Young blood stem cells rejuvenate aging immune systems in old mice

by Jenny Loftrup, Lund University

edited by Lisa Lock, reviewed by Andrew Zinin

Lisa Lock

Scientific Editor

Meet our editorial team
Behind our editorial process

Andrew Zinin

Chief Editor

Meet our editorial team
Behind our editorial process Editors' notes

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:

fact-checked

peer-reviewed publication

trusted source

proofread

The GIST Add as preferred source

By freezing your own healthy blood stem cells in your 20s, thawing them and undergoing a stem cell transplant in your 40s or 50s, it might be possible to rejuvenate your blood-forming and immune systems. Science fiction? At least it works when old mice receive healthy blood stem cells from young mice.

Mice live only a couple of years at most. That makes them suitable for use in aging research: Their aging process happens at a furious pace compared with that of humans.

"The study was conducted in mice, and although biological aging 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 safely replace aging and defective blood stem cells," says David Bryder, professor of molecular hematology at Lund University, of the research published in Nature Communications.

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 many of the different types of blood cells are needed—red blood cells, white blood cells and platelets. Red blood cells carry oxygen, white blood cells are immune cells needed by the body's immune system, and platelets help the blood clot.

"As we age, this ability deteriorates. The biggest problem with aging blood stem cells is immune vulnerability: Our immune system becomes weaker. This increases the risk of many different diseases, such as forms of leukemia and immune disorders. Common infections become more severe and prolonged."

By transplanting blood stem cells from young mice into older ones, the researchers were able to rejuvenate the blood-forming and immune systems of the old mice. They managed to do so without chemotherapy or radiation.

"Being able to do this gently is important. Most 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 bone marrow, older stem cells must be destroyed—or at least tricked into leaving their niche.

"We managed to temporarily draw older blood stem cells 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 increasing the number of 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 naive 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 health care 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 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 be possible to transplant the child's own stem cells. But 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 aging would almost certainly be cost-effective.

"If it were possible to collect stem cells in your 20s and freeze them, then transplanting them in your 40s or 50s 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, 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."

Publication details

Anna Konturek-Ciesla et al, A non-genotoxic stem cell therapy boosts lymphopoiesis and averts age-related blood diseases in mice, Nature Communications (2025). DOI: 10.1038/s41467-025-60464-3

Journal information: Nature Communications

Clinical categories

Healthy agingPreventive medicineCommon illnesses & Prevention Provided by Lund University Who's behind this story?

Lisa Lock

BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021. Full profile →

Andrew Zinin

Master's in physics with research experience. Long-time science news enthusiast. Plays key role in Science X's editorial success. Full profile →

Citation: Young blood stem cells rejuvenate aging immune systems in old mice (2026, July 13) retrieved 17 July 2026 from https://medicalxpress.com/news/2026-07-young-blood-stem-cells-rejuvenate.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.