RESUMEN

PURPOSE: To investigate the effect of transplanted amniotic membrane (AM) on subretinal wound healing. METHODS: Nine Danish Landrace pigs had surgical removal of retinal pigment epithelium (RPE) and mechanical damage of Bruch's membrane (BM) and served as a control group. 15 pigs additionally had AM transplanted to the subretinal space. RESULTS: AM significantly reduces choroidal neovascularisation when complete coverage of the induced defect is obtained (7 pigs) (P < 0.05). In cases where AM did not cover the rupture in BM choroidal tissue covered the transplanted membrane (8 pigs). AM is well tolerated in the subretinal space, causes only limited inflammation, and is covered with a monolayer of pigmented cells when in contact with the host RPE. CONCLUSIONS: AM modifies choroidal neovascularisation after BM damage and may serve as a basement membrane substitute for the RPE.

RESUMEN

To investigate the feasibility of transplanting human neural progenitor cells (hNPCs) to the retina of nonimmunosuppressed pigs, cultured hNPCs were injected into the subretinal space of 5 adult pigs after laser burns were applied to promote donor cell integration. Postoperatively, the retinal vessels appeared normal without signs of exudation, bleeding, or subretinal elevation. Eyes were harvested at 10-28 days. H&E consistently showed mild retinal vasculitis, depigmentation of the RPE, and marked mononuclear cell infiltrate in the choroid adjacent to the site of transplantation. Human-specific antibodies revealed donor cells in the subretinal space at 10-13 days and smaller numbers within the retina on days 12 and 13, with evidence suggesting a limited degree of morphological integration; however, no cells remained at 4 weeks. The strong mononuclear cell reaction and loss of donor cells indicate that modulation of host immunity is likely necessary for prolonged xenograft survival in this model.

RESUMEN

PURPOSE: To study the electrophysiological consequences of experimental branch retinal vein occlusion (BRVO) in pigs and the effect of dorzolamide. METHODS: BRVO was induced in 16 pigs by diathermia. At 4 weeks animals were examined with multifocal electroretinography (mfERG) before and after dorzolamide or vehicle. The direct component P1 (outer retina) and indirect component iN1 (inner retina) were analyzed. Ophthalmoscopy, fundus photography, and fluorescence angiography were performed. RESULTS: BRVO eyes displayed signs of retinal damage and ischemia on ophthalmoscopy, fundus photography, and fluorescence angiography. mfERGs were affected by surgery; amplitude ratios (BRVO/healthy) were less than one (P1 = 0.30 [0.20-0.45]; iN1 = 0.35 [0.23-0.54]), and implicit time ratios were above one (1.04 [1.03-1.06] and 1.03 [1.02-1.05)]. In healthy eyes, iN1 amplitudes after treatment normalized to baseline (after/before) were lower in dorzolamide-treated animals than in the vehicle group (P = 0.05). After dorzolamide iN1 amplitude ratios (BRVO/healthy) were significantly higher than after vehicle (P = 0.01) and were not significantly different from one (0.97 [0.74-1.26]), indicating that the iN1 amplitudes in BRVO eyes were not different from those in healthy eyes after dorzolamide. CONCLUSIONS: BRVO in pig eyes examined by mfERG is a promising model for testing new treatment strategies in retinal ischemia. The local effects of BRVO are detectable on the mfERG and can be altered by dorzolamide. The decreased iN1 amplitudes caused by dorzolamide in healthy eyes were not seen in BRVO eyes possibly because of an increase in preretinal oxygen tension and improved function of the ischemic retina counteracting the effect of inner retinal acidification.

Asunto(s)

