Corneal stem cells in review.
The cornea provides the eye with protection and the refractive properties essential for visual acuity. The transparent epithelium is highly specialized with basal and stratified squamous cells that are renewed throughout life from a stem cell population. The stem cells are thought to reside at the corneal limbus and may be maintained by a variety of intrinsic and extrinsic factors such as the local environment, survival factors, and cytokines. A number of markers have been localized to the limbus in an attempt to identify stem cells; however, definite stem cell identification remains elusive. During homeostasis and following injury to the corneal epithelium, the limbal stem cells divide to produce daughter transient amplifying cells that proliferate, migrate, and differentiate to replace lost cells. However, this cannot occur if the stem cell population is depleted. Limbal stem cell deficiency then results in corneal re-epithelialization by the neighboring conjunctiva, causing pain, poor vision, and even blindness. This review will focus on corneal epithelial stem cells in ocular surface repair and regeneration. The current knowledge of stem cell biology in the corneal epithelium, clinical consequences of stem cell deficiency, and therapeutic strategies aimed at reversing stem cell deficiency will be discussed.
Daniels
J T
JT
Epithelial Repair and Regeneration Group, Wound Healing Research Unit, Department of Pathology, Institute of Ophthalmology; and Moorfields Eye Hospital NHS Trust, London, United Kingdom. j.daniels@ucl.ac.uk
Dart
J K
JK
Tuft
S J
SJ
Khaw
P T
PT
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D003315:Cornea / Q000166:cytology*; D016039:Corneal Transplantation; D016207:Cytokines / Q000502:physiology; D004268:DNA-Binding Proteins; D004847:Epithelial Cells / Q000502:physiology*; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors / Q000502:physiology; D020690:GTPase-Activating Proteins / Q000502:physiology; D016147:Genes, Tumor Suppressor; D006801:Humans; D015603:Keratinocytes / Q000502:physiology; D016850:Limbus Corneae / Q000166:cytology; D008565:Membrane Proteins; D010750:Phosphoproteins / Q000502:physiology; D013234:Stem Cells / Q000502:physiology*; D015534:Trans-Activators / Q000502:physiology; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins
C081876:CKAP4 protein, human; D016207:Cytokines; D004268:DNA-Binding Proteins; C496453:FGF7 protein, human; D020690:GTPase-Activating Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors