The challenge
Human brain tissue models are essential for studying neurodevelopment and neurodegenerative diseases, but current systems face major limitations. Neural organoids and 2D co-cultures often lack reproducibility, show immature cell states, and fail to support long-term maintenance of homeostatic microglia. This hampers investigations into microglial contributions to Alzheimer’s disease and other brain disorders, and limits the physiological relevance of drug testing in fully human systems.
Our approach
We developed a three-dimensional cortical brain tissue model (3BTM) by aggregating iPSC-derived neurons, astrocytes and microglia. Using multi-line validation, proteomics, single-cell RNA-seq, live imaging and functional assays, we characterized maturation, ECM formation and microglial phenotypes. We then engineered 3BTMs with synergistic APP mutations to model Alzheimer’s disease and tested anti-amyloid immunotherapy to assess therapeutic responses.
Our findings
3BTMs showed high reproducibility, stable size, and long-term viability without necrotic cores. Neurons, astrocytes and microglia matured toward in vivo-like states, with brain-specific ECM deposition and synapse formation. Microglia survived for over six months, adopted ramified morphologies, expressed homeostatic markers, and responded dynamically to injury. AD-modeled 3BTMs developed amyloid deposition, increased phospho-tau and neuroinflammation, with microglia shifting to disease-associated transcriptional states. Anti-amyloid immunotherapy cleared deposits and reversed disease signatures in glia.
The implications
These findings establish 3BTMs as a scalable, physiologically relevant platform for studying human brain tissue, mature microglia and neurodegenerative disease mechanisms, and for testing therapeutic interventions in a fully human system.
Creating SyNergies
This work combines expertise in iPSC technology, 3D tissue engineering, microglial biology, 2-photon and electron microscopy, Alzheimer’s disease modeling, multi-omics and drug testing. By integrating neurons, astrocytes and microglia in a reproducible 3D environment, the study provides a versatile tool for basic and translational neuroscience. First and SyNergy authors: Julien Klimmt, Carolina Cardoso Gonçalves, Martina Schifferer, Silvia Capello, Thomas Misgeld, Nikolaus Plesnila, Jochen Herms, Christian Haass, Stefan Lichtenthaler, Dominik Paquet.
