A long-term storable gel-laden chip composite built in a multi-well plate enablingin situcell encapsulation for high-throughput liver model

Hydrogels are widely used as scaffold materials for constructingin vitrothree-dimensional microphysiological systems. However, their high sensitivity to various external cues hinders the development of hydrogel-laden, microscale, and high-throughput chips. Here, we have developed a long-term storable gel-laden chip composite built in a multi-well plate, which enablesin situcell encapsulation and facilitates high-throughput analysis. Through optimized chemical crosslinking and freeze-drying method (C/FD), we have achieved a high-quality of gel-laden chip composite with excellent transparency, uniform porosity, and appropriate swelling and mechanical characteristics. Besides collagen, decellularized extracellular matrix with tissue-specific biochemical compound has been applied as chip composite. As a ready-to-use platform,in situcell encapsulation within the gel has been achieved through capillary force generated during gel reswelling. The liver-mimetic chip composite, comprising HepG2 cells or primary hepatocytes, has demonstrated favorable hepatic functionality and high sensitivity in drug testing. The developed fabrication process with improved stability of gels and storability allows chip composites to be stored at a wide range of temperatures for up to 28 d without any deformation, demonstrating off-the-shelf products. Consequently, this provides an exceptionally simple and long-term storable platform that can be utilized for an efficient tissue-specific modeling and various biomedical applications.

Xeno-Free 3D Bioprinted Liver Model for Hepatotoxicity Assessment

Three-dimensional (3D) bioprinting is one of the most promising methodologies that are currently in development for the replacement of animal experiments. Bioprinting and most alternative technologies rely on animal-derived materials, which compromises the intent of animal welfare and results in the generation of chimeric systems of limited value. The current study therefore presents the first bioprinted liver model that is entirely void of animal-derived constituents. Initially, HuH-7 cells underwent adaptation to a chemically defined medium (CDM). The adapted cells exhibited high survival rates (85-92%) after cryopreservation in chemically defined freezing media, comparable to those preserved in standard medium (86-92%). Xeno-free bioink for 3D bioprinting yielded liver models with high relative cell viability (97-101%), akin to a Matrigel-based liver model (83-102%) after 15 days of culture. The established xeno-free model was used for toxicity testing of a marine biotoxin, okadaic acid (OA). In 2D culture, OA toxicity was virtually identical for cells cultured under standard conditions and in CDM. In the xeno-free bioprinted liver model, 3-fold higher concentrations of OA than in the respective monolayer culture were needed to induce cytotoxicity. In conclusion, this study describes for the first time the development of a xeno-free 3D bioprinted liver model and its applicability for research purposes.

3D Bioprinted Liver-on-a-Chip for Drug Cytotoxicity Screening

Tissues on a chip are sophisticated three-dimensional (3D) in vitro microphysiological systems designed to replicate human tissue conditions within dynamic physicochemical environments. However, the current fabrication methods for tissue spheroids on a chip require multiple parts and manual processing steps, including the deposition of spheroids onto prefabricated "chips." These challenges also lead to limitations regarding scalability and reproducibility. To overcome these challenges, we employed 3D printing techniques to automate the fabrication process of tissue spheroids on a chip. This allowed the simultaneous high-throughput printing of human liver spheroids and their surrounding polymeric flow chamber "chips" containing inner channels in a single step. The fabricated liver tissue spheroids on a liver-on-a-chip (LOC) were subsequently subjected to dynamic culturing by a peristaltic pump, enabling assessment of cell viability and metabolic activities. The 3D printed liver spheroids within the printed chips demonstrated high cell viability (>80%), increased spheroid size, and consistent adenosine triphosphate (ATP) activity and albumin production for up to 14 days. Furthermore, we conducted a study on the effects of acetaminophen (APAP), a nonsteroidal anti-inflammatory drug, on the LOC. Comparative analysis revealed a substantial decline in cell viability (<40%), diminished ATP activity, and reduced spheroid size after 7 days of culture within the APAP-treated LOC group, compared to the nontreated groups. These results underscore the potential of 3D bioprinted tissue chips as an advanced in vitro model that holds promise for accurately studying in vivo biological processes, including the assessment of tissue response to administered drugs, in a high-throughput manner.

