For the first time, scientists have grown 3D brain models, called “chimeroids,” using cells from multiple donors. These hybrid brain organoids mimic the structure and function of a full-size brain more accurately than traditional 2D cellular models or lab animals. Researchers believe these models will significantly enhance drug research and development.
Traditional brain organoids are typically grown from the cells of a single donor, which limits their ability to represent the genetic diversity found among different individuals. This diversity can impact brain development and drug responses.
Creating chimeroids, as described in a new study published in *Nature* on June 26, aims to overcome this limitation. These “village in a dish” models could be especially useful in early drug testing stages. While scientists have previously grown sheets of brain cells from different people, this is the first time 3D brain models have been developed this way.
To create chimeroids, researchers collected stem cells from five individuals and used growth-inducing chemicals to form brain organoids. They then disassembled these organoids and recombined the cells to form chimeroids, ensuring each contained an equal number of cells from each donor. After three months, the chimeroids were about 0.12 to 0.2 inches in diameter and contained all the cell types typically found in the cortex of a fetal brain.
The team exposed the chimeroids to neurotoxic chemicals, such as ethanol and the antiepileptic drug valproic acid, to observe how cells from different donors responded. They found significant variations in how these chemicals affected cell growth, highlighting the potential for chimeroids to predict individual drug responses before clinical trials.
If scaled up, chimeroids could help determine patient responses to drugs, allowing for more personalized treatment approaches. Paola Arlotta, co-senior study author and professor of stem cell and regenerative biology at Harvard University, expressed excitement about using organoids like chimeroids to advance therapeutic innovation for neurological diseases.
