Hardeep Singh Mudhar

LOSS OF CORNEAL EPITHELIAL STEM CELL PROPERTIES IN OUTGROWTHS FROM HUMAN LIMBAL EXPLANTS CULTURED ON INTACT AMNIOTIC MEMBRANE

BACKGROUND The corneal epithelium is renewed by stem cells located at the limbus, the so-called limbal stem cells (LSCs). Absence, damage or loss of the LSC population leads to the painful and blinding condition of LSC deficiency (LSCD). Ex vivo expansion of LSCs is an increasingly well recognized treatment modality for LSCD. One method of ex vivo expansion of LSCs involves the culture of limbal explants on amniotic membrane (AM). The purpose of this study was to analyze the outgrowths from human cadaveric limbal explants cultured on AM for properties associated with LSCs. In particular, the expression of putative stem cell markers and the colony-forming efficiency of the different zones of the outgrowth were studied. METHODS The limbal explants were expanded in the standard way used for clinical transplantation and the outgrowths were divided into three zones depending on proximity to the explant (inner, middle and outer zones). The colony-forming efficiencies (CFEs) of cells from each zone were calculated. In addition, the expression of DeltaNp63, ABCG2 (both putative positive LSC markers) and cytokeratin K3 (marker of corneal differentiation) were assessed using quantitative reverse transcription PCR (RT-PCR). Immunohistochemistry on paraffin-embedded sections was also performed to demonstrate protein localization and allow further confirmation of the quantitative RT-PCR results. RESULTS Successful cultures for both the explant outgrowths and the CFE calculations were obtained in every case. CFE showed a successive decline in zones further away from the explant (p < 0.00005). Quantitative RT-PCR revealed that the expression of the positive putative LSC markers DeltaNp63 and ABCG2 also showed a steady decrease in the zones furthest from the explant (p < 0.05 and p < 0.005, respectively). The expression of cytokeratin K3 was increased in zones furthest from the explant (p < 0.005). Immunohistochemistry on paraffin-embedded sections of intact ex vivo-expanded limbal epithelium for the putative positive marker p63 and cytokeratin K3 confirmed the findings of the quantitative RT-PCR and CFE results. CONCLUSIONS We demonstrate for the first time that outgrowths from human limbal explants, a widely used technique in ex vivo expansion of LSCs for clinical transplantation, show a steady decline in a wide range of stem cell properties with distance from the central explant. These findings support the importance of proximity of stem cells to their niche environment in maintaining their undifferentiated state. These findings suggest the need for modifications of existing techniques to ensure maximum numbers of LSCs following ex vivo expansion protocols, which will then ensure the success of subsequent engraftment.

Successful Application of Ex Vivo Expanded Human Autologous Oral Mucosal Epithelium for the Treatment of Total Bilateral Limbal Stem Cell Deficiency

Ocular surface reconstruction with ex vivo expanded limbal stem cells (LSCs) is a widely used clinical treatment for patients with limbal stem cell deficiency (LSCD). This is not applicable to patients with bilateral LSCD where there are no remaining LSCs. Cultivated oral mucosa epithelium (OME) has been used as an alternative source of autologous epithelial stem cells for ocular reconstruction in few clinical trials. However, successful generation of stratified OME epithelium has only been achieved in the presence of animal feeder cells and/or animal‐derived products in the culture media, likely to contribute to increased risk of pathogen transmission and graft rejection. In this study, we report generation of multilayered OME epithelium that shares many of the characteristics of corneal epithelium using a fully compliant good manufacturing practice, feeder‐ and animal product‐free method. Proof of concept was achieved by transplantation of autologous ex vivo expanded OME in two patients with histologically confirmed bilateral total LSCD that resulted in successful reversal of LSCD in the treated eye up to 24 months. Stem Cells 2014;32:2135–2146

Reduced expression of autotaxin predicts survival in uveal melanoma.

