Detection of CX3CR1 single nucleotide polymorphism and expression on archived eyes with age-related macular degeneration.

There is a significant genetic component in age-related macular degeneration (AMD). CX3CR1, which encodes the fractalkine (chemokine, CX3CL1) receptor, has two single nucleotide polymorphisms (SNPs): V249I and T280M. These SNPs are correlated with other aged-related diseases such as atherosclerosis. We have reported an association of CX3CR1 SNP and AMD. In this study we examined CX3CR1 SNP frequencies and protein expression on archived sections of AMD and normal eyes. We microdissected non-retinal, peripheral retinal and macular cells from archived slides of eyes of AMD patients and normal subjects. CX3CR1 SNP typing was conducted by PCR and restriction fragment length polymorphism analysis. CX3CR1 transcripts from retinal cells were also measured using RT-PCR. CX3CR1 protein expression was evaluated using avidin-biotin complex immunohistochemistry. We successfully extracted DNA from 32/40 AMD cases and 2/2 normal eyes. Among the 32 AMD cases, 18 had neovascular AMD and 14 had non-neovascular AMD. The M280 allele was detected in 19/64 (32 cases x2) with a frequency of 29.7%, which was significantly higher as compared to the frequency in the normal population (11.2%). We detected CX3CR1 expression in the various retinal cells. CX3CR1 transcript and protein levels were diminished in the macular lesions. This study successfully analyzed CX3CR1 SNP and transcript expression in microdissected cells from archived paraffin fixed slides. Our data suggest that the M280 allele, a SNP resulting in aberrant CX3CR1 and CX3CL1 interaction, as well as lowered expression of macular CX3CR1, may contribute to the development of AMD.

Topical corticosteroid therapy for cicatricial conjunctivitis associated with chronic graft-versus-host disease.

A retrospective chart review was performed on seven patients treated with topical ocular corticosteroid therapy for progressive cicatricial conjunctivitis associated with chronic graft-versus-host disease (GVHD) following hematopoietic stem cell transplantation. A clinical grading criteria for conjunctival GVHD based on the degree of cicatrization was developed and patients graded prior to therapy. During the treatment course, the dose and frequency of topical corticosteroids and clinical outcomes were recorded. A complete response was defined as a complete resolution of the conjunctival hyperemia with either total resolution of the conjunctival fibrovascularization or presence of inactive conjunctival scarring. Prednisolone acetate 1% eye drops were used in a total of eight courses of therapy in seven patients. A complete response was documented in all seven patients with a total treatment duration of 7 weeks (median, range: 3-16 weeks). Additional studies are required to determine the long-term safety and efficacy of topical corticosteroids for cicatricial conjunctivitis associated with ocular GVHD in the context of a randomized, prospective clinical trial.

Choroidal neovascular membrane inhibition in a laser treated rat model with intraocular sustained release triamcinolone acetonide microimplants.

