Transplantation of human fetal retinal pigment epithelium rescues photoreceptor cells from degeneration in the Royal College of Surgeons rat retina

Department of Neurobiology, University of Rochester School of Medicine, NY 14642, USA.
Investigative Ophthalmology &amp Visual Science (Impact Factor: 3.4). 02/1996; 37(1):204-11. DOI: 10.1097/00006982-199717050-00030
Source: PubMed


The Royal College of Surgeons (RCS) rat suffers from a well-characterized, early-onset, and relentless form of photoreceptor cell degeneration. It has been shown that allografts of retinal pigment epithelial cells from normal perinatal rats have rescue effects in this condition. In preparation for human application, the authors determined whether human fetal retinal pigment epithelium (RPE) grafts have a photoreceptor rescue effect in RCS dystrophic rat retinas.
Sheets of RPE from human fetal eyes (10 to 16 weeks gestational age) were isolated according to the authors' recently described method. Fragments of the RPE sheets were transplanted to the subretinal space within the superior hemisphere. Transplants were performed within the superior equatorial region of five dystrophic RCS rats, one eye per animal. A similar volume of vehicle was injected into the subretinal space of five age-matched control rats, again one eye per rat. All rats were immunosuppressed with daily injections of cyclosporine. Using light microscopy, photoreceptor cell nuclear profiles of superior equatorial (SE) and inferior equatorial (IE) regions of transplanted and sham-injected control animals were counted.
Four weeks after transplantation, a dramatic rescue effect was observed. Microscopically, presumptive donor RPE cells were seen as single pigmented cells and as cell clusters in the subretinal space. An outer nuclear layer three to four profiles thick was present in the area of the RPE transplant but was nearly absent in the rest of the retina, as well as in the retinas of control rats. The number of photoreceptor nuclear profiles per 100 microns was 34.7 +/- 2.2 (mean +/- SEM) in the SE region of transplanted rats and 3.5 +/- 1.4 in the same region of sham-injected rats. There were 3.0 +/- 1.0 photoreceptor nuclear profiles in the IE region of transplanted rats and 3.5 +/- 1.2 in the IE region of sham-injected eyes. No evidence of graft rejection was seen.
This study provides the first indication that transplanted human fetal RPE cells are able to rescue photoreceptor cells in a model of hereditary retinal degeneration.

