Limbal stem cells

Human embryonic stem cell (hESC)- and human induced pluripotent stem cell (hiPSC)-derived retinal pigment epithelium (RPE) therapies are promising alternatives for the treatment of retinal degenerative diseases caused by RPE degeneration. The generation of autologous RPE cells from human adult donors, which has the advantage of avoiding immune rejection and teratoma formation, is an alternative cell resource to gain mechanistic insight into and test potential therapies for RPE degenerative diseases. Here, we found that limbal stem cells (LSCs) from hESCs and adult primary human limbus have the potential to produce RPE cells and corneal stromal stem cells (CSSCs)...

PURPOSE: To study the clinical characteristics and treatment outcomes of ocular surface pseudoepitheliomatous hyperplasia (PEH) associated with chronic vernal keratoconjunctivitis (VKC). METHODS: This retrospective study includes 39 eyes of 32 patients with VKC induced PEH who presented from 2016-2022. A database search was conducted for diagnosis of PEH, and data on clinical features, imaging characteristics, and treatment were analyzed. RESULTS: Of the 32 patients, 11 (34%) were children and adolescents, 21 (66%) were adults...

PURPOSE: To determine the safety and feasibility of human autologous adipose tissue-derived adult mesenchymal stem cells (ASCs) for ocular surface regeneration in patients with bilateral limbal stem-cell deficiency (LSCD). METHODS: A phase IIa clinical trial was designed (https://Clinicaltrials.gov, NCT01808378) with 8 patients, 3 of whom had aniridia, 2 meibomian glands diseases, 2 multiple surgeries and 1 chronic chemical injury. The therapeutic protocol was as follows: 6-mm of central corneal epithelium was removed, 400,000 ASCs were injected into each limboconjunctival quadrant, 400,000 ASCs were suspended over the cornea for 20 min, and finally the cornea was covered with an amniotic membrane patch...

ABCB5 is a member of the ABC transporter superfamily composed of 48 transporters, which have been extensively studied for their role in cancer multidrug resistance and, more recently, in tumorigenesis. ABCB5 has been identified as a marker of skin progenitor cells, melanoma, and limbal stem cells. It has also been associated with multidrug resistance in several cancers. The unique feature of ABCB5 is that it exists as both a full transporter (ABCB5FL) and a half transporter (ABCB5β). Several studies have shown that the ABCB5β homodimer does not confer multidrug resistance, in contrast to ABCB5FL...

Limbal epithelial stem/progenitor cells (LESCs) proliferate, migrate and differentiate into mature corneal epithelium cells (CECs) that cover the ocular surface. LESCs play a crucial role in the maintenance and regeneration of the corneal epithelium, and their dysfunction can lead to various corneal diseases. Neuregulin 1 (NRG1) is a member of the epidermal growth factor family that regulates the growth and differentiation of epithelial tissues. Here, we depicted the dynamic transcriptomic profiles during human CEC differentiation, identifying six gene co-expression modules that were specific to different differentiation stages...

Limbal stem cell deficiency (LSCD) is a pathologic condition caused by the dysfunction and destruction of stem cells, stem cell precursors and limbal cell niche in the corneal epithelium, leading to severe conjunctivalization of the cornea. Etiologies for LSCD span from congenital (aniridia), traumatic (chemical or thermal injuries), autoimmune (Stevens-Johnson syndrome) and iatrogenic disease to contact lens (CL) wear. Of these, CL wear is the least understood and is often a subclinical cause of LSCD. Even with recent advances in LSCD research, limitations persist in establishing the pathogenesis and treatment guidelines for CL-induced LSCD...

INTRODUCTION: Ocular surface squamous neoplasia (OSSN) is the most common ocular malignancy; the pathophysiology is influenced by molecular, genetic, and epigenetic mechanisms. The incidence of OSSN is associated with the anatomy and physiology of the ocular surface, limbal stem cell configuration, limbal vulnerability, cancer stem cells, dysplasia, neoplasia, angiogenesis, invasion, and metastasis. The key etiological factors involved are human papillomavirus (HPV), human immunodeficiency virus (HIV), immunosuppression, p53 tumor suppressor gene, hypovitaminosis A, and failure of Deoxyribonucleic acid (DNA) repair mechanisms...

BACKGROUND: Limbal stem cells (LSCs) are crucial for the regeneration of the corneal epithelium in patients with limbal stem cell deficiency (LSCD). Thus, LSCs during cultivation in vitro should be in highly homogeneous amounts, while potency and expression of stemness without tumorigenesis would be desirable. Therefore, further characterization and safety evaluation of engineered limbal grafts is required to provide safe and high-quality therapeutic applications. METHODS: After in vitro expansion, LSCs undergo laboratory characterization in a single-cell suspension, cell culture, and in limbal grafts before transplantation...

Organ culture storage techniques for corneoscleral limbal (CSL) tissue have improved the quality of corneas for transplantation and allow for longer storage times. Cultured limbal tissue has been used for stem cell transplantation to treat limbal stem cell deficiency (LSCD) as well as for research purposes to assess homeostasis mechanisms in the limbal stem cell niche. However, the effects of organ culture storage conditions on the quality of limbal niche components are less well described. Therefore, in this study, the morphological and immunohistochemical characteristics of organ-cultured limbal tissue are investigated and compared to fresh limbal tissues by means of light and electron microscopy...

