The basis of this interview was the study, “The importance of inter-individual Kupffer cell variability in the governance of hepatic toxicity in a 3D primary human liver microtissue model,” which highlighted the value of 3D human liver microtissue models containing both primary hepatocytes and Kupffer cells as compared with mono-cultures of hepatocytes to assess particle toxicology. In the study, the microtissues were exposed to different nanomaterials currently used in consumer products including sunscreens, cosmetics, clothing and sporting goods.
To begin our discussion, I asked Shareen if she could explain how one might be exposed to engineered nanomaterial. She explained that engineered nanomaterials have unique physical and chemical features that provide improved properties for a wide range of consumer products. Industries that use nanomaterials include automotive, computing and electronics, cosmetics and sporting.
I then asked her why new toxicity tests are needed for nanomaterials. She said that safety assessments are an important part of any product’s development, but accurate safety assessments are more challenging with nanomaterials. Standard tests tend to test the short-term effects, but with nanomaterials you need to look at the long-term effect because these materials don’t break down as rapidly.
I then discussed with Wolfgang current hepatic toxicology models and the challenges with these models. Wolfgang said that right now the gold standard for this type of testing is in vivo animal models. There are ethical concerns with the use of animal models. In addition there are concerns about limited translatability of animal models to humans. Animal models are also expensive and time consuming. Cell-based in vitro models are available, but they typically rely on one cell type to represent a given organ. As a result, this model has limitations as well.
I then asked Wolfgang to tell us about the 3D cell-based human liver microtissue model used in the nanomaterials study. He said that the culture consists of the self-organization of multiple liver specific cell types that form a “micro liver”.
I asked if he could talk about the culturing of these tissue models and how they are produced. He said that the process took a couple of years to optimize. The liver microtissue is between 0.2-0.3 mm in diameter and is composed of a few thousand cells. The liver microtissues are not uniform in size and composition because they are produced from the liver cell culture suspension. InSphero has a proprietary process that ensures only healthy, functionally robust cells are seeded in wells for self-aggregation. Cells are fed onto a non-adherent cell culture plate where they self organize into a small tissue, to replicating the fundamental architecture of a liver. This allows maximal crosstalk across cell types represented in the liver. The microtissues are produced and delivered in a proprietary standard format 96 or 384 microwell plate, compatible with automation on standard liquid handling systems and therefore highly scalable.
I then asked Shareen if she could provide a summary of the results of the published study. She said that standard cell culture testing is done over 24 hours, but because the liver microtissues are longer lived, they provide a more realistic model. They can be cultured up to 4 weeks, which makes them ideal for long-term studies. In the study, they used nanomaterials that they knew had the capability to cause toxicity via varying methods. The study confirmed that the liver microtissues were suitable for long-term testing of nanomaterial exposure. The fact that the liver microtissues contained multiple cell types was important because it provided greater sensitivity.
Next, we discussed how there is a need for more physiologically relevant 3D models across many applications. Wolfgang shared some of the other uses planned for the human liver microtissue models, including disease models. One example he discussed was simulating different stages of liver deterioration due to a high fat, high carbohydrate diet that would present the clinical features of fatty liver disease. This would be a valuable tool to test therapeutic efficacy of drug candidates.
I closed by asking if they had anything else they would like to add for our listeners. Wolfgang said that this is one of the most advanced in vitro liver models that is amenable to implementation using standard lab equipment. This permits high throughput screening for almost all stages of drug development.
Shareen added that the study was conducted as part of a 12 million Euro project called PATROLS with the primary aim to create more realistic next generation culture systems and to move away from testing of nanomaterials in animals.
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Kermanizadeh, A., Brown, D.M., Moritz, W. et al. The importance of inter-individual Kupffer cell variability in the governance of hepatic toxicity in a 3D primary human liver microtissue model. Sci Rep 9, 7295 (2019) doi:10.1038/s41598-019-43870-8
InSphero is the pioneer of industrial-grade, 3D-cell-based assay solutions and scaffold-free 3D organ-on-a-chip technology. Through partnerships, InSphero supports pharmaceutical and biotechnology researchers in successful decision-making by accurately rebuilding the human physiology in vitro. Its robust and precisely engineered suite of 3D InSight™ human tissue platforms are used by major pharmaceutical companies worldwide to increase efficiency in drug discovery and safety testing. The company specializes in liver toxicology, metabolic diseases (e.g., T1 & T2 diabetes and NAFLD & NASH liver disease), and oncology (with a focus on immuno-oncology and PDX models). The scalable Akura™ technology underlying the company’s 3D InSight™ Discovery and Safety Platforms includes 96- and 384-well plate formats and the Akura™ Flow organ-on-a-chip system to drive efficient innovation throughout all phases of drug development.