Abstrakt
The lack of physiological parity between 2D cell culture and in vivo culture has led to the development of more organotypic models, such as organoids. Organoid models have been developed for a number of tissues, including the liver.
Current organoid protocols are characterized by a reliance on extracellular matrices (ECMs), patterning in 2D culture, costly growth factors and a lack of cellular diversity, structure, and organization. Current hepatic organoid models are generally simplistic and composed of hepatocytes or cholangiocytes, rendering them less physiologically relevant compared to native tissue.
We have developed an approach that does not require 2D patterning, is ECM independent, and employs small molecules to mimic embryonic liver development that produces large quantities of liver-like organoids. Using single-cell RNA sequencing and immunofluorescence, we demonstrate a liver-like cellular repertoire, a higher order cellular complexity, presenting with vascular luminal structures, and a population of resident macrophages: Kupffer cells.
The organoids exhibit key liver functions, including drug metabolism, serum protein production, urea synthesis and coagulation factor production, with preserved post-translational modifications such as N-glycosylation and functionality. The organoids can be transplanted and maintained long term in mice producing human albumin.
The organoids exhibit a complex cellular repertoire reflective of the organ and have de novo vascularization and liver-like function. These characteristics are a prerequisite for many applications from cellular therapy, tissue engineering, drug toxicity assessment, and disease modeling to basic developmental biology.
A unique 3D approach results in an organoid, a laboratory-grown miniature organ model, with high cellular complexity that closely mimics the three-dimensional structure and functions of the liver. The Sullivan lab at Oslo University Hospital, Norway, and co-workers have developed an approach to create liver organoids that results in cellular diversity and is not reliant on costly growth factors or extracellular matrices.
They used suspension culture system, in which human pluripotent stem cells self-aggregate into 3D structures, rather than relying on the 2D patterning. Their organoids demonstrated mature cellular behaviours, included a population of liver-specific macrophages, and is capable of drug metabolism, protein production and other key liver functions.
The team's approach is scalable, inexpensive and has multiple potential applications, from basic biology and disease modelling to tissue engineering and cellular therapies.