RESUMEN

PURPOSE: To examine the effect of intravitreally injected bevacizumab (Avastin) on the histological and angiographic morphology of choroidal neovascularization (CNV) in a masked and placebo-controlled animal study. METHODS: Choroidal neovascularization was induced surgically in 11 porcine eyes by perforating Bruch's membrane with a retinal perforator. After closure of the ports used for the vitrectomy, which was performed to facilitate the Bruch's membrane rupture, 0.05 ml of either bevacizumab or Ringer-Lactat (placebo) was injected into the vitreous cavity. Eyes were enucleated after 14 days. Fundus photographs and fluorescein angiograms (FAs) were obtained immediately prior to enucleation. Sections of formalin- and paraffin-embedded eyes were examined by light microscopy and by immunohistochemical staining. RESULTS: Placebo-injected eyes exhibited the highest propensity to leak, with five of six eyes leaking on FA, whereas only one of five bevacizumab-injected eyes exhibited leakage. On histological examination, all 11 eyes contained CNV membranes of similar size, regardless of treatment. The number of vascular endothelial cells was significantly reduced (p = 0.03) in CNV membranes from eyes that had been injected with bevacizumab when compared with CNV membranes from placebo-injected eyes. There was a trend towards more retinal pigment epithelium cells (p = 0.16) and fewer glial fibres (p = 0.08) in membranes from bevacizumab-treated eyes compared with placebo-treated eyes. Bevacizumab was identified immunohistochemically in the inner limiting membrane (ILM) and to a lesser degree in the remaining retina. Strong staining was also detected in both retinal blood vessels and entire CNV membranes with no cellular predisposition. Vascular endothelial growth factor expression was found in the CNV membranes, in the ILM, in the ganglion cell layer, in Müller cells throughout the neuroretina and in retinal blood vessels. CONCLUSIONS: Bevacizumab significantly reduced the proliferation of vascular endothelial cells in CNV membranes and showed a strong trend towards a reduction of leakage from these membranes. After a single injection, bevacizumab did not exhibit a size reducing effect on CNV, but it was still present in the membranes 14 days after intravitreal injection.

Asunto(s)

RESUMEN

This study investigates whether intravitreal administration of glial cell line-derived neurotrophic factor (GDNF) enhances survival of NeuN positive retinal cells in a porcine model of retinal ischemia. 16 pigs were subjected to an ischemic insult where intraocular pressure was maintained at 5 mmHg below mean arterial blood pressure for 2 h. The mean IOP during the ischemic insult was 79.5 mmHg (s.e.m. 2.1 mmHg, n = 15). Three days after the insult the pigs received an intravitreal injection of GDNF microspheres or blank microspheres. The pigs were evaluated by way of multifocal electroretinography (mfERG), quantification of NeuN positive cells and evaluation of the degree of retinal perivasculitis and inflammation 6 weeks after the insult. In the post-injection eyes (days 14, 28 and 42), the ratios of the iN1 and the iP2 amplitudes were 0.10 (95% CI: 0.05-0.15) and 0.09 (95% CI: 0.04-0.16) in eyes treated with blank microspheres, and 0.24 (95% CI: 0.18-0.32) and 0.23 (95% CI: 0.15-0.33) in eyes treated with GDNF microspheres. These differences were statistically significant (P < 0.05). The number of NeuN positive cells in the area of the visual streak area was significantly higher in eyes injected with GDNF microspheres compared to eyes injected with blank microspheres. In eyes injected with GDNF microspheres the ganglion cell count was 9.5/field (s.e.m.: 2.1, n = 8), in eyes injected with blank microspheres it was 3.5/field (s.e.m.: 1.2, n = 7). This difference was statistically significant (P < 0.05). There was also a significant difference (P < 0.01) in the degree of perivasculiitis between GDNF treated eyes (median perivasculitis score 1.5) and blank treated eyes (median perivasculitis score 3.0). In conclusion, injection of GDNF microspheres 3 days after an ischemic insult results in functional and morphological rescue of NeuN positive cells in a porcine model of acute ocular ischemia.

Asunto(s)

RESUMEN

The purpose of this study was to establish, and characterize a porcine model of acute, controlled retinal ischemia. The controlled retinal ischemia was produced by clamping the ocular perfusion pressure (OPP) in the left eye to 5 mm Hg for 2 h. The OPP was defined as mean arterial blood pressure (MAP) minus the intraocular pressure (IOP). It was clamped to 0-30 mm Hg by continuous monitoring of MAP and adjustment of the IOP, which was controlled by cannulation of the anterior chamber. Inner retinal function was assessed by induced multifocal electroretinography (mfERG) with comparisons of the amplitudes obtained in the experimental, left eye, and the control, right eye. Quantitative histology was performed to measure the survival of ganglion cells, amacrine cells and horizontal cells 2-6 weeks after the ischemic insult. An OPP of 5 mm Hg for 2h induced significant reductions in the amplitudes of iN1 to 20% (CI: 13-30%), and iP2 to 14% (95% CI: 8-22%) of their baseline values. No signs of recovery were found within the 6-week observation period. Quantitative histology revealed a highly significant reduction in the number of ganglion cells, amacrine cells and horizontal cells after the ischemic insult. This model seems to be suitable for investigations of therapeutic initiatives in diseases involving acute retinal ischemia.

