Credit: B. Artegiani, D. Hendriks, H. Clevers, copyright: Hubrecht Institute, Princess Máxima Center 8 January 2024 Novel tissue-derived brain organoids could revolutionize brain research Back to news Scientists at the Hubrecht Institute (Organoid group) and Princess Máxima Center for pediatric oncology have developed 3D mini-organs from human fetal brain tissue. These lab-grown organoids open up a brand-new way of studying how the brain develops. They also offer a valuable means to study the development and treatment of diseases related to brain development, such as brain tumors. The study was published in Cell on 8 January 2024. Scientists use different ways to model the biology of healthy tissue and disease in the lab. These include cell lines, laboratory animals and, since a few years, 3D mini-organs. These so-called organoids have characteristics and a level of complexity that allows scientists to closely model the functions of an organ in the lab. Organoids can be formed directly from cells of a tissue. Scientists can also ‘guide’ stem cells – found in embryos or in some adult tissues – to develop into the organ they aim to study. Until now, brain organoids were grown in the lab by coaxing embryonic or pluripotent stem cells to grow into structures representing different areas of the brain. Using a specific cocktail of molecules, scientists would try to mimic the natural development of the brain – with the ‘recipe’ for each cocktail taking a lot of research to develop. An image of a whole human fetal brain organoid. Stem cells are marked by SOX2 (grey) and neuronal cells (TUJ1) are color coded from pink to yellow based on depth. Credit: B. Artegiani, D. Hendriks, H. Clevers, copyright: Hubrecht Institute, Princess Máxima Center. First brain organoids Now, scientists developed brain organoids directly from human fetal brain tissue. The researchers, led by Delilah Hendriks, Hans Clevers and Benedetta Artegiani, were surprised to find that using small pieces of fetal brain tissue rather than individual cells was vital in growing mini-brains. To grow other organoids from organs such as the gut, scientists normally break down the original tissue to single cells. Instead, working with small pieces of fetal brain tissue, the team found that these pieces could self-organize into organoids. “Until now, we were able to derive organoids from most human organs, but not from the brain – it’s really exciting that we’ve now been able to jump that hurdle as well,” says Hans Clevers. Analogue of human brain The brain organoids were roughly the size of a grain of rice. The scientists found they had a number of features that make them particularly valuable to study the human brain. Firstly, the tissue’s 3D make-up was complex, and it contained a number of different types of brain cells. Importantly, the brain organoids contained many so-called outer radial glia – a cell type found in humans and our evolutionary ancestors. This underlines the organoids’ close similarity to – and use in studying – the human brain. Furthermore, the whole pieces of brain tissue also produced proteins that make up extracellular matrix – a kind of ‘scaffolding’ around cells. The team believes these proteins could be the reason why the pieces of brain tissue were able to self-organize into 3D brain structures. The presence of extracellular matrix in the organoids will allow further study of the environment of brain cells, and what happens when there are errors in the extracellular matrix. Finally, the organoids kept various characteristics of the specific region of the brain from which they were derived. The organoids responded to signaling molecules known to play an important role in brain development. This suggests that these organoids could play an important role in studying the development of the brain. Benedetta Artegiani: “Our new, tissue-derived brain model allows us to gain a better understanding of how the developing brain regulates the identity of cells. It could also help understand how mistakes in that process can lead to neurodevelopmental diseases, as well as other diseases that can stem from derailed development, including childhood brain cancer.” Four zoom-in images of parts of different human fetal brain organoids. Different neural markers are stained, depicting their cellular heterogeneity and architecture. Credit: B. Artegiani, D. Hendriks, H. Clevers, copyright: Hubrecht Institute, Princess Máxima Center. Studying brain cancer The team next investigated the potential of the organoids in modeling brain cancer. The researchers used the gene-editing technique CRISPR-Cas9 to introduce mutations found in glioblastoma (TP53, PTEN and NF1) in a small number of cells in the organoids. After three months, the mutated cells with defective TP53 had completely overtaken the healthy cells in the organoid – meaning they had acquired a growth advantage, a typical feature of cancer cells. They also used these mutant organoids to look at their response to cancer drugs, and found that they can be used to link certain drugs to specific gene mutations. A brightfield image of a culture of human fetal brain organoids pooled together in a well of a culture plate. Credit: B. Artegiani, D. Hendriks, H. Clevers, copyright: Hubrecht Institute, Princess Máxima Center. Valuable tool for future research The tissue-derived organoids continued to grow in a dish for more than six months. Importantly, the scientists could multiply them, allowing them to grow many similar organoids from one tissue sample. Delilah Hendriks says: “Being able to keep growing and using the brain organoids from fetal tissue also means that we can learn as much as possible from such precious material. We’re excited to explore the use of these novel tissue organoids for new discoveries about the human brain.” Next, the researchers aim to further explore the potential of their new tissue-derived brain organoids. They also plan to continue their work with bioethicists – who were already involved in shaping this research – to guide the future development and applications of the new brain organoids. Publication Human fetal brain self-organizes into long-term expanding organoids. Delilah Hendriks, Anna Pagliaro, Francesco Andreatta, Ziliang Ma, Joey van Giessen, Simone Massalini, Carmen López-Iglesias, Gijs J. F. van Son, Jeff DeMartino, J. Mirjam A. Damen, Iris Zoutendijk, Nadzeya Staliarova, Annelien L. Bredenoord, Frank Holstege, Peter J. Peters, Thanasis Margaritis, Susana Chuva de Sousa Lopes, Wei Wu, Hans Clevers, Benedetta Artegiani. Cell, 2024. Source of the fetal brain tissue The human fetal tissue was derived from healthy abortion material, between gestational weeks 12-15, from fully anonymous donors. The anonymous women donated the tissue voluntarily and upon informed consent. They were informed that the material would be used for research purposes only, and that the research included the understanding of how organs normally develop, including the possibility to grow cells derived from the donated material. This study was performed in collaboration with Leiden University Medical Center, Utrecht University, Maastricht University, Erasmus University Rotterdam, and National University of Singapore. Part of this study was funded by the Dutch Research Council (NWO). Delilah Hendriks is a postdoctoral researcher at the Hubrecht Institute and affiliated group leader at the Princess Máxima Center for pediatric oncology. Benedetta Artegiani is research group leader at the Princess Máxima Center for pediatric oncology. Hans Clevers is advisor/guest researcher at the Hubrecht Institute for Developmental Biology and Stem Cell Research (KNAW) and at the Princess Máxima Center for Pediatric Oncology. He holds a professorship in Molecular Genetics from the Utrecht University and is an Oncode Investigator. Hans Clevers has been the Head of Pharma Research and Early Development (pRED) at Roche since 2022. He previously held directorship/President positions at the Hubrecht Institute, the Royal Netherlands Academy of Arts and Sciences and the Princess Máxima Center for pediatric oncology.
