Gene Therapy Shows Promise in Preventing & Removing Alzheimer’s Plaques in Mice

A novel approach to cellular immunotherapy is showing promise in both preventing the formation of, and even reducing existing, amyloid plaques in the brain – a hallmark of Alzheimer’s disease. Researchers at Washington University School of Medicine have engineered a specialized virus to genetically alter brain cells, effectively turning them into “super cleaners” that target and remove harmful proteins. The findings, published in Science, offer a potential new avenue for treating and potentially preventing Alzheimer’s, particularly in the early stages of the disease.

Engineering Brain Cells for Targeted Cleanup

The study centers around astrocytes, star-shaped brain cells that play a crucial role in maintaining brain health. Scientists focused on reprogramming these astrocytes to actively seek out and eliminate amyloid beta proteins, which accumulate in the brains of individuals with Alzheimer’s disease and are thought to contribute to cognitive decline. This method borrows from the principles of chimeric antigen receptor (CAR) T cell therapy, a cancer treatment where immune cells are genetically modified to target and destroy cancer cells.

“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,” explains senior author Marco Colonna, a pathologist at Washington University, according to a statement. The team designed a gene therapy that delivers a gene coding for a CAR receptor onto a harmless virus. When this virus infects astrocytes, it effectively reprograms them to hunt down amyloid beta.

Promising Results in Mouse Models

The researchers tested their approach on mice genetically predisposed to develop amyloid plaques. They divided the mice into two groups: younger mice before plaque formation began, and older mice with existing plaques. A single injection of the gene therapy was administered to both groups, and the results were observed after three months.

In the younger mice, the treatment proved remarkably effective. By six months of age – the point at which these mice typically develop significant plaque buildup – those treated with the gene therapy showed no signs of amyloid plaques. Even in the older mice, where the disease was already underway, the treatment led to a roughly 50% reduction in plaque levels by nine months.

“Consistent with the antibody drug treatments, this new CAR-astrocyte immunotherapy is more effective when given in the earlier stages of the disease,” adds co-author David Holtzman, a neuroscientist at Washington University. “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.”

Context: Existing Alzheimer’s Treatments and Their Limitations

Currently, there is no cure for Alzheimer’s disease, but several approaches aim to slow its progression. Lifestyle factors, such as a nutritious diet and regular exercise, can play a protective role, with some studies suggesting benefits from as little as 5,000 steps a day. More recently, monoclonal antibodies like lecanemab and donanemab have shown promise in slowing cognitive decline by targeting amyloid beta proteins. However, these treatments have limitations, including the need for frequent infusions, high doses, and the risk of amyloid-related imaging abnormalities – a type of brain swelling.

The new cellular immunotherapy approach aims to address some of these limitations by potentially offering a more efficient and less frequent treatment option. By harnessing the natural cleaning capabilities of astrocytes, the therapy could provide a sustained reduction in amyloid plaques with a single injection.

What Does This Mean for Alzheimer’s Prevention and Treatment?

The findings represent a significant step forward in Alzheimer’s research, offering a novel strategy for tackling the disease at its root. Amyloid plaques are a key pathological feature of Alzheimer’s, and reducing their burden is thought to be crucial for slowing or preventing cognitive decline. While the study was conducted in mice, the results suggest that engineering astrocytes to target amyloid beta could be a viable therapeutic approach in humans.

It’s important to note that this research is still in its early stages. Further studies are needed to optimize the gene therapy, assess its safety, and determine its effectiveness in human clinical trials. Researchers will need to carefully evaluate potential side effects and ensure that the treatment does not disrupt the normal functions of astrocytes.

The Path Forward: From Mouse Models to Human Trials

The Washington University team is now focused on refining the gene therapy and conducting preclinical studies to prepare for potential human trials. These trials will be crucial for determining whether the treatment is safe and effective in people with Alzheimer’s disease or those at risk of developing the condition. The researchers are also exploring whether this approach could be adapted to target other neurodegenerative diseases and even brain tumors.

The development of effective Alzheimer’s treatments remains a major public health priority. With an aging global population, the number of people affected by Alzheimer’s is expected to rise dramatically in the coming decades. Innovative approaches like this cellular immunotherapy offer hope for a future where Alzheimer’s can be prevented or effectively managed, allowing individuals to maintain cognitive function and quality of life for longer. For more information on Alzheimer’s disease and ongoing research, resources are available from the Alzheimer’s Association and the National Institute on Aging.