Multi-zonal liver organoids from human pluripotent stem cells

Area of Science:

• Hepatology and Regenerative Medicine
• Stem Cell Biology
• Organoid Technology

Background:

• Distinct hepatocyte subpopulations are spatially segregated along the portal-central axis, crucial for liver function.
• Existing in vitro models have not replicated this zonal liver architecture.
• Bioactive molecules like ascorbate and bilirubin are implicated in directing hepatocyte zonal fates.

Purpose of the Study:

• To develop a self-assembling, zone-specific liver organoid model using human induced pluripotent stem cells.
• To evaluate hepatic zonal polarity and function in vitro.
• To investigate the molecular mechanisms underlying zonal identity.

Main Methods:

• Co-culturing ascorbate- and bilirubin-enriched hepatic progenitors derived from human induced pluripotent stem cells.
• Single-nucleus RNA-sequencing to identify hepatoblast differentiation trajectories.
• Epigenetic and transcriptomic analysis to elucidate molecular regulation of zonal identity.
• Transplantation of organoids into immunodeficient rats.

Main Results:

• Developed a self-assembling liver organoid exhibiting zone-specific functions (urea cycle, glutathione, glutamate synthesis).
• Identified a hepatoblast differentiation trajectory defining periportal, interzonal, and pericentral hepatocytes.
• Determined that ascorbate/bilirubin-dependent EP300 binding to TET1/HIF1α orchestrates zonal identity.
• Transplanted organoids improved survival in rats with bile duct ligation by reducing hyperammonaemia and hyperbilirubinaemia.

Conclusions:

• The developed multi-zonal organoid system successfully recapitulates human hepatic architecture in vitro.
• This model serves as a valuable tool for studying liver development, metabolic homeostasis, and disease.
• The findings provide insights into the molecular mechanisms controlling liver zonation.