Munich researchers develop novel 3D tissue model for Alzheimer’s disease

How can Alzheimer’s research be made faster, better, and more effective? After decades of intensive research worldwide and despite recent therapeutic advances, scientists have not managed to fully arrest the progress of the disease. “What we are still lacking is three-dimensional models that accurately replicate the complex interactions in human brain tissue with Alzheimer’s disease,” explains Dominik Paquet, Professor of Neurobiology at the Institute for Stroke and Dementia Research at LMU University Hospital. This is precisely the area in which his team has now made major progress – with potentially far-reaching consequences for the development of new drugs against Alzheimer’s disease. The group reported the exciting new results in the journal Nature Neuroscience.

For laypeople, it always seems a bit like magic when researchers take stem cells and grow tissues that resemble the human original. According to Dominik Paquet, however, it takes a mixture of scientific creativity, technical skills, and patience: “It took us nine years,” says the neuroscientist, “to develop our new, three-dimensional model of human brain tissue before it worked at all necessary levels.” What does he mean by all necessary levels, we might ask? For Alzheimer’s research, the interaction of different cell types and their biochemical functions are the most important thing – much more so than the exact replication of the structure of the brain.

The right recipe for genuine interplay

The starting material for the new 3D tissue model is human stem cells, which can be converted into various brain cell types – in this case, neurons, astrocytes, and microglial cells. To obtain this set, the stem cells have to be treated with a cocktail of different substances “according to a very specific recipe we developed.” In a special nutrient solution, Paquet continues, the differentiated cells connect and adhere to each other. “Within a week, they form little tissue balls about the size of half a pinhead. These spheroids self-organize and take on key functions of the brain.”

Almost everything just like in a real human brain

Their neurons form extensions and connect with functional synapses. The astrocytes supply their neighbors with nutrients. And the microglial cells – the immune cells of the brain – monitor their environment and ensure that no dead cells or foreign matter that does not belong there can accumulate. “We also tested whether all genes and proteins that are important for the study of Alzheimer’s disease are active in our tissue model,” says the neuroscientist. “And that was indeed the case.

Reproducible, modifiable – and disease-relevant

Another major advantage of the system is its reproducibility. That is to say, if you follow the instructions of the Munich researchers, you will reliably obtain tissue structures with the same composition and the same functions. “However, we can also modify the generated brain tissue from the outside,” says Dominik Paquet. “For example, we can trigger symptoms of a disease like Alzheimer’s, test potential drugs, and so forth.” In fact, the researchers have successfully induced the formation of the Alzheimer’s-typical amyloid aggregates – and then dissolved them again with new drugs that are already available. The microglia that play a key role in the disease were demonstrably active in the process.

Next step: automation for efficient drug development

“Our system,” says Dominik Paquet, “could help accelerate the development of new drugs.” With this goal in mind, his team is currently working on automating and scaling the manufacture of the tissue models using robots. This would mean manufacturing hundreds or even thousands of tissues with the same disease symptoms. This is particularly important for applications in industrial-scale medicine – for example, to be able to efficiently test many new substances in a human system for their effectiveness against Alzheimer’s.