Bridging the Gap Between In Vitro and Animal Models of Liver Disease

When developing novel therapeutics for liver diseases, the drug efficacy must be determined, and to do that, it is important that the architecture and function of the liver is precisely recreated. When using in vitro and animal models however, it is extremely challenging to recreate the whole spectrum of a disease.

We spoke to Dr. Audrey Dubourg, product manager at CN Bio to find out more about how its organ-on-chip (OOC) platform could bridge the gap between the current 2D models and animal models, providing human-relevant insights into diseases such as non-alcoholic steatohepatitis (NASH).

Kate Robinson (KR): Can you talk about the complexity of NASH? Why has it been challenging to develop effective therapeutics to treat it?

Audrey Dubourg (AD): NASH is the most severe, yet still reversible, form of the metabolic disorder known as non-alcoholic fatty liver disease (NAFLD). NAFLD/NASH is a multifactorial metabolic disease in which various human and environmental parameters are at the root cause, e.g., age, ethnicity, gender, sedentary lifestyle, poor diet, disease vectors etc. All of this makes it extremely challenging to recreate the whole spectrum of the disease in vitro or in an animal model. Moreover, although current standard preclinical in vitro models use human cells, they are often flat (two-dimensional), with no flow or shear stress to recapitulate the in vivo conditions in which the liver resides. Lack of flow in in vitro models limits the recapitulation of the liver’s architecture and functions (notably phase I and II metabolism), and often leads to a loss of phenotype (dedifferentiation) of the hepatocytes after a few days of culture. They also enable only short-term studies (less than a week), which is not long enough for chronic dosing to be modelled in vitro and, thus reflect the long-term treatment required to cure NASH. Although animal models offer a more “complex system” advantage over standard in vitro models, they usually only recapitulate a few aspects of the disease spectrum, from genetic to dietary. Because of that, those in vitro and animal models offer poor translatability to humans and are therefore poor efficacy predictors for new anti-NASH therapeutics. This topic is covered in much more detail in a recent blog: Of Mice and Men – Will human organ-on-a-chip disease models replace animal use?

KR: What are the existing challenges when working to bridge the gap between 2D cell culture and animal models?

AD: The biggest issue with both in vitro 2D cell culture and animal models is the lack of relevance. The former lack physiological relevance and the latter human-relevance. This has been the biggest hurdle for the last 30 to 40 years. Human organs and tissues have their own oxygen and nutrient intake, mechanical forces shear stress, and cardiac output requirements which are challenging to recreate in vitro. Animal models address this shortfall and offer insights into the complex interactions between organs; but their physiology, immunity and genetics are species specific and thus data derived from in vivo animal studies frequently fails to translate to the human.

KR: Can you explain a little more about CN Bio’s “in-a-box” range and the benefits this provides drug discovery workflows?

AD: We appreciate that the OOC field is relatively new and thus there is only a small pool of scientists with prior experience available for employment. To circumvent this, the purpose of our “in-a-box” range is to overcome adoption barriers.  Any researcher wanting to develop their own in-house capabilities can incorporate our advanced 3D in vitro models into their drug discovery workflows using a kit. In doing so, they bridge the gap between the current 2D models and animal models, rapidly benefitting from the human-relevant insights that OOC delivers. Essentially, our “in-a-box” range provides instant access to a decade of learned bioengineering, cell culture expertise and reagent validation.

KR: How exactly does NASH-in-a-box emulate the disease in vitro and how does CN Bio envision the NASH-in-a-box kit will aid NASH drug discovery?

AD: NASH-in-a-box is designed for use with our PhysioMimix™ Single-Organ Microphysiological System. Together they provide a straightforward and rapid route to recreating our industry-proven NASH-OOC assay in the user's own laboratory. The kit contains 3D-validated primary human liver cells (hepatocytes, Kupffer and Stellate cells), our ready-made NASH media (plus supplements), PhysioMimix Liver plates, two key endpoint assay kits, to measure cell health and liver function, and software-guided, step-by-step, protocols.

The kit firstly enables researchers to create 3D liver microtissues that accurately mimic the microarchitecture of the human liver. By introducing our bespoke fat media, which includes various fatty acids, researchers then induce the NASH disease, which is characterized by fat accumulation, inflammation and fibrosis. Once created, this in vitro NASH model enables the precise mechanistic effects of drugs and disease to be investigated via high content clinically translatable endpoint analysis. The end goal is to cost effectively and efficiently fast-track the development of successful anti-NASH therapies to treat our “hidden” epidemic before it becomes the next global healthcare burden.

KR: Are you able to discuss any research case studies in which NASH-in-a-box has been utilized? 

AD: NASH-in-a-box was born from a market demand. Many of our pharma customers were keen to recreate our NASH model in their own laboratories rather than paying for a service through the contract research side of our business, the latter of which is the preferred approach for many biotechs. As the product has only just been launched, we do not have any customer case study data to share just yet, however, we have multiple in-house publications with pharma that validate the model and showcase its human translatability (Kostrzewski et al., 2020, Kostrzewski et al., 2017).

In addition, many contract research customers and collaborators have published their data (Kostrzewski et al., 2021; Rao et al., 2021; Vacca et al., 2020). Through a collaboration with the University of Cambridge, UK (Vacca et al., 2020), we successfully identified a new potentially druggable target for NASH treatment, whilst the great potential of this model to assess the efficacy of siRNA treatment was demonstrated in a study with the University of George Washington, US (Rao et al., 2021). Finally, through collaboration with pharma giant AstraZeneca, we have confirmed the model’s reliability, reproducibility and robustness for use in drug discovery workflows (Kostrzewski et al., 2021).

Dr. Audrey Dubourg was speaking to Kate Robinson, Editorial Assistant for Technology Networks.