Maintenance of Primary Hepatocyte Functions In Vitro by Inhibiting Mechanical Tension-Induced YAP Activation

Under mechanically specified circumstances, mature hepatocyte function can be sustained for around two weeks in certain matrix-independent culture platforms.

“Under mechanically specified circumstances, mature hepatocyte function can be sustained for around two weeks in certain matrix-independent culture platforms.”

Interaction between Wnt and Hippo/YAP signaling indicates that mechanically induced YAP activation can either promote regulated plasticity or accelerate identity loss depending on the culture context.

“Expansion is generally facilitated by diploid (2c) hepatocytes, and the interaction between Wnt and Hippo/YAP signaling indicates that mechanically induced YAP activation can either promote regulated plasticity or accelerate identity loss, depending on the culture context [20].”

Expansion is generally facilitated by diploid (2c) hepatocytes.

“Expansion is generally facilitated by diploid (2c) hepatocytes, and the interaction between Wnt and Hippo/YAP signaling indicates that mechanically induced YAP activation can either promote regulated plasticity or accelerate identity loss, depending on the culture context [20].”

Inhibition of signaling pathways linked to cellular stress responses and identity loss can postpone dedifferentiation and preserve drug-metabolizing activity for prolonged durations.

“In addition, the inhibition of signaling pathways linked to cellular stress responses and identity loss can postpone dedifferentiation and preserve drug-metabolizing activity for prolonged durations, thereby enhancing disease modeling and toxicology studies.”

The extracellular matrix significantly modulates hepatocyte plasticity.

“In addition, the ECM significantly modulates hepatocyte plasticity.”

Inhibiting cell spreading and reducing actin tension, Src kinase, tankyrase and PI3K all inhibit YAP activation, enabling hepatocytes to preserve polarity and metabolic activity without re-entering the cell cycle.

“This inhibition enables hepatocytes to preserve polarity and metabolic activity without re-entering the cell cycle [20].”

Collagen, laminin, Matrigel, and decellularized liver scaffolds enhance hepatic identity but reduce actomyosin tension, increasing the risk of dedifferentiation.

“Collagen, laminin, Matrigel, and decellularized liver scaffolds enhance hepatic identity; however, they reduce actomyosin tension, which is achieved through ROCK inhibition, micropatterning, or tension-modulating cocktails, increasing the risk of dedifferentiation.”

Hepatocyte spheroids and organoid-like aggregates are notably robust and reproducible models.

“Within 3D methodologies, hepatocyte spheroids and organoid-like aggregates emerged as notably robust and reproducible models [19,20,25,26].”

Self-assembled microtissues facilitate improved cell-cell interactions and have greater physiological relevance in cell polarity than 2D systems.

“These self-assembled microtissues facilitate improved cell–cell interactions and have greater physiological relevance in cell polarity than 2D systems [19,20,25,26].”

MPH dedifferentiation can only be partially inhibited by combined inhibition of multiple dedifferentiating signaling pathways or by forced expression of supra-physiologic amounts of HNF4A.

“previous reports indicated that MPH dedifferentiation could only be partially inhibited when using combined inhibition of multiple dedifferentiating signaling pathways (Sun et al, 2019; Xiang et al, 2019) or through forced expression of supra‐physiologic amounts of the Hep‐ID TF HNF4A (Nishikawa et al, 2015; Tafaleng et al, 2021; Yang et al, 2021).”

Hepatocytes respond to increase of stiffness by enhancing actin contractility, downregulating HNF4A protein and activating ERK, PI3K and YAP signalling.

“Hepatocytes respond to increase of stiffness by enhancing actin contractility, downregulating HNF4A protein and activating extracellular signal‐regulated kinase (ERK), PI3K and YAP signalling [5, 22, 23].”

Rho/ROCK signalling is an important mechanical response in PH.

“It is known that Rho/ROCK signalling is an important mechanical response in PH [5, 22].”

Hepatocytes lose their epithelial and functional characteristics in stiff culture conditions such as TCPD, developing a partial EMT state.

“Hepatocytes lose their epithelial and functional characteristics in stiff culture conditions such as in a commonly used TCPD, developing a partial EMT state [22].”

Activation of MRTcoF correlates with an increase of actin contractility measured by TFM.

“Activation of MRTcoF correlated with the loss of circularity and the increment of cell area in PH cultured in > 5 kPa HGs; it also correlates with an increase of actin contractility measured by TFM [22] (Fig. 7E).”

All these signals (actin polymerisation, contractibility or SRC/ERK/PI3K pathways) are upstream of the activation of MRTcoF.

“It seems that a full inhibition may be performed in parallel with the blockage of actin polymerisation, contractibility or SRC/ERK/PI3K pathways (latrunculin B, blebbistatin and dasatinib/U0126/LY294002, respectively) because all these signals are upstream of the activation of MRTcoF [22, 70].”