Tissue-Regenerating, Vision-Restoring Corneal Epithelial Stem Cells

Abstract

The cornea, the most anterior segment of the eye, provides us with exquisite vision. Unlike other vital tissues, it is poorly protected from the environment and is thus reliant on a self-renewal program to preserve integrity. This function is reserved for corneal epithelial stem cells located in the basal layer of the limbus, a narrow transition zone that segregates the peripheral cornea from the adjacent conjunctiva. Under physiological conditions, these cells replenish the corneal epithelium when mature or traumatized cells are lost. However, when the limbus is extensively damaged, stem cell activity is compromised, resulting in a condition known as limbal stem cell deficiency (LSCD). This disease is characterized by corneal neovascularization and persistent epithelial defects which impair vision. Over the past 20 years a myriad of treatment options have been developed for LSCD, most of which incorporate stem cell transplantation. Due to the disadvantages associated with the use of allogeneic and xenogeneic material, researchers are currently focusing on refining techniques involving autologous limbal tissue transplantation and are delving into the possibility that stem cells found in other organs can provide an alternative source of corneal epithelium. Determining where donor stem cells reside on the recipient's ocular surface and how long they remain viable will provide further insights into improving current therapeutic options for patients with LSCD.

Using optical coherence tomography to assess the role of age and region in corneal epithelium and palisades of vogt

“…The size, shape, and configuration of POV changes over time and was reported to be response to acquired or congenital conditions, aging, surgery, and medication. [2,4,5,7,10,40–49] Injury to the POV and the limbal stem cells they contain may cause to corneal conjunctivalization, vascular invasion, corneal epithelialization problem, corneal melting, and concomitant blindness.…”

Nature and incidence of severe limbal stem cell deficiency in Australia and New Zealand

“…LSCD is unlikely to be treatable by medical management or conventional corneal transplants because of damage to LESCs and the niche microenvironment . Interestingly, in the cases reported in our study, 93% of treating ophthalmologists managed patients conservatively with topical lubricants and/or steroids in the first year of treatment.…”

Small-Molecule Induction Promotes Corneal Epithelial Cell Differentiation from Human Induced Pluripotent Stem Cells

“…Its outermost layer, the corneal epithelium, is exposed to the external environment and thereby needs to be rapidly regenerating and stratified. It is renewed by limbal stem cells, a type of tissue-specific stem cell located in specialized niche areas in the corneoscleral junction called limbus (Echevarria and Di Girolamo, 2011). Diseases affecting the cornea are a major cause of blindness worldwide and one of the leading causes of vision loss after cataract, with nearly 70% of corneal blindness being due to limbal stem cell deficiency (LSCD)—a disease characterized by abnormal corneal epithelial maintenance, resulting in conjunctivalization of the corneal surface (Ahmad, 2012).…”