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Indian Journal of Ophthalmology Apr 2020The aim of this study is to compare the outcome and complications in patients who underwent double-head pterygium excision with split conjunctival autograft with and...
PURPOSE
The aim of this study is to compare the outcome and complications in patients who underwent double-head pterygium excision with split conjunctival autograft with and without limbus to limbus orientation.
METHODS
In this retrospective, comparative study, 99 eyes with double-head pterygium which underwent split conjunctival autograft with limbus to limbus orientation (Group 1) and 93 eyes which underwent without limbus to limbus orientation (Group 2) during the period of 2011-2016 were included in this study. The primary outcome compared was the recurrence rate. Other complications were included as secondary outcomes.
RESULTS
Mean age in group 1 and group 2 were 46.84 +/- 10.78 years and 54.38 +/- 11.44 years respectively. M:F was 36:63 in group 1 and 45:48 in group 2 with a mean follow up of 18.30 +/- 7.48 months in group 1 and 17.04 +/- 9.98 months in group 2. Recurrence was seen in 4 cases in each of the 2 groups with the mean time of recurrence being 7 +/- 2.34 months in group 1 and 6 +/- 2.01 months in group 2. Other complications included graft edema, SCH, graft retraction, granuloma, dellen and graft loss with only graft loss being statistically significant between 2 groups.
CONCLUSION
This study provides data that recurrence rates are not different among patients who undergo split conjunctival graft with and without limbal orientation. The strict adherence to maintaining limbus to limbus orientation while managing double-headed pterygia may not be necessary in all cases, especially in those with large defects following excision.
Topics: Adult; Autografts; Conjunctiva; Follow-Up Studies; Humans; Limbus Corneae; Middle Aged; Neoplasm Recurrence, Local; Pterygium; Recurrence; Retrospective Studies; Transplantation, Autologous; Treatment Outcome
PubMed: 32174571
DOI: 10.4103/ijo.IJO_1079_19 -
Stem Cells Translational Medicine Feb 2012The cornea is the clear tissue at the front of the eye that transmits light to the retina at the back of the eye. The cornea is covered by an epithelium and surrounded... (Review)
Review
The cornea is the clear tissue at the front of the eye that transmits light to the retina at the back of the eye. The cornea is covered by an epithelium and surrounded by a narrow band of tissue known as the limbus. The limbus has two important roles in maintaining a healthy corneal epithelium. First, stem cells for the corneal epithelium reside at the limbus and not in the cornea. Second, the limbus acts as a barrier separating the clear avascular corneal epithelium from the surrounding vascular conjunctival tissue. A failure of these limbal functions can result in the painful and blinding disease of limbal stem cell deficiency. In this disease, the corneal epithelium cannot be maintained by the stem cells, and the corneal surface becomes replaced by hazy conjunctival tissue. There are many causes of limbal stem cell deficiency, such as burns to the eye, inflammatory diseases, and hereditary diseases. Current understanding of the pathophysiology of the disease is discussed here. In particular, understanding whether the limbal stem cells are lost or become dysfunctional or indeed whether the limbal microenvironment is disturbed is important when developing appropriate management strategies for the disease.
