Ocular regeneration by stem cells: present status and future prospects.

BACKGROUND: Advances in the stem cell field provide much hope for the use of these cells in the regeneration of ocular tissue damaged by diseases for which no treatments are yet available. Here, we discuss the current status and limitations on the application of stem cells to ocular therapies, and consider the future prospects for their use in the restoration of vision. SOURCE OF DATA: The review summarizes the achievements to date and the present areas of stem cell investigations in the ophthalmic field, based on a literature search and knowledge gained by the authors' work in the subject. AREAS OF AGREEMENT: Owing to its accessibility, the cornea constitutes an easy anatomical target for stem cell regeneration. On this basis, limbal epithelial stem transplantation is the only ocular cell-based therapy already in use in the clinical setting. AREAS OF CONTROVERSY: Regeneration of the retina, a less accessible and complex neural tissue, currently constitutes a major challenge. Investigations into the potential use of stem cells for retina regeneration have generated variable data and no therapies have yet been designed for human treatments. GROWING POINTS: Despite the present limitations, it has been progressively accepted that various stem cells may have potential use for the development of cell-based therapies to restore retinal function. AREAS FOR RESEARCH DEVELOPMENT: There is need to understand the cell requirements and environmental conditions that may promote functional integration and long-term survival of stem cells within the diseased retina. At present, this constitutes a major area of research.