Tangible and visible animal-free innovations in Leiden

On 25 September, we organised the very first TPI lab tour together with Leiden University Medical Centre (LUMC). A mixed group was shown around two laboratories where animal-free research models are being developed and there was also an opportunity to visit the Central Animal Facility. With these lab tours, the Transition Programme for Innovation without the use of animals (TPI) aims to give people a tangible insight into the development of animal-free innovations and to allow them to meet the researchers who bring the transition a little closer every day.

Researcher shows well plates with 3D skin models of human cells
Image: Sander Foederer
Researcher shows well plates with 3D skin models of human cells

Different background, same interest

On Wednesday morning, the participants gather at the LUCM Research Building, where they’re welcomed by Tineke Coenen, director of the Central Animal Facility. She has organised the Leiden lab tour together with TPI. The participants represent several sectors: science, NGOs, research funding bodies and donors. They share the same interest: research models without animal experiments and the transition to animal-free innovations. Some are motivated by animal welfare, others by better research or a combination of the two. After the introduction by Tineke Coenen, we’re divided up into three groups for rotating visits to the labs of Abdoel El Ghalbzouri and Ronald Buijsen and – with Tineke – the Central Animal Facility.

Skin models for research into skin cancer, burns and ageing

Dr Abdoel El Ghalbzouri, senior researcher at LUMC whose specialisations include skin cancer and 3D skin models, welcomes us to his lab. Here, he works on 3D models together with PhD students Jolien Wichers Schreur and Alesha Louis. The 3D skin model is an artificial skin made up of human cells from several skin types and consisting of several layers. Human skin can be divided into three layers based on location and specialised cells: the top layer of skin is the epidermis (the outer layer of skin), below that is the dermis (the skin underneath), and the bottom layer is the subcutis (connective tissue layer). The human cells the researchers work with come from leftover medical materials and are isolated and processed before being combined into a 3D skin model.

Microscopes and screens are used to give us a detailed idea of what the 3D skin models look like and what opportunities they afford. We can also look at these models with the naked eye. They are grown in plates containing small wells. The different types of 3D skin models can be used to conduct research into such things as the safety of substances, the absorption of medicines by the skin, wound healing, infections (such as in burns), eczema, psoriasis and the composition of the skin microbiome (composition of micro-organisms). Doctors also use skin models when treating patients with burns, significantly increasing their chances of recovery.

Abdoel and his team are further optimising these models to gain a better understanding of skin cancer types such as squamous cell carcinoma and melanoma. This allows them to research which medicine or treatment is most effective and in which form – cream, pill or injection – it can best be administered. Abdoel’s team also collaborates with industrial parties that develop and test remedies against the consequences of skin ageing, amongst other things. Abdoel and Alesha are facing the challenge of making 3D skin models that mimic aged skin. One of those 3D skin models is geared towards pigmentation, for example. It’s important to include as many skin types and colours in the research as possible. The collaboration with these industry partners is very important for the optimisation of the 3D skin models, for one thing because of the commercial investments in these innovations, but also because the results of the developed remedies in clinical studies are fed back to the laboratory. This allows for further improvement of the 3D skin models.

From big to small: brain cells from simple 2D to complex 3D

The lab that senior researcher Dr Ronald Buijsen runs, together with his PhD student Bas Voesenek, is smaller than Abdoel’s. The small group of participants barely fits into the space. Ronald and Bas specialise in neuro-degenerative conditions in which cells in the cerebellum die, such as spinocerebellar ataxia (SCA) and hereditary forms of Alzheimer's disease. Ronald takes the models he wants to show us from several cabinets that have the perfect temperature for developing and sustaining brain organoids. In the Neuro-D (for neurodegeneration) lab where Ronald and Bas work, they develop 2D and 3D models with brain cells. This allows them to study how brain deterioration caused by diseases such as SCA arises and progresses. They also use the models to develop therapies with RNA. Messenger RNA tells cells how to produce certain proteins. It takes the information from the DNA in the cell nucleus to the place in the cell where those proteins are built. These proteins are essential to the functioning of the cells in our body. RNA therapies can help cells break down or modify harmful proteins by directly addressing the underlying cause, thereby slowing, stopping or even preventing diseases.

Making organoids starts with stem cells that are made from cells from people’s skin, blood or urine. These generic stem cells are converted to specific brain cells. In order to conduct comparative research, Ronald and Bas use models with and without the abnormalities or mutations that partly cause the degenerative brain disease. This allows them to study the effect of just the mistake in the DNA. The researchers combine the in vitro research with patient data, enabling them to better predict the course of the disease and develop therapies.