AIM: To determine if intravitreal microimplants containing triamcinolone acetonide (TAAC) inhibit experimental fibrovascular proliferation (FVP) induced by laser trauma in a rat as a model of choroidal neovascular membranes (CNVMs). METHODS: 20 anaesthetised male Brown Norway rats received a series of eight krypton red laser lesions per eye (647 nm, 0.05 s, 50 micro m, 150 mW). Three types of sterilised TAAC microimplant designs were evaluated: implant A consisting of 8.62% TAAC/20% polyvinyl alcohol (PVA) matrix (by dry weight); implant B consisting of 3.62% TAAC/20% PVA matrix; and implant C consisting of a dual 8.62% TAAC/20% PVA matrix design combined with a central core (0.5 mm) of compressed TAAC to extend the implant release time. For each animal studied, one eye received one of the three aforementioned TAAC implant designs, while the fellow eye received a control implant consisting of PVA but without TAAC. The animals were sacrificed at day 35 and ocular tissues were processed for histological analysis. Serial histological specimens were methodically assessed in a masked fashion to analyse each laser lesion for the presence or absence of FVP; maximum FVP thickness for each lesion was measured from the choriocapillaris. RESULTS: All three types of TAAC implants inhibited FVP relative to controls in a statistically significant fashion. In the eyes that received implant A (n = 8), the mean thickness of the recovered lesions (n = 36) measured 32 (SD 22) micro m, compared to 52 (30) micro m (p <0.005) for the recovered lesions (n = 40) from the fellow control eyes. In the eyes that received implant B (n = 6), the mean thickness of the recovered lesions (n = 31) measured 28 (15) micro m, compared to 50 (29) micro m (p <0.001) for the lesions (n = 19) recovered from the fellow control eyes. In the eyes that received implant C (n = 6), the mean thickness of the recovered lesions (n = 21) measured 39 (24) micro m, compared to 65 (30) micro m (p <0.001) for the lesions (n = 39) recovered from the fellow control eyes. CONCLUSIONS: All three of the tested TAAC microimplant designs produced potent inhibition of FVP in a rat model of CNVMs. There were no differences in inhibition of FVP between the three different types of implants evaluated. This study provides evidence that: (1) corroborates previous investigations that propose TAAC as a potential treatment for CNVMs in humans, and (2) demonstrates TAAC can be effectively delivered via long acting sustained release intraocular microimplants. It should be noted, however, that the FVP observed in this rat laser trauma may not reflect the CNVM observed in human with exudative age related macular degeneration (AMD).

Safety and pharmacokinetics of intravitreal 2-methoxyestradiol implants in normal rabbit and pharmacodynamics in a rat model of choroidal neovascularization.

Choroidal neovascularization (CNV) is the leading cause of severe vision loss associated with age-related macular degeneration. As the pathogenesis of CNV formation is better understood, mechanism-based therapies, including the use of antiangiogenesis inhibitors, have been investigated. 2-methoxyestradiol (2ME2), an endogenous metabolite of estradiol, has been shown in the chick allantoic membrane model and the corneal micropocket assay to have antiangiogenic properties. The authors sought to determine the safety and pharmacokinetics of sustained-release intravitreal 2ME2 implants in normal rabbit and their efficacy in a rat model of CNV. 2ME2 implants were constructed using two designs: implant A, a silicone-based reservoir implant for the rabnbit eye, and implant B, a microimplant matrix design for the rat eye. In vitro release rates of both implants were determined. New Zealand white (NZW) rabbits had implant A placed in the vitreous cavity of one eye and the ocular toxicity was evaluated by clinical examination, serial electroretinography (ERG), and histopathology over a 28 week period. The steady state clearance of 2ME2 in the rabbit eye was calculated from in vivo release rates divided by steady state vitreous concentrations. A CNV model in the Brown-Norway rat was performed by injecting an adenoviral vector encoding human vascular endothelial growth factor in the subretinal space. Following the injection, a 2ME2 or sham (no drug) microimplant was placed in the vitreous cavity. Animals were killed over a 3 week period and the eyes examined for CNV by histopathology. Results showed that following a short burst, the release rate of implant A followed zero-order kinetics, typical of reservoir devices, and the cumulative release of implant B was proportional to the square root of time, as expected for a matrix delivery device. The safety studies in normal rabbit showed no ocular toxicities by clinical examination, ERG, and histopathology. Pharmacokinetic evaluation in the rabbit showed mean 2ME2 vitreous levels within the therapeutic range for the inhibition of endothelial cell proliferation. The experimental rat model showed a significant reduction in CNV in eyes treated with the 2ME2 implant. In conclusion, sustained-release 2ME2 intravitreal implants, which can be designed to deliver potentially therapeutic vitreous levels of 2ME2 for an extended period of time, appeared to be safe in normal rabbit and effective in a rat model of CNV. Sustained-release 2ME2 intravitreal implants may hold promise in the treatment of recurrent CNV refractory to standard therapy.

