Following the success of the beyond meat burger, SciCom-Café member Ana-Magdalena Pineau introduces you to the beyond mice lab.
Beyond meat has showed us that a burger does not necessarily need a cow. Could the same idea work in biomedical research? Instead of studying living lab animals, scientists are learning to grow miniature tissues, organ-like-structures, and even more complex models from stem cells. Welcome to the emerging world of the beyond mice lab where researchers are asking how much of an animal we actually need to understand biology.
Why did scientists develop beyond mice labs?
Have you ever wondered if animal experimentation is the only and best way to find new treatments for humans? Short answer: no! For a long time, researchers have relied on animals to understand human diseases and create treatments. However, even if they share similarities with humans, they have many differences. Thus, the use of human material for research is inevitable to fully understand the human body and to develop medication. In addition, growing ethical concerns about animal experimentation have pushed researchers to find alternatives. Still scientists cannot simply open someone up to experiment on them, so they have had to create other ways to work on human material. For example, a field of research that face this problem is the study of ADHD (Attention Deficit with or without Hyperactivity Disorder). Today, approximately 9 out of 10 new medications for ADHD created with animal experiments fail in humans. Even if an animal brain may be similar to that of a human, it cannot fully show the complexity of ADHD, a typical human disease. Scientists have developed a new method called iPSC (Induced Pluripotent Stem Cells) to study a wide range of diseases including brain conditions like ADHD. What are the advantages of iPSCs to study human brains? This method allows researchers to work directly on cells from patients with the disease that they want to study. They do not have to recreate the disease in a lab and can work directly on sick cells as they exist in the human body. iPSC-based studies are becoming more popular in the ADHD research because the cells used have the complexity of the human disease with all the parameters involved. For example, iPSC-based study lead to the discovery that brain cells of ADHD patients grow slower. The research also revealed that more neuron types are involved in ADHD than we thought which compliments the knowledge from animal experiments.
What are iPSCs? How do you transform skin cells into stem cell?
In 1998, to work on human material in the lab, scientists had to first grow cells (the building blocks of life) collected from embryos. Even if this method allows for a wide range of research using human living material, it still raises ethical questions: what are the rights of embryos? When does human life start? In addition, this method has many technical limits such as the small number of usable embryos. The donation and use of embryos is strictly regulated and thus they are hard to obtain, pushing scientists to find other techniques to make human research more accessible and ethical. But why are cells from embryos so special and why do they interest researchers so much? Cells found in embryos are called stem cells: the only type of cell that can evolve into any other kind of cell in the body (blood, skin, brain cells…) Scientists have known how to go from stem cells to other kind of cells but did not know how to reverse the process. Prof. Yamanaka and his team solved this mystery and transformed skin cells back into stem cells for the first time in 2007. They added a specific genetic material (a sort of building manual) into the skin cells which allowed them to produce elements, now called the “Yamanaka factors». Those factors converted skin cells into stem cells and are now called “induced pluripotent stem cells” (iPSC). In 2012, Prof. Yamanaka and his team received the Nobel Prize of Medicine for this discovery. Now using existing methods, scientists can transform iPSCs in any kind of cells, allowing them to experiment directly on living human material. Nevertheless, even though this method solves the ethical issue of the status of embryos, the production and use of iPSCs is strictly regulated in many countries and even forbidden in some. Two aspects are closely monitored: the informed consent of people donating their cells to produce iPSCs and the purpose for which those cells are taken.
Is this method not limited in comparison to experimenting on whole organisms like mice?
Yes and no. Yes, experimentation on one type of cell at a time grown without structure, misses a lot of organ and body complexity. This is why scientists needed to find a way to study complex material to be able to understand the human body and discover better treatments. To solve this problem, they built mini lab-grown organs called “organoids”. Organoids are cells that gather themselves to form mini-organs that imitate the structure and function of real (human) organs. Among other methods, researchers can use iPSC to grow human organoids. In 2009 Prof. Sato created the first human organoid: a gut organoid. Since then, researchers have managed to create all sorts of organoids…. including brain organoids! In 2013, Prof. Lancaster was studying microencephaly in mice, a disease where the human brain does not grow big enough. However, it was not possible to copy this human disease in mice. When scientists modified mice to cause microencephaly in the same way it occurs in humans, the mice brains always remained a normal size. This is why Prof. Lancaster instead recreated the disease in human brain organoids and succeeded. This technical revolution allowed not only to better understand microencephaly and potential treatments, but it was a big step to improve our knowledge of the human brain. Those techniques need several improvements to get closer to the human body and the human brain. One main limit to this development is financial as the material needed is more expensive than for animal experiment. It is important that these methods gain popularity to increase the funding of labs working on human material. Now, you might worry: are scientists building living beings able to think like humans and have consciousness? No, those capacities are extraordinarily complex, and we are far from being able to create them in a lab, it might never even be possible. Finally, the work on brain organoids is strictly regulated and closely monitored to avoid missuses of this method. Each country has their own regulations and scientists must get approval before starting any project with these methods and carefully document all human material used and produced.
To conclude, scientists can now grow any kind of human cells in the lab and even create mini organs out of them. For now, those methods are an essential complement to animal experimentation. One question remains: will it one day be possible to completely do without animal experimentation when it comes to understanding the human body and finding new treatments? Can we imagine a future where not only beyond meat burgers but also beyond mice labs are everywhere?
Bibliography:
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Lancaster, M., Renner, M., Martin, CA. et al. Cerebral organoids model human brain development and microcephaly. Nature 501, 373–379 (2013). https://doi.org/10.1038/nature12517
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Yde Ohki CM, Walter NM, Bender A, Rickli M, Ruhstaller S, Walitza S, Grünblatt E. Growth rates of human induced pluripotent stem cells and neural stem cells from attention-deficit hyperactivity disorder patients: a preliminary study. J Neural Transm (Vienna). 2023 Mar;130(3):243-252. doi: 10.1007/s00702-023-02600-1. Epub 2023 Feb 17. PMID: 36800023; PMCID: PMC10033475.
McNeill, R.V., Schickardt, Z., Radtke, F. et al. hiPSC-derived cortical neurons from ADHD individuals reveal dysregulated glutamatergic development. Mol Psychiatry 31, 1041–1050 (2026). https://doi.org/10.1038/s41380-025-03213-8
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