Stem cells in ophthalmology

Stem cells are unspecialized cells with the potential to differentiate into a variety of specialized cells that develop into different types of tissue in the body. Depending on the source of the stem cells, they can be categorized as embryonic or adult stem cells. Pluripotent stem cells, including both embryonic stem cells and induced pluripotent stem cells have the ability to differentiate into any of the three germ layers as well as tissue-specific adult stem cells. Multiple studies have reported on the differentiation of pluripotent stem cells into various ocular cell types, including cornea-, lens-, and retina-specific stem cells. Adult stem cells can differentiate into a particular cell lineage and have been identified in multiple tissues, including the eye, hematopoietic system, skin, intestinal epithelia, and nervous system. The ocular stem cells, which reside in different components of the eye, include cornea, conjunctival, iris, ciliary body, scleral, limbal, choroidal, trabecular meshwork, orbital, lens, and retinal stem cells. Ocular stem cells can differentiate into multiple ocular cell lineages and have different functional aspects. In conclusion, pluripotent stem cells and ocular stem/progenitor cells residing in different regions of the eye are capable of differentiation that enables cell repopulation and tissue regeneration, which are capabilities with enormous potential in the field of ophthalmology.