Restoration of visual responses following transplantation of intact retinal sheets in rd mice.
OBJECTIVE
To correlate the functional outcomes with histologic findings following transplantation of fetal retinal sheets in rd mice, and to investigate the mechanisms of visual function restoration.


METHODS
Twenty-one postnatal day 31-38 rd/rd (C3H/HeJ) mice were transplanted in one eye with retinal sheets (1.0 x 0.4 mm) obtained from embryonic day (E) 17 enhanced-green-fluorescent protein (eGFP) mice. Five mice underwent sham surgery without insertion of tissue. Four to five weeks after transplantation, visual responses to a light flash were recorded across the superior colliculus (SC) in seven eyes of seven transplanted mice that had clear corneas and lenses, and in all five sham surgery mice. Following the SC recording, the eyes were enucleated and processed for immunohistochemistry and examined using confocal microscopy.


RESULTS
In three out of the seven eyes (43%), positive responses were recorded in the SC in an area topographically corresponding to the placement of the transplant in the host retina. No responses were recorded in the untreated eyes of 5-week-old and 9-week-old rd/rd mice, and in the 9-week-old sham surgery mice. In contrast, visual responses were recorded over the entire SC in normal eyes. The response onset latencies of the 3 transplanted mice with responses were similar to those of normal control mice. The organization of the graft did not appear to correlate as expected with the electrophysiology results, as eyes with well-organized, laminated grafts showed no response whereas the three light-responsive eyes had rosetted or disorganized grafts. All three light-responsive eyes demonstrated much higher levels of recoverin immunoreactivity in the host retina overlying the graft compared with untreated age-matched rd/rd mice.


CONCLUSIONS
Restoration of the SC visual response does not appear to depend on a well-organized transplant in the rd mouse. Increased recoverin-staining in the host retina in light-responsive animals suggested that host cone rescue was the likely mechanism of vision restoration in this transplant model.
Arai
S
S
Doheny Retina Institute, Keck School of Medicine, University of Southern California, DEI 3610, 1450 San Pablo Street, Los Angeles 90033-3699, USA.
Thomas
B B
BB
Seiler
M J
MJ
Aramant
R B
RB
Qiu
G
G
Mui
C
C
de Juan
E
E
Sadda
S R
SR
D000818:Animals; D002135:Calcium-Binding Proteins / Q000032:analysis; D004396:Coloring Agents / Q000032:analysis; D005074:Evoked Potentials, Visual / Q000502:physiology; D005136:Eye Proteins / Q000032:analysis; D016332:Fetal Tissue Transplantation / Q000379:methods*; D007150:Immunohistochemistry / Q000379:methods; D008074:Lipoproteins / Q000032:analysis; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000502:physiology; D051603:Recoverin; D012160:Retina / Q000196:embryology / Q000637:transplantation*; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology; D012174:Retinitis Pigmentosa / Q000601:surgery; D012243:Rhodopsin / Q000032:analysis; D014796:Visual Perception / Q000502:physiology*
D002135:Calcium-Binding Proteins; D004396:Coloring Agents; D005136:Eye Proteins; D008074:Lipoproteins; C496732:Rcvrn protein, mouse; D051603:Recoverin; D012243:Rhodopsin