scholarly journals The Limbal Niche and Regenerative Strategies

Vision ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 43
Author(s):  
Sohil Amin ◽  
Elmira Jalilian ◽  
Eitan Katz ◽  
Charlie Frank ◽  
Ghasem Yazdanpanah ◽  
...  
Keyword(s):  
Corneal Epithelium ◽  
Epithelial Stem Cells ◽  
Protective Function ◽  
Corneal Regeneration ◽  
Inflammatory Processes ◽  
Regenerative Ability ◽  
Limbal Stem Cell ◽  
Developmental Phases ◽  
Cellular Components ◽  
Considerable Depth

The protective function and transparency provided by the corneal epithelium are dependent on and maintained by the regenerative capacity of limbal epithelial stem cells (LESCs). These LESCs are supported by the limbal niche, a specialized microenvironment consisting of cellular and non-cellular components. Disruption of the limbal niche, primarily from injuries or inflammatory processes, can negatively impact the regenerative ability of LESCs. Limbal stem cell deficiency (LSCD) directly hampers the regenerative ability of the corneal epithelium and allows the conjunctival epithelium to invade the cornea, which results in severe visual impairment. Treatment involves restoring the LESC population and functionality; however, few clinically practiced therapies currently exist. This review outlines the current understanding of the limbal niche, its pathology and the emerging approaches targeted at restoring the limbal niche. Most emerging approaches are in developmental phases but show promise for treating LSCD and accelerating corneal regeneration. Specifically, we examine cell-based therapies, bio-active extracellular matrices and soluble factor therapies in considerable depth.

scholarly journals Clinical Trials of Limbal Stem Cell Deficiency Treated with Oral Mucosal Epithelial Cells

2020 ◽  
Vol 21 (2) ◽  
pp. 411 ◽  
Author(s):  
Joan Oliva ◽  
Fawzia Bardag-Gorce ◽  
Yutaka Niihara
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Corneal Epithelium ◽  
Contact Lenses ◽  
Embryonic Stem ◽  
Epithelial Stem Cells ◽  
Physical Damage ◽  
Limbal Stem Cells ◽  
Cell Therapies ◽  
Limbal Stem Cell

The corneal surface is an essential organ necessary for vision, and its clarity must be maintained. The corneal epithelium is renewed by limbal stem cells, located in the limbus and in palisades of Vogt. Palisades of Vogt maintain the clearness of the corneal epithelium by blocking the growth of conjunctival epithelium and the invasion of blood vessels over the cornea. The limbal region can be damaged by chemical burns, physical damage (e.g., by contact lenses), congenital disease, chronic inflammation, or limbal surgeries. The degree of limbus damage is associated with the degree of limbal stem cells deficiency (partial or total). For a long time, the only treatment to restore vision was grafting part of the healthy cornea from the other eye of the patient or by transplanting a cornea from cadavers. The regenerative medicine and stem cell therapies have been applied to restore normal vision using different methodologies. The source of stem cells varies from embryonic stem cells, mesenchymal stem cells, to induced pluripotent stem cells. This review focuses on the use of oral mucosa epithelial stem cells and their use in engineering cell sheets to treat limbal stem cell deficient patients.

scholarly journals Emerging Therapeutic Strategies for Limbal Stem Cell Deficiency

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ying Dong ◽  
Han Peng ◽  
Robert M. Lavker
Keyword(s):  
Stem Cell ◽  
Corneal Epithelium ◽  
Ocular Surface ◽  
Limbal Stem Cell Deficiency ◽  
Current Status ◽  
Epithelial Stem Cells ◽  
Therapeutic Approaches ◽  
Advantages And Disadvantages ◽  
Limbal Stem Cell ◽  
Novel Therapeutic

Identification and characterization of the limbal epithelial stem cells (LESCs) has proven to be a major accomplishment in anterior ocular surface biology. These cells have been shown to be a subpopulation of limbal epithelial basal cells, which serve as the progenitor population of the corneal epithelium. LESCs have been demonstrated to play an important role in maintaining corneal epithelium homeostasis. Many ocular surface diseases, including intrinsic (e.g., Sjogren’s syndrome) or extrinsic (e.g., alkali or thermal burns) insults, which impair LESCs, can lead to limbal stem cell deficiency (LSCD). LSCD is characterized by an overgrowth of conjunctival-derived epithelial cells, corneal neovascularization, and chronic inflammation, eventually leading to blindness. Treatment of LSCD has been challenging, especially in bilateral total LSCD. Recently, advances in LESC research have led to novel therapeutic approaches for treating LSCD, such as transplantation of the cultured limbal epithelium. These novel therapeutic approaches have demonstrated efficacy for ocular surface reconstruction and restoration of vision in patients with LSCD. However, they all have their own limitations. Here, we describe the current status of LSCD treatment and discuss the advantages and disadvantages of the available therapeutic modalities.

