Will young blood help with Alzheimer's disease?
An unprecedented clinical trial is scheduled to begin in October this year, in which patients with Alzheimer's disease will be injected with the blood of young people in the hope of improving their condition.
This experiment was based on the results of animal studies, which showed that the introduction of blood from young mice improves cognitive functions and the condition of a number of organs of old animals. At the same time, even the appearance of animals changes, they begin to look younger. Reproducing these results in clinical trials would produce a boom in the cosmetic and pharmaceutical industries.
If we ignore the legends about vampires, the first mention of the idea of rejuvenation of old blood dates back to the 50s of the last century, when Cliv McCay from Cornell University in Ithaca, New York combined the circulatory systems of an old and young mouse using a technique called heterochronous parabiosis. He found that after some time spent in tandem with a young mouse, the cartilage tissue of the old mouse returned to a state corresponding to a much earlier age.
However, the mechanisms underlying this phenomenon remained a mystery until recently. In 2005, Thomas Rando from Stanford University, California and his colleagues discovered that in heterochronous parabiosis, young blood returns liver stem cells and skeletal muscles of old mice to a younger state. They also showed that at the same time, the ability of skeletal muscles of old animals to repair damage improves to the level characteristic of young mice.
At the same time, the ingress of old blood into the circulatory system of young animals led to their premature aging. In some cases, this was accompanied by a slowdown in the healing of damaged muscles.
Similar results were obtained during a number of independent experiments. In 2012, a group of Amy Wagers from Harvard University showed that young blood is able to eliminate the manifestations of the aging process of the heart muscle in mice. The researchers paired the blood flows of healthy young mice and old mice with myocardial hypertrophy. After four weeks, the heart sizes of the old mice and their young partners were equal. During this experiment, the ingress of old blood into the circulation of young mice did not have a visible negative effect on the health of the latter.
After eliminating the effect of lowering blood pressure in old animals, scientists identified a blood plasma protein known as growth and differentiation factor-11 (growth differentiation factor 11, GDF11), the level of which decreases with age. To confirm the involvement of this compound in the rejuvenating effect of young blood, GDF11 was administered daily to old mice with myocardial hypertrophy for 30 days. The results of this were comparable to the results of parabiosis.
A year later, the same research team demonstrated that daily injections of GDF11 also increased the number of blood vessels and stem cells in the brain. It is believed that both of these factors can improve the functioning of the brain. Another group of scientists from Stanford University, working under the leadership of Tony Wyss-Coray, conducted similar experiments in which blood plasma from young mice was injected into old animals. As a result, the old mice showed a significant improvement in physical endurance and cognitive functions.
In both mice and humans, GDF11 levels decrease with age. The reason for this is unclear, but it is known that this factor is involved in a number of mechanisms that control the growth of the organism. It is also believed that GDF11 mediates a number of age-related brain changes, which is partly due to the activation of another protein involved in the growth of neurons and the formation of long-term memory.
Therefore, the main question is as follows: will an increase in the level of GDF11 have a similar effect on a person? Based on the results obtained by injecting old mice with blood plasma from young people, Wiss-Corey believes that this is quite realistic. He states that human plasma had a pronounced rejuvenating effect on all the organs of old mice analyzed to date.
In the near future, the final stage of this series of studies will begin – the introduction of blood plasma from young people to elderly patients with Alzheimer's disease. According to Wiss-Corey, obtaining permission to conduct it was a very simple task, since the transfusion of donated blood is a routine medical procedure. However, he warns that its implementation at home is fraught with serious consequences, since the transfused blood must be checked for markers of infectious diseases and selected by group. Moreover, it is not whole blood that should be transfused, but blood plasma, which is isolated in sterile conditions with the help of special equipment.
Encouraged by the impressive results of animal experiments, experts hope to see immediate improvements in the participants of the clinical trial. They plan to assess the level of cognitive functions of participants immediately before the plasma transfusion and daily for several days after the procedure. Subsequently, the patients' condition will be monitored for several months. According to the researchers, even if plasma transfusion will have only temporary effects, it will serve as a confirmation of the viability of the concept.
All researchers involved in the work agree that, most likely, GDF11 is not the only factor supporting the youth of organs, and the identification of other anti-aging ingredients of blood plasma is an extremely important task. In the future, this will help to develop a drug or a cocktail of drugs that will allow you to refuse transfusion of potentially unsafe donor material.
At the same time, experts note that the potential of such therapy is not limited to rejuvenation. Theoretically, it can be used to treat chronic diseases, as well as conditions such as muscle tissue atrophy in cancer patients.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of New Scientist:
Young blood to be used in ultimate rejuvenation trial.
02.09.2014