How Does Blood-Retinal Barrier Breakdown Relate to Death and Disability in Pediatric Cerebral Malaria?

BACKGROUND: In cerebral malaria, the retina can be used to understand disease pathogenesis. The mechanisms linking sequestration, brain swelling, and death remain poorly understood. We hypothesized that retinal vascular leakage would be associated with brain swelling. METHODS: We used retinal angiography to study blood-retinal barrier integrity. We analyzed retinal leakage, histopathology, brain magnatic resonance imaging (MRI), and associations with death and neurological disability in prospective cohorts of Malawian children with cerebral malaria. RESULTS: Three types of retinal leakage were seen: large focal leak (LFL), punctate leak (PL), and vessel leak. The LFL and PL were associated with death (odds ratio [OR] = 13.20, 95% confidence interval [CI] = 5.21-33.78 and OR = 8.58, 95% CI = 2.56-29.08, respectively) and brain swelling (P < .05). Vessel leak and macular nonperfusion were associated with neurological disability (OR = 3.71, 95% CI = 1.26-11.02 and OR = 9.06, 95% CI = 1.79-45.90). Large focal leak was observed as an evolving retinal hemorrhage. A core of fibrinogen and monocytes was found in 39 (93%) white-centered hemorrhages. CONCLUSIONS: Blood-retina barrier breakdown occurs in 3 patterns in cerebral malaria. Associations between LFL, brain swelling, and death suggest that the rapid accumulation of cerebral hemorrhages, with accompanying fluid egress, may cause fatal brain swelling. Vessel leak, from barrier dysfunction, and nonperfusion were not associated with severe brain swelling but with neurological deficits, suggesting hypoxic injury in survivors.

Histopathological Changes and Clinical Outcomes following Intervention for Sub-Internal Limiting Membrane Haemorrhage.

INTRODUCTION: Haemorrhage confined to the sub-internal limiting membrane (ILM) space can be associated with good visual recovery. There is controversy as to the best management of purely sub-ILM haemorrhage, which ranges from observation to immediate surgical intervention. METHODS: We studied a retrospective case series of patients with sub-ILM haemorrhage who underwent vitrectomy with subsequent histological analysis of the removed ILM. RESULTS: Sixteen patients underwent vitrectomy for sub-ILM haemorrhage. Five patients had underlying Terson syndrome, 6 had ruptured macro-aneurysms, and 5 had Valsalva retinopathy. Seven patients demonstrated cellular proliferation on the retinal surface of the ILM with staining for glial fibrillary acidic protein and cytokeratin 7, as well as CD68pg and Prussian blue. All but 1 of these cases were isolated from patients undergoing surgery >4 weeks following initial symptoms, the other presented at >2 weeks. Serial optical coherence tomography (OCT) was available in 8 patients; serial OCT in patients with delayed intervention demonstrated persistent inner retinal layer hyper-reflectance. Fourteen of 15 patients demonstrated symptomatic recovery and showed visual improvement with acuity ranging from -0.1 to 1.8 (mean 0.43) within 3 months of intervention (1 was lost to follow-up). The post-operative vision was 0.11 logMAR (mean; range -0.1 to 0.4) at 3 months in the group with intervention within 2 weeks of symptoms, and 0.9 logMAR (mean; range 0.0 to HM) in the group with delayed surgery. CONCLUSIONS: Early surgical intervention for sub-ILM haemorrhage resulted in good visual outcomes; delayed surgery may lead to proliferative vitreoretinopathy-like changes on the inner retinal surface of the ILM, and untreated cases may demonstrate persistent inner retinal changes potentially limiting visual prognosis despite subsequent surgical intervention.

Severity of retinopathy parallels the degree of parasite sequestration in the eyes and brains of malawian children with fatal cerebral malaria.

