Iris Pigment Epithelial Cells of Long Evans Rats Demonstrate Phagocytic Activity

Rezai, Kourous A.; Lappas, Alexandra; Farrokh-Siar, Lili; Kohen, Leon; Wiedemann, Peter; Heimann, Klaus

doi:10.1006/exer.1997.0307

Cited by 53 publications

(35 citation statements)

References 20 publications

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“…Likewise, other cells being investigated for these tissue engineering approaches, such as the IPE, would be required to show the same functions as RPE in order to replace RPE in vivo. Some RPE functions such as formation of barrier membranes, and rod outer segment phagocytosis have been extensively investigated for IPE cultures (Rezai et al, 1997b(Rezai et al, , 1997cSchraermeyer et al, 1997) ; however, retinoid metabolism, which is required for maintenance of the visual cycle, has either not been investigated or assumed lost in serial culture.…”

Section: Discussionmentioning

confidence: 99%

Maintenance of Retinoid Metabolism in Human Retinal Pigment Epithelium Cell Culture

Recum

Okano

Kim

et al. 1999

Experimental Eye Research

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Section: Discussionmentioning

confidence: 99%

Maintenance of Retinoid Metabolism in Human Retinal Pigment Epithelium Cell Culture

Recum

Okano

Kim

et al. 1999

Experimental Eye Research

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“…Therefore, fixation in the area of RPE atrophy after IPE translocation in this study may signal a protective effect of IPE on retinal photoreceptors over 1 year. IPE cells have been shown to synthesize similar growth factors as RPE cells in vitro [15] and to be capable of phagocytosis of photoreceptor rod outer segments to some extent [28,36]. The supportive effect of translocated IPE cells within the RPE defect may be so weak that it does not result in a measurable improvement of visual acuity.…”

Section: Fixationmentioning

confidence: 99%

Translocation of iris pigment epithelium in patients with exudative age-related macular degeneration — long term results

Lappas¹,

Foerster²,

Weinberger³

et al. 2004

The Macula

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Purpose: To report the practicability and efficacy of autologous iris pigment epithelium (IPE) translocation in exudative age-related macular degeneration (ARMD) over 1 year. Methods: The consecutive interventional case series included 56 patients with exudative ARMD. During vitrectomy the submacular neovascular membrane (CNV) was removed and IPE cells, harvested from a peripheral iridectomy, were injected into the submacular space. Included were patients with subfoveal occult CNV (11 eyes), classic CNV (10 eyes), mixed CNV (17 eyes), CNV with a pigment epithelial detachment (13 eyes) or CNV with a hemorrhage (5 eyes). Outcome measures were visual acuity, foveal fixation, size of CNV and rate of recurrence based on fluorescence angiographic imaging. Results: All patients underwent successful surgical removal of the CNV with consecutive subretinal IPE injection.

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“…The IPE is anatomically continuous with the RPE and has the same embryonic origin. In vitro, IPE cells share functional properties with RPE cells such as phagocytosis (4,5), degradation of rod outer segments (ROS) (6), and synthesis of trophic factors (7). However, autologous transplantation of IPE cells has not resulted in a prolonged improvement of the vision of ARMD patients, potentially because of the lack of expression of one or several (so far unknown) factors that are an important part of RPE function.…”

mentioning

confidence: 99%

Autologous transplantation of genetically modified iris pigment epithelial cells: A promising concept for the treatment of age-related macular degeneration and other disorders of the eye

Semkova

Kreppel²,

Welsandt³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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Age-related macular degeneration (ARMD) is the leading cause for visual impairment and blindness in the elder population. Laser photocoagulation, photodynamic therapy and excision of neovascular membranes have met with limited success. Submacular transplantation of autologous iris pigment epithelial (IPE) cells has been proposed to replace the damaged retinal pigment epithelium following surgical removal of the membranes. We tested our hypothesis that the subretinal transplantation of genetically modified autologous IPE cells expressing biological therapeutics might be a promising strategy for the treatment of ARMD and other retinal disorders. Pigment epithelium-derived factor (PEDF) has strong antiangiogenic and neuroprotective activities in the eye. Subretinal transplantation of PEDF expressing IPE cells inhibited pathological choroidal neovascularization in rat models of laserinduced rupture of Bruch's membrane and of oxygen induced ischemic retinopathy. PEDF expressing IPE transplants also increased the survival and preserved rhodopsin expression of photoreceptor cells in the RCS rat, a model of retinal degeneration. These findings suggest a promising concept for the treatment of ARMD and other retinal disorders. In the western world in individuals over 60 years of age, age-related macular degeneration (ARMD) is the primary cause for visual impairment and blindness. Pathological changes in the retinal pigment epithelium (RPE) and in the choriocapillaris are associated with the progressive degeneration of macular photoreceptor cells. Vision loss in patients with the exudative form of ARMD (wet ARMD) is caused by the formation of subretinal fibrovascular membranes during a late stage of the disease. When this occurs it sometimes can be ablated by laser photocoagulation or photodynamic therapy, but neither treatment addresses underlying stimuli for blood vessel growth. Therefore, recurrent disease is a problem of significant clinical relevance. Surgical excision of submacular neovascular membranes leads to the additional damage of the RPE (1), a cell type that is known to play a central role in the homeostasis of the retina having phagocytic, metabolic, neurotrophic, antioxidative, and antiangiogenic functions. The most frequent form of ARMD (dry ARMD) is characterized by primary degeneration and atrophy of the RPE layer. Subretinal transplantation of autologous (from the same patient) iris pigment epithelial (IPE) cells has been a recent experimental treatment strategy to functionally replace the lost or damaged RPE in the macular area (2, 3). The IPE is anatomically continuous with the RPE and has the same embryonic origin. In vitro, IPE cells share functional properties with RPE cells such as phagocytosis (4, 5), degradation of rod outer segments (ROS) (6), and synthesis of trophic factors (7). However, autologous transplantation of IPE cells has not resulted in a prolonged improvement of the vision of ARMD patients, potentially because of the lack of expression of one or several (so far unknown) factors tha...

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Iris Pigment Epithelial Cells of Long Evans Rats Demonstrate Phagocytic Activity

Cited by 53 publications

References 20 publications

Maintenance of Retinoid Metabolism in Human Retinal Pigment Epithelium Cell Culture

Maintenance of Retinoid Metabolism in Human Retinal Pigment Epithelium Cell Culture

Translocation of iris pigment epithelium in patients with exudative age-related macular degeneration — long term results

Autologous transplantation of genetically modified iris pigment epithelial cells: A promising concept for the treatment of age-related macular degeneration and other disorders of the eye

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