This month, we sat down with Dr. Tamara Zietek, a pioneer in 3D intestinal modelling and a leading voice pushing for the replacement of animal testing in life science with New Approach Methodologies (NAMs). We discuss her journey, the evolution of in-vitro 3D models, regulatory hurdles, and how we can achieve a paradigm shift in drug development.
Could you could give a brief introduction of yourself, a bit of your background, the journey and your expertise in life science and how it relates to this field of 3D culture?
Dr. Zietek: Yes, so I started with biochemistry in Bochum, Germany. Then I went for my PhD in Cologne, also in biochemistry. Until that point, it was mainly molecular biology and plant biotechnology. It was microbiology with microorganisms like yeast and bacteria, things like that. After my Ph.D., I went to Munich Technical University and became a lecturer and research group leader at the Department of Nutritional Physiology.
I worked with processes related to intestinal absorption, nutrient transport and drug uptake. My main research focus was the link between nutrient absorption and incretin hormone secretion for diabetes research.
We used different models – 2D cell lines, different mouse models, knockout models of different transporters etc. Human studies were conducted as well. Basically, all the model systems that were available.
And I worked with animal experiments for the first time at that point. I was not working in the lab, but as a PI, I had students working with the animals.
From the data and my scientific experiences that I got there, I quickly realised that there are some problems with these animal experiments, disregarding ethical aspects. Firstly, bad reproducibility and bad transferability to humans.
Then organoids came up in 2010. It was this Nature publication of Hans Cleavers on intestinal organoids. And I said wow, that is the system! Because I was looking for a system that had both endocrine and enterocytes in-vitro. That was the problem with co-culture of normal cell lines. They didn’t connect, they did not grow together.
So, I established these organoid models, and in 2015 we had our first publication on different things related to biomedical and nutritional research and what you can do with intestinal organoids.
That was when I started to work with organoids. We were almost the only ones in Germany who were working with organoids at the time, so people were very interested.
After eight years, I left academia and started to work for Doctors Against Animal Experiments (DAAE). I started as a scientific coordinator, but I recently changed to the position of CEO.
What spurred that transition?
Dr. Zietek: I didn’t want to work with mice anymore, or with animal experiments. I wanted to do the individual culture with organoids and that was not so easy at that time, especially to get funding. They still wanted to have animal experiments included.
And I did not want to do that, because even scientifically it didn’t make any sense. Why should I have a project that uses human-based cultures and then compare it with animal experiments?
This idea that animal experiments can be reduced or replaced by these organoids was also a driving force.
Dr. Tamara Zietek
So, like it is in life, I saw the advertisement for the job, and I thought, wow, that would be cool. Not just to continue with the research but to go more into the science communication and regulatory side, which I’m mainly doing — regulatory testing and international stakeholder work.
Describe the work that you engage in now with DAAE.
Dr. Zietek: Our NGO has different parts. We have public relations and campaigns. All the classic NGO things that you do because we are representing people who have an interest in replacing animal experiments. The science department is a team of 6 people. We write articles, have a very extensive website with a lot of information on non-animal New Approach Methodologies (NAMs).
The international work is one part of it, and this is what I’m actually doing. It’s important because we have many developments in the regulatory area. We have momentum now, and we don’t want to miss the opportunity to change things on a regulatory level.
We work with the European Commission, with ECHA, and other agencies. They want to have a road map for non-animal testing which all resulted from the European Citizens’ Initiative (ECI) that we initiated with others international partners. The ECI resulted in actions that the European Commission is willing to undertake or to support to accelerate the transition to non-animal testing. This is what we are working on a lot.
There are also applied science projects. For example, the MPS World Summit or the International Microphysiological Systems Society (IMPSS) which formed during the last 2-3 years. This is where I’m also quite involved because I’m a member of the Scientific Advisory Board.
These societies are important to show that we have better alternatives. We do have them. And you can see them because the best researchers worldwide present their models. Key academic and regulatory stakeholders, like the FDA and OECD, are also involved. We have all stakeholders on a global level.
In the end, the prime focus isn’t even on finding animal alternatives. It’s clear we want to achieve that. But it’s more about better science, better safety, human-relevant science, lower failure rates, and better safety for humans.
Dr. Tamara Zietek
The ONTOX project is an EU project under the Horizon 2020 funding. I’m also doing some stakeholder work there. We’re developing NAM-based strategies for animal-free safety testing of chemicals.
We have projects like our Non-Animal Technologies (NAT) database, which has around 2000 entries of non-animal methods all over the world. We are constantly working on it and we will have a webinar series for companies working in the NAM field as well.