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    • "This pathology is autologous to a human form of RP (Gal et al., 2000), and by virtue of the primary defect being in the RPE cells, it may serve as an analogous model of some aspects of AMD. A series of studies has shown that subretinal injections of cells obtained from a range of human and animal cell lines can limit rod and cone cell death in RCS rats (Arnhold et al., 2006; Gamm et al., 2007; Huang et al., 2006; Inoue et al., 2007; Lawrence et al., 2000, 2004; Lin, Fan, Sheedlo , Aschenbrenner, & Turner, 1996; Little et al., 1996; Lund et al., 2001; Lund, Wang, Klimanskaya, Holmes, & Ramos-Kelsey, 2006; Mizumoto, Mizumoto, Shatos, Klassen, & Young, 2003; Pinilla, Cuenca, Sauvé, Wang, & Lund, 2007; Rezai, Kohen, Wiedemann, & Heimann, 1997; Schraermeyer et al., 2001; Schraermeyer, Kociok, & Heimann, 1999; Seiler, Sagdullaev, Woch, Thomas, & Aramant, 2005; Thumann, Salz, Walter, & Johnen, 2009; Wang, Lu, & Lund, 2005; Wang, Lu, Wood, & Lund, 2005; Wojciechowski, Englund, Lundberg, Wictorin, & Warfvinge, 2002). Moreover, electrophysiological (Lund et al., 2001; Sauvé, Girman, Wang, Keegan, & Lund, 2002; Sauvé, Klassen, Whiteley, & Lund, 1998; Sauvé, Lu, & Lund, 2004) and psychophysical (McGill, Douglas, Lund, & Prusky, 2004; McGill, Lund, Douglas, Wang, Lu, & Prusky, 2004) assessments have shown that some level of visual function can be preserved in such treated animals. "
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    ABSTRACT: Royal College of Surgeon (RCS) rats undergo retinal degeneration due to the inability of retinal pigment epithelial (RPE) cells to phagocytose shed outer segments. We explored the effect of introducing Schwann cells to the subretinal space of RCS rats (before the onset of retinal degeneration), by relying on electroretinogram (ERG) recordings and correlative retinal morphology. Scotopic ERGs recorded from cell-injected eyes showed preserved amplitudes of mixed a-wave b-wave, rod b-waves, and cone b-waves over controls (sham-injected eyes); photopic b-wave amplitudes and critical flicker fusion were also improved. Normal retinal morphology was found in areas of retinas that had received cell injections. Since Schwann cells have no phagocytic properties, their therapeutic effect is best explained through a paracrine mechanism (secretion of factors that ensure photoreceptor survival).
    Vision research 07/2009; 49(16):2067-77. DOI:10.1016/j.visres.2009.05.014 · 1.82 Impact Factor
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    • "The RCS rat is used widely to study retinal degeneration and to develop experimental therapies directed at limiting the progress of photoreceptor loss (Eisenfeld et al., 1984; Sheedlo et al., 1989; Li & Turner, 1991; Lin et al., 1996; Little et al., 1996; LaVail, 2001; Lund et al., 2001, 2003; Vollrath et al., 2001). Most anatomical studies have focused on thickness of the outer nuclear layer as the index of the progress of degeneration and the effects of treatment. "
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    ABSTRACT: The Royal College of Surgeons (RCS) rat has a retinal pigment epithelial cell defect that causes progressive loss of photoreceptors. Although it is extensively used in retinal degeneration and repair studies, how photoreceptor degeneration affects retinal circuitry has not been fully explored. This study examined the changes in synaptic connectivity between photoreceptors and their target cells using immunocytochemistry and correlated these changes with retinal function using the electroretinogram (ERG). Immunostaining with bassoon and synaptophysin (as presynaptic markers) and metabotropic glutamate receptor (mGluR6, a postsynaptic marker for ON-bipolar dendrites) was already impaired at postnatal day (P) 21 and progressively lost with infrequent pairing of presynaptic and postsynaptic elements at P60. By P90 to P120, staining became increasingly patchy and was eventually restricted to sparsely and irregularly distributed foci in which the normal pairing of presynaptic and postsynaptic markers was lost. ERG results showed that mixed scotopic a-waves and b-waves were already reduced by P21 but not oscillatory potentials. While cone-driven responses (photopic b-wave) reached normal levels at P30, they were impaired by P60 but could still be recorded at P120, although with reduced amplitude; rod responses never reached normal amplitudes. Thus, only cone-driven activity attained normal levels, but declined rapidly thereafter. In conclusion, the synaptic markers associated with photoreceptors and processes of bipolar and horizontal cells show abnormalities prior to significant photoreceptor loss. These changes are paralleled with the deterioration of specific aspects of ERG responsiveness with age. Besides providing information on the effects of photoreceptor dysfunction and loss on connection patterns in the retina, the work addresses the more general issue of how disorder of input neurons affects downstream circuitry.
    European Journal of Neuroscience 10/2005; 22(5):1057-72. DOI:10.1111/j.1460-9568.2005.04300.x · 3.18 Impact Factor
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    • "There are numerous transplantation studies on rodents, which would improve and augment the initial clinical trials. Several groups showed encouraging results with the transplants of RPE cells in animal models of retinitis pigmentosa/ age related macular degeneration [2] [3] [4] [5] [6] [7] [8] [9]. There also have been a number of experimental studies on human volunteers, in which retinal pigment epithelium has been grafted into the eyes of patients with advanced agerelated macular degeneration [10] [11]. "
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    ABSTRACT: There is currently no effective treatment for the retinal disorders caused by retinal pigment epithelium (RPE) degeneration. Transplantation of allografts is the main strategy towards correction of this malady. Tissue engineering could offer hope and involve the use of biodegradable polymeric templates to replace diseased or lost RPE. In this study PHBV8 film was chosen as a temporary substrate for growing retinal pigment epithelium cells as an organized monolayer before their subretinal transplantation. The surface of the PHBV8 film was rendered hydrophilic by oxygen plasma treatment to increase the reattachment of D407 cells on the film surface. Power and duration was changed, from 50 W, 10 min to 100 W, 20 min during plasma treatment. The effect of these two parameters on surface hydrophilicity, morphology, topography, surface composition of PHBV8 thin films was studied using AFM, SEM, and phase contrast microscopy. The effect of changes in surface characteristics on cell reattachment, spreading and cell growth rate was investigated. It was found that as the treatment level was increased the surface hydrophilicity increased and roughness was decreased probably due to ablation. The PHBV8 film treated with 100 W 10 min was found to be the most suitable for 24 h reattachment of D407 cells. The cells were also grown to confluency as an organized monolayer suggesting PHBV8 film as a potential temporary substrate for subretinal transplantation to replace diseased or damaged retinal pigment epithelium.
    Biomaterials 12/2003; 24(25):4573-83. DOI:10.1016/S0142-9612(03)00302-8 · 8.56 Impact Factor
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