Age-related accumulation of 3-nitrotyrosine and nitro-A2E in human Bruch's membrane.

Age-related macular degeneration (AMD) is a disease leading to severe visual loss and legal blindness in the elderly population. The pathophysiology of AMD is complex and may include genetic predispositions, accumulation of lipofuscin and drusen, local inflammation and neovascularization. Recently four independent research groups have identified a commonly inherited variant (Y402H) of the complement factor H gene in the genome from different groups of AMD patients. The Y402H variant of CFH significantly increases the risk of AMD and links the genetics of the disease with inflammation. During inflammation there is activation of inducible nitric oxide synthase and release of nitric oxide, which in principal could lead to non-enzymatic nitration within extracellular deposits and/or intrinsic extracellular matrix protein components of human Bruch's membrane. We have identified two biomarkers for non-enzymatic nitration in aged human Bruch's membrane, indicative of inflammation, that include 3-nitrotyrosine identified in Bruch's membrane preparations and nitrated A2E from the lipid soluble extract of the Bruch's membrane preparation. Approximately 30-40 times more A2E is observed in samples of the organic soluble extract of lipofuscin compared to the extract of Bruch's membrane. It is of interest to note that although A2E is a major constituent of RPE lipofuscin, nitrated A2E could not be detected in RPE extracts. We show here that nitro-A2E is a specific biomarker of nitrosative stress in Bruch's membrane and its concentration correlates directly with tissue age.

Duration of action of intravitreal ranibizumab and bevacizumab in exudative AMD eyes based on macular volume measurements.

BACKGROUND/AIMS: Sequential macular volume and central foveal point thickness (CFPT) measurements on optical coherence tomography (OCT) were used to determine the efficacy and duration of action of ranibizumab versus bevacizumab in wet age-related macular degeneration (AMD). METHODS: Retrospective chart review of patients who received their first treatment of intravitreal ranibizumab or bevacizumab for exudative AMD. 316 patients (202 ranibizumab;114 bevacizumab) who received 823 injections (313 ranibizumab;510 bevacizumab) were identified. 74 patients had pre- and post-treatment OCTs performed to determine CFPT and macular volume changes. RESULTS: Ranibizumab caused a significant reduction in CFPT (278 (SD 84) before treatment vs 227 (80) microm after treatment; p = 0.001) and macular volume (7.22 (0.96) vs 6.69 (0.74) mm(3); p = 0.002). Intravitreal bevacizumab caused a similar reduction in CFPT (288 (94) vs 220 (55) microm; p = 0.008) and macular volume (7.36 (1.08) vs 6.50 (0.42) mm(3); p<0.001). The mean duration of action was 74.0 (19.1) days for ranibizumab compared with 101.8 (16.6) days for bevacizumab (p = 0.036; t test). The ratio of the relative duration of action of bevacizumab versus ranibizumab was 1.40 (0.19). CONCLUSIONS: Both drugs are equally effective at reducing CFPT or macular volume. Bevacizumab appears to take longer to achieve the minimum macular volume, and its effects take longer to wear off, suggesting it can be given less often.

Epiretinal membrane removal in diabetic eyes: comparison of viscodissection with conventional methods of membrane peeling.

AIMS: To compare conventional methods of epiretinal membrane peeling with viscodissection. METHODS: 154 eyes with proliferative diabetic retinopathy (PDR) that underwent pars plana vitrectomy with membrane dissection (89 traditional, 65 viscodissection) were studied retrospectively. Incidence of retinal breaks (RBs), length of time under anaesthesia, postoperative intraocular pressure, retinal reattachment rate, and final visual acuity (VA) were measured. RESULTS: To compare cases of similar complexity, a "complexity score" was defined. The average complexity score for cases done with and without viscodissection was 4.7 and 3.2, respectively. The mean frequency of RBs in eyes undergoing viscodissection was 0.43 (SD 0.5) v 0.14 (0.35) RBs/eye without viscodissection. In complex cases, the frequency of posterior/peripheral RBs was 0.31 (0.47)/0.13 (0.34) RBs/eye, respectively, with viscodissection v 0.12 (0.33)/0.23 (0.43) RBs/eye without viscodissection. None of these differences were statistically significant. The average preoperative/postoperative VA (logMAR) in the viscodissection cohort was 1.7/1.3 (range 0.3 to >1.9/0.1 to >1.9) v 1.4/1 (range 0.48 to >1.9/0.1 to >1.9) in the non-viscodissection cohort, among eyes with 6 months of follow up. Anaesthesia duration was significantly shorter for cases done without viscodissection (p=0.03), but cases done with viscodissection were significantly more complex than cases done without viscodissection (p<0.0001). CONCLUSION: Viscodissection appears to be a safe and effective alternative technique in eyes with PDR. Owing to the retrospective nature of the study, additional studies are warranted.