Aqueous humor and plasma vascular endothelial growth factor in uveitis-associated cystoid macular edema.

PURPOSE: To determine the association between cystoid macular edema and vascular endothelial growth factor concentration in the aqueous humor and plasma of uveitis patients. METHODS: Cross-sectional study. Vascular endothelial growth factor concentrations were measured by enzyme-linked immunosorbent assay in the aqueous humor of 20 uveitis patients (9 with and 11 without cystoid macular edema), and in the plasma of 40 uveitis patients (20 with and 20 without cystoid macular edema) and 20 healthy volunteers. RESULTS: Mean aqueous humor vascular endothelial growth factor concentrations for uveitis patients with and without cystoid macular edema were 152.3 and 109.5 pg/ml, respectively, P =.044. Mean plasma vascular endothelial growth factor concentrations in uveitis patients with and without cystoid macular edema and in healthy volunteers were 32.2, 29.6, and 55.0 pg/ml, respectively. Uveitis patients had lower plasma vascular endothelial growth factor levels than did healthy volunteers, P =.0002. CONCLUSION: In uveitis patients, vascular endothelial growth factor concentration is increased in the aqueous humor of eyes with cystoid macular edema. It may be useful to investigate vascular endothelial growth factor antagonists as a treatment for uveitis-associated cystoid macular edema.

Regulated heat shock protein 27 expression in human retinal pigment epithelium.

PURPOSE: To examine the expression and regulation of an injury-related protein, heat shock protein (Hsp) 27, in retinal pigment epithelium (RPE), since RPE injury may be an important feature of age-related macular degeneration (ARMD). METHODS: Retinal cross sections from eyes of Lewis rats were examined for Hsp27 in vivo by immunohistochemistry, and in vitro expression of Hsp27 in human ARPE-19 cells was determined by Northern and Western blot analysis. Oxidant-mediated injury was performed by exposing ARPE-19 cells to myeloperoxidase and hydrogen peroxide. Cell lines stably expressing green fluorescent protein (GFP) targeted to the cell membrane were used to study injury-induced membrane blebbing, and XTT conversion was used to detect cell viability. RESULTS: High level of Hsp27 expression was detected in vivo in ganglion cells, RPE, and photoreceptor outer segments of rat retina. ARPE-19 cells also expressed high levels of Hsp27 in vitro. Oxidative injury in ARPE-19 cells resulted in transcriptional and translational activation of Hsp27 and induced extensive membrane blebbing. A high level of Hsp 27 protein was detected within membrane blebs. Increased expression of Hsp27 was also observed in differentiated ARPE-19 cells when compared with dividing cells. Higher Hsp27 levels in differentiated RPE cells correlated with increased viability and phenotypically different blebbing after exposure to the injury stimulus. In addition, sublethal injury doses caused a moderate amount of membrane blebbing, which was well tolerated by differentiated ARPE-19 cells. CONCLUSIONS: These results indicate that Hsp27 may be an important component of the RPE injury response and may contribute to injury-induced membrane blebbing in differentiated RPE cells. It is hypothesized that Hsp27 levels may play a role in disease states in the retina, such as ARMD.

Assessment of visual function in patients with gyrate atrophy who are considered candidates for gene replacement.

OBJECTIVE: To assess the course of change of visual function outcome variables in 5 patients with gyrate atrophy before a gene replacement therapy clinical trial. METHODS: The outcome variables selected were visual field sensitivity and electroretinogram amplitude. The course of change of these outcome variables was determined by calculation of their half-lives. RESULTS: In the 4 to 6 years during which each patient was followed up for this study, median visual field half-lives were 17.0 years (static perimetry) and 11.4 years (kinetic perimetry). Median electroretinogram half-lives were 16.0 years (maximal response) and 10.7 years (flicker response). CONCLUSIONS: The course of the decline of visual function outcome variables is frequently slow. Thus, a long-term clinical trial would be required to assess the efficacy of the intervention in the preservation of visual function.

