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Protection of visual functions by human neural progenitors in a rat model of retinal disease.

Gamm DM, Wang S, Lu B, Girman S, Holmes T, Bischoff N, Shearer RL, Sauvé Y, Capowski E, Svendsen CN, Lund RD - PLoS ONE (2007)

Bottom Line: Principal outcomes were quantified using electroretinography, visual acuity measurements and luminance threshold recordings from the superior colliculus.Functional efficacy was further enhanced when hNPC were genetically engineered to secrete glial cell line-derived neurotrophic factor.A concomitant preservation of host cone photoreceptors was also observed.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States of America. dgamm@wisc.edu

ABSTRACT

Background: A promising clinical application for stem and progenitor cell transplantation is in rescue therapy for degenerative diseases. This strategy seeks to preserve rather than restore host tissue function by taking advantage of unique properties often displayed by these versatile cells. In studies using different neurodegenerative disease models, transplanted human neural progenitor cells (hNPC) protected dying host neurons within both the brain and spinal cord. Based on these reports, we explored the potential of hNPC transplantation to rescue visual function in an animal model of retinal degeneration, the Royal College of Surgeons rat.

Methodology/principal findings: Animals received unilateral subretinal injections of hNPC or medium alone at an age preceding major photoreceptor loss. Principal outcomes were quantified using electroretinography, visual acuity measurements and luminance threshold recordings from the superior colliculus. At 90-100 days postnatal, a time point when untreated rats exhibit little or no retinal or visual function, hNPC-treated eyes retained substantial retinal electrical activity and visual field with near-normal visual acuity. Functional efficacy was further enhanced when hNPC were genetically engineered to secrete glial cell line-derived neurotrophic factor. Histological examination at 150 days postnatal showed hNPC had formed a nearly continuous pigmented layer between the neural retina and retinal pigment epithelium, as well as distributed within the inner retina. A concomitant preservation of host cone photoreceptors was also observed.

Conclusions/significance: Wild type and genetically modified human neural progenitor cells survive for prolonged periods, migrate extensively, secrete growth factors and rescue visual functions following subretinal transplantation in the Royal College of Surgeons rat. These results underscore the potential therapeutic utility of hNPC in the treatment of retinal degenerative diseases and suggest potential mechanisms underlying their effect in vivo.

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The capacity of human neural progenitors to preserve retinal function is augmented by GDNF expression. ERG response amplitudes to full field light stimulation were recorded at approximately P100 in RCS rats injected with hNPCctx–GDNF (n = 9), hNPCctx (n = 21) or medium alone (n = 3) into the subretinal space. Individual components of the ERG waveform (a-wave, composite b-wave, cone b-wave and rod b-wave) reveal relative contributions of different retinal cells to the overall functional activity of the retina. Cone b-waves were delineated by a double flash protocol and the rod-attributable b-wave was derived by subtraction from the composite level. Eyes injected with hNPCctx–GDNF demonstrated significantly greater a-wave and cone b-wave amplitudes than those receiving hNPCctx (*p<0.05; **p<0.01; Student's unpaired t-test). In contrast, the composite b-wave and rod b-wave amplitudes were not statistically different between the two groups. Control eyes injected with medium alone (sham-operated eyes) had no recordable ERG waves and are not included in the graph. Data are expressed as mean ± SEM.
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pone-0000338-g002: The capacity of human neural progenitors to preserve retinal function is augmented by GDNF expression. ERG response amplitudes to full field light stimulation were recorded at approximately P100 in RCS rats injected with hNPCctx–GDNF (n = 9), hNPCctx (n = 21) or medium alone (n = 3) into the subretinal space. Individual components of the ERG waveform (a-wave, composite b-wave, cone b-wave and rod b-wave) reveal relative contributions of different retinal cells to the overall functional activity of the retina. Cone b-waves were delineated by a double flash protocol and the rod-attributable b-wave was derived by subtraction from the composite level. Eyes injected with hNPCctx–GDNF demonstrated significantly greater a-wave and cone b-wave amplitudes than those receiving hNPCctx (*p<0.05; **p<0.01; Student's unpaired t-test). In contrast, the composite b-wave and rod b-wave amplitudes were not statistically different between the two groups. Control eyes injected with medium alone (sham-operated eyes) had no recordable ERG waves and are not included in the graph. Data are expressed as mean ± SEM.