Topics: Animals; Cell Count; Cell Lineage; Conjunctiva; Corneal Transplantation; Epithelium, Corneal; Humans; Limbus Corneae; Stem Cell Niche; Stem Cell Transplantation; Stem Cells; Transplantation, Homologous
PubMed: 23197757
DOI: 10.5966/sctm.2011-0037 -
International Journal of Molecular... Jul 2018Keeping the integrity and transparency of the cornea is the most important issue to ensure normal vision. There are more than 10 million patients going blind due to the... (Review)
Review
Keeping the integrity and transparency of the cornea is the most important issue to ensure normal vision. There are more than 10 million patients going blind due to the cornea diseases worldwide. One of the effective ways to cure corneal diseases is corneal transplantation. Currently, donations are the main source of corneas for transplantation, but immune rejection and a shortage of donor corneas are still serious problems. Graft rejection could cause transplanted cornea opacity to fail. Therefore, bioengineer-based corneas become a new source for corneal transplantation. Limbal stem cells (LSCs) are located at the basal layer in the epithelial palisades of Vogt, which serve a homeostatic function for the cornea epithelium and repair the damaged cornea. LSC-based transplantation is one of the hot topics currently. Clinical data showed that the ratio of LSCs to total candidate cells for a transplantation has a significant impact on the effectiveness of the transplantation. It indicates that it is very important to accurately identify the LSCs. To date, several putative biomarkers of LSCs have been widely reported, whereas their specificity is controversial. As reported, the identification of LSCs is based on the characteristics of stem cells, such as a nuclear-to-cytoplasm ratio (N/C) ≥ 0.7, label-retaining, and side population (SP) phenotype. Here, we review recently published data to provide an insight into the circumstances in the study of LSC biomarkers. The particularities of limbus anatomy and histochemistry, the limits of the current technology level for LSC isolation, the heterogeneity of LSCs and the influence of enzyme digestion are discussed. Practical approaches are proposed in order to overcome the difficulties in basic and applied research for LSC-specific biomarkers.
Topics: Animals; Biomarkers; Cell Separation; Corneal Diseases; Corneal Transplantation; Epithelium, Corneal; Humans; Limbus Corneae; Mice; Models, Animal; Regeneration; Stem Cell Transplantation; Stem Cells
PubMed: 29986467
DOI: 10.3390/ijms19071982 -
Experimental Eye Research Oct 2020Homeostasis of the corneal epithelium is ultimately maintained by stem cells that reside in a specialized microenvironment within the corneal limbus termed palisades of... (Review)
Review
Homeostasis of the corneal epithelium is ultimately maintained by stem cells that reside in a specialized microenvironment within the corneal limbus termed palisades of Vogt. This limbal niche nourishes, protects, and regulates quiescence, self-renewal, and fate decision of limbal epithelial stem/progenitor cells (LEPCs) toward corneal epithelial differentiation. This review focuses on our current understanding of the mechanism by which limbal (stromal) niche cells (LNCs) regulate the aforementioned functions of LEPCs. Based on our discovery and characterization of a unique extracellular matrix termed HC-HA/PTX3 (Heavy chain (HC1)-hyaluronan (HA)/pentraxin 3 (PTX3) complex, "-" denotes covalent linkage; "/" denotes non-covalent binding) in the birth tissue, i.e., amniotic membrane and umbilical cord, we put forth a new paradigm that HC-HA/PTX3 serves as a surrogate matrix niche by maintaining the in vivo nuclear Pax6+ neural crest progenitor phenotype to support quiescence and self-renewal but prevent corneal fate decision of LEPCs. This new paradigm helps explain how limbal stem cell deficiency (LSCD) develops in aniridia due to Pax6-haplotype deficiency and further explains why transplantation of HC-HA/PTX3-containing amniotic membrane prevents LSCD in acute chemical burns and Stevens Johnson syndrome, augments the success of autologous LEPCs transplantation in patients suffering from partial or total LSCD, and assists ex vivo expansion (engineering) of a graft containing LEPCs. We thus envisage that this new paradigm based on regenerative matrix HC-HA/PTX3 as a surrogate niche can set a new standard for regenerative medicine in and beyond ophthalmology.
Topics: C-Reactive Protein; Cell Differentiation; Cells, Cultured; Corneal Diseases; Humans; Limbus Corneae; Serum Amyloid P-Component; Stem Cell Niche
PubMed: 32795525
DOI: 10.1016/j.exer.2020.108181 -
Aging Sep 2023This study aimed to investigate the senescent phenotypes of human corneal and conjunctival epithelial cells.
PURPOSE
This study aimed to investigate the senescent phenotypes of human corneal and conjunctival epithelial cells.
METHODS
We examined cell morphology, senescence-associated β-galactosidase (SA-β-gal) activity, cell proliferation, and expression of senescence markers (p16 and p21). RNA sequencing analysis was conducted to compare gene expression profiles between senescent and non-senescent cells. Finally, the potential involvement of senescent cells in the pathogenesis of ocular surface diseases was investigated.