BACKGROUND: Malarial retinopathy (MR) has diagnostic and prognostic value in children with Plasmodium falciparum cerebral malaria (CM). A clinicopathological correlation between observed retinal changes during life and the degree of sequestration of parasitized red blood cells was investigated in ocular and cerebral vessels at autopsy. METHODS: In 18 Malawian children who died from clinically defined CM, we studied the intensity of sequestration and the maturity of sequestered parasites in the retina, in nonretinal ocular tissues, and in the brain. RESULTS: Five children with clinically defined CM during life had other causes of death identified at autopsy, no MR, and scanty intracerebral sequestration. Thirteen children had MR and died from CM. MR severity correlated with percentage of microvessels parasitized in the retina, brain, and nonretinal tissues with some neuroectodermal components (all P < .01). In moderate/severe MR cases (n = 8), vascular congestion was more intense (ρ = 0.841; P < .001), sequestered parasites were more mature, and the quantity of extraerythrocytic hemozoin was higher, compared with mild MR cases (n = 5). CONCLUSIONS: These data provide a histopathological basis for the known correlation between degrees of retinopathy and cerebral dysfunction in CM. In addition to being a valuable tool for clinical diagnosis, retinal observations give important information about neurovascular pathophysiology in pediatric CM.

Cerebral malaria in children: using the retina to study the brain.

Cerebral malaria is a dangerous complication of Plasmodium falciparum infection, which takes a devastating toll on children in sub-Saharan Africa. Although autopsy studies have improved understanding of cerebral malaria pathology in fatal cases, information about in vivo neurovascular pathogenesis is scarce because brain tissue is inaccessible in life. Surrogate markers may provide insight into pathogenesis and thereby facilitate clinical studies with the ultimate aim of improving the treatment and prognosis of cerebral malaria. The retina is an attractive source of potential surrogate markers for paediatric cerebral malaria because, in this condition, the retina seems to sustain microvascular damage similar to that of the brain. In paediatric cerebral malaria a combination of retinal signs correlates, in fatal cases, with the severity of brain pathology, and has diagnostic and prognostic significance. Unlike the brain, the retina is accessible to high-resolution, non-invasive imaging. We aimed to determine the extent to which paediatric malarial retinopathy reflects cerebrovascular damage by reviewing the literature to compare retinal and cerebral manifestations of retinopathy-positive paediatric cerebral malaria. We then compared retina and brain in terms of anatomical and physiological features that could help to account for similarities and differences in vascular pathology. These comparisons address the question of whether it is biologically plausible to draw conclusions about unseen cerebral vascular pathogenesis from the visible retinal vasculature in retinopathy-positive paediatric cerebral malaria. Our work addresses an important cause of death and neurodisability in sub-Saharan Africa. We critically appraise evidence for associations between retina and brain neurovasculature in health and disease, and in the process we develop new hypotheses about why these vascular beds are susceptible to sequestration of parasitized erythrocytes.

Does the presence of an epiretinal membrane alter the cleavage plane during internal limiting membrane peeling?

PURPOSE: To determine whether the presence of a clinically and/or microscopically detectable epiretinal membrane (ERM) alters the cleavage plane during internal limiting membrane (ILM) peeling. DESIGN: Retrospective, observational, immunohistochemical study of ILM specimens using archival formalin-fixed, paraffin-embedded tissue. PARTICIPANTS: Fifty-one patients who had had ILM excision. METHODS: Fifty-one ILM specimens peeled during vitrectomy for various etiologies were examined by light microscopy. The removal of ILM was assisted using Trypan blue (n = 30), indocyanine green (n = 7), or brilliant blue G (n = 14). Monoclonal antibodies to glial fibrillary acidic protein and to neurofilament protein were used to detect glial or neuronal cells respectively on the vitreous or retinal surfaces of the ILM. Specimens were divided into 2 groups: ILM peeled for full-thickness macular hole (MH; n = 31) and ILM peeled after removal of clinically detectable ERM (n = 20). MAIN OUTCOME MEASURES: Primary outcome measure was the localization of immunohistochemical markers to neuronal or glial cells on the vitreous or retinal surfaces of ILM. The secondary outcome measure was the correlation of the results of the primary measure with the dyes used to facilitate ILM peeling. RESULTS: Glial and/or neuronal cells were detected on the retinal surface of the ILM in 10 of 31 (32%) of the MH ILM specimens and in 13 of 20 (65%) of the ILM peeled after ERM excision; the difference was significant (P = 0.02). There was no association between the presence of neuronal and glial cells with the type of dye used (P = 0.2). Of the 23 ILM specimens with cells attached to the retinal surface, 21 (91%) were associated with clinical and/or histologic evidence of ERM and 2 (9%) were not. The correlation between the presence of cells on the vitreous and the retinal surfaces of ILM was high (P<0.0001). CONCLUSIONS: The findings suggest that ERM may be associated with sub-ILM changes that alter the plane of separation during ILM peeling. This study does not confirm any influence of dyes on the cleavage plane during surgery.