We are currently working on a systematic review that analyses clinical failure rates. We are seeing that in the last sixty years the failure has been around 92% and this is not improving. And preclinical trials largely contribute to this failure rate because safety and efficacy testing is not well reflected in the preclinical phase by animal experiments.
Let’s quickly go back to your intestinal models. You said that if you have a 2D model, it doesn’t form a certain way and then doesn’t express something that you were looking for. Did I understand that correctly?
Dr. Zietek: Absolutely.
For our studies, we needed a model that contained absorptive enterocytes as well as enteroendocrine cells. The first problem was that it was very hard to combine different cell types, subtypes of an organ, in a dish.
Then you have the cell lines themselves, which are quite artificial. For example, enterocytes in the intestine have certain transporters that are expressed. These aren’t reflected in cell lines, and they’re expressed differently in animals.
So models like animals or simple cell lines don’t reflect a human in-vivo situation. This is why it’s important to have human systems to be sure that you look at the right thing. I think for a lot of questions you need connections and interplay between different cell types which you only have in organoid models.
There are 2D models using primary cells, but in three dimensions it’s been shown that the expression levels and differentiation increases, which is advantageous.
If they’re better, then why haven’t they been fully adopted yet into pharmaceutical workflows for drug development? What are the big obstacles that are still preventing wide-scale adoption?
Dr. Zietek: There was a 3D organ model conference in London and this question was discussed. We were talking about the scalability of organ models versus complexity.
If you want to have a 3D model, why do you want to have a 3D model?
Because it better reflects Physiology.
The thing is, do you need this complexity for everyone? I think that’s not the case.
There are so many stakeholders and so many disciplines involved in these technologies. Some need more complexity, others don’t. There is space for every model. I think we need models that are very complex if we want to do disease modelling, for example.
But we also need models for high throughput where you screen hundreds of samples continuously. And that is where a complex 3D brain organoid model would struggle. You might just need a simple spheroid culture. We have excellent models in this field, neurospheres, that you can use for testing that will hopefully be accepted by OECD soon.
So this is then what industry might need, because the models need to be reproducible, valid, and robust.
If you have complex organoid models, they’re different depending on the donor. They have different characteristics which produce different results. Of course, this is a chance for personalized medicine. Roche is big in this field. You will see that there is a future for these complex models. Roche is developing a new institute in Switzerland for human biology. They have the best researchers in the world at this centre developing the most complex models. So there is a need for these models.
But there is also a need for these less complex, more robust, more high throughput compatible models that are good enough to show that something is safe. You might only need certain organs. You might only need a certain pathway.
I’m totally in favour of complex. This is still the academic researcher in me who will never die.
The more complex the cooler. The closer to in-vivo physiology. Plus, there is enough space for every model and that’s what we showed.
I remember there was this paper on this ten-organ chip, a few years ago, and they talked about the whole body on a chip concept.
This is also useful, but maybe a company like AstraZeneca or any other pharma company would rather have a three-organ chip. Why? Because 10 organs are too complicated or too costly. Or maybe they only want the relevant organs for a certain drug. A drug for a certain heart disease, for example, might not need skin on-a-chip.
Do you see animal models being completely replaced by these 3D models, or is it more to reduce the dependency?
Dr. Zietek: I see that the whole replacement of the animal model. It doesn’t matter if it’s safety or basic research, relying on animal models to predict human biology is a concept that needs to be replaced.
It’s I think there is no other way.
There needs to be a change of the whole system. It’s a mindset that needs to change. It’s a paradigm shift. This is why it takes so long. It will not be tomorrow. It will not be next year. But we are on the way, and it’s a problem that we know how to solve.
You will have a phase of reducing animal experiments, it’s already being done. And this, hopefully, will be accelerated. But the final aim needs to be phasing out animal experiments. Scientifically, it does not make sense to mix animal data with human data.
If I would publish a paper, and I had a mouse model and used data from a human cell line and compared them and put them in one model, everyone would say, “No, no, no. You can’t . Because you could have species specific differences”. No one would say, OK I see this in a mouse and it will be for sure the same in the dog. You have to check because it’s another species, and the species is relevant.
I’m not saying that all data from animal experiments doesn’t translate to humans. There are certain aspects that you have in both species. But we need specificity. We are talking about complex diseases – human-specific diseases. We have diabetes, Alzheimer’s, cardiac diseases and neurological diseases. And modelling these complex diseases in animals is absolutely not effective. Which is why we end up with over 90% failure rates.
