Exploring Interactions between Primary Hepatocytes and Non-Parenchymal Cells on Physiological and Pathological Liver Stiffness

Abstract

Chronic liver disease is characterized by progressive hepatic fibrosis leading to the formation of cirrhosis irrespective of the etiology with no effective treatment currently available. Liver stiffness (LS) is currently the best clinical predictor of this fibrosis progression irrespective of the etiology. LS and hepatocytes-nonparenchymal cells (NPC) interactions are two variables known to be important in regulating hepatic function during liver fibrosis, but little is known about the interplay of these cues. Here, we use polydimethyl siloxane (PDMS) based substrates with tunable mechanical properties to study how cell–cell interaction and stiffness regulates hepatocytes function. Specifically, primary rat hepatocytes were cocultured with NIH-3T3 fibroblasts on soft (2 kPa) and stiff substrates that recreates physiologic (2 kPa) and cirrhotic liver stiffness (55 kPa). Urea synthesis by primary hepatocytes depended on the presence of fibroblast and was independent of the substrate stiffness. However, albumin synthesis and Cytochrome P450 enzyme activity increased in hepatocytes on soft substrates and when in coculture with a fibroblast. Western blot analysis of hepatic markers, E-cadherin, confirmed that hepatocytes on soft substrates in coculture promoted better maintenance of the hepatic phenotype. These findings indicate the role of stiffness in regulating the hepatocytes interactions with NPCs necessary for maintenance of hepatocytes function.

In Vitro Models for the Study of Liver Biology and Diseases: Advances and Limitations

“…An innovative platform called bio-engineered adhesive siloxane substrate with tunable stiffness based on a polydimethyl siloxane substrate in combination with polyelectrolyte multilayer film-coating technology was developed to engineer mechanically tunable substrates mimicking physiologic and pathologic liver stiffness. 44 , 45 , 46 , 47 , 48 More recently, 3-dimensional (3D) bioprinting has emerged for precise spatial positioning of both cells and biomaterials or bioinks such as alginate together in 3D complex geometries and providing mechanical support. 49 , 50 Nguyen et al 51 have bioprinted hepatocytes and nonparenchymal cells in 3D architecture and developed models of drug-induced liver injury.…”

The native liver as inspiration to create superior in vitro hepatic models

“…84 The hydrogel stiffness is also very important. 9,85 On the one hand, the scaffolds need to provide structural stability to maintain its shape, but on the other hand, they need to be soft enough for their application in liver tissue engineering (being a soft tissue). From previous research, it is known that hepatocytes are highly influenced by the stiffness of the matrix they are cultured on.…”

Pathogenesis of Alcohol-Associated Liver Disease

“…168 Recent studies have shown that, not only inflammation and activation of HSC to produce extracellular matrix affect the progression of ALD to endstage liver diseases, but also pre-existing increases in liver stiffness promote pathological changes in liver cells. Studies conducted on hepatocytes plated on surfaces that mimic the stiffness of healthy (soft gels, 2 kDa) and cirrhotic (stiff gels, 55 kDa) livers revealed that cells grown on stiff surfaces exhibit lower albumin synthesis and cytochrome P450 enzyme activity 169 indicating that extracellular stiffness regulates hepatocyte function. Additionally, hepatocytes plated on stiff matrices and then exposed to second hits, including HCV-HIV coinfections, exhibited higher levels of apoptosis and viral infectivity.…”