a-simple-mechanical-procedure-to-create-limbal-stem-cell-deficiency

A Simple Mechanical Procedure to Create Limbal Stem Cell Deficiency in Mouse

Limbal stem cell deficiency (LSCD) is a state of malfunction or loss of limbal epithelial stem cells, after which the corneal epithelium is replaced with ...

University of Illinois at Chicago

To determine the role of Notch signaling in corneal epithelial migration and wound healing.

Notch inhibition during corneal epithelial wound healing promotes migration.

The corneal epithelium is the outermost layer of the cornea that directly faces the outside environment, hence it plays a critical barrier function. Previously, conditional loss of Notch1 on the ocular surface was found to cause inflammation and keratinization of the corneal epithelium. This was in part attributed to impaired vitamin A metabolism, loss of the meibomian glands and recurrent eyelid trauma. We hypothesized that Notch1 plays an essential role in the corneal epithelial barrier function and is a contributing factor in the pathologic changes in these mice. Notch1 was conditionally deleted in adult Notch1(flox/flox), K14-Cre-ERT(+/-) mice using hydroxy-tamoxifen. The results indicated that conditional deletion of Notch1 on the ocular surface leads to progressive impairment of the epithelial barrier function before the onset of corneal opacification and keratinization. Loss of the barrier was demonstrated both by an increase in in vivo corneal fluorescein staining and by enhanced penetration of a small molecule through the epithelium. Corneal epithelial wounding resulted in significant delay in recovery of the barrier function in conditional Notch1(-/-) mice compared to wild type. Mice with conditional deletion of Notch1 did not demonstrate any evidence of dry eyes based on aqueous tear production and had normal conjunctival goblet cells. In a calcium switch experiment in vitro, Notch1(-/-) cells demonstrated delayed membrane localization of the tight junction protein ZO-1 consistent with a defect in the epithelial tight junction formation. These findings highlight the role of Notch1 in epithelial differentiation and suggest that intrinsic defects in the corneal epithelial barrier recovery after wounding is an important contributing factor to the development of inflammatory keratinization in Notch1(-/-) mice.

Loss of Notch1 disrupts the barrier repair in the corneal epithelium.

We evaluated the role of Toll-like receptor 4 (TLR4) in corneal epithelial wound healing.

The role of toll-like receptor 4 in corneal epithelial wound healing.

In this article we review essentials of diagnosis and management of ocular surface disease in patients who undergo cataract surgery. It is clearly shown that dry eye disease worsens following the cataract surgery in patients with prior history of ocular surface disease, Also new cases of dry eye might appear. Current strategies for the timely diagnosis and proper management of dry eye syndrome in the face of cataract surgery patients are mainly emphasized. To achieve the best outcome in cataract surgery, a healthy ocular surface is crucial. While ocular surface preparation is indispensable in patients with established ocular surface disease, it is also helpful in those with minimal signs or symptoms of surface disease. The current approach begins with early diagnosis and drastic management of ocular surface disease before cataract surgery using a stepwise regimen customized to each patient and disease severity. These measures are continued throughout and after the surgery.

Cataract surgery in patients with ocular surface disease: An update in clinical diagnosis and treatment.

We studied the reproducibility and stability of limbal stem cell deficiency (LSCD) in mice following controlled injuries to the corneal and limbal epithelia. In one method, corneal and limbal epithelia were entirely removed with a 0.5 mm metal burr. In the other, limbus to limbus epithelial removal with the burr was followed by thermal injury to the limbus. These two methods were compared with a previously published one. Unwounded corneas were used as control. The corneas were examined monthly for three months by slit lamp with fluorescein staining. Immunofluorescence staining for cytokeratin 12 and 8 on corneal wholemount and cross sections were performed to determine the phenotype of the epithelium. Mechanical shaving of the epithelium, with or without thermal injury, resulted in a reproducible state of LSCD marked by superficial neovascularization, reduce of keratin 12 expression and presence of goblet cells on the cornea. The phenotype was stable in 100% of the eyes up to at least three months. Thermal injury produced a more severe phenotype with more significant stromal opacification. These corneal injury models may be useful for studying the mechanisms leading to limbal stem cell deficiency.

Stability of limbal stem cell deficiency after mechanical and thermal injuries in mice.

Notch1 was previously shown to play a critical role in murine meibomian gland function and maintenance. In this study, we have examined the expression and activation of Notch pathway in human meibomian gland epithelial cells in vitro.

Article	Year
Notch inhibition during corneal epithelial wound healing promotes migration. Investigative ophthalmology & visual science\| PubMed ID: 23049092	2012
Loss of Notch1 disrupts the barrier repair in the corneal epithelium. PloS one\| PubMed ID: 23874882	2013
The role of toll-like receptor 4 in corneal epithelial wound healing. Investigative ophthalmology & visual science\| PubMed ID: 25183764	2014
Cataract surgery in patients with ocular surface disease: An update in clinical diagnosis and treatment. Saudi journal of ophthalmology : official journal of the Saudi Ophthalmological Society\| PubMed ID: 25278791	2014
Stability of limbal stem cell deficiency after mechanical and thermal injuries in mice. Experimental eye research\| PubMed ID: 26607808	2016
Notch Signaling in Meibomian Gland Epithelial Cell Differentiation. Investigative ophthalmology & visual science\| PubMed ID: 26943148	2016

Neda Afsharkhamseh

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