Influence of Liver Extracellular Matrix in Predicting Drug-Induced Liver Injury: An Alternate Paradigm

In vitro drug-induced liver injury (DILI) models are promising tools for drug development to predict adverse events during clinical usage. However, the currently available DILI models are not specific or not able to predict the injury accurately. This is believed to be mainly because of failure to conserve the hepatocyte phenotype, lack of longevity, and difficulty in maintaining the tissue-specific microenvironment. In this study, we have assessed the potential of decellularized liver extracellular matrix (DLM) in retaining the hepatic cellular phenotype and functionality in the presence of a tissue-specific microenvironment along with its role in influencing the effect of the drug on hepatic cells. We show that DLM helps maintain the phenotype of the hepatic cell line HepG2, a well-known cell line for secretion of human proteins that is easily available. Also, the DLM enhanced the expression of a metabolic marker carbamoyl phosphate synthetase I (CPS1), a regulator of urea cycle, and bile salt export pump (BSEP), a marker of hepatocyte polarity. We further validated the DLM for its influence on the sensitivity of cells toward different classes of drugs. Interestingly, the coculture model, in the presence of endothelial cells and stellate cells, exhibited a higher sensitivity for both acetaminophen and trovafloxacin, a toxic compound that does not show any toxicity on preclinical screening. Thus, our results demonstrate for the first time that a multicellular combination along with DLM can be a potential and reliable DILI model to screen multiple drugs.

Modelling human liver microphysiology on a chip through a finite element based design approach

Organ-on-a-chip (OoaC) are microfluidic devices capable of growing living tissue and replicate the intricate microenvironments of human organs in vitro, being heralded as having the potential to revolutionize biological research and healthcare by providing unprecedented control over fluid flow, relevant tissue to volume ratio, compatibility with high-resolution content screening and a reduced footprint. Finite element modelling is proven to be an efficient approach to simulate the microenvironments of OoaC devices, and may be used to study the existing correlations between geometry and hydrodynamics, towards developing devices of greater accuracy. The present work aims to refine a steady-state gradient generator for the development of a more relevant human liver model. For this purpose, the finite element method was used to simulate the device and predict which design settings, expressed by individual parameters, would better replicate in vitro the oxygen gradients found in vivo within the human liver acinus. To verify the model's predictive capabilities, two distinct examples were replicated from literature. Finite element analysis enabled obtaining an ideal solution, designated as liver gradient-on-a-chip, characterised by a novel way to control gradient generation, from which it was possible to determine concentration values ranging between 3% and 12%, thus providing a precise correlation with in vivo oxygen zonation, comprised between 3%-5% and 10%-12% within respectively the perivenous and periportal zones of the human liver acinus. Shear stress was also determined to average the value of 0.037 Pa, and therefore meet the interval determined from literature to enhance liver tissue culture, comprised between 0.01 - 0.05 Pa.

The Use of a 3D Printing Model in Planning a Donor Hepatectomy for Living Donor Liver Transplantation: First in India

INTRODUCTION

Three-dimensional (3D) anatomical relationships between the hepatic veins and portal structures can serve as a guide to plan resections in donor hepatectomy during living donor liver transplantation. We present the first case report from India on the use of a 3D printed liver model, as an assist to living donor liver transplantation.

METHODS

A 3D model of the donor liver with hepatic venous structures printed within it was prepared using image acquisition data. The model was used for a simulated cut preoperatively, to mimic the donor hepatectomy based on the venous structures seen through the transparent material used for making the liver model. The volume of the graft measured by volume displacement in the actual surgery was compared with the volume of the model after the simulated cut.

RESULTS

The calculated volume of the graft was 359 ml as per the preoperative simulation, and the observed weight/volume was 380 gm/310 ml.

CONCLUSION

Three-dimensional printing of liver models using imaging data can help predict the actual size of the graft after donor hepatectomy, in patients undergoing living donor liver transplantation.