Asunto(s)

Asunto(s)

RESUMEN

PURPOSE: This study aimed to investigate the spatial resolution of a porcine multifocal electroretinogram (mfERG) protocol by testing its ability to detect laser-induced retinal lesions. Furthermore, we wanted to describe time-dependent changes in implicit time and amplitude of the different mfERG peaks after laser-induced retinal damage. METHODS: Three pigs underwent a three-port pars plana vitrectomy, followed by laser photocoagulation of different lesion sizes within the visual streak. In an additional six non-vitrectomized pigs, we studied changes in mfERG signals with time after a uniform laser photocoagulation within the visual streak. The animals were evaluated with mfERG 1 and 6 weeks after treatment. After the last mfERG examination, selected eyes were processed for histological examination. RESULTS: The size of the smallest lesion detected was approximately 1/4 of the longest diameter of the optic disc (LDOD) measured in pixels. When analysing the uniform lesions we found that signals deriving from the centre of the laser lesions were characterized by a significant reduction in the amplitude of all three peaks after 1 week of observation. After 6 weeks, the amplitudes of P1 and N2 were still significantly reduced. The implicit times were unaffected by laser treatment in the acute phase. After 6 weeks only P1 was significantly delayed. CONCLUSION: We have determined the spatial resolution of the mfERG in the porcine retina to be smaller than or equal to the area of two adjacent hexagons, corresponding to a width of approximately 288 pixels or 1.2 mm. Laser lesions of uniform size resulted in a significant reduction of the amplitudes 1 and 6 weeks after treatment.

Asunto(s)

RESUMEN

PURPOSE: To study an expanded time course of surgically induced choroidal neovascularization (CNV) in a porcine model applying fluorescence angiography and immunohistology. METHODS: Twenty-two porcine eyes underwent vitrectomy, a retinal bleb was raised and the detached retina perforated using endodiathermy. Bruch's membrane was perforated with a retinal perforator at a site where the overlying neuroretina was normal. Eyes were enucleated in a time interval between 30 min and 42 days after the perforation, and the pigs were subsequently killed. Immediately prior to enucleation, fundus photographs and fluorescein angiograms were obtained. Sections of paraffin-embedded eyes were immunohistochemically stained. RESULTS: On fluorescein angiography, membranes aged 14 days or less exhibited leakage in 10/11 cases while the remaining showed persistent staining. The propensity to leak diminished with time and only 1/3 of the oldest membranes leaked. In eyes enucleated immediately after surgery, neuroretinas overlying the induced lesions were intact without apparent atrophy of cells. At day 3, macrophages and myofibroblasts formed membrane-like structures in the subretinal space. At day 7, the outer surface of the membrane was covered by retinal pigment epithelium (RPE) cells and the neuroretinas had suffered damage in the form of outer segment loss. In the time period 14-42 days, the CNV membrane became completely enveloped by RPE cells. The degree of membrane vascularization increased with time and was at its maximum after 42 days. Intact outer segments were identified over the oldest membranes. CONCLUSION: The formation of surgical CNV membranes followed the normal reparatory pathway and the degree of vascularization of CNV membranes continued to increase during the 42 days. However, propensity to leak diminished with time. We believe that this was because of the fact that RPE cells completely enveloped older membrane and thus prevented leakage from the newly formed vessels. Photoreceptor outer segments, which had atrophied after 7 days, were able to regenerate over CNV membranes and could be identified again after 42 days.

