L’émergence des modèles miniatures de foie gras humain en 3D générés en laboratoire

Les organoïdes constituent une approche de choix pour modéliser a minima une maladie humaine et tester l’efficacité thérapeutique de certaines drogues. La stéatopathie métabolique ou maladie du foie gras, dont l’incidence a considérablement augmenté avec l’accroissement de l’obésité dans les pays développés, se caractérise par l’accumulation de triglycerides dans l’hépatocyte et une atteinte hépatique pouvant évoluer vers la fibrose. Il n’existe pas de traitement efficace, mais de nombreuses pistes sont actuellement explorées. Deux équipes américaines ont récemment utilisé les cellules souches pluripotentes induites (iPS) et la culture muticellulaire pour modéliser un mini-foie stéatosique par deux approches différentes, offrant ainsi de nouveaux outils pour tester les drogues en cours de développement

Expression of SIRT1 in human fetal and adult liver and isolated hepatocytes.

<p>(A) Immunohistochemistry of SIRT1 in human fetal and adult liver, (B) Immunofluorescence staining of SIRT1 in fetal and adult hepatocytes after 2 days of culture. (C) Quantification of hepatic SIRT1 mRNA expression measured by qRT- PCR in human fetal and adult hepatocytes in vitro and in vivo (n≥3/group).</p

Expression of SIRT1 in human fetal and adult liver and isolated hepatocytes.

<p>(A) Immunohistochemistry of SIRT1 in human fetal and adult liver, (B) Immunofluorescence staining of SIRT1 in fetal and adult hepatocytes after 2 days of culture. (C) Quantification of hepatic SIRT1 mRNA expression measured by qRT- PCR in human fetal and adult hepatocytes in vitro and in vivo (n≥3/group).</p

Lipids and glucose levels in human fetal hepatocytes after Sirt1 inhibition.

<p>(A) Fluorescent staining of lipids (red droplets, white arrow) inside human fetal hepatocytes (HFH) with or without 50uM Sirtinol for 3 days (20x). (B) Triglycerides quantification of human fetal hepatocytes with or without +50uM Sirtinol for 3 days analyzed by a colorimetric assay. (C) Glucose concentration between normal HFH and HFH +50uM Sirtinol for 3 days. (n≥7/group; *, P < .05).</p

Increased activation of Glucogenesis pathway in human fetal hepatocytes after exposure to Sirtinol.

<p>(A) Expression of hepatic PEPCK and G6PC mRNA measured by qRT- PCR in human fetal hepatocytes exposed to +50uM Sirtinol compared to controls. (B) Immunofluorescence of S-473 AKT in human fetal hepatocytes with or without 50uM Sirtinol (10x). (C) Fluorescence intensity quantification for S-473 AKT signal (arbitrary units) using ImageJ (n≥7/group; *, P < .05). (D) Western blot analysis for S-473 AKT/AKT, S-256 FOXO1/FOXO1 in human fetal hepatocytes exposed to 50uM Sirtinol compared to controls. GAPDH was used as a loading control. (E) Immunofluorescence staining of S-256 FOXO1 in human fetal hepatocytes with or without 50uM Sirtinol (20x).</p

Donor Demographics.

<p>Donor Demographics.</p

Representation of SIRT1 regulation of lipid and glucose balances in human fetal hepatocytes.

<p>In normal conditions, SIRT1 inhibits De Novo Lipogenesis and Gluconeogenesis through the AKT/FOXO1 pathway inside human fetal hepatocytes, keeping a normal balance inside the cells. Upon SIRT1 inhibition, both the lipid and glucose balance will be disrupted, leading to an increase of lipid and carbohydrates levels in human fetal hepatocytes.</p