciliary Neurotrophic Factor / Q000378:metabolism; D005260:Female; D015316:Genetic Therapy; D055495:Neurogenesis / Q000187:drug effects; D017120:Nystagmus, Optokinetic / Q000187:drug effects; D009900:Optic Nerve / Q000637:transplantation; D010525:Peripheral Nerves / Q000637:transplantation*; D051381:Rats; D012025:Reflex, Pupillary / Q000187:drug effects; D012160:Retina / Q000033:anatomy & histology*; D012165:Retinal Ganglion Cells / Q000187:drug effects; D012584:Sciatic Nerve / Q000637:transplantation; D014785:Vision, Ocular / Q000187:drug effects; D014795:Visual Pathways / Q000033:anatomy & histology*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D020934:Ciliary Neurotrophic Factor
keywords: Adult rat visual system; Axonal regeneration; Gene therapy; Neurotrophic factors; Peripheral nerve transplantation; Retinal ganglion cells; Superior colliculus