The use of silicone oil-RMN3 (Oxane HD) as heavier-than-water internal tamponade in complicated inferior retinal detachment surgery.

BACKGROUND: Conventional silicone oil provides suboptimal support of the inferior retina. In this study we evaluated the efficacy of Oxane HD in the management of complex retinal detachments involving lower quadrants of the retina. METHODS: A prospective, interventional, comparative study. Eighteen patients were recruited. Treatment outcomes were compared with a historical control group of 14 patients. Patients with grade C3 PVR or greater and inferior retinal breaks, recurrent inferior retinal detachments (with or without PVR) and giant retinal tears were included. In those patients who re-detached under heavy silicone oil (n = 4), retro-oil epiretinal membranes (ERMs) were obtained at the time of subsequent surgery to analyse the immunopathological response to oxane HD. Immunohistochemistry was used to detect glia, retinal pigment epithelium cells (RPE), macrophages, T lymphocytes, or neural elements in the tissue using well-characterised monoclonal antibodies. RESULTS: Retinal attachment of the posterior pole following removal of silicone oil was achieved in 66.6% of the treatment group (n = 12) and 64.3% of controls (n = 9) (p = 1.0). Post-operative PVR developed in five patients in the treatment group (27.8%) and five control patients (35.8%). Following removal of silicone oil, residual oil was observed in 27.8% of the treatment group and 7.1% of controls. Median visual acuity, 3 months following removal of silicone oil, was 2.0 (IQR 0.9-2.0) in the treatment group and 1.0 (IQR 0.6-1.8) in the control group. Complications in the treatment group included, hypotony (n = 3), uveitis (n = 2), glaucoma (n = 1). All ERMs analysed demonstrated microscopic appearances typical of PVR. The membranes were fibrocellular in nature, contained RPE and glial cells, and variable amounts of intracellular and extracellular pigment. In addition, all had a dense infiltrate of vacuolated (presumed oil-filled) macrophages. CONCLUSION: We failed to observe an advantage following the use of Oxane HD in the treatment of inferior retinal detachments. Moreover, Oxane HD was difficult to remove and was associated with a higher incidence of complications.

Fibrous membranes in diabetic retinopathy and bevacizumab.

PURPOSE: The purpose of this study was to determine the histopathologic characteristics of bevacizumab-treated human proliferative diabetic retinopathy (PDR) membranes with particular regard to membrane vasculature as a step toward addressing the effects of the drug on PDR membranes. Intravitreous injection of bevacizumab, an antivascular endothelial growth factor monoclonal antibody, has recently been advocated as an adjunct in surgery for PDR. In this context, a clinically observed decrease in PDR epiretinal membrane vascularity (vascular regression) occurs from 24 hours to 48 hours after injection, but the exact mechanisms of drug action are unknown. METHODS: A consecutive series of seven PDR membrane specimens that had been removed sequentially from seven bevacizumab-treated patients were studied retrospectively. The membrane specimens were examined using light microscopic methods, including immunohistochemistry. RESULTS: Five of the seven membranes were clinically avascular (one contained "ghost" vessels) and did not hemorrhage during excision. Of these 5 specimens, which included 1 removed 7 days after a total of 6 intravitreous injections of 1.25 mg bevacizumab, 4 contained histologically detectable capillaries (1 did not). These blood vessels were lined by endothelial cells as determined by immunohistochemistry for the endothelial markers CD31 and CD34. The two remaining membranes were clinically and histologically still vascularized despite bevacizumab treatment. All the specimens also contained smooth muscle actin-containing fibroblastic cells within the collagenous stroma. CONCLUSION: The findings do not support the concept that the clinical phenomenon of vascular regression in PDR membranes after bevacizumab injection in the vitreous is resulting from obliteration of the membrane blood vessels. Another mechanism appears to be involved in at least some patients, possibly a vasoconstrictive response. Such a mechanism might explain reversal of the effects of bevacizumab that has been reported after this treatment.