Mentions: RCS rats received unilateral subretinal injections of hNPCctx, hNPCctx-GDNF or medium alone (sham) at P21. Fellow, untreated eyes served as internal controls for each animal. The first test performed was ERG, which provides a gross measure of retinal function and an indication of relative rod and cone efficacy. In the scotopic-adapted RCS rat, the ERG a-wave (indicative mainly of rod activity) disappears by P60, while the composite b-wave (comprising rod and cone activity) is largely lost around P100 [39]. At approximately P100, eyes receiving either hNPCctx (n = 21) or hNPCctx-GDNF (n = 9) injections retained robust ERG responses (Figure 2). In contrast, sham-treated eyes (n = 3) had no measurable ERG responses at this age. Further comparison of eyes injected with hNPCctx-GDNF or hNPCctx revealed significantly greater a-wave and cone b-wave amplitudes in the GDNF-secreting group (a-wave: 164.3±63.7 µv vs. 35.2±6.2 µv (p<0.05); cone b-wave: 195.4±38.1 µv vs. 77.7±10.6 µv (p<0.01), respectively). For perspective, non-dystrophic rats yielded a-wave and cone b-wave responses of 279±172 µv and 357±183 µv, respectively. Thus, eyes grafted with hNPCctx-GDNF retained ERG activity at approximately 58.8% (a-wave) and 54.6% (cone b-wave) of the level of normal, non-dystrophic animals. Composite b-wave and rod b-wave amplitudes were also well-preserved in the cell-injected eyes, but no significant difference was observed between the hNPCctx-GDNF and hNPCctx groups (composite b-wave: 244.9±45.3 µv vs. 156.4±18.7 µv (p = 0.12); rod b-wave: 57.6±34.5 µv vs. 78.7±10.5 µv (p = 0.84), respectively).


Protection of visual functions by human neural progenitors in a rat model of retinal disease.

Gamm DM, Wang S, Lu B, Girman S, Holmes T, Bischoff N, Shearer RL, Sauvé Y, Capowski E, Svendsen CN, Lund RD - PLoS ONE (2007)

The capacity of human neural progenitors to preserve retinal function is augmented by GDNF expression. ERG response amplitudes to full field light stimulation were recorded at approximately P100 in RCS rats injected with hNPCctx–GDNF (n = 9), hNPCctx (n = 21) or medium alone (n = 3) into the subretinal space. Individual components of the ERG waveform (a-wave, composite b-wave, cone b-wave and rod b-wave) reveal relative contributions of different retinal cells to the overall functional activity of the retina. Cone b-waves were delineated by a double flash protocol and the rod-attributable b-wave was derived by subtraction from the composite level. Eyes injected with hNPCctx–GDNF demonstrated significantly greater a-wave and cone b-wave amplitudes than those receiving hNPCctx (*p<0.05; **p<0.01; Student's unpaired t-test). In contrast, the composite b-wave and rod b-wave amplitudes were not statistically different between the two groups. Control eyes injected with medium alone (sham-operated eyes) had no recordable ERG waves and are not included in the graph. Data are expressed as mean ± SEM.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC1828619&req=5