BACKGROUND/AIMS: The Ectrodactyly-Ectodermal dysplasia-Clefting (EEC) and Ankyloblepharon-ectodermal defect-cleft lip/palate (AEC) syndromes are rare autosomal dominant diseases caused by heterozygous mutations in the p63 gene. Patients are characterized by abnormalities of the skin, teeth, and hair and have limb defects, orofacial clefting and ectodermal dysplasia. In addition, they often show ocular surface alterations, leading to progressive corneal clouding and eventually blindness...

Recently, the murine cornea has reemerged as a robust stem cell (SC) model, allowing individual SC tracing in living animals. The cornea has pioneered seminal discoveries in SC biology and regenerative medicine, from the first corneal transplantation in 1905 to the identification of limbal SCs and their transplantation to successfully restore vision in the early 1990s. Recent experiments have exposed unexpected properties attributed to SCs and progenitors and revealed flexibility in the differentiation program and a key role for the SC niche...

PURPOSE: The aim of this study was to report a rare observation of corneal superficial plaque formation after topical recombinant human nerve growth factor (rhNGF) treatment for a nonhealing epithelial defect in a patient with advanced mucous membrane pemphigoid, limbal stem cell deficiency, and neurotrophic keratopathy. METHODS: This study was a case report. RESULTS: A 72-year-old man with a complex course of mucous membrane pemphigoid, leading to cicatrizing keratoconjunctivits, limbal stem cell deficiency, and neurotrophic keratopathy presented with a recurrent persistent epithelial defect in the right eye...

In the biomedical field, there is a demand for the development of novel approaches for the investigation of optical epithelial anatomical features with biomimetic materials. These materials are not only required to replicate structures but also enable dynamic modelling for disease states such as limbal stem cell deficiency and ageing. In the present study, the effective generation of reversible wrinkled polydimethylsiloxane (PDMS) substrates was undertaken to mimic the undulating anatomy of the limbal epithelial stem cell niche...

The corneal epithelial layer is continuously replaced by limbal stem cells. Reconstructing this layer in vitro using synthetic scaffolds is highly needed. Poly-lactic-co-glycolic acid (PLGA) is approved for human use due to its biocompatibility and biodegradability. However, PLGA is hydrophobic, preventing cell adherence to PLGA membranes. PLGA scaffolds were prepared by electrospinning on a custom-made target drum spinning at a rate of 1000 rpm with a flow rate of 0.5 mL/h and voltage at 20 kV, then treated with oxygen plasma at 30 mA using a vacuum coater...

Here we report a standard procedure for the isolation and identification of limbal niche cells (LNCs). Limbus tissue obtained from an eye bank was used for LNCs isolation. The tissue was divided into 12 pieces under aseptic conditions and digested for 18 h at 37 °C in the cell culture incubator using collagenase A to obtain cell clusters with LNCs and limbal epithelial progenitor cells. The cell clusters were further digested for 15 min at 37 °C using 0.25% trypsin-EDTA to obtain single cells and then cultured in modified embryonic stem cell medium (MESCM) on a plastic surface coated with 5% Matrigel...

Epithelial and stromal/mesenchymal limbal stem cells contribute to corneal homeostasis and cell renewal. Extracellular vesicles (EVs), including exosomes (Exos), can be paracrine mediators of intercellular communication. Previously, we described cargos and regulatory roles of limbal stromal cell (LSC)-derived Exos in non-diabetic (N) and diabetic (DM) limbal epithelial cells (LECs). Presently, we quantify the miRNA and proteome profiles of human LEC-derived Exos and their regulatory roles in N- and DM-LSC. We revealed some miRNA and protein differences in DM vs...

BACKGROUND: Axenfeld-Rieger syndrome (ARS) is a rare cause of congenital glaucoma and may result in loss of vision. ARS is mostly autosomal dominant in nature characterized by developmental abnormalities in the angle of anterior chamber and iris of the eye, also associated with structural abnormalities in the body. AIM: To study and observe the demographics and clinical findings in a very rare ocular disease known as ARS. METHODS: Case records of symptomatic patients attending Ophthalmology outpatient department and diagnosed to have ocular hypertension or glaucoma in 3 years from March 2017 to March 2020 were evaluated to search for cases diagnosed with ARS...

The article reviews the main properties of the cornea and the mechanisms of its physiological regeneration and repair in response to damage and describes the most promising methods of treatment aimed at stimulating limbal stem cells and based on the use of native tissues of perinatal origin, umbilical cord mesenchymal stromal cells, and cell-free therapeutic products.

Chemical agents have been utilized for centuries in warfare and pose a health threat to civilians and military personnel during armed conflict. Despite treaties and regulations against their use, chemical agent exposure remains a threat and measures to understand their effects and countermeasures for systemic and organ-specific health are needed. Many of these agents have ocular complications, both acute and chronic. This mini-review focuses on key chemical agents including vesicants (mustards, lewisite), nerve agents (sarin, VX), knockdown gasses (hydrogen cyanide), and caustics (hydrofluoric acid)...

Single-cell RNA-sequencing (scRNA-seq) is a powerful technique that can barcode individual cells and thus used to obtain a gene expression profile for every individual cell within a tissue. This makes scRNA-seq an excellent method for characterizing rare cell populations such as stem cells. We describe how scRNA-seq can be utilized to examine limbal epithelial stem cell population as well as investigate the contribution of autophagy to the function of limbal epithelial stem cells. To accomplish this, we used the Beclin1 heterozygous (Beclin1 het) mouse, a well-established model of autophagy deficiency...