Metalloprotease inhibitors regulate biliary progenitor cells through sDLK1 in organoid models of liver injury.

Understanding cell fate regulation in the liver is necessary to advance cell therapies for hepatic disease. Liver progenitor cells (LPC) contribute to tissue regeneration after severe hepatic injury yet signals instructing progenitor cell dynamics and fate are largely unknown. The Tissue Inhibitor of Metalloproteinases, TIMP1 and TIMP3 control the sheddases ADAM10 and ADAM17, key for NOTCH activation. Here we uncover the role of the TIMP/ADAM/NOTCH/DLK1 axis in LPC maintenance and cholangiocyte specification. Combined TIMP1/TIMP3 loss in vivo caused abnormal portal triad stoichiometry accompanied by collagen deposits, dysregulated Notch signalling and increased soluble DLK1. The MIC1-1C3+CD133+CD26- biliary progenitor population was reduced following acute CCl4 or chronic DDC liver injury and in aged TIMP deficient livers. ScRNA-seq data interrogation and RNAscope identified portal mesenchymal cells co-expressing ADAM17/DLK1 as enzymatically equipped to process DLK1 and direct LPC differentiation. Specifically, TIMP deficient biliary fragment-derived organoids displayed increased propensity for cholangiocyte differentiation. ADAM17 inhibition reduced Sox9-mediated cholangiocyte differentiation, prolonging organoid growth and survival, whereas soluble DLK1-treated WT organoids triggered Sox9 expression and cholangiocyte specification in mouse and patient-derived liver organoids. Thus, metalloprotease inhibitors regulate instructive signals for biliary cell differentiation and LPC preservation within the portal niche, providing a new basis for cell therapy strategies.