Retinal pigment epithelial cell transplantation after subfoveal membranectomy in age-related macular degeneration: clinicopathologic correlation.

PURPOSE: To report the histopathology after retinal pigment epithelial cell transplantation and subfoveal membranectomy in age-related macular degeneration. METHODS: An 85-year-old white woman with bilateral choroidal neovascularization underwent subfoveal membranectomy combined with transplantation of a sheet of human adult retinal pigment epithelium (retinal pigment epithelium) under the foveal center in the right eye. The patient was immunosuppressed postoperatively with prednisone, cyclosporine, and azathioprine. The patient died from congestive heart failure 114 days after surgery. RESULTS: A patch of hyperpigmentation was visible at the transplant site under the foveola after surgery. Mound-like clusters of individual round, large densely pigmented cells were present in the subretinal space and outer retina in this area. There was loss of the photoreceptor outer segments and native retinal pigment epithelium in the center of the transplant bed, with disruption of the outer nuclear layer predominantly over regions of multilayered pigmented cells. Cystic spaces were present in the inner and outer retina. A residual intra-Bruchs membrane component of the original choroidal neovascular complex was present under the transplant site. CONCLUSIONS: The transplant site contained clusters of round, pigmented cells that did not form a uniform monolayer in most areas. The morphology at the transplant site is consistent with the lack of visual improvement seen after surgery in this patient.

TGF beta secretion modulates the density-dependent growth of pig retinal pigment epithelium in vitro.

BACKGROUND: We aimed to identify the cytokine(s) responsible for the density-dependent growth regulation of pig retinal pigment epithelium (RPE) in vitro. METHODS: Confluent monolayers of primary pig RPE were established on bovine corneal endothelial extracellular matrix-coated tissue culture well inserts wrapped with dialysis membranes with different molecular weight cutoffs (0.5-50 kDa). These confluent RPE monolayers were then cocultured with first passage porcine RPE plated at a density of 1 cell/mm2, so that the newly plated RPE was bathed with different molecular weight fractions of the confluent cell media. Growth rates of the newly plated RPE were determined 72 h after plating and the molecular weight fraction of the confluent cell medium that inhibits the RPE proliferation was determined. First passage pig RPE (1 cell/mm2) were cocultured with confluent monolayers of primary pig RPE on inserts in the presence of different amounts of TGF-beta neutralizing antibody (0.1-100 microg/ml). Growth rates of the newly plated RPE were calculated 72 h after plating to determine the antibody concentration that would maximize the growth rate of the newly plated RPE in the presence of an adjacent confluent RPE monolayer. RESULTS: The growth rate of the newly plated RPE decreased when RPE were bathed with the 10- to 25-kDa fractions of medium from an adjacent confluent RPE monolayer. This growth inhibition reached statistical significance with the 25- to 50-kDa fractions (p < 0.05), and was abolished by adding pan-specific neutralizing antibody against TGF-beta (0.1-5 microg/ml). Blocking greater amounts of TGF-beta in the medium with higher doses of antibody (>10 microg/ml) also inhibited the growth of the newly plated RPE, in the presence or absence of a neighboring confluent cell layer. CONCLUSION: The TGF-beta family of cytokines mediates the density-dependent growth suppression of RPE in vitro. Neutralizing the effect of these cytokines by adding anti-TGF-beta antibodies can result in more rapid growth of the RPE in vivo.

Treatment choice and quality of life in patients with choroidal melanoma.