Asunto(s)

RESUMEN

Work in rodents has demonstrated that progenitor transplantation can achieve limited photoreceptor replacement in the mammalian retina; however, replication of these findings on a clinically relevant scale requires a large animal model. To evaluate the ability of porcine retinal progenitor cells to survival as allografts and integrate into the host retinal architecture, we isolated donor cells from fetal green fluorescent protein (GFP)-transgenic pigs. Cultures were propagated from the brain, retina, and corneo-scleral limbus. GFP expression rapidly increased with time in culture, although lower in conjunction with photoreceptor markers and glial fibrillary acid protein (GFAP), thus suggesting downregulation of GFP during differentiation. Following transplantation, GFP expression allowed histological visualization of integrated cells and extension of fine processes to adjacent plexiform layers. GFP expression in subretinal grafts was high in cells expressing vimentin and lower in cells expressing photoreceptor markers, again consistent with possible downregulation during differentiation. Cells survived transplantation to the injured retina of allorecipients at all time points examined (up to 10 weeks) in the absence of exogenous immune suppression without indications of rejection. These findings demonstrate the feasibility of allogeneic progenitor transplantation in a large mammal and the utility of the pig in ocular regeneration studies.

Asunto(s)

RESUMEN

PURPOSE: To study the effect of dorzolamide on the preretinal oxygen tension (RPO(2)) in retinal areas affected by experimental branch retinal vein occlusion (BRVO) in pigs. METHODS: Experimental BRVO was induced by diathermy close to the optic disc. RPO(2) was measured with an oxygen-sensitive electrode 0.5 mm above the BRVO-affected area, which was compared to the retinal areas not affected by BRVO. In one group of five pigs, RPO(2) was measured at baseline, 1 and 3 hours after BRVO, and after intravenous injection of 500 mg dorzolamide. In a second group of five pigs, RPO(2) was measured 1 week after the BRVO, both before and after intravenous injection of 500 mg dorzolamide. RESULTS: The average baseline RPO(2) was 2.64 +/- 0.09 kPa (mean +/- SD). In the BRVO-affected areas, RPO(2) decreased significantly (by 0.67 +/- 0.29 and 0.94 +/- 0.13 kPa) at 1 hour and 3 hours after BRVO induction. In the non-BRVO areas RPO(2) increased significantly (by 0.51 +/- 0.14 kPa) 1 hour after BRVO induction, but subsequently decreased and reached baseline 3 hours after BRVO induction. One week after BRVO induction, RPO(2) was 0.67 +/- 0.29 kPa lower in affected areas when compared with the non-BRVO areas. In the BRVO-affected areas, dorzolamide increased RPO(2) significantly (by 0.36 +/- 0.21 kPa at 3 to 4 hours and by 0.67 +/- 0.40 kPa) 1 week after BRVO induction. CONCLUSIONS: Retinal hypoxia induced by experimental BRVO remained significant 1 week after BRVO. Dorzolamide increased retinal oxygen tension in the BRVO-affected areas both at 4 hours and 1 week after experimental BRVO in pigs.

Asunto(s)

RESUMEN

PURPOSE: The aim of the study was to determine the type and magnitude of detectable changes in pig multifocal electroretinography (mfERG) induced by the vitreoretinal surgical procedures necessary to gain access to the subretinal space. METHODS: Twenty pigs underwent posterior segment surgery. Six animals had a vitrectomy (V), six had in addition a retinal bleb detachment (V + B); five had in addition a retinal diathermia on the bleb (V + B + D) and three received a retinotomy in the diathermized retinal area (V + B + D + R). mfERG evaluation was performed at baseline and 1 and 6 weeks postoperatively. Selected eyes were enucleated for histological evaluation. RESULTS: The retinal detachments blebs all reattached spontaneously. All four surgical sequences resulted in slight, non-significant changes in the mfERG peaks. A trend towards an amplitude reduction of the mfERG peaks N1, P1 and N2 were observed within the first postoperative week. After 6 weeks, all amplitudes had normalized. Of the implicit times only that of peak N1 (after retinal diathermia) was prolonged significantly at 1 week (P = 0.037). However, it returned to the preoperative level after 6 weeks. Histologically, the retinal detachment bleb was characterized by transient double layering of the retinal pigment epithelium (RPE) and loss photoreceptor outer segments. CONCLUSION: Access to the subretinal space in pigs can be gained without permanent detectable changes in the mfERG. A short-term retinal detachment was found to cause only reversible electrophysiological and histological changes in the outer retina, which suggests that this procedure is tolerated well in the porcine retina. The size of the known destructive lesion (retinotomy) was too small to be detected, given the spatial resolution of the mfERG method applied. In the future, the presented protocol can be used to assess the functional outcome of surgery and transplantation in the subretinal space in pigs.

