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Since ancient times, mankind has been trying to invent an elixir of youth – this is the name of a magical substance that can prevent old age and make a person immortal. Around 200 BC, the Chinese ruler Qin Shi Huangdi sent two expeditions in search of a rejuvenating elixir, but his subjects could not find anything. Ultimately, the emperor died as a result of exposure to the “elixir of youth”, which contained deadly mercury in its composition.
The search for a means that will increase the life expectancy of people is still ongoing. For several years, scientists have been experimenting with blood transfusions – once they even found evidence that young blood can improve the condition of older people. So what is it, humanity is already close to creating a cure for old age?
Young organisms can save the lives of the elderly
For thousands of years, scientists have tried to develop a cure for old age through the use of herbs and even hazardous metals. In the 20th century, scientific work of a different kind became widespread – scientists tried to improve the condition of older organisms by transfusing the blood of young individuals into them. Sometimes experiments crossed the line: researchers tried to sew the bodies of young animals with old ones. Although the experiments were very cruel, the scientists eventually made very interesting conclusions.

Young and old mice in parabiosis
Experiments on the stitching of young and old mice were especially frequent in the second half of the 20th century. The biological construct in which two individuals of different ages “cohabit” is called parabiosis . In daring experiments, scientists did find that as a result of connecting with a young body, older individuals began to feel much better. In particular, parabiosis could cure muscular dystrophy that leads to physical weakness, and in some cases even extend the life of old individuals.
How to rejuvenate an elderly body
There really is a rejuvenating effect, but what exactly it is connected with, scientists still find it difficult to answer. However, there are some interesting suggestions. Firstly, with parabiosis, the organs of a young individual can work for two – because of this, an elderly individual feels better. Secondly, the blood of young mice may contain substances that somehow rejuvenate the old organism. Thirdly, the reason for the improvement in the state of health in parabiosis may be a change in the composition of elderly blood – maybe it contains aging compounds, the concentration of which drops as a result of dilution with young blood?

How young organisms improve the health of the elderly is a big mystery
Blood transfusion to rejuvenate the body
Recently, in the scientific journal Nature Metabolism , an interesting experiment was described. Young mice at the age of three months were transfused with the blood of older mice under the age of 24 months. After some time, the recipients were measured endurance and muscle strength. In particular, they were forced to run inside the wheel – rodents that did not want to do this were stimulated by a strong air flow and they ran until they were exhausted. The treadmill test was performed immediately after the transfusion and seven days later.

Transfusion of blood from older mice makes young mice weak
At the beginning of the experiment, mice with “older” blood were almost as fast and hardy as rodents from the control group, which were transfused with the blood of individuals of the same age. But during the race on the seventh day, scientists noticed that compared to the control group of mice, individuals with “older” blood showed very poor results: they ran less and more slowly. In addition, biomarkers of kidney damage and signs of liver aging were found in their bodies.

In addition to fatigue, the mice showed signs of damage to internal organs.
Based on the results of this scientific work, we can conclude that in the blood of elderly living organisms there are indeed substances that lead to aging. The authors of the study tend to suggest that the culprit of old age is the so-called senile secretory phenotype (SASP) – in fact, these are old cells that have ceased to reproduce, but have not been removed from the body. They could potentially affect nearby cells within a younger organism and cause them to age.
Unfortunately, at the moment this is just a hypothesis, and scientists still have a lot of research to do. But one thing is for sure – blood transfusions do in some way have a beneficial effect on people’s health. Perhaps someday scientists will still be able to develop a technology for rejuvenating the human body.