title: Retinal transplants restore visual responses: trans-synaptic tracing from visually responsive sites labels transplant neurons.
abstract: This study aimed to test the hypothesis that visual responses in the superior colliculus (SC) originate from synaptic connections between fetal retinal transplants and degenerating host retinas. Sheets of embryonic day 19 rat retina expressing human placental alkaline phosphatase were transplanted to the subretinal space of 3- to 4-week-old S334ter-line-3 rats with fast retinal degeneration. Several months later, visual responses were recorded from the SC. Attenuated pseudorabies virus that is specifically transferred between neurons at synapses (strains PRV-152, expressing green fluorescent protein (GFP) or BaBlu, expressing Escherichia colibeta-galactosidase) was injected into the visually responsive site of the SC. After survival times of 1-2 days, the virus was detected in the retina by immunohistochemistry in combination with different retinal cell markers, such as protein kinase C, recoverin, calcium-calmodulin-dependent protein kinase II and glutamine synthetase. Transplanted rats had a mean response threshold of -3.1 log cd/m(2) in a small area of the SC corresponding to the location of the graft in the retina. By 30 h after injection into this SC area, the virus traced back to host ganglion cells overlying the transplant and in close proximity to the transplant. By 2 days after injection, extensive virus label was found in the host retina and many cells in the transplant were also labeled. Virus-labeled cells in the transplant were double labeled for neuronal and glial cell markers. This study provides anatomical evidence that synaptic connections between fetal retinal transplants and host retinas contribute to the visual responses in the SC.
authors.affiliation: Ophthalmology-USC, Doheny Eye Institute, 1355 San Pablo Street, DVRC 402, Los Angeles, CA 90033, USA.
authors.forename: Magdalene J
authors.initials: MJ
authors.lastname: Seiler
authors.forename: Biju B
authors.initials: BB
authors.lastname: Thomas
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Chen
authors.forename: Rongjuan
authors.initials: R
authors.lastname: Wu
authors.forename: Srinivas R
authors.initials: SR
authors.lastname: Sadda
authors.forename: Robert B
authors.initials: RB
authors.lastname: Aramant
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D015415:Biomarkers / Q000378:metabolism; D016332:Fetal Tissue Transplantation; D011558:Herpesvirus 1, Suid / Q000378:metabolism; D006801:Humans; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D051381:Rats; D012160:Retina / Q000166:cytology / Q000378:metabolism / Q000637:transplantation*; D013194:Staining and Labeling; D013477:Superior Colliculi / Q000378:metabolism; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D014785:Vision, Ocular / Q000502:physiology*; D014795:Visual Pathways / Q000033:anatomy & histology*; D014796:Visual Perception / Q000502:physiology
chemical_list: D015415:Biomarkers