Summary: Current Alzheimer’s treatments typically require frequent, high-dose infusions of monoclonal antibodies to slow cognitive decline. But researchers have engineered a potentially game-changing alternative: CAR-astrocytes. Taking inspiration from CAR-T cell therapy used in cancer, scientists used a harmless virus to “reprogram” astrocytes—the most abundant cells in the brain—with a specialized “homing device.”
These modified cells, dubbed “super cleaners,” are designed to specifically target and engulf amyloid-beta plaques. In a study published in Science, a single injection of these CAR-astrocytes completely prevented plaque development in young mice and cut existing plaque levels in half in older mice.
Key Facts
- The “Homing Device”: Researchers equipped astrocytes with a Chimeric Antigen Receptor (CAR) that allows them to identify and “grab” amyloid-beta proteins for destruction.
- Single-Shot Potential: Unlike monthly antibody infusions, this cellular immunotherapy showed massive effectiveness with just a single injection in mouse models.
- Prevention & Treatment: When given before plaques formed, the therapy kept the brain plaque-free. In brains already saturated with amyloid, it reduced the plaque load by 50% within three months.
- Reducing the Burden: Traditionally, microglia (the brain’s immune cells) handle “trash removal,” but they become overwhelmed in Alzheimer’s. CAR-astrocytes provide much-needed reinforcement.
- Beyond Alzheimer’s: The team believes this technology could be adapted to target brain tumors by switching the CAR device to recognize cancer markers instead of amyloid.
Source: WUSTL
The new generation of Alzheimer’s disease drugs — the first proven to change the course of the disease — typically extend independent living for patients by 10 months. Called monoclonal antibodies, they reduce the accumulations of a harmful protein, amyloid, in the brain and require high-dose, once- or twice-monthly infusions of the medication.
Now, to reduce the frequency of treatment and potentially improve the efficacy of an anti-amyloid therapy, researchers at Washington University School of Medicine in St. Louis have engineered a new cellular immunotherapy that requires just a single injection to prevent amyloid plaques from developing when given before plaques start to form in mice. Furthermore, a single treatment in mice that had already developed plaques cut the amount of amyloid plaques in half.
The study was published March 5 in Science.
Like CAR-T cell therapies used for cancer treatment, in which T cells of the immune system are genetically modified to attack cancer cells, this new approach equips cells — in this case, brain cells called astrocytes — with a CAR homing device to grab onto a target for destruction. These new CAR-astrocyte cells have features that transform them into super cleaners that remove damaging proteins from the brain that play a role in cognitive decline.
“This study marks the first successful attempt at engineering astrocytes to specifically target and remove amyloid beta plaques in the brains of mice with Alzheimer’s disease,” said the study’s senior author, Marco Colonna, MD, the Robert Rock Belliveau, MD, Professor of Pathology at WashU Medicine.
“Although more work needs to be done to optimize the approach and address potential side effects, these results open up an exciting new opportunity to develop CAR-astrocytes into an immunotherapy for neurodegenerative diseases and even brain tumors.”
Removing brain waste
Alzheimer’s disease starts with a sticky protein called amyloid beta that builds up into plaques in the brain, setting off a chain of events that results in brain atrophy and cognitive decline.
Microglia, immune cells that reside in the brain, are responsible for removing brain waste but can become dysfunctional when overwhelmed in the context of neurodegenerative disease.
To reduce the cleaning burden on microglia, first author Yun Chen, PhD, then a graduate student in the labs of Colonna and David M. Holtzman, MD, the Barbara Burton and Reuben M. Morriss III Distinguished Professor of Neurology at WashU Medicine, transformed astrocytes, the most abundant cell type in the brain, into amyloid-cleaning machines.
He custom-designed and delivered a gene to astrocytes that codes for the chimeric antigen receptor (CAR) via a harmless virus injected into mice. The CAR, now present on the surface of astrocytes, enabled the cells to capture and engulf amyloid beta proteins.
With their newly acquired ability, the astrocytes — generally responsible for keeping the brain tidy — concentrated their efforts on only cleaning amyloid beta plaques in mice prone to its buildup.
Mice carrying genetic mutations that increase people’s risk of developing Alzheimer’s disease develop amyloid beta plaques that saturate the brain by six months of age. Chen, now a postdoctoral researcher in the Holtzman lab, injected two groups of mice with the virus carrying the CAR-expressing gene: young mice before they developed plaques and older mice with brains saturated with plaques. Then he waited three months.
As the younger mice aged, the CAR-astrocytes prevented amyloid beta plaque development. At nearly six months of age, when untreated mice normally have brains saturated with harmful plaques, brains of treated mice were plaque-free. Meanwhile, older mice with plaque-saturated brains at the time of treatment saw a 50% reduction in the amount of amyloid beta plaques compared to mice receiving an injection of a virus lacking the CAR gene.
The researchers have filed a patent, with help from the Office of Technology Management at WashU, related to the approach used to engineer CAR-astrocytes.
“Consistent with the antibody drug treatments, this new CAR-astrocyte immunotherapy is more effective when given in the earlier stages of the disease,” said Holtzman, who is a co-author on the paper.
“But where it differs, and where it could make a difference in clinical care, is in the single injection that successfully reduced the amount of harmful brain proteins in mice.”