Secretory proteostasis of the retinal pigmented epithelium: Impairment links to age-related macular degeneration.

Secretory proteostasis integrates protein synthesis, processing, folding and trafficking pathways that are essential for efficient cellular secretion. For the retinal pigment epithelium (RPE), secretory proteostasis is of vital importance for the maintenance of the structural and functional integrity of apical (photoreceptors) and basal (Bruch's membrane/choroidal blood supply) sides of the environment it resides in. This integrity is achieved through functions governed by RPE secreted proteins, which include extracellular matrix modelling/remodelling, angiogenesis and immune response modulation. Impaired RPE secretory proteostasis affects not only the extracellular environment, but leads to intracellular protein aggregation and ER-stress with subsequent cell death. Ample recent evidence implicates dysregulated proteostasis as a key factor in the development of age-related macular degeneration (AMD), the leading cause of blindness in the developed world, and research aiming to characterise the roles of various proteins implicated in AMD-associated dysregulated proteostasis unveiled unexpected facets of the mechanisms involved in degenerative pathogenesis. This review analyses cellular processes unveiled by the study of the top 200 transcripts most abundantly expressed by the RPE/choroid in the light of the specialised secretory nature of the RPE. Functional roles of these proteins and the mechanisms of their impaired secretion, due to age and genetic-related causes, are analysed in relation to AMD development. Understanding the importance of RPE secretory proteostasis in relation to maintaining retinal health and how it becomes impaired in disease is of paramount importance for the development and assessment of future therapeutic advancements involving gene and cell therapies.

Labeling of stem cells with monocrystalline iron oxide for tracking and localization by magnetic resonance imaging.

Precise localization of exogenously delivered stem cells is critical to our understanding of their reparative response. Our current inability to determine the exact location of small numbers of cells may hinder optimal development of these cells for clinical use. We describe a method using magnetic resonance imaging to track and localize small numbers of stem cells following transplantation. Endothelial progenitor cells (EPC) were labeled with monocrystalline iron oxide nanoparticles (MIONs) which neither adversely altered their viability nor their ability to migrate in vitro and allowed successful detection of limited numbers of these cells in muscle. MION-labeled stem cells were also injected into the vitreous cavity of mice undergoing the model of choroidal neovascularization, laser rupture of Bruch's membrane. Migration of the MION-labeled cells from the injection site towards the laser burns was visualized by MRI. In conclusion, MION labeling of EPC provides a non-invasive means to define the location of small numbers of these cells. Localization of these cells following injection is critical to their optimization for therapy.

Expression of hypoxia-inducible factor-1alpha and -2alpha in human choroidal neovascular membranes.

PURPOSE: Up-regulation of pro-angiogenic cytokine expression occurring secondary to hypoxia in physiologic and pathophysiologic conditions is mediated by the family of transcription regulators know as hypoxia inducible factors (HIF). The present study was undertaken to investigate the expression of HIF occurring in human choroidal neovascularization (CNV) and the posterior segment of young and old eyes. METHODS: Surgically excised CNV from patients with either age-related macular degeneration (AMD; n = 9), punctuate inner choroidopathy (PIC; n = 3) and young normal eyes were immunohistochemically probed with monoclonal antibodies against HIF-1alpha and -2alpha and compared to that for cell markers specific for vascular endothelial cells (CD34), macrophages (CD68), retinal pigment epithelial cells (RPE; panel cytokeratins/CK18) and VEGF. Following secondary antibody amplification, reactions were visualized with fast red chromogen. RESULTS: Cellular immunoreactivity of membranes for HIF-2alpha was strong in eight out of nine AMD specimens but it was only weakly positive for HIF-1alpha in five specimens. In contrast, two out of three PIC specimens were weakly positive for HIF-1alpha but demonstrated no staining for HIF-2alpha. Immunohistochemical analysis revealed areas within the CNV membranes that were predominantly immunopositive for CD68 and cytokeratin indicating the presence of RPE and/or macrophages and that these cells strongly co-localized with the presence of HIF and VEGF. No immunochemical co-localization was observed with HIF and the endothelial cell marker CD34 in any membranes studied. Normal globes also demonstrated HIF-2 positivity to be predominantly localized to the central RPE rather than peripheral RPE irrespective of age of donor. CONCLUSIONS: The localization of HIF expression supports the concept that hypoxia is a major stimulus for the development of submacular wound healing and within this context CNV is but one component of this process.

