Alison Abbott in Nature:
Stem-cell researcher Carolina Florian didn’t trust what she was seeing. Her elderly laboratory mice were starting to look younger. They were more sprightly and their coats were sleeker. Yet all she had done was to briefly treat them — many weeks earlier — with a drug that corrected the organization of proteins inside a type of stem cell. When technicians who were replicating her experiment in two other labs found the same thing, she started to feel more confident that the treatment was somehow rejuvenating the animals. In two papers, in 2020 and 2022, her team described how the approach extends the lifespan of mice and keeps them fit into old age1,2.
The target of Florian’s elixir is the immune system. The stem cells she treated are called haematopoietic, or blood, stem cells (HS cells), which give rise to all immune cells. As blood circulates, the mix of cells pervades every organ, affecting all bodily functions. But the molecular composition of the HS cells changes with age, and this distorts the balance of immune cells that they produce. “Fixing the drift in them that occurs with time seems to fix a lot of the problems of ageing — not only in the immune system but also in the rest of the body,” says Florian, who is now at the Bellvitge Biomedical Research Institute in Barcelona, Spain. In March3, another team showed that restoring the balance between two key types of immune cell gives old mice more youthful immune systems, improving the animals’ ability to respond to vaccines and to stave off viral infections.
More here.