Abstracto

Limbal epithelial stem cells and their clinical significance

Mehmet Gurdal, Ozlem Barut Selver

The cornea should be transparent for the maintenance of good visual function. The superficial epithelium of the cornea, which is renewed continuously by corneal stem cells, plays a critical role for permanency of this transparency. These stem cells are localized at the cornea-conjunctival transition zone, which is called “limbus”. When this zone is affected or destroyed by pathological conditions, such as chemical burns, Limbal Stem Cell Deficiency (LSCD) ensues. Loss of limbal stem cell function allows colonization of the corneal surface by conjunctival epithelium. However, this epithelium has a poor protection that causes scarring and promotes vascularization. Worldwide, over 6 million people are affected with corneal blindness, and LSCD is one of the most important reasons. Fortunately, it is becoming possible to recover vision by autologous/allogenic limbal tissue transplantation. Due to the potential risks such as rejection or donor eye distress, alternative treatment options have been investigated. Ex vivo expansion of limbal stem cells for the treatment of LSCD was first reported in 1997. Through these 25 years, various protocols for cultivation of limbal epithelial cells were experienced. In this approach, a small limbal biopsy is surgically removed from the donor eye for invivo expansion. The cells are then surgically transferred to the recipient eye. The high percentage of cells with high proliferative potential among the culture cells is one of the most important factors for the successful limbal epithelial cell culture. Strong efforts are being made to expand limbal stem cells in culture for preserving or even enriching the stem cell population for better clinical outcomes.