The Efficacy of the Hepatocyte Spheroids for Hepatocyte Transplantation

Establishment of an Idiosyncratic Drug-Induced Liver Injury Model on a Stacked Array Chip for Identification of CCL5-Mediated Paracrine Dynamics

Idiosyncratic drug-induced liver injury (iDILI) poses significant challenges in both drug development and clinical practice due to its unpredictable nature and poorly understood mechanism. The current in vitro iDILI models are limited in their ability to replicate dynamic paracrine signaling in the inflammatory microenvironment. Here, we develop an iDILI model on a stacked array chip, allowing ease of assembly and disassembly for precise temporal manipulation of 3D liver microtissue and macrophages. First, the iDILI model is constructed and optimized on the chip to effectively distinguish drugs inducing idiosyncratic versus intrinsic liver injuries. Next, the iDILI mechanism is investigated using nimesulide (NIM) as a case study. Our organ-on-a-chip model successfully recapitulates iDILI, offering a platform to distinguish drugs between intrinsic and idiosyncratic liver injury. Our findings revealed that NIM-induced iDILI triggered inflammation-induced injury in the liver microtissues through activating the TNF pathways. Moreover, NIM-induced iDILI promotes the M1 polarization of macrophages through CCL5-mediated paracrine dynamics, influenced by the interactions between hepatocytes and macrophages. Leveraging the flexibility of the chip, we observe a dynamic equilibrium between preactivation of inflammation and the pretreatment of NIM during iDILI process. Therefore, our developed iDILI model on a stacked array chip provides a valuable tool for identifying iDILI drugs and understanding the importance of temporal specificity in intercellular signaling in iDILI.

Developing Liver Microphysiological Systems for Biomedical Applications

Microphysiological systems (MPSs), also known as organ chips, are micro-units that integrate cells with diverse physical and biochemical environmental cues. In the field of liver MPSs, cellular components have advanced from simple planar cell cultures to more sophisticated 3D formations such as spheroids and organoids. Additionally, progress in microfluidic devices, bioprinting, engineering of matrix materials, and interdisciplinary technologies have significant promise for producing MPSs with biomimetic structures and functions. This review provides a comprehensive summary of biomimetic liver MPSs including their clinical applications and future developmental potential. First, the key components of liver MPSs, including the principal cell types and engineered structures utilized for cell cultivation, are briefly introduced. Subsequently, the biomedical applications of liver MPSs, including the creation of disease models, drug absorption, distribution, metabolism, excretion, and toxicity, are discussed. Finally, the challenges encountered by MPSs are summarized, and future research directions for their development are proposed.

Intraocular liver spheroids for non-invasive high-resolution in vivo monitoring of liver cell function

Longitudinal monitoring of liver function in vivo is hindered by the lack of high-resolution non-invasive imaging techniques. Using the anterior chamber of the mouse eye as a transplantation site, we have established a platform for longitudinal in vivo imaging of liver spheroids at cellular resolution. Transplanted liver spheroids engraft on the iris, become vascularized and innervated, retain hepatocyte-specific and liver-like features and can be studied by in vivo confocal microscopy. Employing fluorescent probes administered intravenously or spheroids formed from reporter mice, we showcase the potential use of this platform for monitoring hepatocyte cell cycle activity, bile secretion and lipoprotein uptake. Moreover, we show that hepatic lipid accumulation during diet-induced hepatosteatosis is mirrored in intraocular in vivo grafts. Here, we show a new technology which provides a crucial and unique tool to study liver physiology and disease progression in pre-clinical and basic research.

Scalable production of homogeneous cardiac organoids derived from human pluripotent stem cells

Three-dimensional (3D) cultures are known to more closely mimic in vivo conditions compared with 2D cultures. Cardiac spheroids (CSs) and organoids (COs) are useful for 3D tissue engineering and are advantageous for their simplicity and mass production for regenerative therapy and drug discovery. Herein, we describe a large-scale method for producing homogeneous human induced pluripotent stem cell (hiPSC)-derived CSs (hiPSC-CSs) and COs without scaffolds using a porous 3D microwell substratum with a suction system. Our method has many advantages, such as increased efficiency and improved functionality, homogeneity, and sphericity of hiPSC-CSs. Moreover, we have developed a substratum on a clinically relevant large scale for regenerative therapy and have succeeded in producing approximately 40,000 hiPSC-CSs with high sphericity at once. Furthermore, we efficiently produced a fused CO model consisting of hiPSC-derived atrial and ventricular cardiomyocytes localized on opposite sides of one organoid. This method will facilitate progress toward hiPSC-based clinical applications.

