Human induced pluripotent stem cells-derived liver organoids grown on a Biomimesys® hyaluronic acid-based hydroscaffold as a new model for studying human lipoprotein metabolism.

The liver plays a key role in the metabolism of lipoproteins, controlling both production and catabolism. To accelerate the development of new lipid-lowering therapies in humans, it is essential to have a relevant in vitro study model available. The current hepatocyte-like cells (HLCs) models derived from hiPSC can be used to model many genetically driven diseases but require further improvement to better recapitulate the complexity of liver functions. Here, we aimed to improve the maturation of HLCs using a three-dimensional (3D) approach using Biomimesys®, a hyaluronic acid-based hydroscaffold in which hiPSCs may directly form aggregates and differentiate toward a functional liver organoid model. After a 28-day differentiation 3D protocol, we showed that many hepatic genes were upregulated in the 3D model (liver organoids) in comparison with the 2D model (HLCs). Liver organoids, grown on Biomimesys®, exhibited an autonomous cell organization, were composed of different cell types and displayed enhanced cytochromes P450 activities compared to HLCs. Regarding the functional capacities of these organoids, we showed that they were able to accumulate lipids (hepatic steatosis), internalize low-density lipoprotein and secrete apolipoprotein B. Interestingly, we showed for the first time that this model was also able to produce apolipoprotein (a), the apolipoprotein (a) specific of Lp(a). This innovative hiPSC-derived liver organoid model may serve as a relevant model for studying human lipopoprotein metabolism, including Lp(a).

Generation of an induced pluripotent stem cell line (ITXi012-A) from a patient with genetically determined high-lipoprotein(a) plasma levels.

Elevated circulating lipoprotein(a) (Lp(a)) is a genetically determined risk factor for coronary artery disease and aortic valve stenosis (Tsimikas, 2017). Importantly, the LPA gene, which encodes the apolipoprotein(a) (protein-component of Lp(a)), is missing in most species, and human liver cell-lines do not secrete Lp(a). There is a need for the development of human in vitro models suitable for investigating biological mechanisms involved in Lp(a) metabolism. We here generated and characterized iPSCs from a patient with extremely high Lp(a) plasma levels genetically determined (Coassin et al., 2022). This unique cellular model offers great opportunities and new perspectives for investigations on biological mechanisms involved in Lp(a) metabolism.

Generation of a GPR146 knockout human induced pluripotent stem cell line (ITXi001-A-1).

Dyslipidemia is a key modifiable causal risk factor involved in the development of atherosclerotic cardiovascular disease. Recently, the G protein-coupled receptor 146 (GPR146), a member of the G-coupled protein receptors' family, has been shown to be a regulator of plasma cholesterol. Inhibition of hepatic GPR146 in mice displays protective effect against both hypercholesterolemia and atherosclerosis. Here, we characterize a genetically engineered human induced pluripotent stem cell (hiPSC) model invalidated for GPR146 (ITXi001-A-1) using CRISPR-Cas9 editing technology. Differentiation of ITXi001-A-1 towards hepatic fate will provide a suitable model for deciphering the molecular mechanisms sustaining the beneficial metabolic effects of GPR146 inhibition.