Stem cell transplantation – the key to healthier ageing?

Mice live only a couple of years at most. That makes them suitable to use in ageing research, while also meaning that their ageing process happens at a furious pace compared with that of humans.

"The study was conducted in mice, and although biological ageing in mice and humans is very similar, clinical treatments are still a long way off. But the study has shown that it’s possible to replace ageing and defective blood stem cells safely," says David Bryder, professor of molecular haematology at Lund University.

Perfect balance


When we are young and healthy, there is a perfect balance in our blood-forming system. Every second, millions of blood cells are produced in our bodies at a steady rate. Stem cells in the bone marrow can sense how much is needed of the different types of blood cells – red blood cells, white blood cells and platelets. The red blood cells carry oxygen, the white blood cells are immune cells needed by the body’s immune system, and the platelets help the blood to clot.
 
"As we age, this ability deteriorates. The biggest problem with ageing blood stem cells is immune vulnerability: our immune system becomes weaker. This increases the risk of many different diseases, such as different forms of leukaemia and immune disorders. Common infections become more severe and more prolonged."
 
By transplanting blood stem cells from young mice into older ones, the researchers were able to rejuvenate the blood-forming system and immune system of the old mice. And they managed to do so without chemotherapy or radiation.
 
"Being able to do this gently is important. Most of the patients who need a stem cell transplant are older, and not all of them can cope with the harsh treatments required today."

Major problems


There are two major problems with stem cell transplantation today: a shortage of donors, and the chemotherapy and radiation needed to prepare the recipient’s body. For healthy blood stem cells to make room for themselves in the soft bone marrow, older stem cells must be destroyed – or at least tricked into leaving their niche.

The biggest problem with ageing blood stem cells is immune vulnerability: our immune system becomes weaker.

"We managed to temporarily draw older blood stem cells out into the bloodstream in large numbers at the same time as we injected new healthy blood stem cells. Then a race begins in the blood to see which cells can get into the bone marrow first, because that is the only place where they can multiply. The younger, healthier stem cells won."
 
An important step was to increase the number of the young, healthy blood stem cells in the laboratory before transplantation, because it is difficult to obtain enough blood stem cells to achieve the desired effect. The researchers also used a medicine with antibodies that target defective stem cells, instead of killing both healthy and diseased cells indiscriminately, as chemotherapy does.

Young cells strengthen the body


After the transplant, the old mice showed a strong recovery in the production of naïve B and T lymphocytes – the cells best equipped to attack pathogens such as viruses and bacteria.
 
"These are cells that play a key role in the immune system and that normally decline with age. These young cells not only survived – they reshaped the entire immune landscape in the older body."

For now, stem cell transplantation is used mainly in healthcare to treat blood disorders, certain cancers and immune diseases. But there is also a kind of stem cell tourism, in which clinics in countries with weak or poorly enforced regulations sell expensive treatments without evidence to seriously ill people. There are also a small number of healthy tech billionaires who are willing to subject themselves to harsh stem cell treatments in their pursuit of eternal youth. Bryan Johnson, who founded the Don’t Die movement in the United States, has, for example, injected young stem cells into his joints to make them younger and more supple – at the cost of his body feeling “as if I had been in a car crash” after the preparatory treatments.
 
"If they want to put themselves through that, that’s up to them. The sad part is that sick people, sometimes families with severely ill children, go abroad and spend all their money and precious time on treatments that have no evidence to back them up."

Storing cord blood


There are also companies that offer to store your child’s cord blood in a biobank, for a fee of around SEK 30,000. The idea is that if the child later develops a disease, it may then be possible to transplant the child’s own stem cells. But David Bryder thinks this is a bad idea.
 
"There are too few stem cells in the umbilical cord, and the diseases in which they might possibly make a difference are few and rare. The money would be better spent on other things for the child."
 
The idea of donating to yourself is not foolish, however, since there is a shortage of donors and it is difficult to match donor and recipient. There are also major socioeconomic challenges linked to the fact that an ever larger proportion of the population is older, and therefore sicker, in large parts of the world. Preventive treatments that enable healthier ageing would almost certainly be cost-effective.
 
"If it were possible to collect stem cells in your twenties and freeze them, then transplanting them in your forties or fifties might be about the right time – provided it could be done safely and without major side effects."
 
If gentle stem cell treatments become possible in the future, David Bryder sees major health benefits.
 
"Imagine being able to replace your blood-forming system in the same way as you replace a hip joint – that would be fantastic."
 
Text and Photo: Jenny Loftrup
The article was previously published in Vetenskap & Hälsa, 2026.