In future studies, the authors aim to continue improving their CAR-astrocyte immunotherapy by fine-tuning its design to better target harmful proteins, while ensuring no harmful effects on normal brain cell functions.
Additionally, by adjusting the CAR homing device to recognize specific markers on brain tumors, they could potentially switch astrocytes’ function from cleaning up debris to directly killing tumor cells. Such an approach could offer a promising new way to treat brain tumors and other central nervous system diseases.
Key Questions Answered:
A: Exactly! It uses the same core technology (CAR). Instead of teaching immune cells to find and eat cancer, scientists are teaching brain cells (astrocytes) to find and eat the “sticky” plaques that cause Alzheimer’s.
A: Antibodies have to be pumped into the body constantly and don’t always cross into the brain efficiently. By “upgrading” the cells already inside your brain, you create a permanent cleaning crew. This study showed that one single “upgrade” was more effective and lasted longer than current methods in mice.
A: We are still in the early stages. While the results in mice are “plaque-free” spectacular, the researchers need to ensure these super-cleaners don’t accidentally eat healthy brain parts or cause inflammation. Human trials are the next major hurdle.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this neurology and Alzheimer’s disease research news
Author: Jessica Church
Source: Washington University
Contact: Jessica Church – Washington University
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Targeting amyloid-β pathology by chimeric antigen receptor astrocyte (CARA) therapy” by Yun Chen, Yizhou Liu, Khai Nguyen, Junjie Wu, Sihui Song, Kent Lin, Patrick F. Rodrigues, Siling Du, Charles Zhou, Kyle Xiong, Megan Bosch, Peter Bor-Chian Lin, Darya Khantakova, Shitong Wu, May Wu, Carla Yuede, David M. Holtzman, and Marco Colonna. Science
DOI:10.1126/science.ads3972
Abstract
Targeting amyloid-β pathology by chimeric antigen receptor astrocyte (CARA) therapy
INTRODUCTION
Alzheimer’s disease (AD) is the most common cause of age-related dementia worldwide. Its pathology progresses from the accumulation of extracellular amyloid-β (Aβ) to the development of intraneuronal tauopathy, ultimately resulting in neurodegeneration. Currently, the most effective strategy for slowing AD progression involves anti-Aβ monoclonal antibodies, three of which have recently received clinical approval.
However, these therapies share several limitations, including the need for high doses and repeated administration, a narrow therapeutic window, risks such as amyloid-related imaging abnormalities, and dependence on Fc receptor gamma subunit (FcRγ) signaling. These challenges underscore the need for new therapeutic approaches.
RATIONALE
Chimeric antigen receptors (CARs) can be engineered by fusing an anti-Aβ single-chain variable fragment (scFv) to the intracellular domain of selected phagocytic receptors, creating a self-sustaining system that enables brain glia to recognize and clear Aβ aggregates.
This approach avoids repeated dosing and allows intracellular signaling to be precisely tuned, a capability not offered by conventional antibody therapies. Because replacing endogenous microglia with CAR-expressing myeloid cells remains challenging for achieving durable, brain-wide coverage, we instead targeted an alternative phagocytic glial population—astrocytes.
We therefore generated CAR-expressing astrocytes (CAR-A) and tested their ability to clear amyloid pathology in a mouse model of amyloid plaques using systemic AAV-PHP.eB delivery to achieve central nervous system (CNS)–wide expression.
RESULTS
We present a framework for engineering CAR systems in which anti-Aβ scFv are fused to the intracellular domains of phagocytic receptors. We designed four FcRγ-independent anti-Aβ CARs that function robustly in immortalized and primary astrocytes, enhancing phagocytosis and promoting degradation of Aβ42 oligomers in vitro. On the basis of these data, we selected two CARs for in vivo delivery to CNS astrocytes through peripheral, noninvasive AAV-PHP.eB-GFAP administration.
One construct links crenezumab to the phagocytic domain of MEGF10 (Cre-Megf10), and the other links aducanumab to the phagocytic domain of Dectin1 (Adu-Dectin1). A single administration of either CAR-A after plaque formation significantly reduced amyloid burden and neuritic dystrophy within 3 months, whereas early delivery prevented Aβ accumulation and associated pathology for 2.5 months.
Single-nucleus RNA sequencing and immunostaining showed that both CARs induced disease-associated astrocytes and shifted microglia toward a more homeostatic state with reduced exhaustion signatures.
Notably, the constructs diverged in part in their downstream effects, with Cre-Megf10 acting mainly on astrocytic states and Adu-Dectin1 additionally engaging microglial activation through astrocyte-microglia communication.
CONCLUSION
Beyond the success of CAR-based therapies in oncology, this work establishes the potential of adapting phagocytic CAR technology to the CNS. By targeting astrocytes, we reveal a new therapeutic axis for AD that complements the phagocytic functions classically attributed to microglia and expands the repertoire of cellular targets for neuroimmune intervention.
The observation that distinct CAR designs drive partially divergent glial programs highlights the flexibility of this platform and the opportunity to tailor CAR signaling to achieve specific therapeutic goals.
Looking ahead, continued optimization will be critical to maximize amyloid clearance while preserving neuronal integrity, minimize off-target effects, and extend this approach to additional cell types. Together, these findings position CAR engineering as a scalable and tunable strategy for treating neurodegenerative disease.
