Where are limbal stem cells placed to repair damage from injury?
The stem cell niche is precisely located at the level of palisades of Vogt, in the limbus . Injury to the limbal niche prevents corneal epithelial cell renewal and results in the growth of conjunctival epithelium over the cornea.
How many people have limbal stem cells?
Loss of limbal stem cell function allows colonization of the corneal surface by conjunctival epithelium. Over 6 million people worldwide are affected by corneal blindness, and limbal stem cell deficiency is one of the main causes.
What is limbal cell transplantation?
Limbal stem cell transplantation is a surgical treatment to address LSCD and restore a corneal epithelial phenotype. Based on the source of cells, limbal transplant can be autologous or allogenic. Many surgical techniques are defined according to the source of the stem cells and the carrier tissues that are used.
How are limbal stem cells harvested?
The donor stem cells are obtained by excising a small area of the conjunctiva at the limbus and is a minor procedure. The tissue so obtained is then grown in tissue culture and once the cells have multiplied sufficiently, small sheets are transplanted on to the affected eye(s), backed with an amniotic membrane.
What is the purpose of limbal stem cell?
The microenvironment of the limbus is considered to be important in maintaining the stemness of stem cells. Limbal stem cells also act as a “barrier” to conjunctival epithelial cells and normally prevent them from migrating on to the corneal surface.
Which heritable ophthalmic disorder is associated with limbal stem cell deficiency?
Patient history and clinical observation of corneal conjunctivalization associated with persistent epithelial defects hints strongly at limbal stem cell deficiency. This can be confirmed by cytological analysis of cells from the superficial corneal epithelium.
Are limbal stem cells pluripotent?
Purpose: : Corneal epithelial stem cells (SC) are located in the limbal zone. Recent studies have shown that several adult stem cells express pluripotency markers and can under certain conditions differentiate into a wide range of cell types.
What is limbal ischemia?
Perilimbal ischemia: The degree of limbal ischemia (blanching) is perhaps the most significant prognostic indicator for future corneal healing because the limbal stem cells are responsible for repopulating the corneal epithelium. In general, the greater the extent of blanching, the worse the prognosis.
What happens when the limbus is damaged?
If the stem cells at the limbus are damaged, the renewal process is interrupted. The complete or partial loss of these stem cells — limbal stem-cell deficiency (LSCD) — allows the opaque conjunctiva to grow over the cornea. This can lead to intense pain and, in the most-severe cases, blindness.
Where are limbal stem cells found?
TAC are fast-dividing progenitor cells that provide the proliferative compartment of the limbal and corneal epithelia [5–10]. Limbal stem cells are located on the basal epithelium in the limbal crypts of the Vogt’s palisades located in the narrow zone between the cornea and the bulbar conjunctiva (arrow).
Where are limbal stem cells?
Limbal stem cells, also known as corneal epithelial stem cells, are stem cells located in the basal epithelial layer of the corneal limbus. They form the border between the cornea and the sclera.
What happens to the eyes with limbal stem cell deficiency?
With a reduced ability to repopulate the corneal epithelium and an unstable ocular surface, patients with limbal stem cell deficiency (LSCD) can have ocular pain from corneal erosions and decreased vision from stromal scarring or epithelial irregularity.
How to treat limbal stem cell deficiency ( LSCD )?
Limbal Stem Cell Deficiency 1 Disease Entity. The corneal epithelium is a stratified squamous epithelium from which superficial terminal cells are naturally shed. 2 Diagnosis. The diagnosis of LSCD is largely made on clinical grounds. 3 Management. Management is typically symptomatic in nature early in the disease.
When do you need surgery for limbal stem cell injury?
When limbal stem cell injury is transient, sometimes termed limbal stem cell disease or limbal stem cell distress, conservative medical measures as above may be sufficient. However, total LSCD must be surgically managed.
Can a nasal ulceration be a limbal stem cell deficiency?
Early ulceration or peripheral infectious keratitis may resemble limbal stem cell deficiency. Pterygium may resemble limbal stem cell deficiency and would typically be nasal or temporal. Ocular surface squamous neoplasia may be mistaken for a limbal stem cell deficiency but can be differentiated by surface markers.