RESULTS
X-irradiated corneal and conjunctival epithelial cells exhibited typical senescence phenotypes, i.e., flattened morphologies, increased SA-β-gal activity, decreased cell proliferation, and increased expression of senescence markers, p16 and p21. RNA-seq analysis revealed substantial differences in gene expression profiles between senescent corneal (SCo) and conjunctival epithelial cells (SCj). Moreover, SCj were detected in pathological conjunctival tissues associated with limbal stem cell deficiency (LSCD) due to Stevens-Johnson syndrome or chemical burns, potentially being involved in abnormal differentiation.
CONCLUSION
This study highlights the cellular and molecular characteristics of senescent ocular surface cells, particularly in SCj that show abnormal keratin expression, and their potential roles in severe ocular surface diseases and pathology.
Topics: Humans; Transcriptome; Limbus Corneae; Cornea; Epithelial Cells; Conjunctiva
PubMed: 37770232
DOI: 10.18632/aging.205113 -
International Journal of Molecular... Nov 2021Limbal epithelial stem/progenitor cells (LSCs) reside in a niche that contains finely tuned balances of various signaling pathways including Wnt, Notch, BMP, Shh, YAP,... (Review)
Review
Limbal epithelial stem/progenitor cells (LSCs) reside in a niche that contains finely tuned balances of various signaling pathways including Wnt, Notch, BMP, Shh, YAP, and TGFβ. The activation or inhibition of these pathways is frequently dependent on the interactions of LSCs with various niche cell types and extracellular substrates. In addition to receiving molecular signals from growth factors, cytokines, and other soluble molecules, LSCs also respond to their surrounding physical structure via mechanotransduction, interaction with the ECM, and interactions with other cell types. Damage to LSCs or their niche leads to limbal stem cell deficiency (LSCD). The field of LSCD treatment would greatly benefit from an understanding of the molecular regulation of LSCs in vitro and in vivo. This review synthesizes current literature around the niche factors and signaling pathways that influence LSC function. Future development of LSCD therapies should consider all these niche factors to achieve improved long-term restoration of the LSC population.
Topics: Animals; Epithelium, Corneal; Eye; Humans; Limbus Corneae; Mechanotransduction, Cellular; Stem Cell Niche; Stem Cells
PubMed: 34769405
DOI: 10.3390/ijms222111975 -
Romanian Journal of Ophthalmology 2016The purpose of our review was to familiarize the readers with the new concepts in ocular surface diseases and reconstruction. Limbal stem cell deficiency is... (Review)
Review
The purpose of our review was to familiarize the readers with the new concepts in ocular surface diseases and reconstruction. Limbal stem cell deficiency is characterized by the progressive invasion of conjunctival epithelial cells onto the cornea, superficial vascularisation, destruction of the corneal basement membrane, and chronic inflammatory cell infiltration. Depending on the severity of the disease and the time passed from the primary injury amniotic membrane transplantation, keratolimbal allograft and autograft are the available treatments hoping that, in the nearest future, stem cell transplantation and tissue engineering will become the usual therapeutic choices.
Topics: Amnion; Basement Membrane; Corneal Neovascularization; Disease Progression; Epithelium, Corneal; Humans; Limbus Corneae; Ophthalmologic Surgical Procedures; Severity of Illness Index; Treatment Outcome
PubMed: 27220223
DOI: No ID Found -
The British Journal of Ophthalmology Jul 2022To report the global uptake of simple limbal epithelial transplantation (SLET) and compare the economic, clinical and social outcomes of SLET with those of cultured... (Review)
Review
AIMS
To report the global uptake of simple limbal epithelial transplantation (SLET) and compare the economic, clinical and social outcomes of SLET with those of cultured limbal epithelial transplantation (CLET).
