Scar-associated endothelial-stellate cellular crosstalk drives fibrosis resolution in MASH.

Fibrosis contributes to ∼40% of mortality in the industrialized world. Fibrosis in the liver can spontaneously resolve when injury terminates. In this study, we establish a robust mouse model of fibrosis regression in MASH (metabolic dysfunction-associated steatohepatitis), a highly prevalent chronic liver disease worldwide, and perform single-cell and in situ molecular profiling to define the molecular drivers of fibrosis regression. Prediction of cell-cell communication identifies a Wnt9b-Sfrp2 crosstalk that emerges as fibrosis resolves, the perturbation of which attenuates spontaneous fibrosis regression. We further identify a subset of liver endothelial cells termed "Endo4" as the source of Wnt9b. Immunostaining for the Endo4 marker VWF using tissue clearing and 3D imaging reveals VWF+ vasculature juxtaposing activated hepatic stellate cells that penetrate deep into the fibrotic septa and exhibit in situ protease activity, establishing them as de facto scar-associated endothelial cells and a regulatory node in murine MASH fibrosis regression.