Scientists ‘rejuvenate’ mouse immune system, technique also seems applicable to humans

By rejuvenating the immune system, the rodents proved to be more resistant to viral infections. The scientists published their findings on Wednesday in the leading scientific journal Nature.

The mechanism of the new rejuvenation technique affects the stem cells in the bone marrow of mice. Gerald de Haan, aging expert and director of research at Sanquin, explains: “As mice grow older, a certain type of stem cell – the ‘old’ variant – becomes predominant in the body. Compared to ‘young’ stem cells, old stem cells produce fewer white blood cells, which in turn are responsible for immune responses against viruses or bacteria.”

Older mice, like older people, are therefore less well protected against infections. This fact became clear, among other things, with the Covid-19 virus, which hit the elderly the hardest.

Turn back time

It was known from previous research that the outside of old and young stem cells show differences in so-called surface markers. Precisely that distinction turned out to be the key to the new findings. By administering antibodies to the mice that only attach to the surface of the old stem cells, the scientists were able to specifically eliminate the old stem cells. Then the young stem cells took over. The result: more immune cells and a better immune response in the mice’s bodies.

According to De Haan, the research fits into a broader trend. “We previously thought that aging could only be accelerated and not reversed. That perspective is changing.”

Scientists have been looking for a way to combat aging for decades. Previous methods, such as transfusing ‘young blood’ to old patients, turned out not to work as well as initially thought.

Wilbert Vermeij, molecular geneticist and aging researcher at the Princess Máxima Center, is impressed by the findings. “We have never seen turning back time in the immune system with this method before.”

Follow-up research needed

The authors of the study, from Stanford University, believe the results are easy to translate to humans because the immune systems of humans and mice show important similarities. For example, the old stem cells in humans have the same surface markers as in mice.

Moreover, the technique used, disabling specific cells with antibodies, has been common for a long time. De Haan: “Many patients are given antibodies for all kinds of diseases. So it is technically very feasible.” However, before that happens, further research must be conducted. The question, for example, is what administering the antibodies does to other tissues in the body. Only when it is known that only stem cells in the bone marrow respond to the treatment can safety be guaranteed with any certainty.

Moreover, the results of the new study are limited to the immune system. Vermeij: “I am curious whether the treated mice really lived longer and grew older healthier. Elderly mice often become humped or start to tremble. These characteristics have not now been included in the research.”