scholarly journals Avtologni veznično-limbalni presadek pri enostranskem popolnem pomanjkanju limbalnih epitelnih matičnih celic

2017 ◽  
Vol 86 (7-8) ◽  
Author(s):  
Petra Schollmayer ◽  
Zala Lužnik
Keyword(s):  
Stem Cells ◽  
Surgical Technique ◽  
Corneal Epithelium ◽  
Ocular Surface ◽  
Autologous Transplantation ◽  
Corneal Transplantation ◽  
Epithelial Stem Cells ◽  
Corneal Surface ◽  
Limbal Transplantation

Background: Corneal epithelium is renewed by stem cells (SC) that reside at the corneal limbus. Reduced number of SC or their abnormal function lead to the ocular surface disease called limbal stem cell deficiency (LSCD), characterized by corneal conjunctivalization, vascularization, persistent epithelial defects, chronic inflammation, and loss of vision. In a case of total unilateral LSCD, autologous transplantation of limbal epithelial stem cells (LESC) from the healthy eye is needed. We describe the surgical technique of choice for autologous limbal transplantation, called conjunctival limbal autograft (CLAU) that we combined with amniotic membrane (AM) use. We present the results of CLAU in three patients with total unilateral LSCD due to chemical injury.Methods: Autologous limbal transplantation CLAU begins with the removal of fibrovascular pannus from the diseased corneal surface and the harvesting of two conjunctival-limbal grafts from the healthy eye. The grafts are then transplanted on to the limbal area of the recipient eye. AM is used as a patch to cover the denuded cornea and limbal grafts, as well as a barrier preventing the conjunctival epithelium from encroaching on to the temporal and nasal side of the corneal surface. In the donor eye, AM is used to cover the donor sites. CLAU with the use of AM was performed in 3 patients with unilateral LSCD due to chemical eye injury. In one patient limbal transplantation was combined with symblepharon lysis for entropium repair. In all cases AM was removed 3–6 days postoperatively to assess the growth of new epithelium from the limbal grafts. In all patients the ocular surface was covered with another AM until the cornea was completely epithelized and the new epithelium stable. In one patient the corneal regrafting and cataract removal was performed subsequently.Results: CLAU was successful in 2 patients and partially successful in 1 patient during the follow up. In all cases the growth of new epithelium from the limbal grafts was noted on day 3–6 after CLAU. The cornea was completely epithelized within 2 weeks in 2 patients and after 35 days in one patient. In two patients the corneal epithelium remained clear, smooth and stable during the follow up of 3.5 years and 4 months, respectively. In one patient, uneven epithelium probably representing a mosaic of corneal and conjunctival cells was noted in the central corneal region, where a small corneal ulcer developed 5 months after CLAU. In donor eyes no postoperative complications were noted, the donor sites epithelized within few days.Conclusions: Autologous limbal transplantation according to CLAU surgical technique combined with the use of AM is a successful and safe therapy for restoring corneal surface in total unilateral LSCD after chemical injury. It enables further surgical procedures for restoring the vision such as corneal transplantation and cataract surgery.

scholarly journals Derivation and Characterization of EGFP-Labeled Rabbit Limbal Mesenchymal Stem Cells and Their Potential for Research in Regenerative Ophthalmology

Biomedicines ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1134
Author(s):  
Julia I. Khorolskaya ◽  
Daria A. Perepletchikova ◽  
Daniel V. Kachkin ◽  
Kirill E. Zhurenkov ◽  
Elga I. Alexander-Sinkler ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Stem Cell ◽  
Fluorescent Protein ◽  
Rabbit Model ◽  
Stem Cell Markers ◽  
Epithelial Stem Cells ◽  
Limbal Stem Cell ◽  
Green Fluorescent

The development of cell-based approaches to the treatment of various cornea pathologies, including limbal stem cell deficiency (LSCD), is an area of current interest in regenerative biomedicine. In this context, the shortage of donor material is urgent, and limbal mesenchymal stem cells (L-MSCs) may become a promising cell source for the development of these novel approaches, being established mainly within the rabbit model. In this study, we obtained and characterized rabbit L-MSCs and modified them with lentiviral transduction to express the green fluorescent protein EGFP (L-MSCs-EGFP). L-MSCs and L-MSCs-EGFP express not only stem cell markers specific for mesenchymal stem cells but also ABCG2, ABCB5, ALDH3A1, PAX6, and p63a specific for limbal epithelial stem cells (LESCs), as well as various cytokeratins (3/12, 15, 19). L-MSCs-EGFP have been proven to differentiate into adipogenic, osteogenic, and chondrogenic directions, as well as to transdifferentiate into epithelial cells. The possibility of using L-MSCs-EGFP to study the biocompatibility of various scaffolds developed to treat corneal pathologies was demonstrated. L-MSCs-EGFP may become a useful tool for studying regenerative processes occurring during the treatment of various corneal pathologies, including LSCD, with the use of cell-based technologies.