OBJECTIVE: To determine if quality of life differs between patients with choroidal melanoma treated with enucleation and those treated with radiation therapy. MATERIALS AND METHODS: Patients treated for choroidal melanoma at 5 Midwest centers were asked to participate. There were 65 participants treated with enucleation and 82 treated with radiation therapy. Quality of life was assessed using the Medical Outcome Study Short Form 36 and the National Eye Institute Visual Function Questionnaire and by the Time-Tradeoff interview method. RESULTS: The average length of follow-up was 4.9 years for the group treated with radiation therapy and 6.3 years for the group treated with enucleation (P = .05). After adjusting for age, sex, years of follow-up, and the number of chronic conditions, there were few differences in any of the quality-of-life measures by treatment status. Participants in the group treated with radiation therapy were more likely to have higher (better) scores on the Vitality and Mental Component subscales of the Medical Outcome Study Short Form 36 than participants treated with enucleation. There were no differences on the National Eye Institute Visual Function Questionnaire or the Time-Tradeoff measures of quality of life. CONCLUSION: Choice of treatment for choroidal melanoma does not seem to be associated with large differences in quality of life in long-term follow-up.

Repopulation of different layers of host human Bruch's membrane by retinal pigment epithelial cell grafts.

PURPOSE: To determine the morphology of human retinal pigment epithelium (RPE) after reattachment to different ultrastructural layers of human Bruch's membrane (BM). METHODS: Bruch's membrane explants were prepared from eyes of 23 human donors (age range, 11-89 years). The basal lamina of the RPE, inner collagenous layer, and elastin layer were removed sequentially by mechanical and enzymatic techniques. First-passage cells of human RPE (15,000 cells/6 mm explant) from three donors (ages, 52, 64, and 80 years) were plated onto different layers of human BM, and the explants were examined by scanning and transmission electron microscopy up to 21 days later. RESULTS: RPE flattened and extended footplates 6 hours after plating onto basal lamina. Cells remained round 6 and 24 hours after plating onto the inner collagenous, elastin, or outer collagenous layer. The RPE cells became confluent 14 days after plating onto basal lamina but did not become confluent up to 21 days after plating onto the inner collagenous or elastin layer. Sparse round cells were observed 21 days after plating onto deeper layers, suggesting extensive loss of RPE. CONCLUSIONS: The morphology and subsequent behavior of the RPE reattached to BM depends on the anatomic layer of BM available for cell reattachment. The results suggest that the ability of transplanted RPE to repopulate BM in age-related macular degeneration and other disorders may depend on the layer of BM available to serve as a substrate for cell reattachment.

Fate of human retinal pigment epithelial cells seeded onto layers of human Bruch's membrane.

PURPOSE: To determine the fate of human retinal pigment epithelial (RPE) cells seeded onto different layers of human Bruch's membrane (BM). METHODS: Bruch's membrane explants were prepared from 16 human cadaver eyes (7 eyes age <50 years; 9 eyes >50 years) by removing native RPE cells with ammonium hydroxide to expose the RPE cell basal lamina (BL). The inner collagenous layer (ICL) and elastin layer (EL) were exposed by removing apical layers sequentially by mechanical and enzymatic means. Synchronized first passage human RPE cells (15,000 cells/(6-mm-diameter explant) were plated onto each layer of human BM. The RPE cell reattachment and apoptosis rates at 24 hours, proliferation rates and mitotic index 24 hours after growth stimulation, and the ability of RPE cells to repopulate the explant surface were determined on each layer. RESULTS: RPE cell reattachment was highest on BL but decreased on deeper layers of BM. The apoptosis rate of attached cells increased as deeper layers of BM were exposed. The proliferation rate and mitotic index of the grafted cells were higher on BL than on deeper layers. RPE cells plated onto BL repopulated the explant surface within 14 +/- 3 days, whereas cells plated onto the ICL and EL eventually died and never reached confluence. CONCLUSIONS: The fate of RPE cells seeded onto BM depends on the ultrastructural layer of BM available for reattachment. These findings suggest that the ability of transplanted RPE cells to repopulate bare BM will depend on the layer of BM available for RPE cell reattachment.

Minimum number of adult human retinal pigment epithelial cells required to establish a confluent monolayer in vitro.

