Could ‘young blood’ treat Alzheimer’s disease?

A clinical trial will soon begin in the USA testing whether transfusing the blood of younger people into those with Alzheimer’s disease can improve their cognition.

This may sound a bit strange, however this is not a new approach, and there is evidence from animal trials suggesting that it might actually work. In light of this, Dementia News investigated the current evidence showing how a blood transfusion could potentially be used as a treatment for Alzheimer’s disease.

The hypothesis
Researchers believe that exposure to certain cells and proteins found within ‘young blood’ can counteract and even reverse pre-existing effects of neurodegeneration at the molecular, structural, functional and cognitive level. Specifically, it is thought that certain ‘young blood’ cells may be able to enhance neuroplasticity and increase the production of brain cells (i.e. neurons).

What is currently known?
To date, the only evidence to support this hypothesis comes from mouse studies. In October 2012, Dementia News first reported on this research by Dr Saul Villeda and researchers from the Stanford University, who presented their findings at the Annual Meeting of the Society for Neuroscience in the USA. They recently published their full findings in May of this year, in the Journal Nature Medicine. However, it was intriguing to read about how they got to the point where they realised that a blood transfusion might work.

In the initial phase, the research team surgically joined older and younger mice (a process known as parabiosis) to investigate the effects on cognition and brain chemistry of shared blood. They reported that when these mice were connected with a shared circulatory system, the blood from the younger mouse was able to increase the expression of proteins related to enhanced synaptic plasticity in the older mouse, as well as improve their memory and learning.

Parabiosis is a process that has been around for over 150 years and is commonly used in experimental animal studies. However, it is obviously a technique that could not translate into human use. So the next step was to assess the effects of whether injecting the blood of younger mice into the older mice, can have the same positive outcomes. For 21 days, the researchers injected blood plasma from young mice (~three months of age) into the older mice (~18 months of age). The older mice were found to have improved memory performance, comparable to those of the younger mice leading the scientists to suggest that ‘young blood’ may actually be able to reverse age-related cognitive impairment. However, it should be noted that the older mice in this study did not have Alzheimer’s disease, so the animal studies could not conclude that blood transfusions can actually relieve the symptoms of Alzheimer’s disease.

How does it work?
‘Young blood’ contains a different concentration of proteins than ‘older blood’. One of these proteins in particular is called the Growth Differentiation Factor 11 (GDF11), found in many studies to be abundant in younger mice, but scarce in older mice. In a separate study, published in the Journal Science, researchers found that mice injected with GDF11 had increased growth of blood vessels and neurons in the area of the brain responsible for smell, compared to mice of the same age that weren’t injected. Moreover, it has been found that GDF11 may also have positive effects on muscle and tissue growth as well as heart health. However, researchers are being cautious until they know the full role and mechanism of GDF11, particularly in relation to potential side effects.

The future
This new human clinical trial set to begin in October in the USA will involve giving blood plasma (donated by people under the age of 30) to people with mild to moderate Alzheimer’s disease. Cognitive function will be assessed both before and after the trial begins, and family members or carers have also been asked to report and note any improvements during the trial.

However, while this new treatment trial is exciting and we all eagerly await the results, it should be reiterated that the previous animal trials have only had positive results in older mice that did not have Alzheimer’s disease. So, it will be interesting to see the effects on those with Alzheimer’s disease. Dementia News will certainly keep you posted with the results of this trial.




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