scholarly journals Extracellular Vesicles: An Emerging Mechanism Governing the Secretion and Biological Roles of Tenascin-C

2021 ◽  
Vol 12 ◽  
Author(s):  
Lucas Albacete-Albacete ◽  
Miguel Sánchez-Álvarez ◽  
Miguel Angel del Pozo
Keyword(s):  
Extracellular Vesicles ◽  
Molecular Mechanisms ◽  
Cell Communication ◽  
Cell Types ◽  
Target Cells ◽  
Tenascin C ◽  
Signalling Molecules ◽  
Inflammatory Processes ◽  
Bona Fide ◽  
Cellular Components

ECM composition and architecture are tightly regulated for tissue homeostasis. Different disorders have been associated to alterations in the levels of proteins such as collagens, fibronectin (FN) or tenascin-C (TnC). TnC emerges as a key regulator of multiple inflammatory processes, both during physiological tissue repair as well as pathological conditions ranging from tumor progression to cardiovascular disease. Importantly, our current understanding as to how TnC and other non-collagen ECM components are secreted has remained elusive. Extracellular vesicles (EVs) are small membrane-bound particles released to the extracellular space by most cell types, playing a key role in cell-cell communication. A broad range of cellular components can be transported by EVs (e.g. nucleic acids, lipids, signalling molecules and proteins). These cargoes can be transferred to target cells, potentially modulating their function. Recently, several extracellular matrix (ECM) proteins have been characterized as bona fide EV cargoes, exosomal secretion being particularly critical for TnC. EV-dependent ECM secretion might underpin diseases where ECM integrity is altered, establishing novel concepts in the field such as ECM nucleation over long distances, and highlighting novel opportunities for diagnostics and therapeutic intervention. Here, we review recent findings and standing questions on the molecular mechanisms governing EV–dependent ECM secretion and its potential relevance for disease, with a focus on TnC.

Comparative Study of Limbal Stem Cell Deficiency Diagnosis Methods: Detection of MUC5AC mRNA and Goblet Cells in Corneal Epithelium

Ophthalmology ◽  
2012 ◽  
Vol 119 (5) ◽  
pp. 923-929 ◽  
Author(s):  
Iker Garcia ◽  
Jaime Etxebarria ◽  
Ana Boto-de-Los-Bueis ◽  
David Díaz-Valle ◽  
Luis Rivas ◽  
...  
Keyword(s):  
Stem Cell ◽  
Comparative Study ◽  
Corneal Epithelium ◽  
Goblet Cells ◽  
Limbal Stem Cell Deficiency ◽  
Limbal Stem Cell

scholarly journals Canonical NF-κB signaling maintains corneal epithelial integrity and prevents corneal aging via retinoic acid

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Qian Yu ◽  
Soma Biswas ◽  
Gang Ma ◽  
Peiquan Zhao ◽  
Baojie Li ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Acid Synthesis ◽  
Plaque Formation ◽  
Epithelial Stem Cells ◽  
Corneal Epithelial ◽  
Corneal Regeneration ◽  
Inhibition Of Angiogenesis ◽  
Acid Pathway ◽  
Acid Administration ◽  
Epithelial Metaplasia

Disorders of the transparent cornea affect millions of people worldwide. However, how to maintain and/or regenerate this organ remains unclear. Here, we show that Rela (encoding a canonical NF-kB subunit) ablation in K14+ corneal epithelial stem cells not only disrupts corneal regeneration but also results in age-dependent epithelial deterioration, which triggers aberrant wound healing processes including stromal remodeling, neovascularization, epithelial metaplasia, and plaque formation at the central cornea. These anomalies are largely recapitulated in normal mice that age naturally. Mechanistically, Rela deletion suppresses expression of Aldh1a1, an enzyme required for retinoic acid synthesis from vitamin A. Retinoic acid administration blocks development of ocular anomalies in Krt14-Cre; Relaf/f mice and naturally aged mice. Moreover, epithelial metaplasia and plaque formation are preventable by inhibition of angiogenesis. This study thus uncovers major mechanisms governing corneal maintenance, regeneration and aging and identifies the NF-kB-retinoic acid pathway as a therapeutic target for corneal disorders.

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