Ronald shows us a range of models: from simple (a few cells) to complex 3D models in which the cells communicate and cluster. The challenge that Ronald is currently working on is to have the organoids develop separately instead of in a cluster, so they are more uniform and can be better linked to a chip. The more complex, the smaller the model we can view and hold. We see there are already lots of possibilities without animal experiments. But there are also still limitations and challenges. For example, organoids can’t be used to determine the best way of administering a medicine or what the distribution and effects are like in a complete organism like a human or animal. Lab animals continue to be necessary for these things. For the moment, these organoids are also unable to mimic our very complex brains, with the different parts that each have their own function and that work together.

Laboratory Animal Center: protocols, diligence and avoiding unnecessary distress

Tineke Coenen, director of LUMC’s ProefDierCentrum (Laboratory Animal Center) and former independent advisor and animal welfare officer, uses her card to open the door to the facility for us. Tineke explains that not everyone at LUMC can just enter here, as there are strict rules and protocols in place. At the facility, researchers in separate units work on pathogens such as parasites, bacteria and viruses. One of these units concerns itself with pathogens that cause life-threatening, untreatable diseases.

Tineke shows us around research rooms, which have mice cages and everything else you need for research involving lab animals. The Central Animal Facility works closely together with researchers, medical specialists and physician-researchers affiliated to the hospital. The expertise of the people at the facility is crucial in devising and carrying out the animal experiments. Animal caretakers also have an important role. They make sure all rules and regulations governing animal welfare and the prevention of unnecessary distress are followed. The research conducted here is very diverse, with topics ranging from the origin and development of genetic abnormalities and diseases, such as cancer, to the development and testing of medicines. The number of animal experiments has decreased in recent years, although Tineke expects a slight increase in 2024. This is due to European agreements making it mandatory to register the breeding of certain animals as animal experiments as of this year.

Some participants don’t want to visit the Central Animal Facility, which is why Tineke has also included a virtual visit in the programme.

The possibilities (and impossibilities) of animal-free innovations

After the lab visits, all of us gather again for a closing discussion. The visits to the labs of Abdoel and Ronald show a lot is possible already: the models are applicable and in some cases even validated. The work that Abdoel does with both private and public parties leads to very wide-ranging and ambitious research questions, which allow for the development of new models and the improvement of existing ones. Not everything’s possible yet; for the moment, the models don’t have sebaceous glands or immune systems. This is why animal models are still required. These human skin models are actually cheaper than animal experiments.

This is not the case for brain research with human models, the cost of which is comparable. When it comes to research into the brain, the challenges seem even bigger. Promising steps have been made, such as 3D organoids and organs-on-a-chip, but the complexity of the brain makes it very challenging indeed. Combining organoids and data (in vitro and in silico) appears to be a promising route for research into the brain, among others.

There are also other routes to accelerate the transition to animal-free models. Several ones are mentioned during the discussion: stacking data and human models, re-assessment of animal experiments, reusing historical data, systematic reviews, open science and the publication of all research results, including neutral and negative ones that don’t confirm the hypothesis of the research. These results are very important, if only to prevent unnecessary research and unnecessary use of lab animals.

Is it possible to bring the number of animal experiments down to zero?

Research without lab animals isn’t just a scientific challenge. Societal demand for verifying the safety of the latest chemical substances and medicines also comes into play. And in some animal-free innovations, animal products are used, such as foetal calf serum (FCS) and Matrigel. Researchers are in the process of developing animal-free alternatives in this area as well, for instance at the 3Rs Centre Utrecht. LUMC is committed to responsible research: choosing the right model for the research question, if possible animal-free.

Inspirational, tangible and visible

The TPI Leiden lab tour has given us a tangible and visible insight into the possibilities of animal-free innovation for skin and brain research. There are many new answers, but also many new questions. The researchers still have a lot of wishes and lab animals are still needed, especially if we wish to meet society’s needs and demands in the area of health and safety.

We would like to thank Tineke Coenen, Abdoel El Ghalbzouri, Ronald Buijsen, Jolien Wichers Schreur, Alesha Louis and Bas Voesenek for making this very first and very inspirational TPI lab tour possible and allowing us to see for ourselves what animal-free innovations are and which researchers are working on accelerating the transition to better research without lab animals.