Preparation of recombinant adenoviruses.

Adenoviruses are viruses with genomes of double-stranded DNA approx 36 kb in size. There are more than 100 different serotypes that have been identified, 47 of them of human origin. Human serotypes have been grouped into six subgenera (A-F) and whereas sequence similarity between genera is low, other molecular biologic aspects of the viruses are almost identical. Of all the human adenoviruses, serotypes 2 and 5 (subgenus C) have been the most extensively studied (1).

Immune-recovery uveitis in patients with cytomegalovirus retinitis taking highly active antiretroviral therapy.

PURPOSE: To investigate the clinical features associated with immune recovery in human immunodeficiency virus (HIV)-infected patients with cytomegalovirus retinitis who are taking highly active antiretroviral therapy. METHODS: Sixteen patients were evaluated prospectively at the National Eye Institute, Bethesda, Maryland. Evaluation included a medical history and a complete ophthalmologic examination. The examination included best-corrected visual acuity score measured by means of logarithmic charts, slit-lamp biomicroscopy, dilated retinal examination, retinal photography, and fluorescein angiography. Immune-recovery uveitis was defined as the ocular inflammation associated with clinical immune recovery in patients taking potent antiretroviral regimens. The ophthalmic characteristics of immune-recovery uveitis were identified, and their effect on visual acuity was statistically analyzed. RESULTS: The mean CD4+ T-lymphocyte count for the 16 patients taking highly active antiretroviral therapy at the time of evaluation was 393 cells/microl (range, 97-1,338 cells/microl). Immune-recovery uveitis was characterized by vitreitis and optic disk and macular edema. Clinically important complications of immune-recovery uveitis included cataract and epiretinal membrane formation. The visual acuity scores were significantly worse in the 23 eyes with cytomegalovirus retinitis (mean, 67.2 letters, 20/50) than in the nine eyes without cytomegalovirus retinitis (mean, 89.8 letters, 20/16) (P <.001). Regression analysis showed that a lower visual acuity score was associated with the presence of moderate to severe macular edema on fluorescein angiography and vitreous haze (P < or =. 001). CONCLUSIONS: Immune-recovery uveitis is an important cause of visual morbidity in HIV-infected patients with cytomegalovirus retinitis in the era of highly active antiretroviral therapy. Although immune recovery associated with highly active antiretroviral therapy has allowed some patients to discontinue specific anticytomegalovirus therapy, the rejuvenated immune response can be associated with sight-threatening inflammation.

Choroidal neovascularization in the rat induced by adenovirus mediated expression of vascular endothelial growth factor.

PURPOSE: To determine the effects of an adenovirus vector encoding vascular endothelial growth factor(165) (Ad.VEGF) delivered to the subretinal space in the rat. METHODS: An E1-deleted adenoviral vector encoding VEGF was injected into the subretinal space of Long-Evans rats. Immunohistochemistry identified VEGF expression. Histopathologic changes in the retina were determined by light and electron microscopy, immunohistochemistry, fluorescein angiography, and examination of wholemounts of choroid and retina. RESULTS: Increased expression of VEGF only in the retinal pigment epithelium (RPE) was detected after Ad.VEGF injection. Histopathology of these eyes revealed minimal subretinal exudation at 1 week followed by the appearance of vascular structures in the subretinal space by week 2, which persisted up to 4 weeks. Shortening of photoreceptor outer segments and reduction of the outer nuclear layer were present overlying areas of neovascularization. Fluorescein angiography of animals injected with fluorescein-dextran revealed a deep complex of new vessels. Choroidal flatmounts showed new vessel formation, verified by detection of endothelial cells via immunohistochemistry, arising from the choroid with absence of change in the overlying retinal vasculature. Electron microscopy confirmed the presence of sub-RPE endothelial cells and pericytes and the loss of integrity of Bruch's membrane, and serial sectioning demonstrated choroidal vascular growth through Bruch's membrane. CONCLUSIONS: These results support the hypothesis that overexpression of VEGF from RPE cells is capable of inducing choroidal neovascularization in the rat and provide a framework for further examining angiogenic processes in the RPE-choroid complex.