PURPOSE: To determine the minimum number of cells required to establish a confluent monolayer of retinal pigment epithelium (RPE) with an epitheloid morphology in vitro. METHODS: Primary or passaged human RPE were harvested by trypsinization from 6 donors and plated onto bovine corneal endothelium extracellular matrix-coated tissue culture plastic in 96-well plates. Plating densities ranged from 1 to 66,000 viable cells/well (0.03-2062 viable cells/mm2) for primary cells or 1 to 100,000 viable cells/well (0.03-3112 viable cells/mm2) for passaged cells. The time required to reach confluence was determined by monitoring the cultures daily until they reached confluence. Mean cell area and circularity index at confluence was calculated to determine the effect of different plating densities on final RPE morphology. RESULTS: Primary RPE plated at densities above 10 viable cells/mm2 (320 cells/well) and passaged RPE plated above 2 viable cells/mm2 (64 cells/well) reached confluence on every occasion. There was a negative correlation between the plating density and time required to reach confluence. Plating densities above 3 viable cells/mm2 (96 cells/well) and 50 viable cells/mm2 (1600 cells/well) yielded smaller, rounder cells at confluence for primary and passaged RPE, respectively. CONCLUSIONS: As few as 96 primary RPE cells and 1600 passaged RPE are required to obtain a confluent, 6mm (4-disc diameter) patch of RPE in vitro. This suggests that autologous RPE grafts can be prepared with high efficiency for subsequent transplantation into the subretinal space in vivo.

Surgical removal of extensive peripapillary choroidal neovascularization associated with presumed ocular histoplasmosis syndrome.

OBJECTIVE: This study aimed to report the visual outcome of surgical removal of extensive peripapillary choroidal neovascularization (CNV) due to presumed ocular histoplasmosis syndrome (POHS). DESIGN: Retrospective review of the records of all patients seen at the Barnes Retina Institute who underwent surgical removal of extensive peripapillary CNV associated with POHS and who had at least 12 months of follow-up. PARTICIPANTS: Seventeen consecutive eyes (in 14 patients) undergoing surgical removal of extensive peripapillary CNV associated with POHS were studied. INTERVENTION: Pars plana vitrectomy and surgical removal of CNV were performed. MAIN OUTCOME MEASUREMENTS: Best-corrected Snellen visual acuity, funduscopic examination, and intravenous fluorescein angiography were obtained before surgery and at regular intervals after surgery. RESULTS: In 14 of 17 eyes, the peripapillary CNV was subfoveal, and in 3 eyes, it was extrafoveal. All three eyes with extrafoveal CNV were not eligible for laser treatment according to Macular Photocoagulation Study guidelines because treatment would have spared less than 1.5 contiguous clock-hours of retina temporal to the optic disc. Follow-up ranged from 17 to 57 months, with a median of 32 months. In eyes with subfoveal CNV, best-corrected preoperative Snellen visual acuity ranged from 20/25 to counting fingers at 2 feet with a median of 20/200, and best-corrected final Snellen visual acuity ranged from 20/25 to 20/200 with a median of 20/40. In 7 (50%) of 14 eyes, a final Snellen acuity of 20/40 or better was achieved, and in all cases except 1, visual acuity improved or did not change with surgery. In the three eyes with extrafoveal CNV, best-corrected preoperative Snellen visual acuity ranged from 20/20 to 20/400 with a median of 20/200, and best-corrected final Snellen visual acuity was 20/20 in all cases. In addition, visual acuity improved with surgery. CONCLUSIONS: The data from this small retrospective study suggest that surgical removal may provide visual benefit in selected cases of extensive peripapillary CNV due to POHS.

Serum-free media for culturing and serial-passaging of adult human retinal pigment epithelium.

