Biology subjects

Ohman, L.

Publications and source records attributed to Ohman, L..

2 recordsLinked to original sources

bioRxiv2024

Sox9 marks limbal stem cells and is required for asymmetric cell fate switch in the corneal epithelium

Adult tissues with high cellular turnover require a balance between stem cell renewal and differentiation, yet the mechanisms underlying this equilibrium are unclear. The cornea exhibits a polarized lateral flow of progenitors from the peripheral stem cell niche to the center; attributed to differences in cellular fate. To identify genes that are critical for regulating the asymmetric fates of limbal stem cells and their transient amplified progeny in the central cornea, we utilized an in vivo cell cycle reporter to isolate proliferating basal cells across the anterior ocular surface epithelium and performed single-cell transcriptional analysis. This strategy greatly increased the resolution and revealed distinct basal cell identities with unique expression profiles of structural genes and transcription factors. We focused on Sox9; a transcription factor implicated in stem cell regulation across various organs. Sox9 was found to be differentially expressed between limbal stem cells and their progeny in the central corneal. Lineage tracing analysis confirmed that Sox9 marks long-lived limbal stem cells and conditional deletion led to abnormal differentiation and squamous metaplasia in the central cornea. These data suggest a requirement for Sox9 for the switch to asymmetric fate and commitment toward differentiation, as transient cells exit the limbal niche. By inhibiting terminal differentiation of corneal progenitors and forcing them into perpetual symmetric divisions, we replicated the Sox9 loss-of-function phenotype. Our findings reveal an essential role for Sox9 for the spatial regulation of asymmetric fate in the corneal epithelium that is required to sustain tissue homeostasis.

developmental biology↗

bioRxiv2022

mRNA-mediated induced regeneration of the corneal endothelium

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.

cell biology↗