Saturation of, and competition for entry into, the apical secretory pathway.

To investigate mechanisms of apical sorting in the secretory pathway of epithelial cells, we expressed varying amounts of the 165 amino acid isoform of vascular endothelial growth factor (VEGF(165)) and transforming growth factor beta1 (TGF-beta1) via replication defective adenoviruses. Apical sorting of both proteins was efficient at low expression levels but saturated or was reversed at high expression levels. High expression levels of TGF-beta1 were effective at competing VEGF(165) out of the apical pathway; however, VEGF(165) did not compete out TGF-beta1. Tunicamycin inhibition experiments showed that the apical polarity of VEGF(165) was independent of N-glycosylation. We conclude that the apical sorting of these two molecules is a saturable, signal-mediated process, involving competition for apical sorting receptors. The sorting of the two proteins does not appear to involve N-glycans as sorting signals, or lectin sorters. The observations are particularly relevant to gene therapy because they demonstrate that overexpression of a transgene can result in undesirable missorting of the encoded protein.

Results after lens extraction in patients with diabetic retinopathy: early treatment diabetic retinopathy study report number 25.

OBJECTIVE: To assess the visual results after surgical lens removal in patients with diabetic retinopathy. DESIGN: A multicenter randomized clinical trial designed to assess the effect of photocoagulation and aspirin in patients with mild to severe nonproliferative or early proliferative diabetic retinopathy and/or macular edema. PARTICIPANTS: Of the 3711 patients enrolled in the Early Treatment Diabetic Retinopathy Study, lens surgery was performed on 205 patients (270 eyes) during follow-up that ranged from 4 to 9 years. OUTCOME MEASUREMENTS: Visual acuity, macular edema status, and degree of diabetic retinopathy. In addition, risk factors associated with lens extraction and with poor postoperative visual acuity (worse than 20/100) were assessed. RESULTS: The risk of lens extraction increased with increasing age, female sex, and baseline proteinuria. Ocular variables associated with increased risk of lens surgery included poor baseline visual acuity and vitrectomy performed during the course of the study. At 1 year after lens surgery, visual acuity improvement of 2 or more lines from preoperative levels occurred in 64.3% of the operated-on eyes assigned to early photocoagulation and 59.3% of eyes assigned to deferral of photocoagulation. In eyes assigned to early photocoagulation, 46% of eyes achieved visual acuity better than 20/40; 73%, better than 20/100; and 8%, 5/200 or worse at 1 year after surgery. Visual acuity results for eyes assigned to deferral of laser photocoagulation at 1 year were not as favorable; 36% achieved visual acuity better than 20/40; 55%, better than 20/100; and 17%, 5/200 or worse at 1 year after surgery. Evaluation of 1-year postoperative visual acuities for all eyes with mild to moderate nonproliferative diabetic retinopathy at the annual visit before lens surgery showed that 53% were better than 20/40; 90%, better than 20/100; and 1%, 5/200 or worse. However, for eyes with severe nonproliferative or worse retinopathy at the annual visit before lens surgery, only 25% were better than 20/40; 42%, better than 20/100; and 22%, 5/200 or worse at 1 year after lens surgery. There was little change in visual acuity between 1 and 2 years postoperatively. Increased severity of retinopathy and poor visual acuity before surgery were associated with visual acuity of worse than 20/100 at 1 year after surgery. Lens surgery was associated with a borderline statistically significant increased risk of progression of diabetic retinopathy in the adjusted analyses (P = .03). No statistically significant long-term increased risk of macular edema was documented after lens surgery. CONCLUSIONS: Visual acuity results after lens surgery in patients in the Early Treatment Diabetic Retinopathy Study were better than published results for similar patients. This may be because of more intensive photocoagulation for lesions of diabetic retinopathy in the Early Treatment Diabetic Retinopathy Study than in previously reported studies. Although patients with severe nonproliferative retinopathy or worse before lens surgery had poorer visual results, visual improvement was seen in 55% of these patients at 1-year follow-up. The main causes of poor visual results in eyes after lens surgery were complications of proliferative retinopathy and/or macular edema.