METHODS
A comprehensive literature review and an online survey of eye surgeons were conducted to understand the efficacy and current uptake of SLET surgery. A de novo economic model was developed to estimate the cost savings with SLET compared with CLET. Our economic analysis is conducted from an Indian perspective, as this is where the technique originated. A scenario analysis using the UK cost data and a user-friendly Excel model is included to allow users to input the costs from their setting to estimate the cost savings with using SLET compared with using CLET RESULTS: The anatomical success with SLET in adults (72.6% (range 62%-80%)) was the same as CLET (70.4% (range 68%-80.9%)). For children, the outcome for SLET (77.8% (range 73%-83%)) was better than with CLET (44.5% (range 43%-45%)). In response to our informal questionnaire, 99 surgeons reported to have performed SLET on 1174 patients in total. They appreciated that SLET negates the requirement for costly tissue engineering facilities. Results of economic analysis suggested that SLET provided an estimated cost-savings of US$6470.88 for adults and US$6673.10 for children. In broad terms, the cost of SLET is approximately 10% of the cost of CLET for adults and 8% for children.
CONCLUSION
SLET offers a more accessible and financially attractive alternative to CLET to treat limbal stem cell deficiency.
Topics: Adult; Child; Corneal Diseases; Epithelium, Corneal; Humans; Limbus Corneae; Scleral Diseases; Social Change; Stem Cell Transplantation; Transplantation, Autologous
PubMed: 33688000
DOI: 10.1136/bjophthalmol-2020-318642 -
Regenerative Medicine 2015“…in light of the result that ABCB5 helps to amplify a PAX6-positive limbal stem cell population … it will now be important to test whether ABCB5 selection could...
“…in light of the result that ABCB5 helps to amplify a PAX6-positive limbal stem cell population … it will now be important to test whether ABCB5 selection could also enhance the conversion of skin epithelial stem cells to corneal epithelial stem cells.”
Topics: ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1; Biomarkers; Cell Separation; Corneal Diseases; Humans; Limbus Corneae; Stem Cell Transplantation; Stem Cells; Translational Research, Biomedical
PubMed: 25562345
DOI: 10.2217/rme.14.66 -
Investigative Ophthalmology & Visual... Mar 2020In contact with the external environment, the cornea can easily be injured. Although corneal wounds generally heal rapidly, the pain and increased risk of infection...
PURPOSE
In contact with the external environment, the cornea can easily be injured. Although corneal wounds generally heal rapidly, the pain and increased risk of infection associated with a damaged cornea, as well as the impaired healing observed in some individuals, emphasize the need for novel treatments to accelerate corneal healing. We previously demonstrated in epidermal keratinocytes that the glycerol channel aquaporin-3 (AQP3) interacts with phospholipase D2 (PLD2) to produce the signaling phospholipid phosphatidylglycerol (PG), which has been shown to accelerate skin wound healing in vivo. We hypothesized that the same signaling pathway might be operational in corneal epithelial cells.
METHODS
We used co-immunoprecipitation, immunohistochemistry, scratch wound healing assays in vitro, and corneal epithelial wound healing assays in vivo to determine the role of the AQP3/PLD2/PG signaling pathway in corneal epithelium.
RESULTS
AQP3 was present in human corneas in situ, and AQP3 and PLD2 were co-immunoprecipitated from corneal epithelial cell lysates. The two proteins could also be co-immunoprecipitated from insect cells simultaneously infected with AQP3- and PLD2-expressing baculoviruses, suggesting a likely direct interaction. A particular PG, dioleoylphosphatidylglycerol (DOPG), enhanced scratch wound healing of a corneal epithelial monolayer in vitro. DOPG also accelerated corneal epithelial wound healing in vivo, both in wild-type mice and in a mouse model exhibiting impaired corneal wound healing (AQP3 knockout mice).
CONCLUSIONS
These results indicate the importance of the AQP3/PLD2/PG signaling pathway in corneal epithelial cells and suggest the possibility of developing DOPG as a pharmacologic therapy to enhance corneal wound healing in patients.
Topics: Animals; Aquaporin 3; Blotting, Western; Cell Movement; Cell Proliferation; Cells, Cultured; Epithelium, Corneal; Humans; Immunoprecipitation; Limbus Corneae; Male; Mice; Mice, Knockout; Microscopy, Fluorescence; Phosphatidylglycerols; Phospholipase D; Sf9 Cells; Signal Transduction; Transfection; Wound Healing
PubMed: 32186673
DOI: 10.1167/iovs.61.3.29