Aquaporin could be key to repairing corneal defects, suggests new study

Investigators generated an Aqp5 knockout (Aqp5-/-) mouse model and performed corneal wound healing on corneas from which epithelial cells had been scraped away. They used 75 male Aqp5 +/+ mice and 189 male Aqp5-/- mice aged 10 to 12 weeks. Time to corneal epithelial and nerve regeneration was significantly delayed in the Aqp5-/- mice. To determine the role of NGF in the repair of corneal epithelial injury, NGF was injected in the subconjunctival space after corneal epithelium was scraped off in Aqp5-/- mice. The epithelial and nerve regeneration rate were significantly promoted in Aqp5-/- mice with the treatment of NGF, which also improved the recovery of corneal nerve fiber density and sensitivity in Aqp5-/- mice, accompanied by recovered levels of phosphorylated Akt.

The investigators also administered an Akt inhibitor in addition to NGF in Aqp5-/- mice to determine the mechanism of NGF regulating the repair rate of corneal epithelial injury. However, the promotion of NGF induced corneal epithelial and nerve regeneration rate and Akt reactivation was reversed by the Akt inhibitor.

"It is exciting to find that Aqp5 deficiency can affect the nerve regeneration of mice by affecting the activation of NGF and Akt signaling pathways, which is not found in previous studies," commented Dr. Chen. "These results need to be confirmed in a clinical setting, but they provide evidence for the involvement of aquaporins in cell proliferation and nerve regeneration and suggest AQP5 induction as a possible therapy to accelerate the resurfacing of corneal defects."

Aquaporins (AQPs), also called water channels, are channel proteins that form pores in the membrane of biological cells, mainly facilitating transport of water between cells and are expressed in the corneal epithelium. Thirteen different types of AQPs have been detected in mammals. As transmembrane proteins, they play a significant role in maintaining cell water homeostasis.