Gene therapy in the treatment of ocular inflammation.

Gene therapy may become a powerful therapeutic modality in the treatment of both ocular inflammatory disease and as a means of preventing rejection following tissue transplantation. By directly introducing into ocular cells genes that encode proteins capable of down-regulating the immune response, gene therapy has potential for both therapy and as a method for studying mechanisms of disease. While marked and rapid advances in the study of gene therapy have been realized, technical questions regarding the appropriate vector or the choice of efficacious immunomodulatory protein still remain.

Cloning and characterization of a novel orphan G-protein-coupled receptor localized to human chromosome 2p16.

We report the identification and characterisation of a novel human orphan G-protein-coupled receptor (GPR) which maps to chromosome 2p16. We have determined the full-length coding sequence and genomic structure of a gene corresponding to the anonymous expressed sequenced tag, WI-31133. This gene encodes a novel protein that is 540 amino acids in length. Protein sequence analysis predicts the presence of seven transmembrane domains, a characteristic feature of GPRs. In situ hybridisation to human retina and Northern blot analysis of human retinal pigment epithelium (RPE) showed localisation of this transcript to the RPE and cells surrounding retinal arterioles. In contrast, the transcript was localised to the photoreceptor inner segments and the outer plexiform layer in mouse sections. Northern blot analysis demonstrated a 7 kb transcript highly expressed in the brain. No mutations were identified during a screen of patients suffering from Doyne's honeycomb retinal dystrophy (DHRD), an inherited retinal degeneration which maps to chromosome 2p16.

Apical polarity of N-CAM and EMMPRIN in retinal pigment epithelium resulting from suppression of basolateral signal recognition.

Retinal pigment epithelial (RPE) cells apically polarize proteins that are basolateral in other epithelia. This reversal may be generated by the association of RPE with photoreceptors and the interphotoreceptor matrix, postnatal expansion of the RPE apical surface, and/or changes in RPE sorting machinery. We compared two proteins exhibiting reversed, apical polarities in RPE cells, neural cell adhesion molecule (N-CAM; 140-kD isoform) and extracellular matrix metalloproteinase inducer (EMMPRIN), with the cognate apical marker, p75-neurotrophin receptor (p75-NTR). N-CAM and p75-NTR were apically localized from birth to adulthood, contrasting with a basolateral to apical switch of EMMPRIN in developing postnatal rat RPE. Morphometric analysis demonstrated that this switch cannot be attributed to expansion of the apical surface of maturing RPE because the basolateral membrane expanded proportionally, maintaining a 3:1 apical/basolateral ratio. Kinetic analysis of polarized surface delivery in MDCK and RPE-J cells showed that EMMPRIN has a basolateral signal in its cytoplasmic tail recognized by both cell lines. In contrast, the basolateral signal of N-CAM is recognized by MDCK cells but not RPE-J cells. Deletion of N-CAM's basolateral signal did not prevent its apical localization in vivo. The data demonstrate that the apical polarity of EMMPRIN and N-CAM in mature RPE results from suppressed decoding of specific basolateral signals resulting in randomized delivery to the cell surface.

Disparity between fundus camera and scanning laser ophthalmoscope indocyanine green imaging of retinal pigment epithelium detachments.

PURPOSE: Indocyanine green (ICG) angiograms of each of five patients with retinal pigment epithelium (RPE) detachments were made using first a Topcon fundus camera and then a Heidelberg scanning laser ophthalmoscope (SLO); for each patient, both types of angiograms were obtained on the same day. In each case, the serous fluid appeared bright throughout the fundus camera studies and dark throughout the SLO studies. This study sought to explain the disparity in the appearance of the lesions in the two kinds of images and to determine whether there was dye in the serous fluid. METHODS: Simple model eyes were constructed to demonstrate the effects of Mie light scatter and integrating sphere behavior of the sclera on ICG image formation by the fundus camera and SLO optics. Analysis was made of both the clinical angiograms and model eye images to structure an explanation for the disparate RPE detachment angiographic images. RESULTS: Indocyanine green fluorescent light from choroidal vessels adjacent to the lesions and scattered by the turbid serous fluid accounted for the lesion brightness seen in the fundus camera images. The models confirmed that SLOs suppress scattered light. CONCLUSIONS: The apparent fluorescence of serous fluid beneath RPE detachments in fundus camera early-phase ICG angiogram images is not attributable to the presence of dye; rather, it appears to be attributable to serous fluid light scatter of fluorescent light arising from adjacent fluorescent structures. This light scatter is a consequence of the fundus camera illumination and recording optics and is not present in SLO-generated images. The necessity of understanding such phenomena as absorption, diffraction, polarization, and scatter of light and routinely applying them to ICG angiogram interpretation is underscored when it is shown that they offer simple explanations for unusual or unexpected angiographic results, as in the case of the patients with RPE detachment discussed here.

Recombinant adenovirus-mediated gene transfer into the adult rat retina.

PURPOSE: The present study was designed to evaluate the feasibility of gene transfer into the retina of adult rats, using a recombinant replication-defective adenovirus vector expressing a reporter gene. METHODS: Purified recombinant adenovirus expressing beta-galactosidase (lacZ) (Ad5.hCMV.lacZ) at doses ranging from 1.4 x 10(2) to 1.4 x 10(6) plaque-forming units (pfu) were injected into the subretinal space of adult Lewis rats. The presence of lacZ was determined by histochemical assay and reverse transcription and polymerase chain reaction analysis (RT PCR) of total RNA extracted from eyes injected with recombinant adenovirus expressing lacZ. RESULTS: As assessed by biomicroscopy, the expression of lacZ was highest in the retinal pigment epithelium in a localized area corresponding to the site of injection. The level of lacZ expression was correlated with the amount of virus delivered to the subretinal space. Persistent but decreasing expression of lacZ was noted over time. RT PCR revealed the expression of messenger RNA for at least sixty days. CONCLUSIONS: The results of this study demonstrate that efficient and stable transfer of genetic material into the subretinal space of adult rats may be achieved using a recombinant adenoviral vector. The use of such vectors should prove useful in developing novel applications and approaches to the study of recombinant protein expression in vivo.

Retrovirus-mediated gene transfer of ornithine-delta-aminotransferase into keratinocytes from gyrate atrophy patients.

Gyrate atrophy is a progressive blindness associated with deficiency of ornithine aminotransferase (OAT). The strategy of using an autologous keratinocyte graft, modified to express high levels of OAT as an ornithine-catabolizing skin-based enzyme sink, is investigated. Two OAT-containing retroviral vectors were constructed with or without a resistance gene. When packaged in a retroviral vector particle generated with the gibbon ape leukemia (GALV) virus envelope (PG13), these vectors could readily transduce >50% of target keratinocytes. The transduced keratinocytes in culture expressed up to 75-fold more OAT than normal control keratinocytes and these gene-modified cells extracted [14C]ornithine more efficiently than controls. The vector prepared without neo transduced cells more efficiently and led to higher levels of OAT expression than the neo-containing vector. Ornithine catabolism was maintained at high levels when the transduced patient keratinocytes were differentiated in vitro as a multilayered cutaneous organoid.