Limbal stem cell deficiency and corneal neovascularization.

The corneal limbus harbors corneal epithelial stem cells and contributes to the unique microenvironment of the stem cell niche. Corneal conditions, such as infections, tumors, immunological disorders, trauma, and chemical burns, often lead to the deficiency of the corneal stem cells, and subsequent vision loss. One key feature of limbal stem cell deficiency is corneal neovascularization. There is a delicate balance between pro-angiogenic and anti-angiogenic factors that, in a normal cornea, maintain an avascular state. A pro-angiogenic shift in this balance can occur due to various mechanisms, such as inflammation, gene mutations, physical breach in the limbal barrier, and decreased production of anti-angiogenic molecules. Currently available treatment options for limbal stem cell deficiency include allogeneic and autologous limbal transplants, and more recently, transplantation of alternative sources of epithelium, such as cultivated corneal and oral mucosal stem cells. Further studies are needed to investigate the combination of limbal and stem cell transplantation and concurrent anti-angiogenic therapy.