What are regulatory bodies saying?
Dr. Zietek: Our regulatory system has been based on animal testing for a very long time, and it’s huge. It’s not easy to change things. We will have to change a lot to replace animal experiments. We need to change the entire regulatory framework.
You don’t have the same endpoints. For example, you can’t look at increase in liver size, but you can look at adverse outcome pathways (AOPs). You can look at molecular markers which can be an even better approach to assess certain toxicity.
So you need new endpoints. You need a combination of NAMs. Also, the fact that people used to talk about a one-to-one replacement. Replacing a certain animal test with a single in-vitro method.
That this is not the solution. You cannot do that, and we will not do that. It will be batteries of NAMs. This is what will happen.
We have approaches like IATA (Integrated Approaches to Testing and Assessment), and next-generation risk assessment (NGRA) that combine Omics, KI, in-silico, in-chemico, and in-vitro, etc.
But this needs to be human based.
Because what would you do if your NAM-based testing showed you that a drug is safe and then a certain animal test in a mouse showed toxicity?
There are ways to get there, but we need to create confidence. And this is one of the central issues that we are working on. We are working to create confidence.
It seems that we need to map what combination of NAM experiments we could do that would give us the same, or better, indication as certain animal tests.
Dr. Zietek: Yes, we need whole approaches that have in vitro, organoid models, and organ-on-a-chip models and combine this data with computational analyses.
What is an end point for?
It’s to be certain that something is, for example, not toxic for reproduction.
You can take mouse models and you can do cruel experiments on them, but they won’t be very reliable because the reproductive system is highly species specific. We have better human endometrium in-vitro 3D models. And these should be part of the pipeline. They should be part of the testing.
The problem that the industry has is a company will submit a NAM-based dossier, let’s say to ECHA or EMA. And then the agencies say that they still would like to have some animal experiments to be performed during the registration process.
What do you think the major reasons for that are?
Dr. Zietek: This is the discussion in so many meetings and workshops. How can we increase confidence?
So I think it’s different things.
It’s the unclear regulatory framework. It’s partially political policy — laws that are not so well defined.
It needs to be clear: no animal testing is the standard. NAM-based testing is enough.
Some of the agencies still do not have this confidence because, to be honest, these models are quite new. They’re maybe 10 or 15 years old.
So people who are working at regulatory agencies have always worked with animal data. This is what they know. They are only thinking about safety. This is the prime goal. They’re not thinking about animal experiments.
They’re saying, “Of course, we would like to reduce”. But it’s not the focus.
They want to provide safety assessment, and if they believe a method is safe enough, or safer, they might adopt it. But then the framework needs to be clear. And this is why I think there is a lot of education and training that needs to be done.
Part of the roadmap needs to be educational training.
Like in the US. In the Modernization Act, one of the central points is education — training of agencies. The people who are using the data later. And stakeholder work to create the connection of the agency people to the models that they see.
In your eyes, what are some of the most exciting technologies in the 3D culture space that you’ve got your eye on?
Dr. Zietek: I think one of the major advances is in personalized medicine.
This is highly interesting. Having organoids from different patients, having biobanks from different patients.
Also, we have microphysiological systems (MPS) in space. Organoids and organs-on-a-chip were sent to the ISS to perform experiments on the immune system and ageing processes and things like that.
Regenerative medicine is also a field which I’m very curious to see where we will be in 10 years. It will be faster to have this solution than to have hearts transplanted from pigs.
How do you go about keeping up to date on the most recent developments in the field both in industry and academia?
Dr. Zietek: The NAT database, for example. It’s free. It’s in English and German. If you’re interested in toxicology, oncology, gastrointestinal research or cardiology, etc., you can filter by country or even city. So, if you’re looking to collaborate with someone working with liver organoids or who is working on Alzheimer’s you can find out where these people are sitting.
If you would like to know what’s going on in the field of a certain disease, let’s say in the last year in Sweden, or what kind of companies do you have in Sweden that are working on NAMs, then you can filter for Sweden.
We received the LUSH prize 2022 for the NAT database in the Training category, which we are very proud of.
I read newsletters a lot and I track relevant developments on LinkedIn.
For example:
Final thoughts?
Dr. Zietek: The most important thing is that we realize that non-animal methods and 3D culture enable safer testing and better disease modelling for humans, and they make more economic sense.
This is an innovative field. The EU should focus on these technologies and promote them because there’s a big market.
These are the technologies of the future.
Want to connect with Dr. Zietek? You can find her here:
LinkedIn: Tamara Zietek