Transplantation of porcine adrenal spheroids for the treatment of adrenal insufficiency

Primary adrenal insufficiency is a life-threatening disorder, which requires lifelong hormone replacement therapy. Transplantation of xenogeneic adrenal cells is a potential alternative approach for the treatment of adrenal insufficiency. For a successful outcome of this replacement therapy, transplanted cells should provide adequate hormone secretion and respond to adrenal physiological stimuli. Here, we describe the generation and characterization of primary porcine adrenal spheroids capable of replacing the function of adrenal glands in vivo. Cells within the spheroids morphologically resembled adult adrenocortical cells and synthesized and secreted adrenal steroid hormones in a regulated manner. Moreover, the embedding of the spheroids in alginate led to the formation of cellular elongations of steroidogenic cells migrating centripetally towards the inner part of the slab, similar to zona Fasciculata cells in the intact organ. Finally, transplantation of adrenal spheroids in adrenalectomized SCID mice reversed the adrenal insufficiency phenotype, which significantly improved animals' survival. Overall, such adrenal models could be employed for disease modeling and drug testing, and represent the first step toward potential clinical trials in the future.

A multiscale, vertical-flow perfusion system with integrated porous microchambers for upgrading multicellular spheroid culture

Spheroid formation assisted by microengineered chambers is a versatile approach for morphology-controlled three-dimensional (3D) cell cultivation with physiological relevance to human tissues. However, the limitation in diffusion-based oxygen/nutrient transport has been a critical issue for the densely packed cells in spheroids, preventing maximization of cellular functions and thus limiting their biomedical applications. Here, we have developed a multiscale microfluidic system for the perfusion culture of spheroids, in which porous microchambers, connected with microfluidic channels, were engineered. A newly developed process of centrifugation-assisted replica molding and salt-leaching enabled the formation of single micrometer-sized pores on the chamber surface and in the substrate. The porous configuration generates a vertical flow to directly supply the medium to the spheroids, while avoiding the formation of stagnant flow regions. We created seamlessly integrated, all PDMS/silicone-based microfluidic devices with an array of microchambers. Spheroids of human liver cells (HepG2 cells) were formed and cultured under vertical-flow perfusion, and the proliferation ability and liver cell-specific functions were compared with those of cells cultured in non-porous chambers with a horizontal flow. The presented system realizes both size-controlled formation of spheroids and direct medium supply, making it suitable as a precision cell culture platform for drug development, disease modelling, and regenerative medicine.

A non-human primate model of acute liver failure suitable for testing liver support systems

Acute hepatic failure is associated with high morbidity and mortality for which the only definitive therapy is liver transplantation. Some fraction of those who undergo emergency transplantation have been shown to recover native liver function when transplanted with an auxiliary hepatic graft that leaves part of the native liver intact. Thus, transplantation could have been averted with the development and use of some form of hepatic support. The costs of developing and testing liver support systems could be dramatically reduced by the availability of a reliable large animal model of hepatic failure with a large therapeutic window that allows the assessment of efficacy and timing of intervention. Non-lethal forms of hepatic injury were examined in combination with liver-directed radiation in non-human primates (NHPs) to develop a model of acute hepatic failure that mimics the human condition. Porcine hepatocyte transplantation was then tested as a potential therapy for acute hepatic failure. After liver-directed radiation therapy, delivery of a non-lethal hepatic ischemia-reperfusion injury reliably and rapidly generated liver failure providing conditions that can enable pre-clinical testing of liver support or replacement therapies. Unfortunately, in preliminary studies, low hepatocyte engraftment and over-immune suppression interfered with the ability to assess the efficacy of transplanted porcine hepatocytes in the model. A model of acute liver failure in NHPs was created that recapitulates the pathophysiology and pathology of the clinical condition, does so with reasonably predictable kinetics, and results in 100% mortality. The model allowed preliminary testing of xenogeneic hepatocyte transplantation as a potential therapy.

Mesenchymal stem cells improve liver fibrosis and protect hepatocytes by promoting microRNA-148a-5p-mediated inhibition of Notch signaling pathway

Background

Mesenchymal stem cells (MSCs) are considered to be a potential therapeutic tool for liver fibrosis. Inhibiting the activation of hepatic stellate cells (HSCs) and protecting hepatocytes are important mechanisms for the anti-fibrotic effect of MSCs. However, how MSCs inhibit liver fibrosis by regulating the expression of microRNAs (miRNAs) has not been fully clarified.