pone-0000338-g002: The capacity of human neural progenitors to preserve retinal function is augmented by GDNF expression. ERG response amplitudes to full field light stimulation were recorded at approximately P100 in RCS rats injected with hNPCctx–GDNF (n = 9), hNPCctx (n = 21) or medium alone (n = 3) into the subretinal space. Individual components of the ERG waveform (a-wave, composite b-wave, cone b-wave and rod b-wave) reveal relative contributions of different retinal cells to the overall functional activity of the retina. Cone b-waves were delineated by a double flash protocol and the rod-attributable b-wave was derived by subtraction from the composite level. Eyes injected with hNPCctx–GDNF demonstrated significantly greater a-wave and cone b-wave amplitudes than those receiving hNPCctx (*p<0.05; **p<0.01; Student's unpaired t-test). In contrast, the composite b-wave and rod b-wave amplitudes were not statistically different between the two groups. Control eyes injected with medium alone (sham-operated eyes) had no recordable ERG waves and are not included in the graph. Data are expressed as mean ± SEM.
Mentions: RCS rats received unilateral subretinal injections of hNPCctx, hNPCctx-GDNF or medium alone (sham) at P21. Fellow, untreated eyes served as internal controls for each animal. The first test performed was ERG, which provides a gross measure of retinal function and an indication of relative rod and cone efficacy. In the scotopic-adapted RCS rat, the ERG a-wave (indicative mainly of rod activity) disappears by P60, while the composite b-wave (comprising rod and cone activity) is largely lost around P100 [39]. At approximately P100, eyes receiving either hNPCctx (n = 21) or hNPCctx-GDNF (n = 9) injections retained robust ERG responses (Figure 2). In contrast, sham-treated eyes (n = 3) had no measurable ERG responses at this age. Further comparison of eyes injected with hNPCctx-GDNF or hNPCctx revealed significantly greater a-wave and cone b-wave amplitudes in the GDNF-secreting group (a-wave: 164.3±63.7 µv vs. 35.2±6.2 µv (p<0.05); cone b-wave: 195.4±38.1 µv vs. 77.7±10.6 µv (p<0.01), respectively). For perspective, non-dystrophic rats yielded a-wave and cone b-wave responses of 279±172 µv and 357±183 µv, respectively. Thus, eyes grafted with hNPCctx-GDNF retained ERG activity at approximately 58.8% (a-wave) and 54.6% (cone b-wave) of the level of normal, non-dystrophic animals. Composite b-wave and rod b-wave amplitudes were also well-preserved in the cell-injected eyes, but no significant difference was observed between the hNPCctx-GDNF and hNPCctx groups (composite b-wave: 244.9±45.3 µv vs. 156.4±18.7 µv (p = 0.12); rod b-wave: 57.6±34.5 µv vs. 78.7±10.5 µv (p = 0.84), respectively).

Bottom Line: Principal outcomes were quantified using electroretinography, visual acuity measurements and luminance threshold recordings from the superior colliculus.Functional efficacy was further enhanced when hNPC were genetically engineered to secrete glial cell line-derived neurotrophic factor.A concomitant preservation of host cone photoreceptors was also observed.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States of America. dgamm@wisc.edu

ABSTRACT

Background: A promising clinical application for stem and progenitor cell transplantation is in rescue therapy for degenerative diseases. This strategy seeks to preserve rather than restore host tissue function by taking advantage of unique properties often displayed by these versatile cells. In studies using different neurodegenerative disease models, transplanted human neural progenitor cells (hNPC) protected dying host neurons within both the brain and spinal cord. Based on these reports, we explored the potential of hNPC transplantation to rescue visual function in an animal model of retinal degeneration, the Royal College of Surgeons rat.

Methodology/principal findings: Animals received unilateral subretinal injections of hNPC or medium alone at an age preceding major photoreceptor loss. Principal outcomes were quantified using electroretinography, visual acuity measurements and luminance threshold recordings from the superior colliculus. At 90-100 days postnatal, a time point when untreated rats exhibit little or no retinal or visual function, hNPC-treated eyes retained substantial retinal electrical activity and visual field with near-normal visual acuity. Functional efficacy was further enhanced when hNPC were genetically engineered to secrete glial cell line-derived neurotrophic factor. Histological examination at 150 days postnatal showed hNPC had formed a nearly continuous pigmented layer between the neural retina and retinal pigment epithelium, as well as distributed within the inner retina. A concomitant preservation of host cone photoreceptors was also observed.

Conclusions/significance: Wild type and genetically modified human neural progenitor cells survive for prolonged periods, migrate extensively, secrete growth factors and rescue visual functions following subretinal transplantation in the Royal College of Surgeons rat. These results underscore the potential therapeutic utility of hNPC in the treatment of retinal degenerative diseases and suggest potential mechanisms underlying their effect in vivo.

Show MeSH
Related in: MedlinePlus