Unlocking the therapeutic potential of the corneal endothelium: Intravital imaging reveals endogenous regenerative capabilities

Loss of vision due to corneal endothelial dysfunction affects millions worldwide. The development of new treatments is hampered by the incomplete knowledge of the regenerative capacity of corneal endothelial cells in vivo . Herein, we developed a mouse model to directly monitor corneal endothelial regeneration in real time, and at the single cell level, by two-photon microscopy. We show that the mouse corneal endothelium recapitulates the main features of human endothelial physiology, including complete cellular quiescence and a decline in cell density with aging. Critically, we demonstrate the endogenous regenerative potential of the tissue by capturing the proliferation of corneal endothelial cells during repair of large injuries. By single cell lineage tracing analysis, we provide evidence that corneal endothelial cells are equipotent in their ability to activate the cell cycle and contribute to tissue regeneration. Based on these findings we developed a feasible therapeutic approach to stimulate the regeneration of the corneal endothelium, using modified mRNA technology. To reprogram corneal endothelial cells in vivo and unlock their ability to escape quiescence, we combined five modified mRNAs encoding for proteins involved in cell cycle activation. Injection of the encapsulated mRNAs directly into the eye of older mice induced transient proliferation of corneal endothelial cells that led to an increase in endothelial cell density, effectively reversing the effect of aging. This therapeutic strategy offers a compelling paradigm for treating ocular disease and modulating tissue regeneration in organs with limited endogenous ability.