Multi-omics analysis of hiPSCs-derived HLCs matured on-chip revealed patterns typical of liver regeneration

Liver Extracellular Vesicles and Particles Enriched β-Sitosterol Effectively Promote Liver Regeneration in Mice

Background

The liver's regenerative capacity allows it to repair itself after injury. Extracellular vesicles and particles (EVPs) in the liver's interstitial space are crucial for signal transduction, metabolism, and immune regulation. Understanding the role and mechanism of liver-derived EVPs in regeneration is significant, particularly after partial hepatectomy, where the mechanisms remain unclear.

Methods

A 70% hepatectomy model was established in mice, and EVPs were isolated and characterized using electron microscopy, nanocharacterization, and Western blot analysis. Combined metabolomic and transcriptomic analyses revealed β-sitosterol enrichment in EVPs and activation of the Hedgehog signaling pathway during regeneration. The role of β-sitosterol in EVPs on the Hedgehog pathway and its targets were identified using qRT-PCR, Western blot analysis. The regulation of carnitine synthesis by this pathway was determined using a dual luciferase assay. The effect of a β-sitosterol diet on liver regeneration was verified in mice.

Results

After 70% hepatectomy, the liver successfully regenerated without liver failure or death. At 24 hours post-surgery, tissue staining showed transient regeneration-associated steatosis (TRAS), with increased Ki67 positivity at 48 hours. EVPs displayed a spherical lipid bilayer structure with particle sizes of 70-130 nm. CD9, CD63, and CD81 in liver-derived EVPs were confirmed. Transcriptomic and metabolomic analyses showed EVPs supplementation significantly promoted carnitine synthesis and fatty acid oxidation. Tissue staining confirmed accelerated TRAS resolution and enhanced liver regeneration with EVP supplementation. Mass spectrometry identified β-sitosterol in EVPs, which binds to Smo protein, activating the Hedgehog pathway. This led to the nuclear transport of Gli3, stimulating Setd5 transcription and inducing carnitine synthesis, thereby accelerating fatty acid oxidation. Mice with increased β-sitosterol intake showed faster TRAS resolution and liver regeneration compared to controls.

Conclusion

Liver-derived EVPs promote regeneration after partial hepatectomy. β-sitosterol from EVPs accelerates fatty acid oxidation and promotes liver regeneration by activating Hedgehog signaling pathway.

[Evaluation and Clarification of Enterohepatic Interactions in Pharmacokinetics]

The evaluation and prediction of pharmacokinetics in humans is important in the field of drug discovery and development. Generally, human pharmacokinetics is predicted using physiologically based pharmacokinetic models that include physiological and physicochemical (drug) parameters obtained from in vitro assays. Specific organ dysfunction, such as liver disease, also affects the functions of other organs, causing unexpected pharmacokinetic fluctuations. I investigated the effect of cholestasis on intestinal drug absorption in mice subjected to bile duct ligation (BDL). The intestinal absorption and permeability of imatinib was decreased in BDL mice compared with sham-operated mice, and this may be attributed to the up-regulation of the efflux transporter, breast cancer resistance protein. However, a single-organ experimental system cannot predict such pharmacokinetic changes. To overcome this challenge, I investigated a microphysiological system (MPS) equipped with intestinal and hepatic cells for pharmacokinetic evaluation. The glucuronidation of triazolam was significantly increased in an enterohepatic MPS compared with a single-culture system. These results suggested that the elucidation of organ interactions requires the use of an MPS loaded with human cells in combination with laboratory animal studies. In this review, I present the results of my evaluation of organ interactions using animal models and MPSs in the Award for Young Scientists from the Pharmaceutical Society of Japan, Hokuriku Branch.

Mass spectrometry-based quantitation combined with time-dependent metabolomics to discover metabolic features in human neurogenesis using neural constructs generated from neural progenitor cells

Direct studies focusing on the human brain are difficult to plan and conduct due to ethical and practical reasons. The advent of human pluripotent stem cell (hPSC)-derived neurons has revolutionized the research of the human brain and central nervous system, but relevant analytical techniques have been much less explored. Herein, we have designed a novel bioanalytical strategy to discover the characteristics of human neurogenesis using liquid chromatography-mass spectrometry-based quantitation and time-dependent metabolomics in combination with hPSC-derived neural constructs. To examine the growth of neurons in vitro, a quantitative method for the simultaneous measurement of N-acetylaspartic acid (NAA) and N-acetylglutamic acid (NAG) in a culture medium was established. The analysis of endogenous NAA and NAG concentrations over 28 days of neural cell culture not only illustrated the growth and maturation process of neural progenitors, but also confirmed the successful achievement of human neural constructs. Depending on the quantitative results, day 0, 10, 18, and 28 samples representing different growth phases were selected for further investigation of the global metabolic changes in developing human neurons. A versatile non-targeted, time-dependent metabolomics study identified 17 significantly changed metabolites and revealed the altered metabolic pathways including amino acid metabolism (tryptophan, phenylalanine, aspartate and beta-alanine metabolisms), pantothenate and coenzyme A biosynthesis, fatty acid metabolism, and purine and pyrimidine metabolism. The new metabolite profiles and overall metabolic pathways advance our understanding of human neurodevelopment. Additionally, the bioanalytical approach proposed in this study opens an interesting window for the capture and evaluation of the complex metabolic states of human neural cells, which would potentially be utilized in other in vitro models relevant to pathophysiology and treatment of neurological disorders, benefiting biomarker discovery and metabolic mechanism interpretation.

Microfluidic devices: The application in TME modeling and the potential in immunotherapy optimization

With continued advances in cancer research, the crucial role of the tumor microenvironment (TME) in regulating tumor progression and influencing immunotherapy outcomes has been realized over the years. A series of studies devoted to enhancing the response to immunotherapies through exploring efficient predictive biomarkers and new combination approaches. The microfluidic technology not only promoted the development of multi-omics analyses but also enabled the recapitulation of TME in vitro microfluidic system, which made these devices attractive across studies for optimization of immunotherapy. Here, we reviewed the application of microfluidic systems in modeling TME and the potential of these devices in predicting and monitoring immunotherapy effects.

Development of Liver-on-Chip Integrating a Hydroscaffold Mimicking the Liver’s Extracellular Matrix

The 3Rs guidelines recommend replacing animal testing with alternative models. One of the solutions proposed is organ-on-chip technology in which liver-on-chip is one of the most promising alternatives for drug screening and toxicological assays. The main challenge is to achieve the relevant in vivo-like functionalities of the liver tissue in an optimized cellular microenvironment. Here, we investigated the development of hepatic cells under dynamic conditions inside a 3D hydroscaffold embedded in a microfluidic device. The hydroscaffold is made of hyaluronic acid and composed of liver extracellular matrix components (galactosamine, collagen I/IV) with RGDS (Arg-Gly-Asp-Ser) sites for cell adhesion. The HepG2/C3A cell line was cultured under a flow rate of 10 µL/min for 21 days. After seeding, the cells formed aggregates and proliferated, forming 3D spheroids. The cell viability, functionality, and spheroid integrity were investigated and compared to static cultures. The results showed a 3D aggregate organization of the cells up to large spheroid formations, high viability and albumin production, and an enhancement of HepG2 cell functionalities. Overall, these results highlighted the role of the liver-on-chip model coupled with a hydroscaffold in the enhancement of cell functions and its potential for engineering a relevant liver model for drug screening and disease study.