title: On the adhesion-cohesion balance and oxygen consumption characteristics of liver organoids.
abstract: Liver organoids (LOs) are of interest in tissue replacement, hepatotoxicity and pathophysiological studies. However, it is still unclear what triggers LO self-assembly and what the optimal environment is for their culture. Hypothesizing that LO formation occurs as a result of a fine balance between cell-substrate adhesion and cell-cell cohesion, we used 3 cell types (hepatocytes, liver sinusoidal endothelial cells and mesenchymal stem cells) to investigate LO self-assembly on different substrates keeping the culture parameters (e.g. culture media, cell types/number) and substrate stiffness constant. As cellular spheroids may suffer from oxygen depletion in the core, we also sought to identify the optimal culture conditions for LOs in order to guarantee an adequate supply of oxygen during proliferation and differentiation. The oxygen consumption characteristics of LOs were measured using an O2 sensor and used to model the O2 concentration gradient in the organoids. We show that no LO formation occurs on highly adhesive hepatic extra-cellular matrix-based substrates, suggesting that cellular aggregation requires an optimal trade-off between the adhesiveness of a substrate and the cohesive forces between cells and that this balance is modulated by substrate mechanics. Thus, in addition to substrate stiffness, physicochemical properties, which are also critical for cell adhesion, play a role in LO self-assembly.
authors.affiliation: Research Centre "E. Piaggio", University of Pisa, Largo Lucio Lazzarino, Pisa, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Mattei
authors.affiliation: Research Centre "E. Piaggio", University of Pisa, Largo Lucio Lazzarino, Pisa, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Magliaro
authors.affiliation: Research Centre "E. Piaggio", University of Pisa, Largo Lucio Lazzarino, Pisa, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Giusti
authors.affiliation: Medicyte GmbH, Im Neuenheimer Feld, Heidelberg, Germany.
authors.forename: Sarada Devi
authors.initials: SD
authors.lastname: Ramachandran
authors.affiliation: Medicyte GmbH, Im Neuenheimer Feld, Heidelberg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Heinz
authors.affiliation: Tissue Engineering and Regenerative Medicine, University Hospital Wuerzburg, Roentgering, Wuerzburg, Germany.
authors.forename: Joris
authors.initials: J
authors.lastname: Braspenning
authors.affiliation: Research Centre "E. Piaggio", University of Pisa, Largo Lucio Lazzarino, Pisa, Italy.
authors.forename: Arti
authors.initials: A
authors.lastname: Ahluwalia
mesh_terms: D000465:Algorithms; D015415:Biomarkers; D002448:Cell Adhesion; D018929:Cell Culture Techniques; D003470:Culture Media; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism; D005782:Gels / Q000737:chemistry; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008954:Models, Biological; D009940:Organoids; D010101:Oxygen Consumption; D054457:Tissue Scaffolds / Q000737:chemistry
chemical_list: D015415:Biomarkers; D003470:Culture Media; D005782:Gels