A 3D Cell Culture Organ-on-a-Chip Platform With a Breathable Hemoglobin Analogue Augments and Extends Primary Human Hepatocyte Functions in vitro

Remarkable advances in three-dimensional (3D) cell cultures and organ-on-a-chip technologies have opened the door to recapitulate complex aspects of human physiology, pathology, and drug responses in vitro. The challenges regarding oxygen delivery, throughput, assay multiplexing, and experimental complexity are addressed to ensure that perfused 3D cell culture organ-on-a-chip models become a routine research tool adopted by academic and industrial stakeholders. To move the field forward, we present a throughput-scalable organ-on-a-chip insert system that requires a single tube to operate 48 statistically independent 3D cell culture organ models. Then, we introduce in-well perfusion to circumvent the loss of cell signaling and drug metabolites in otherwise one-way flow of perfusate. Further, to augment the relevancy of 3D cell culture models in vitro, we tackle the problem of oxygen transport by blood using, for the first time, a breathable hemoglobin analog to improve delivery of respiratory gases to cells, because in vivo approximately 98% of oxygen delivery to cells takes place via reversible binding to hemoglobin. Next, we show that improved oxygenation shifts cellular metabolic pathways toward oxidative phosphorylation that contributes to the maintenance of differentiated liver phenotypes in vitro. Lastly, we demonstrate that the activity of cytochrome P450 family of drug metabolizing enzymes is increased and prolonged in primary human hepatocytes cultured in 3D compared to two-dimensional (2D) cell culture gold standard with important ramifications for drug metabolism, drug-drug interactions and pharmacokinetic studies in vitro.

Combined magnetic resonance imaging and optical surgical navigation system guidance of percutaneous liver cryoablation in a porcine model

The efficacy and safety of combining open-configuration magnetic resonance imaging (MRI) and an optical surgical navigation system (OSNS) for guidance of percutaneous liver cryoablation were evaluated in a pig model. This approach was successfully executed in eight test pigs under general anesthesia. Another two pigs spared from ablation served as controls. MRI studies, blood testing, and pathologic examinations were performed at various time points. MRI-determined minimal and maximal cryolesion diameters were 19.4 ± 1.5 mm and 44.3 ± 1.8 mm, respectively (mean volume, 8.32 ± 2.41 cm³). The lesions were readily visible by MRI on postablation Days 2 and 7, all presenting as teardrop-shaped regions of low signal intensity in T1-weighted images and high signal intensity in T2-weighted images. Mean serum alanine aminotransferase concentration transiently increased postablation, and mean blood platelet count transiently declined (both, P < 0.05). The mean necrotic tissue volume generated by pathologic assessment was less than that determined by MRI (4.24 ± 2.3 cm³ vs. 8.32 ± 2.41 cm³, P < 0.05). Cell necrosis isotherms in MRI views were within 6.0 ± 0.8 mm of cryolesion edges. Inflammatory cell infiltrates and exuberant granulation tissue surrounded necrotic areas on postablation Day 7. Combined open-configuration MRI and OSNS guidance of percutaneous liver cryoablation proved effective and safe in our animal model. This concept seems ideal for precision image-guided hepatic ablation in a clinical setting.

Liver sinusoid on a chip: Long-term layered co-culture of primary rat hepatocytes and endothelial cells in microfluidic platforms

We describe the generation of microfluidic platforms for the co-culture of primary hepatocytes and endothelial cells; these platforms mimic the architecture of a liver sinusoid. This paper describes a progressional study of creating such a liver sinusoid on a chip system. Primary rat hepatocytes (PRHs) were co-cultured with primary or established endothelial cells in layers in single and dual microchannel configurations with or without continuous perfusion. Cell viability and maintenance of hepatocyte functions were monitored and compared for diverse experimental conditions. When primary rat hepatocytes were co-cultured with immortalized bovine aortic endothelial cells (BAECs) in a dual microchannel with continuous perfusion, hepatocytes maintained their normal morphology and continued to produce urea for at least 30 days. In order to demonstrate the utility of our microfluidic liver sinusoid platform, we also performed an analysis of viral replication for the hepatotropic hepatitis B virus (HBV). HBV replication, as measured by the presence of cell-secreted HBV DNA, was successfully detected. We believe that our liver model closely mimics the in vivo liver sinusoid and supports long-term primary liver cell culture. This liver model could be extended to diverse liver biology studies and liver-related disease research such as drug induced liver toxicology, cancer research, and analysis of pathological effects and replication strategies of various hepatotropic infectious agents. .