Abstract

The cornea represents two thirds of the eye’s refractive power and, together with the sclera, is the protective shield of intraocular structures. The cornea is composed of three cellular layers (epithelium, stroma and endothelium) and three acellular layers (Bowman’s, Dua’s and Descemet’s). Corneal pathologies can affect one or all corneal layers, producing corneal opacities. Penetrating keratoplasty is currently being displaced by lamellar techniques that selectively replace the diseased layer, but neither solves the classical difficulties encountered in corneal transplantation, such as immune rejection and a shortage of organs. The development of bioengineered corneas composed of prosthetic or natural scaffolds and autologous stem cells that differentiate into corneal cells could overcome these difficulties.

In recent years, much research has been carried out to find the optimal scaffold and the best source of stem cells to regenerate the corneal layers. Limbal stem cells (LSC) have arised as one of these sources, and the need to find a marker to distinguish them from more differentiated cells has also emerged. Both limbal and extraocular stem cells have been tested, and some techniques are already being used in clinical practice. These novel techniques for tissue engineering of functional corneal equivalents represent a new and fascinating way to treat corneal diseases. The new techniques allow us to treat patients with autologous grafts and can prevent the use of corneal stem cells, which are scarce and often unavailable.