Stem Cells and Ocular Tissue Regeneration.

Abstract

Millions worldwide have visual impairments caused by dysfunctional eye components, including cornea, lens, retina, and optic nerve, or the visual cortex in the brain. Insufficient cornea donation and inherent artificial lens problems demand alternative treatment strategies for cornea diseases and cataracts, whereas retinal degenerative diseases, including glaucoma, macular degeneration, and retinitis pigmentosa, still lack effective treatments. Stem cells have been investigated for their potential in various eye-specific pathologies to replace lost retinal ganglion cells and photoreceptors in retinal degenerative diseases and toward engineering transplantable patient-specific cornea or lens. Many stem cell types, including putative resident eye stem cells, mesenchymal stem cells, embryonic stem cells, and induced pluripotent stem cells, have been investigated for their potential to generate specific cell types in the eye in culture and after transplantation and to engineer eye tissues in combination with structural scaffolds. Cultured stem cells and in vitro differentiated eye-specific cells are transplanted into different locations of the eye to test their ability to produce functional cells for supporting eye functions. In addition, stem cells have been directly tested in vitro for their capacity to engineer eye-specific tissues. Different stem cell types have been shown to have distinct capacities to produce eye-specific cells or even the entire retina. Stem cells offer great hope for treating various eye pathologies. Despite recent progress, many challenges must still be overcome before the era of stem cell-based therapy in the eye truly arrives.