Asunto(s)

RESUMEN

PURPOSE: To establish a method allowing multifocal electroretinography (mfERG) recording with simultaneous fundus monitoring on anaesthetized pigs. In addition we characterize the peaks of the porcine mfERG trace, and compare the visual streak area with the optic nerve head, a known non-response area. Finally we illustrate the feasibility of the method by performing mfERG after an induced laser burn in the visual streak. METHODS: Fifteen pigs underwent mfERG recordings at baseline, and after 1 and 6 weeks of observation. One pig was evaluated before and after retinal diode laser treatment in the visual streak. RESULTS: The porcine mfERG trace appears similar to the human mfERG trace, and can be described by three peaks named N1, P1 and N2. Significantly faster implicit time was found in the visual streak regarding N1 (P < 0.001) than in areas outside the visual streak. Amplitudes of all three peaks were increased in the visual streak (P < 0.005). The laser-treated area was characterized by a response similar to what is found at the location of the optic nerve head. CONCLUSION: Porcine mfERG is similar in appearance to the human response and can be described by the same three peaks. Significantly higher amplitudes of all three peaks are found in the visual streak when compared to the optic nerve head and inferior retina. We have detected the functional deficit caused by a laser burn at the size of 3 x 3 mm.

Asunto(s)

RESUMEN

Work in rodents has shown that cultured retinal progenitor cells (RPCs) integrate into the degenerating retina, thus suggesting a potential strategy for treatment of similar degenerative conditions in humans. To demonstrate the relevance of the rodent work to large animals, we derived progenitor cells from the neural retina of the domestic pig and transplanted them to the laser-injured retina of allorecipients. Prior to grafting, immunocytochemical analysis showed that cultured porcine RPCs widely expressed neural cell adhesion molecule, as well as markers consistent with immature neural cells, including nestin, Sox2, and vimentin. Subpopulations expressed the neurodevelopmental markers CD-15, doublecortin, beta-III tubulin, and glial fibrillary acidic protein. Retina-specific markers expressed included the bipolar marker protein kinase Calpha and the photoreceptor-associated markers recoverin and rhodopsin. In addition, reverse transcription-polymerase chain reaction showed expression of the transcription factors Dach1, Hes1, Lhx2, Pax6, Six3, and Six6. Progenitor cells prelabeled with vital dyes survived as allografts in the subretinal space for up to 5 weeks (11 of 12 recipients) without exogenous immune suppression. Grafted cells expressed transducin, recoverin, and rhodopsin in the pig subretinal space, suggestive of differentiation into photoreceptors or, in a few cases, migrated into the neural retina and extended processes, the latter typically showing radial orientation. These results demonstrate that many of the findings seen with rodent RPCs can be duplicated in a large mammal. The pig offers a number of advantages over mice and rats, particularly in terms of functional testing and evaluation of the potential for clinical translation to human subjects. Disclosure of potential conflicts of interest is found at the end of this article.

Asunto(s)

RESUMEN

PURPOSE: To study topographical differences in porcine retinal pigment epithelial (RPE) cell proliferation (1) in vivo, after experimental central surgical subretinal injury, and (2) in vitro. METHODS: Domestic pigs underwent either experimental RPE debridement (n = 5), subretinal amniotic membrane transplantation (n= 4), or both (n= 1) in the left eye. RPE cell proliferation was assayed by injection of the thymidine analogue 5-bromodeoxyuridine (5-BrdU) at postoperative day 0 and 1. RPE cells in S-phase were identified by their incorporation of 5-BrdU, as detected by immunohistochemistry. The in vitro proliferation of primary RPE isolates from the peripheral and central retina was assayed by a colorimetric assay and by [(3)H]thymidine incorporation. RESULTS: After subretinal surgery, in vivo incorporation of 5-BrdU was seen in peripheral RPE cells in 8 of 10 surgically treated eyes, but never in central RPE cells. This observation was true of both types of experimental surgery performed. In vitro, RPE isolates from the pre-equatorial region consistently yielded higher cell densities than did RPE cell isolates from more central parts of the epithelium. This was apparent through the three first passages of porcine RPE cells in culture. After 1 and 4 days in culture, pre-equatorial RPE cells had incorporated significantly more [(3)H]thymidine than had the more central RPE cells. CONCLUSIONS: Experimental subretinal surgical injury of the RPE below the central retina is followed within 48 hours by a peripheral, but not a central, proliferation of RPE cells. In vitro, peripheral RPE cells have a higher proliferative capacity than do central RPE cells.

