Introduction

Hepatic function is precisely regulated by the cellular building blocks that form the innermost lining of the hepatic vasculature, the liver sinusoidal endothelial cells (LSEC)1. Being strategically positioned at the interface of the circulation and surrounding stroma, liver endothelial cells (EC) sense dynamic changes in fluctuating milieu factors and display a remarkable adaptive plasticity towards graded biophysical cues, including hypoxia, oxidative stress, and haemodynamic forces2,3. Thus, the hepatic endothelium has emerged as an active gatekeeper of homeostatic liver function by decoding exogenous stimuli into instructive EC-derived angiocrine factors, which ultimately regulate organ size and regeneration, host defence and the metabolic fate of hepatocytes4–12. Given the crucial roles of LSEC in shaping liver function, recent studies have focused on key organotypic transcription factors that modulate LSEC fate and have developed robust protocols to generate LSEC for therapeutic purposes13–15.

Recent advances in single cell genomics have permitted the dissection of cellular heterogeneity. Most of hepatic cell types, including hepatocytes and LSEC were identified to express gradual gene expression programmes alongside the liver sinusoids16,17. This zonation pattern coincides with biophysical gradients, which are established by the unique features of the hepatic vasculature that is defined by a dual blood supply. Oxygenated blood entering the liver lobule through the hepatic artery is mixed with nutrient-rich blood from the portal vein in the liver sinusoidal vessels. Hepatocytes lining the sinusoids consume oxygen and metabolites resulting in the drainage of hypoxic and nutrient-depleted blood by the central vein. This gradient of availability in oxygen and macromolecules establishes the spatial division of labour in the liver, which is essential for hepatic function and, hence, systemic health. The balance between periportal and pericentral hepatic function orchestrates the total energy supply and xenobiotic metabolism18. Losing this balance, thus losing the metabolic zonation of the liver, eventually results in impaired hepatic function and is associated with a poor prognosis in hepatic diseases such as hepatocellular carcinoma or leads to metabolic dysfunction such as hyperammonaemia19,20. Understanding how liver zonation is established and maintained is therefore of high pathophysiological relevance.

Pericentral LSEC are major determinants of hepatic function and the spatial coordination of the hepatic architecture by secreting morphogenic Wnt factors Wnt2, Wnt9b, and the Wnt potentiator R-spondin3 (Rspo3)4,9–12. These vascular Wnt factors establish and sustain a highly metabolic pericentral hepatocyte niche and they have been shown to be regulated by the endothelial-specific receptor tyrosine kinase Tie121,22. In fact, one-third of the endothelial transcriptome and roughly 25% of the endothelial proteome were found to be zonated alongside the portal-central venous axis22. While hepatic zonation and its consequences have been characterised in substantial detail, microenvironmental factors that establish zonated gene programmes remain elusive. Indirect evidence implies that mechanical stimuli may trigger the expression of vascular Wnt factors in the liver23,24. Yet, a systematic investigation of biophysical factors that enforce hepatic zonation has not been conducted.