Small-Molecule Inhibition of the Hippo Pathway Induces Regeneration of Retinal Pigment Epithelium.

Abstract

PURPOSE: To investigate whether Hippo pathway inhibition via a novel Lats kinase inhibitor (LKI) induces regeneration of retinal pigment epithelium (RPE). METHODS: An in vitro scratch "injury" on confluent RPE monolayers was produced using the Woundmaker Tool. A 6&#xd7;6 grid of laser spots was delivered to the central retinae of Dutch Belted rabbits via indirect laser. Following laser injury, eyes received 50&#xa0;&#xb5;L intravitreal LKI or vehicle. Fundus photography and optical coherence tomography (OCT) were performed prior to sacrifice for immunohistological analyses. RESULTS: In vitro RPE demonstrated accelerated wound healing 24 to 96&#xa0;hours after injury with LKI versus control treatment (P < 0.0001). In the in vivo rabbit model of retinal degeneration, laser spots in LKI-injected eyes demonstrated hyperpigmentation and RPE layer thickening with shadowing on OCT beginning at 1 week after treatment. There was a marked increase in RPE cross-sectional area (P < 0.0001) and percentage of Ki67+ RPE and M&#xfc;ller glia (P < 0.001), specifically at the laser spots. At 4 weeks, the increase in RPE cross-sectional area persisted (P < 0.001), but Ki67+ cells were no longer observed within the RPE (P = 0.36) or M&#xfc;ller glia (P = 0.48). The response was limited to the damaged regions, and there was no proliferation seen in the intact retina in either control or LKI-treated eyes. CONCLUSIONS: Hippo pathway inhibition via a novel LKI promotes wound healing and RPE proliferation in RPE monolayers in vitro. In a rabbit model of geographic atrophy, LKI treatment facilitated robust RPE regeneration and M&#xfc;ller glia proliferation specifically at the sites of injury.