Expression of COX-2 and prognostic outcome in uveal melanoma.

PURPOSE: The expression of cyclooxygenase-2 (COX-2) and its prognostic value in uveal melanoma was examined. METHODS: Paraffin-embedded sections from 32 clinicopathologically well-characterized cases of primary uveal melanoma were immunohistochemically stained for COX-2. COX-2 expression was evaluated in terms of both the intensity and the extent of staining for each tumor. A COX-2 score encompassing both intensity and extent was also calculated for each specimen. RESULTS: 29 specimens (90.6%) contained moderate or intense positive immunoreactivity for COX-2. A statistically significant association (p<0.05) between COX-2 expression (intensity and score) and metastatic death was established. CONCLUSION: Upregulation of COX-2 expression appears to be associated with poor prognosis in uveal melanoma.

Neurovascular sequestration in paediatric P. falciparum malaria is visible clinically in the retina.

Retinal vessel changes and retinal whitening, distinctive features of malarial retinopathy, can be directly observed during routine eye examination in children with P. falciparum cerebral malaria. We investigated their clinical significance and underlying mechanisms through linked clinical, clinicopathological and image analysis studies. Orange vessels and severe foveal whitening (clinical examination, n = 817, OR, 95% CI: 2.90, 1.96-4.30; 3.4, 1.8-6.3, both p<0.001), and arteriolar involvement by intravascular filling defects (angiographic image analysis, n = 260, 2.81, 1.17-6.72, p<0.02) were strongly associated with death. Orange vessels had dense sequestration of late stage parasitised red cells (histopathology, n = 29; sensitivity 0.97, specificity 0.89) involving 360° of the lumen circumference, with altered protein expression in blood-retinal barrier cells and marked loss/disruption of pericytes. Retinal whitening was topographically associated with tissue response to hypoxia. Severe neurovascular sequestration is visible at the bedside, and is a marker of severe disease useful for diagnosis and management.

Trafficking of osteonectin by retinal pigment epithelial cells: evidence for basolateral secretion.

Osteonectin is a glycoprotein that modulates several aspects of cellular behaviour including proliferation and adhesion. The retinal pigment epithelium forms a continuous monolayer of polarised cells immediately bellow the neuroretina, and is integral to the homeostasis of photoreceptor cells. While osteonectin is expressed by normal retinal pigment epithelium in situ, its expression is significantly increased in retinal pigment epithelial cells associated with several common retinal diseases. This pattern of expression implies an important role for osteonectin in the biology of retinal pigment epithelial cells. However, the trafficking, processing, and eventual fate of osteonectin in these cells is not clear at present. Although the theoretical report of a leader sequence within the osteonectin open reading frame and its extracellular presence in some tissues indirectly support secretion of the protein, there is no direct experimental demonstration of the secretion route to date. As a first step towards understanding the role of osteonectin in retinal pigment epithelium, we studied the intracellular distribution and trafficking of the protein in living cells. Here, we present experimental evidence that a precursor osteonectin fusion protein is targeted to the endoplasmic reticulum/Golgi pathway, with a likely basal secretion in retinal pigment epithelial cells. In addition, we show that the precursor osteonectin protein having the leader sequence masked fails to undergo secretion leading to cell death, a phenotype which may be of relevance not only for retinal pathology, but also for other diseases such as the bone disorder known as pseudoachondroplasia that is associated with a lack of osteonectin secretion.

Cytogenetics of uveal melanoma: a 7-year clinical experience.

PURPOSE: Chromosome 3 loss and chromosome 8 gains in uveal melanoma are associated with metastatic death. Since 1999, we have offered cytogenetic analysis to patients treated by local resection or enucleation. This study correlated our cytogenetic results with clinical and histologic predictors and disease-specific mortality. DESIGN: Nonrandomized case series. PARTICIPANTS: Three hundred fifty-six patients with uveal melanoma with data on chromosome 3 and chromosome 8. METHODS: Tumor diameter was measured by echography. Cell type, presence of closed connective tissue loops, and mitotic rate were determined histopathologically. Fluorescence in-situ hybridization was performed using centromeric probes for chromosomes 3 and 8 and for c-myc. Patients were flagged at the National Health Service Cancer Registry, which notified us of any deaths. Statistics included Cox multivariate analysis and Kaplan-Meier analysis. MAIN OUTCOME MEASURES: Disease-specific mortality, according to clinical, histologic and cytogenetic features as well as correlation between cytogenetic variables and other mortality predictors, including a predictive index. RESULTS: The patients had a mean age of 61.9 years. The tumors showed no cytogenetic abnormalities of chromosomes 3 or 8 in 42%, chromosome 8 gains in 11%, monosomy 3 in 21%, and both abnormalities in 27%. These correlated with ciliary body involvement (P<0.001), extraocular spread (P = 0.007), large basal tumor diameter (P<0.001), epithelioid cellularity (P<0.001), closed connective tissue loops (P<0.001), and mitotic rate exceeding 4/40 high power fields (P<0.001). By the study close, 76 patients had died (67 from metastasis). Cox multivariate analysis showed the most significant factors to be basal tumor diameter (P<0.001), monosomy 3 (P<0.001), and epithelioid cellularity (P = 0.004). A predictive index (PI) was derived from these variables. Kaplan-Meier analysis showed that 5-year metastatic death rates ranged from 0% in 84 patients with low-grade melanoma (PI<19) to 66% in 100 patients with high-grade tumor (PI>26; 95% confidence interval, 53%-80%). CONCLUSION: Cytogenetic analysis of chromosomes 3 and 8 enhances prediction of disease-specific mortality after treatment of uveal melanoma but must be interpreted together with tumor diameter and cell type.

Thrombospondin 1, thrombospondin 2 and the eye.

Thrombospondin 1 and thrombospondin 2 (TSP1 and TSP2), which comprise the subgroup A thrombospondins, are matricellular proteins. As matricellular proteins, they modulate interactions between cells and the cellular environment, regulate cell adhesion and typically are expressed during tissue formative processes. In general, TSP1 and TSP2 counter angiogenesis (including tumour angiogenesis) and play important but contrasting roles during cutaneous repair. The two proteins are involved in development, including that of the eye, although evidence suggests that they have their greatest impact during tissue production in the adult. In the normal adult eye, they tend to be found at sites of ongoing matrix synthesis or cell-matrix interactions. At these sites, the two proteins possibly influence cellular differentiation and/or basement membrane deposition. TSP1 is also present in the intraocular fluids and drainage pathway, where it may function in maintaining the anti-angiogenic environment and in intraocular pressure control, respectively. TSP1 could also be involved in ocular immune privilege. Unlike in skin wounds, where TSP1 is derived from the blood and is present only in the early phases of repair, ocular tissue damage appears to lead to protacted TSP1 synthesis by local cells. This response might help suppress angiogenesis in the transparent tissues of the eye and so lessen visual axis opacification following injury. However, TSP2, which is also produced by damaged ophthalmic tissue and may be especially important in matrix organisation, seems to augment contraction in anomalous intraocular fibrosis. Elucidating the roles of TSP1 and TSP2 in ocular physiology and pathobiology may lead to improved therapies for neovascular, neoplastic, reparative and other ophthalmic diseases.

Neoplastic transformation of ciliary body epithelium is associated with loss of opticin expression.

BACKGROUND: Opticin is a recently discovered glycoprotein present predominantly in the vitreous humour. It is synthesised and secreted by the ciliary body epithelium (CBE) from the initiation of CBE development in the embryo, and production continues throughout life. AIM: To determine whether a variety of ciliary body tumours synthesise opticin to characterise further its role in ciliary body health and disease. METHODS: Immunohistochemistry was used to determine the distribution of opticin in normal human CBE, and in hyperplastic and neoplastic CBE lesions. RESULTS: Opticin was immunolocalised to the basal cell surface and basement membrane material of the non-pigmented CBE in nine donor eyes as well as four hyperplastic lesions of the CBE (Fuchs's adenoma). By contrast, none of eight neoplastic lesions (two adenoma and six adenocarcinoma) of CBE stained for opticin. CONCLUSION: The present series supports the theory that opticin is produced by the non-pigmented CBE throughout adult life. Loss of opticin expression by this tissue is associated with and could contribute towards neoplastic transformation.

