Context
As of 2021, over 57 million people worldwide were living with dementia (World Health Organization, 2025). Alzheimer’s disease (AD) is the most common cause of dementia, representing 60–70% of its cases (World Health Organization, 2025). Most people develop AD in their sixties, and the disease is mostly characterized by a person’s difficulty in remembering recent events, yet symptoms also include problems with mood swings and language (National Institute on Aging, 2022). However, the causes of AD remain poorly understood (Knopman et al., 2021); although significant progress has been made in finding genetic factors, the environmental factors are not as clear. One biological definition of AD underlines the presence of malformed protein deposits in the brain, called amyloid-beta plaques and neurofibrillary tangles (“waste proteins”), which accumulate and damage neurons (Knopman et al., 2021).
No treatments are publicly available to stop or reverse the progression of AD. General advice, such as maintaining a healthy diet and physical activity, may temporarily improve symptoms. It has only been a few years since it has been shown for the first time that medications like lecanemab and donanemab can slow the progression of AD, yet these drugs are controversial due to their potentially dangerous side effects, such as brain swelling (Bitar et al., 2025).
Recent research
However, recent research focusing on the blood-brain barrier (BBB) has revealed that it might, after all, be possible to stop and reverse AD. The BBB, a highly selective permeability barrier that protects the central nervous system (CNS) from harmful substances and regulates the transport of essential molecules like glucose, helps move things in and out of the brain (Abbott, 2010). Dysfunction of the BBB is increasingly being seen as a factor in development of AD, as poor performance of the BBB means that it clears out the amyloid-beta plaques at a slower rate. Chen et al. present a novel therapeutic strategy that targets one specific receptor, the low-density lipoprotein receptor-related protein 1 (LRP1), in the BBB. LRP1 is a protein that helps clear amyloid-beta from the brain by facilitating its transport (Shinohara et al., 2017). It also influences amyloid-beta production by regulating certain enzymes (Shinohara et al., 2017). It is known that LRP1 levels are low in AD patients and low levels correlate with cognitive decline.
Methods
Polymersome design
The researchers engineered nanoscale vesicles (polymersomes) that bind LRP1 receptors. They synthesized four different versions carrying 0, 1, 40, and 200 peptides (ligands) to test how multivalency influences BBB transport. Multivalency increases the binding strength with the receptor. However, when binding is too strong, the LRP1 receptors degrade. Even though LRP1 levels are lower in AD patients, the goal of this method is to take advantage of what’s available by having these nanoparticles (vesicles) display just the right number of ligands to promote LRP1-mediated endocytosis (when the cell membrane engulfs substances to take them in) of the polymersome. This is why four different versions with varying amounts of peptides were tested; the ideal number of peptides was unknown. (Ultimately, the 40-peptide version performed the best.)
Post-binding
Once the polymersome binds to the LRP1 receptor, the receptor induces endocytosis and transports the polymersome inside the cell. Therefore, because the nanoparticle (polymersome) increases the number of LRP1 transport cycles per receptor, amyloid-beta also get to move via the LRP1-induced endocytosis (for example, soluble amyloid-beta may attach to the polymersome). This can solve the problem of having insufficient levels of LRP1 receptors (which leads to slower amyloid-beta removal, which can lead to AD).
Evaluation
- In vitro (outside a living organism) BBB models: the authors compared multivalent and monovalent constructs and found that multivalent ligands (molecules that bind to receptors) bound the LRP1 receptor more effectively.
- In vivo (inside a living organism) AD mouse models: after the administration of the treatment, biochemical assays confirmed that brain amyloid-beta plaque levels decreased. Imaging confirmed reduced brain amyloid-beta signals, and cognitive testing showed learning and memory improvements.
Results
The results in this study are significant. In AD model mice, this strategy reduced the level of brain amyloid plaques by nearly 45% and increased soluble plasma amyloid plaques 8 times in two hours (measured by ELISA, a laboratory blood test). This increase means that the plaque material is being “exported” out of the brain into the blood rather than accumulating in the brain. The imaging techniques used confirmed that brain amyloid-β signals had reduced after the intervention. Also, cognitive assessments showed that these AD model mice had improved in spatial learning and memory for up to 6 months post-treatment.
It is important to remember that the BBB of mice is not nearly as complex as the BBB of humans. Therefore, this intervention does not necessarily apply to humans. The study does not explore the off-target uptake in organs like the liver. The next steps for this research may be to repeat it in different AD models, perhaps even with ex vivo human brain microvessels, or to explore the effects of the intervention in different parts of the organism.
Recent research in Alzheimer’s disease has shown that slowing the progression of the disease may indeed be possible. This paper outlines just one of the methodologies that try to slow down the progression of AD. However, slowing down the progression of AD is not the same as reversing the effects of it. This research paper, as well as most research in AD, does not focus on reversing cognitive decline caused by AD; this is because to reverse such effects, we must first understand how to slow down the progression of the disease.
References
Abbott, N. J., Patabendige, A. A. K., Dolman, D. E. M., Yusof, S. R., & Begley, D. J. (2010). Structure and function of the blood–brain barrier. Neurobiology of Disease, 37(1), 13–25. https://doi.org/10.1016/j.nbd.2009.07.030
Bitar, I., Alabdalrazzak, M., Zamzam, M., Desai, Y., & Abushaban, K. (2025). Clinically silent amyloid-related imaging abnormality with edema following lecanemab therapy: A case report. Cureus, 17(8). https://doi.org/10.7759/cureus.91230
Knopman, D. S., Amieva, H., Petersen, R. C., Chételat, G., Holtzman, D. M., Hyman, B. T., Nixon, R. A., & Jones, D. T. (2021). Alzheimer disease. Nature Reviews Disease Primers, 7, 33. https://doi.org/10.1038/s41572-021-00269-y
National Institute on Aging. (2022, October 18). What Are the Signs of Alzheimer’s Disease? https://www.nia.nih.gov/health/alzheimers-symptoms-and-diagnosis/what-are-signs-alzheimers-disease
Shinohara, M., Tachibana, M., Kanekiyo, T., & Bu, G. (2017). Role of LRP1 in the pathogenesis of Alzheimer’s disease: evidence from clinical and preclinical studies. Journal of Lipid Research, 58(7), 1267–1281. https://doi.org/10.1194/jlr.R075796
World Health Organization. (2025, March 31). Dementia. https://www.who.int/news-room/fact-sheets/detail/dementia
Cover image by Robina Weermeijer on Unsplash. https://unsplash.com/photos/brown-brain-decor-in-selective-focus-photography-3KGF9R_0oHs