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J.J. Reidy, W. Sun, R. Salvi, L.M. Campbell, S. Sullivan, G.M. Seigel; Human Corneal Stem Cells Exhibit Functional Neuronal Properties . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2035.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Human corneal limbal stem cells have the capacity to mature and repopulate the superficial layers of the cornea throughout life. In this study, we tested the hypothesis that human corneal stem cells, derived from neural ectoderm, can exhibit functional neuronal properties. Methods: Human corneal limbal tissue (donor age 6 weeks to 89 years) was obtained from Upstate New York Transplant Services. Tissues were grown as explants on coverslips in DMEM with 10% calf serum. After 7-14 days in vitro, tissues on coverslips were double-immunostained for the stem cell marker p63, along with neurotransmitter receptors GABA, dopamine, serotonin, glycine or acetylcholine. We also carried out whole cell current clamp and voltage clamp recordings on corneal stem cell cultures in order to determine their functional neurophysiological properties.Results:Co-localization of p63 with GABA receptor, glycine receptor, and serotonin receptor immunoreactivity was seen in a small number of cells in the corneal stem cell cultures. The resting potential of corneal stem cells was relatively low, approximately -13±8 mV (n=13; range –6 mV to -40 mV) measured in current clamp. No action potentials or voltage sensitive Na+ and K+ currents were detected. However, in a small number of cells, kainic acid (0.5 mM), a non-NMDA glutamate receptor agonist, and GABA induced a small inward current. Glutamate receptor antagonist, CNQX, and GABA receptor antagonist, bicuculline and CGP-35348 blocked the agonist response. Other neurotransmitters are still under investigation.Conclusions: A subpopulation of human corneal stem cells exhibit neuronal properties in vitro, as evidenced by immunoreactivity to GABA receptor, glycine receptor, and serotonin receptor, as well as functional neurophysiological responses to GABA and kainic acid. Further treatments with neurotrophic factors may enhance the differentiation of human corneal stem cells toward neuronal phenotypes, with the ultimate goal of replacing lost/damaged neurons of the central nervous system. Human corneal stem cells may represent a potential source of non-embryonic, autologous, surgically-accessible graft material with neuronal potential.
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