The presence of AC133-positive cells suggests a possible role of endothelial progenitor cells in the formation of choroidal neovascularization.

PURPOSE: Recent evidence suggests that vasculogenesis as well as angiogenesis occurs throughout the body during neovascularization. The recruitment of circulating stem cells is a key feature of vasculogenesis. The purpose of the present study was to determine whether markers of endothelial progenitor cells (EPCs) are present in choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD). METHODS: Surgically excised CNV (n = 9) membranes from patients with AMD were probed with immunohistochemical techniques using the following monoclonal antibodies: AC133 a putative marker of EPCs and hematopoietic stem cells (HSCs); the endothelial cells markers CD31, CD34, and von Willebrand factor (vWF); and cytokeratins and CD68, markers for retinal pigment epithelium (RPE) and macrophages, respectively. After secondary antibody amplification, reactions were visualized with fast red substrate. RESULTS: Six of nine specimens demonstrated cells positive for AC133 that were all found within predominantly cellular regions of the specimens. In the avascular fibrous stromal core of all specimens, the predominant cells were RPE cells and macrophages. The peripheral component of all CNV membranes was highly vascular and showed varying immunoreactivity for all endothelial markers. The greatest immunoreactivity for endothelial markers was observed with CD34 and vWF and least for CD31. CONCLUSIONS: These findings support animal studies that vasculogenesis, in addition to angiogenesis, may contribute to the neovascularization that occurs in AMD.

Transretinal choroidal tumor biopsy with a 25-gauge vitrector.

OBJECTIVE: To describe and evaluate transretinal biopsy of choroidal tumors using 25-gauge vitrectomy instrumentation. DESIGN: Retrospective, consecutive, noncomparative case series. PARTICIPANTS: Fourteen patients undergoing choroidal tumor biopsy at an ocular oncology center. METHODS: The biopsies were performed under local or general anesthesia, alone or in combination with ruthenium plaque or tantalum marker insertion. Immunohistochemistry was performed on all samples, and some melanomas were also analyzed cytogenetically. RESULTS: Surgery was uneventful in all cases. A positive tissue diagnosis was made in 13 of 14 patients, albeit at the second attempt in 1 patient. The only failure occurred because the tumor was calcified. CONCLUSION: Transretinal choroidal biopsy with 25-gauge instrumentation yields a larger sample than fine-needle aspiration biopsy, usually producing sufficient tissue for cytogenetic studies. We did not identify safety concerns in this series of patients. Insufficient samples can occur in some patients, and further studies are needed to understand the reason for such failure.

Expression of ADAMTS metalloproteinases in the retinal pigment epithelium derived cell line ARPE-19: transcriptional regulation by TNFalpha.

ADAMTS (A Disintegrin-like And Metalloprotease domain with ThromboSpondin type I motifs) are multidomain proteins with demonstrated metalloproteinase functionality and have potential roles in embryonic development, angiogenesis and cartilage degradation. We present here investigations of ADAMTS expression in an ocular cell type, ARPE-19, with a view to implicating them in retinal matrix turnover. Expression analysis was undertaken using a combination of reverse transcription polymerase chain reaction (RT-PCR) and Northern blotting experiments, which together detected the expression of mRNAs for several ADAMTS proteins, all of which have active site motifs characteristic of matrix metalloproteases (MMPs). These included ADAMTS1, ADAMTS2, ADAMTS3, ADAMTS5, ADAMTS6, ADAMTS7 and ADAMTS9. The expression of mRNA isoforms for ADAMTS7 and ADAMTS9 were also detected. Following stimulation with TNFalpha, ADAMTS1, ADAMTS6 and both ADAMTS9 transcripts expressed in ARPE-19 cells showed a potent upregulation. The expression of ADAMTS genes in ARPE-19 cells and the transcriptional stimulation of some family members by TNFalpha may implicate them in inflammatory eye disease and the compromise of retinal matrix structure, which is evident in age-related macular degeneration (ARMD) and other retinal pathologies.