The ability of a chemically-defined serum-free culture medium to support the attachment, growth and serial passaging of primary adult human retinal pigment epithelial (RPE) cells was studied. Primary cultures of adult human RPE were established in a chemically-defined serum-free culture medium on both bare or bovine corneal endothelial extracellular matrix-coated tissue-culture plastic. Confluent cells were serially passaged in chemically-defined serum-free culture medium three times by trypsinization, and trypsin activity was quenched with aprotinin. First passage RPE cells were plated onto tissue-culture plastic precoated with bovine corneal endothelial extracellular matrix or uncoated tissue-culture plastic in 24 well plates at a density of 50 viable cells mm-2. Cells were maintained either in chemically-defined serum-free culture medium, DMEM without serum, or DMEM with 15% fetal bovine serum. For each medium plating, efficiencies were determined 24 hours after plating, and growth rates were determined on the first, third and seventh days after plating. Morphometric image analysis was performed on cells cultured for up to 6 weeks and three serial passages. Seeding efficiency on bovine corneal endothelial extracellular matrix-coated tissue-culture plastic and treated tissue-culture plastic were higher for chemically-defined serum-free culture medium (88.9+/-2.7% and 47.1+/-4.1%, respectively) and DMEM with serum (87.2+/-5.6% and 52.9+/-10.5%, respectively) than DMEM without serum (59.2+/-5.6% and 33.1+/-6.9%, respectively; P<0.01). The RPE proliferation rate in chemically-defined serum-free culture medium was comparable to DMEM with serum on both substrates within the first 3 days, although cells in DMEM with serum had a higher proliferation rate on day 7. Cells cultured in DMEM without serum, eventually decreased in number. RPE maintained in chemically-defined serum-free culture medium maintained a consistent proliferation rate, reached confluence, and retained an epitheloid morphology on either extracellular matrix or tissue-culture plastic for up to 6 weeks and three serial passages. Primary RPE reached confluence at 12+/-3 days on bovine corneal endothelial extracellular matrix-coated tissue-culture plastic and 21+/-5 days on treated tissue-culture plastic. Confluent cultures were composed of small hexagonal cells with epitheloid morphology on both substrates. We concluded that primary adult human RPE can be cultured in this chemically-defined serum-free culture medium. RPE will proliferate, reach confluence, retain their epitheloid morphology and can be serially passaged in the absence of serum.

Photosensitization of retinal pigment epithelium by protoporphyrin IX.

BACKGROUND: Clinical evidence of injury to the retinal pigment epithelium is an important feature of age-related macular degeneration, but the mechanism of this injury is unknown. Blue-light-dependent activation of the blood-borne photosensitizer protoporphyrin IX is known to produce free radicals which may damage cells and tissues. This study was undertaken to determine the effect of blue light and protoporphyrin IX on retinal pigment epithelial cells in vitro. METHODS: Third-passage porcine retinal pigment epithelial cells were plated in six-well culture plates at 100,000 cells/well and grown to confluence. Retinal pigment epithelial cells were then incubated in culture media with and without 35 micrograms/dl protoporphyrin IX and exposed to low intensity (118 microW/cm2) blue, blue-free, or full-spectrum white light in an irradiating incubator for 16 h on/8 h off cycles for 7 days. Some of the wells were shielded from light (dark controls). Retinal pigment epithelial cells were examined by light microscopy and were trypsinized and counted after 7 days. RESULTS: White light with and without protoporphyrin IX and protoporphyrin IX in dark conditions did not decrease the retinal pigment epithelial cell count significantly. Blue light alone and blue light with protoporphyrin IX decreased the cell count by 22 +/- 4% and 35 +/- 3% compared to the controls, respectively. CONCLUSION: Blue wavelength light without exogenous protoporphyrin IX has a cytotoxic effect on confluent cultures of retinal pigment epithelium, suggesting that endogenous photosensitizers may be present in retinal pigment epithelial cells. Protoporphyrin IX has an additive cytotoxic effect in the presence of blue light, suggesting that this photosensitizer is capable of mediating blue-light-induced retinal pigment epithelial damage. Since protoporphyrin IX is present in blood and tissue fluids, and the retina is chronically exposed to light, protoporphyrin IX-mediated free radical formation may occur in vivo and may play a role in retinal pigment epithelial changes that occur early in the pathogenesis of age-related macular degeneration.

Spontaneous resolution of retinal detachment occurring after macular hole surgery.

OBJECTIVE: To document the spontaneous resolution of retinal detachment developing after macular hole surgery. METHODS: We identified all patients who developed a postoperative retinal detachment after undergoing macular hole surgery at Washington University School of Medicine, St Louis, Mo; the surgery was performed by one of us (L.V.D.P. or H.J.K.) between 1991 and 1996. RESULTS: Six of 73 eyes developed a postoperative retinal detachment; the retinal detachment was inferior in all cases. Two eyes that had inferior retinal breaks underwent further surgery to repair the retinal detachment. Retinal breaks could not be identified in the other 4 eyes; the retinal detachment resolved without further surgery in all 4 of these eyes. CONCLUSION: The recognition that retinal detachment occurring after macular hole surgery can resolve without additional surgery may result in the avoidance of further surgical intervention in some eyes.

