Researchers in Germany have turned blood cells from an 80-year-old donor into neural stem cells whose molecular age reads as younger than 20, reversing more than 60 years of cellular ageing in the lab.
Skipping the pluripotent stage
The team at the University Hospital of Bonn and the University of Bonn converted immature red blood cell precursors directly into neural stem cells, which can go on to form brain cells. Older methods first push a cell back into a pluripotent state and then steer it toward a new identity.
Going direct changed the timing. "In our approach, rejuvenation occurred gradually and could be tracked for over 100 days," said Professor Oliver Brustle, director of the Institute of Reconstructive Neurobiology. The cells had shed roughly 60 years of molecular age after 50 days, and the process kept going.
Reading the epigenetic clock
To measure the change, the researchers used epigenetic clocks. These read chemical marks on DNA that accumulate with age without changing the genetic sequence itself. After reprogramming, the marks looked like those of a person under 20.
"We also know that this epigenetic rejuvenation ensures that the cells actually behave like young cells," Brustle said. Earlier work by the group showed that nerve cells made this way can connect with existing neurons after being transplanted into mouse brains.
A model, not a treatment
The value for now is as an experimental system. Because the clock resets slowly over weeks, scientists can test which molecules speed up or slow the process, and study the pathways behind it.
That matters for neuroscience, where age is the strongest risk factor for conditions such as Alzheimer's disease. The study does not show that ageing can be reversed in a living person, and no therapy is close. What it offers is a workable way to watch cells grow younger and ask why.
The work, published in the journal Aging Cell, involved teams from Bonn and RWTH Aachen University and was funded by the EU's Horizon 2020 programme, the German Research Foundation and the Federal Ministry of Research, Technology and Space.