Asunto(s)

RESUMEN

PURPOSE: To develop a reproducible surgical technique for the induction of choroidal neovascularization (CNV) in the subretinal space of porcine eyes and to analyse the resulting CNV clinically and histologically. METHODS: Two different modifications of a surgical technique previously described were compared with the original method. In ten porcine eyes retinal pigment epithelial (RPE) cells were removed using a silicone tipped cannula, in ten porcine eyes Bruch's membrane was perforated once with a retinal perforator without prior RPE removal and in ten eyes RPE removal was followed by a single perforation of Bruch's membrane. Fifteen of the eyes, five from each group, were enucleated 30 minutes after surgery, while the remaining eyes were enucleated after 14 days. Prior to enucleation, at day 14, fundus photographs and fluorescein angiograms were obtained. Eyes were examined by light microscopy and by immunohistochemical staining. In addition to these 30 eyes, two eyes underwent surgery with the purpose of subsequent scanning electron microscopic (SEM) examination. RESULTS: In eyes enucleated immediately after surgery neuroretinas overlying the induced lesions were intact without apparent atrophy of cells regardless of the surgical technique applied. The process of RPE removal was found to induce breaks in Bruch's membrane and both the size and the number of breaks varied between eyes. CNV membranes were identified in 15 of 15 eyes enucleated after 14 days. CNV membranes induced by perforation of Bruch's membrane without prior RPE removal were significantly thicker than membranes from eyes undergoing both RPE removal and Bruch's perforation (p = 0.03) and also thicker than membranes from eyes with only RPE-removal (p < 0.01). CNV membranes from eyes with perforation of Bruch's membrane without prior RPE removal had a higher cellular content and were more richly vascularized and also exhibited the highest propensity to leak in fluorescense angiograms. CONCLUSION: All three surgical techniques were capable of inducing CNV, but the one applying perforation of Bruch's membrane without RPE removal was easier to reproduce and involved fewer variables than the techniques utilizing RPE removal. The presence of RPE cells seems to affect both the morphology and cellular composition of induced CNV.

Asunto(s)

RESUMEN

We evaluated the host response to murine retinal progenitor cells (RPCs) following transplantation to the subretinal space (SRS) of the pig. RPCs from GFP mice were transplanted subretinally in 18 nonimmunosuppressed normal or laser-treated pigs. Evaluation of the SRS was performed on hematoxylin-eosin (H&E)-stained sections. Serum samples were taken from naive and RPC-grafted pigs and mouse-reactive antibody responses were assessed. At 1 week, histology showed a few perivascular lymphocytes consistent with a mild retinal vasculitis, and depigmentation of the RPE with large numbers of mononuclear inflammatory cells in the choroid near the transplantation site. Large choroidal infiltrates were evident at 2-5 weeks. Serum from naive and RPC-xenografted pigs contained significant levels of preformed IgG and IgM antibodies against murine antigens. Xenogeneic RPCs transplanted to the porcine SRS induced mononuclear infiltration in the choroid with graft rejection occurring over 2-5 weeks. Serum analysis confirmed that mice and pigs are discordant species; however, a cell-mediated acute mechanism appears to be responsible, rather than an antibody-mediated rejection.

Asunto(s)