Aim: In an effort to identify patients with uveal melanoma at high risk of metastasis, the authors undertook correlation of gene expression profiles with histopathology data and tumour-related mortality. Methods: The RNA was isolated from 27 samples of uveal melanoma from patients who had consented to undergo enucleation, and transcripts profiled using a cDNA array comprised of sequence-verified cDNA clones representing approximately 4000 genes implicated in cancer development. Two multivariate data mining techniques—hierarchical cluster analysis and multidimensional scaling—were used to investigate the grouping structure in the gene expression data. Cluster analysis was performed with a subset of 10 000 randomly selected genes and the cumulative contribution of all the genes in making the correct grouping was recorded. Results: Hierarchical cluster analysis and multidimensional scaling revealed two distinct classes. When correlated with the data on metastasis, the two molecular classes corresponded very well to the survival data for the 27 patients. Thirty two discrete genes (corresponding to 44 probe sets) that correctly defined the molecular classes were selected. A single gene (ectonucleotide pyrophosphatase/phosphodiesterase 2; autotaxin) could classify the molecular types. The expression pattern was confirmed using real-time quantitative PCR. Conclusions: Gene expression profiling identifies two distinct prognostic classes of uveal melanoma. Underexpression of autotaxin in class 2 uveal melanoma with a poor prognosis needs to be explored further.

Xanthogranulomatous variant of immunoglobulin G4 sclerosing disease presenting as ptosis, proptosis and eyelid skin plaques

A 70-year-old male was referred to the oculoplastic clinic with left-sided ptosis and floppy eyelids. During follow-up, bilateral upper lid xanthelasma developed with worsening ptosis and proptosis, which was worse on the left side. A left orbital biopsy showed xanthogranulomatous inflammation of the orbit. The patient was treated with a variety of immune modulator regimes but due to a variety of side-effects, treatment was discontinued. The left orbit was surgically debulked twice and histology revealed xanthogranulomatous inflammation, with the additional features of sclerosis, lymphoid aggregates and a prominent population of plasma cells. Around 80% of the plasma cells expressed immunoglobulin G4 (IgG4). This case report reveals an association between xanthogranulomatous inflammation of the orbit and a prominent population of IgG4-positive plasma cells. We propose that the overall disease is a novel variant of IgG4 sclerosing disease of the orbit and suggest that cases of histologically proven xanthogranulomatous inflammation should be stained for IgG4 if there is an accompanying plasma cell population.

Observational prospective cohort study of patients with newly-diagnosed ocular sebaceous carcinoma

Purpose To investigate the epidemiology and clinicopathological management for ocular sebaceous carcinoma (OSC) in the UK. Methods Observational prospective cohort study of patients with newly-diagnosed OSC. The British Ophthalmological Surveillance Unit captured incident cases of OSC between 2008 and 2010. Incident and 6-month follow-up questionnaires from reporting ophthalmologists captured OSC demographic and clinical data. Results Data were available on 51 patients with unilateral OSC (response rate 85%). The UK estimated annual incidence was 0.41 cases per million population (95% CI 0.31 to 0.54). Median age was 70 years (SD 14, range 28–98) with 57% women. OSC location was upper lid (54%), lower lid (20%), multicentric (14%) and caruncle (12%). Most common misdiagnoses included chalazion (42%), basal cell carcinoma (30%) and blepharoconjunctivitis (16%), with median delay in diagnosis of 10 months (SD 9, range 0.5–36). Specialist ophthalmic pathologists performed diagnostics in 62%, with pagetoid/intraepithelial spread present in 39%. Misdiagnosis of chalazion (p=0.019) and pagetoid tumour spread (p=0.016) was associated with a significant diagnostic delay (one-way ANOVA/R2). Primary surgical management involved excision with reconstruction (49%), primary exenteration (10%) and Mohs surgery (8%). There were three deaths (out of 51) during the study period; one patient died of OSC-related disease and the other two due to other causes. Conclusions This population-based prospective study confirms OSC as a rare cancer in the UK. Masquerade syndromes result in significant diagnostic delays and increase the risk of pagetoid tumour spread. There is considerable UK variation in pathological and surgical management, and ocular reconstruction and radical surgery is often required for OSC due to delayed presentation.

