Reconstruction of the Corneal Surface using Stem Cell Biology

The cornea is the clear front of the eye and its clarity is important for the transmission of light to the retina for visual perception. The corneal surface is composed of an epithelium that is renewed by stem cells located at the periphery of the cornea, in a region known as the limbus. These so-called limbal stem cells can become deficient or dysfunctional as a result of many causes including chemical and thermal burns to the eye, hereditary causes such as Aniridia and Ectodermal Dysplasia, inflammatory diseases such as StevensJohnson Syndrome and Mucous Membrane Pemphigoid, and iatrogenic causes such as radiation therapy and topical chemotherapy. In the resulting disease of of Limbal Stem Cell Deficiency the corneal epithelium cannot be maintained resulting in chronic epithelial defects and the surface becomes replaced by the conjunctival epithelium and its blood vessels which surrounds the cornea and limbus resulting in visual loss. Limbal Stem Cell Deficiency is therefore a painful and blinding disease. It is difficult to manage at the best of times.

Dr. Sajad Ahmad has developed an animal free culture method for limbal stem cells that has been used to successfully regenerate the corneal epithelium in patients with unilateral chemical burns and restore their vision. He is currently collaborating with centres in Edinburgh (UK), Oslo (Norway), Harvard University (Boston, USA) and Dublin (Ireland) to develop this technique in those centers for future mulitcenter clinical trials. He will outline this method. He was also the first to differentiate human embryonic stem cells into the corneal epithelial lineage and he will discuss this approach and the opportunities this presents.