Methods

Transforming growth factor-β1 (TGF-β1)-activated HSCs LX-2 were single cultured or co-cultured with human umbilical cord mesenchymal stem cells (HUC-MSCs). High-throughput sequencing was used to evaluate the differentially expressed microRNAs (DEMs) between the two groups. Quantitative real-time PCR (qRT-PCR), Western blot, and transfection experiments were used to investigate and screen the most significantly up-regulated DEM. Bioinformatics analysis was used to predict the target mRNAs and the potential functions of the DEM. The possible mechanism of HUC-MSCs against liver fibrosis was analyzed by co-culture experiment of HUC-MSCs with LX-2 cells, and HUC-MSCs treatment of Bile duct ligation (BDL)-induced liver fibrosis in mice. Finally, the mechanism of the DEM regulating liver fibrosis was confirmed in human liver fibrosis specimens.

Results

MicroRNA-148a-5p (miR-148a-5p) was the most significantly up-regulated DEM in activated LX-2 cells co-cultured with HUC-MSCs compared with LX-2 cells single cultured. Up-regulation of the expression of miR-148a-5p in activated LX-2 cells could significantly inhibit the expression of hepatic fibrosis markers α-SMA and Col1α1. Notch2 was one target gene of miR-148a-5p. Co-cultured with HUC-MSCs could inhibit the activation of LX-2 cells by inhibiting the expression of the Notch2 and the Notch signaling pathway. In addition, HUC-MSCs treatment could up-regulate the expression of miR-148a-5p in liver tissue and hepatocytes, promote the proliferation and avoid the apoptosis of hepatocytes, and reduce the degree of fibrosis by inhibiting expression of the Notch2 and the Notch signaling pathway in BDL-induced liver fibrosis mice. Moreover, miR-148a-5p was down-regulated and Notch2 was up-regulated in fibrotic human liver tissues compared with the normal livers.

Conclusions

HUC-MSCs treatment could inhibit HSCs activation, protect hepatocytes, and alleviate BDL-induced liver fibrosis in mice by up-regulating the expression of miR-148-5p and inhibiting the Notch signaling pathway. The down-regulation of miR-148-5p and up-regulation of Notch2 could be used as biomarkers to monitor the progression of liver fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03030-8.

Preservation of heparin-binding EGF-like growth factor activity on heparin-modified poly(N-isopropylacrylamide)-grafted surfaces

A heparin-modified poly(N-isopropylacrylamide) (PIPAAm)-grafted surface bound with heparin-binding epidermal growth factor-like growth factor (HB-EGF) was able to culture hepatocytes maintaining high albumin secretion and high expression of hepatocyte-specific genes. However, the activity of HB-EGF on the surface and its binding effects on hepatocytes remain unclear. In this study, we investigated the temperature-dependent interactions of HB-EGF and EGF receptor (EGFR) with heparin-modified PIPAAm to evaluate the activity of HB-EGF on the surface. Quartz crystal microbalance (QCM) measurements revealed that the amounts of adsorbed HB-EGF on either the heparin-modified PIPAAm-grafted surface (heparin-IC1) or PIPAAm-grafted surfaces were almost the same regardless of swelling/deswelling of grafted PIPAAm chains. The heparin-IC1 surface bound to HB-EGF at 37 °C had the ability to bind to hepatocytes through specific affinity interaction with EGFR, whose activation was confirmed by western blotting. However, the physisorbed HB-EGF on the PIPAAm surface greatly diminished its activity. Taken together, the introduction of heparin into grafted PIPAAm chains on the surface plays a pivotal role in holding HB-EGF while preserving its activity. Hydration and swelling of surface-grafted PIPAAm chains at 20 °C greatly diminished the attachment of hepatocytes with HB-EGF bound to heparin-IC1, whereas hepatocytes were able to bind to HB-EGF bound to heparin-IC1 at 37 °C. Thus, the equilibrated affinity interaction between EGFRs and surface-bound HB-EGF was considered to be attenuated by steric hindrance due to hydration and/or swelling of grafted PIPAAm chains.

Activity of HB-EGF bound to a heparin-modified poly(N-isopropylacrylamide) (PIPAAm)-grafted surface was preserved through specific binding to heparin, whereas physisorbed HB-EGF on a PIPAAm-grafted surface greatly diminished its activity.