Corneal regeneration by means of somatic cell therapy

The cornea is the anterior surface of the eye and principal optical element; it has multiple specialized functions. The first is to form a protective physical barrier that shields the inner eye from the external environment, defining what belongs to the body from what does not. The second important function lies in its ability to protect itself and many underlying ocular structures from various types of damage, ranging from physical trauma and biochemical injury to infection by pathogenic organisms to dangerous effects of long-term exposure to light. Moreover the cornea serves as the main refractive element of the visual system, directing incoming light onto the crystalline lens, which focuses it onto the retina. Refraction depends on the cornea acquiring transparency during embryonic development and maintaining it throughout adult life. Although the cornea appears to be one clear membrane, it is composed of several discrete layers. The outermost layer is the corneal epithelium that is renewable, transparent and forms a refracting optical surface along with the tear film. Only the corneal tissue is innervated and can signal pain. This epithelium can also signal to underlying layers, strongly affecting their behavior and function. An important peculiarity of corneal tissue is the total lack of blood vessels, making it a privileged immune site for transplantation. The past decade has witnessed much major progres in the field of ocular surrace reconstruction. Recent advances in stem cell biology have led to exploration of stem cell-based therapies to treat a wide range of human diseases. In the ophthalmology field, much hope has been placed on the potential use or these cells to restore sight, particularly in those condition in which which other established treatment has failed and in which visual function has been damaged or lost. Development of modified natural polymers and synthetic polymers either as cell-carriers or for their potential to replace damaged portions of the human cornea account for the most recent updates in the field.