A unique case of IgG4 sclerosing dacryocystitis.

IgG4-related ocular adnexal disease, a relatively recently described clinical entity, is important to diagnose because during the acute phase, it responds favorably to corticosteroid treatment. The diagnosis can be confirmed by simple blood tests and histology. IgG4-related dacryoadenitis and generalized orbital disease have been reported; however, this is the first report of IgG4-related disease of the lacrimal sac. We describe an 80-year-old female who presented with a painless erythematous indurated swelling in the right lacrimal sac area with complete obstruction of the right nasolacrimal system. A 9-mm lacrimal sac mass was noted on CT dacryocystogram. Blood tests revealed an elevated serum IgG4 level, and the lacrimal sac histology was characteristic of IgG4-related disease. Corticosteroid treatment was declined by the patient. She was kept under close observation for signs of progression, systemic involvement, and potential malignant transformation.

Evidence of macrophage and lymphocyte, but not dendritic cell, infiltration in posterior uveal melanomas, whilst cultured uveal melanomas demonstrate pluripotency by expressing CD68 and CD163

Although variation in the level of macrophage infiltration has been reported in uveal melanoma, little is known about the expression of other leucocyte markers. An immuno‐ histochemistry study of the levels of expression of macrophage and other leucocyte markers, in a series of 10 primary choroidal melanoma biopsies, was undertaken. Biopsies were either fixed immediately in formalin and embedded in paraffin wax or established as short‐term cultures. Using single‐ and double‐labelling immunohistochemistry, cultured cells and paraffin sections were analysed for a range of melanoma (HMB45, Melan A, S100 and tyrosinase) and immune cell (CD68, CD163, CD45 and CD1a) markers. All samples expressed at least two known melanoma markers. Infiltrating macrophages were present in the majority of sections. When cultured specimens were studied by double‐labelling immunofluorescence, uveal melanoma cells were seen to express macrophage markers or have cross‐reactivity with related proteins. Expression of the leucocyte antigen CD45 was observed in three tumours but was not present in any cultured cells, whilst the expression of the dendritic cell marker CD1a was absent from all samples.

Fluorescence in situ hybridisation (FISH) in histologically challenging conjunctival melanocytic lesions

Background Even in experienced hands, the classification of some melanocytic lesions of the conjunctiva remains challenging. In skin pathology, the recent application of fluorescence in situ hybridisation (FISH) has been demonstrated to be of use for the analysis and diagnosis of ambiguous melanocytic neoplasms of the skin. This study set out to evaluate this method on seven prospective conjunctival cases that were histologically equivocal. Methods 18 unequivocal retrospective melanocytic controls were exposed to FISH. Commercially available probes assessing copy numbers of RREB1 (6p25), MYB (6q23) and CCND1 (11q13) genes compared with CEP6 (a chromosome six centromeric reference point) were used. After control verification, seven prospective, equivocal cases were identified and exposed to FISH. Results There was complete correlation between FISH result and the control section histopathology report. Control cases of melanoma cases were all positive for FISH and control benign lesions were negative. Of the seven equivocal cases, five were positive and classed as invasive melanoma or melanoma-in situ, one was negative and one tetraploid, classed as negative (these last two cases were classed as naevi with careful clinical observation). Conclusions FISH is very useful in classifying equivocal conjunctival melanocytic lesions, especially those with atypical junctional activity and naevoid melanocytic proliferations of the conjunctiva.

Colonic angiodysplasia and true diverticula: is there an association?

Aims : To investigate the pathology of colectomy specimens, from patients presenting with lower gastrointestinal haemorrhage, who had undergone preoperative mesenteric angiography. The angiography diagnoses ranged from active bleeding of unknown aetiology to angiodysplasia.

PAX6 mutation in association with ptosis, cataract, iris hypoplasia, corneal opacification and diabetes: A new variant of familial aniridia?

We report a family with ptosis, cataract, iris hypoplasia and gradual corneal opacification occurring in association with a PAX6 mutation.