RESUMEN

OBJECTIVE: To investigate the survival, integration, and differentiation of mouse retinal progenitor cells after transplantation to the subretinal space of adult pigs. METHODS: Green fluorescent protein-positive (GFP+) murine retinal progenitor cells were transplanted subretinally as single cells, spheres, or biodegradable polymer-progenitor composites into 24 nonimmunosuppressed adult pigs. Of these, 14 pigs received laser lesions (n = 11) or outer retinal scraping injury (n = 3). Recipients were killed at 30 minutes to 5 weeks after grafting. RESULTS: The GFP+ murine retinal progenitor cells survived well for up to 14 days after transplantation to the pig retina. After 5 weeks, fewer GFP+ cells were found. In the pigs that received laser treatment before grafting of cell suspension, GFP+ cells integrated into the retinal pigment epithelium and all layers of the retina. The GFP+ cells exhibited morphologic evidence of differentiation into mature retinal neurons, although evaluation of marker expression found only nestin and glial fibrillary acidic protein colocalization. In noninjured pigs, cells mainly integrated into the retinal pigment epithelium. In pigs that received composites, cells appeared to mature and extended processes through pores in the polymer matrix. CONCLUSIONS: Retinal progenitor cell xenografts survive for a sufficiently long period to integrate into areas of injury and exhibit morphologic differentiation. By 5 weeks, survival diminishes. Biodegradable polymers may be useful for transplanting retinal progenitor cells in a structurally organized manner. Clinical Relevance Central nervous system (CNS) diseases may cause long-term disabilities. Substantial tissue destruction can be sustained by the complex structures of the brain, spinal cord, or retina without loss of life, yet the lack of effective CNS regeneration frequently results in disruption of activities of daily living and marked degradation in quality of life. It has become clear that an enormous potential for repair is present within the mammalian CNS. The challenge is to harness this potential to treat disease. Transplantation of neuronal tissue to the CNS represents a promising, albeit challenging, approach to the replacement of neurons lost owing to injury or disease.

Asunto(s)

RESUMEN

PURPOSE: To characterize the phenotype of two families with high hypermetropia from the Faroe Islands. METHODS: Ophthalmologic evaluation including ultrasound oculometry and anthropometric measurements. RESULTS: Of the 40 examined family members, 15 individuals (8 males, 7 females; ages: 6-77 years; mean: 36.5 years) had small deep-set eyes with high hypermetropia (median: + 16.5 D; range: + 7.75 to + 22), short axial eye length (< 21 mm), and a thickened eye wall. The median corrected visual acuity was 0.4 (0.2-0.9). Ocular complications included angle-closure glaucoma in six eyes, uveal effusion in three eyes, cataract in two eyes, and esotropia with amblyopia in three eyes. An emergency case of uveal effusion and retinal detachment after Yag iridotomy eventually responded to systemic corticosteroids and scleral resection surgery with a slow visual recovery. No associated ocular or systemic malformations were found in the series. In addition to the two examined families, six smaller Faroese families with high hypermetropia are briefly reported. CONCLUSIONS: The study highlights the signs and symptoms of a rare hereditary phenotype characterized by a short axial length mainly confined to the posterior segment of the eye, a shallow anterior chamber, and a thickened eye wall. The morphological characteristics predispose for sight-threatening complications such as angle-closure glaucoma, chorioretinal pathology including uveal effusion, and amblyopia. Regular ophthalmic follow-up is therefore of obvious importance in families known to have small eyes/high hypermetropia. An endemic high prevalence in the Faroe Islands suggests the presence of a founder effect, and further genetic research would probably indicate pseudodominant rather than dominant transmission

Asunto(s)

RESUMEN

PURPOSE: To examine the in vivo pharmacokinetics of intravitreal 5-Fluorouracil (5-FU) following tamponade with 5-FU prodrug silicone oil formulations. METHOD: Two different alkoxycarbonyl 5-FU prodrugs denoted C12 and C18 were synthesized and formulated as silicone oil suspensions. A total of 26 pigs underwent conventional three-port lens-sparing pars plana vitrectomy. Approximately 1.6 ml of the prodrug-silicone oil formulation was placed in the vitreous cavity. Operated eyes were enucleated between 20 min and 168 hours postoperatively, and analysed for their content of free 5-FU by high performance liquid chromatography. RESULTS: With the C12 prodrug silicone oil formulation, the concentration of free 5-FU in the vitreous water phase 1 hour after surgery was 3.30 +/- 1.62 microg/ml. After 4 hours this concentration had declined to 1 microg/ml. With the C18 prodrug, the concentration of free vitreal 5-FU never reached 1 microg/ml during the 7 days these experiments lasted. A mathematical model is presented that can explain the measured data if the clearance of 5-FU from the vitreous water phase follows first order kinetics with a half-life of 20 min. CONCLUSION: These experiments, and the model analysis, suggest that the elimination half-life of 5-FU in the vitreous cavity of a vitrectomized, silicone oil-filled eye is very fast. The model analysis indicates that an alkoxycarbonyl 5-FU prodrug with a specific release rate constant of 10.7 microg/square root h cm(2) can maintain an intravitreal 5-FU concentration above 1 microg/ml for 5 days in the porcine eye.

Asunto(s)