Reattachment rate of human retinal pigment epithelium to layers of human Bruch's membrane.

OBJECTIVES: To determine the reattachment rate of human retinal pigment epithelium (RPE) to different layers of human Bruch's membrane (BM). METHODS: Explants of BM were prepared from 10 human cadaver eyes by removing native RPE. The RPE basal lamina, inner collagenous layer, elastin layer, and outer collagenous layer were exposed by sequentially removing each apical layer by mechanical or enzymatic means. First-passage human RPE was plated onto the surface and the RPE reattachment rate to each layer of BM was determined. RESULTS: Retinal pigment epithelial cell reattachment was highest to the inner aspects of BM and decreased as deeper layers of BM were exposed (ie, reattachment rate to basal lamina was higher than to the inner collagenous layer, which was higher than to the elastin layer, which was higher than to the outer collagenous layer). The reattachment rate to the inner collagenous layer, elastin layer, and outer collagenous layer harvested from elderly donors (age >60 years) was less than the reattachment rate to corresponding layers harvested from younger (age <50 years) donors. CONCLUSIONS: Retinal pigment epithelial cell reattachment depends on the anatomical layer of BM present in the host tissue. Age-related changes in BM may interfere with RPE reattachment. Our observations may have implications for understanding the pathogenesis of age-related macular degeneration and its potential treatment with RPE transplantation techniques.

Posterior vitreous detachment with dispase.

PURPOSE: To induce a posterior vitreous detachment (PVD) in porcine and human cadaver eyes in vitro with Dispase (Gibco, Grand Island, NY). METHODS: Dispase (0.5 mL) was injected into the vitreous cavity of enucleated porcine (0.05-25 U/mL) and human (5 U/mL) eyes. After incubation at 37 degrees C for 15-120 minutes, the globes were hemisected and the extent of PVD was graded as complete, partial, or absent. The structural integrity of the retina was estimated by measuring the elastic constant and maximal stretching before fracture. Retinal cell viability was determined by an intracellular esterase assay. Light, transmission, and scanning electron microscopy were performed to examine the ultrastructure of the vitreoretinal interface. RESULTS: After 15 minutes, a partial or total PVD was present in 7/10, 8/10, or 9/10 enucleated porcine eyes incubated with 1, 5, or 10 U/mL Dispase, respectively, versus 3/10 control eyes (P < 0.05). A partial or complete PVD was present in 3/5, 4/5, 5/5, or 14/15 porcine eyes after 15, 30, 60, or 120 minutes of treatment with 0.1 U/mL Dispase, respectively. Similarly, 19/20 human cadaver eyes developed a complete and 1/20 an incomplete PVD after incubation with 5 U/mL Dispase for 15 minutes. Microscopy demonstrated that Dispase cleaved the attachment of the posterior hyaloid to the internal limiting membrane with minimal damage to the inner retina. Retinal cell viability and the mechanical properties of the retina were similar for Dispase-treated and control eyes. CONCLUSION: Dispase disrupts the attachment of the posterior hyaloid to the inner limiting membrane with minor morphologic changes in the inner retina. The enzyme may be useful in removing cortical vitreous during vitreous surgery.

Human photoreceptor transplantation in retinitis pigmentosa. A safety study.

OBJECTIVE: To establish the technical feasibility and safety of photoreceptor transplantation in retinitis pigmentosa. METHODS: A sheet of human photoreceptor cells was harvested from 2 human cadaveric eyes with a vibratome and transplanted into the subretinal spaces of 2 patients with advanced retinitis pigmentosa and visual acuity of no light perception by means of submacular surgery techniques. Preoperative and postoperative electrophysiologic testing, fundus photography, fluorescein angiography, and scanning laser ophthalmoscopy were performed. RESULTS: Twelve months after photoreceptor transplantation, the visual acuity of each patient remained no light perception. The temporal edge of the retinotomy in 1 patient was folded but was not associated with a retinal detachment. The patients were not immunosuppressed, and there was no evidence of rejection of the allogeneic transplant. Cystoid macular edema, uveitis, and macular pucker were not observed. CONCLUSION: A sheet of adult human photoreceptor cells can be harvested from human cadaveric eyes and safely transplanted to the subretinal spaces of patients with retinitis pigmentosa without systemic immunosuppression.