80-year-old blood cells reprogrammed into young neural stem cells

Key takeaways

• University of Bonn researchers converted red blood cell precursors from an 80-year-old donor directly into neural stem cells whose epigenetic age measured under 20 years.
• The method skips the pluripotent stem cell stage, and the "de-aging" happened slowly: roughly 60 years by about day 50, tracked for more than 100 days.
• The study, led by Oliver Brüstle with RWTH Aachen University, appears in Aging Cell (DOI 10.1111/acel.70751).
• This is lab work on cells in a dish. It is not a rejuvenation therapy and was not tested in people.
• The main value is a slow, observable model of cellular rejuvenation that could help study brain ageing and Alzheimer's disease.

80-year-old blood cells reprogrammed into neural stem cells scored an epigenetic age below 20, University of Bonn researchers report in Aging Cell. The cells skipped the pluripotent stage, and the shift was gradual: roughly 60 years by about day 50 in a lab dish.

The headline figure travelled fast, with ScienceDaily, Newswise and Nautilus all covering the result this month. What the experiment shows is narrower than "reversing ageing", but it is still useful science. This explainer covers what the team did, how an epigenetic clock assigns an age to a cell, why the slow pace of the change matters, and what the work does not show.

How were 80-year-old blood cells reprogrammed into neural stem cells?

The team at the University Hospital of Bonn and the University of Bonn, working with RWTH Aachen University, started with red blood cell precursors taken from ordinary blood samples. According to the university's release, donors ranged up to 101 years old; Italian business daily Il Sole 24 Ore reports an age range from newborns to 101.

The cells were pushed directly into a neural stem cell identity using transcription factors, proteins that switch sets of genes on and off. Brüstle's group described its blood-to-neural protocol in Nature Communications in 2018. That version used two factors, SOX2 and c-MYC, delivered in a way that does not integrate into the cell's genome. Il Sole 24 Ore reports the same two-factor approach in the new study.

"Using this method, we have directly converted red blood cell precursors into neural stem cells," Brüstle, director of the Institute of Reconstructive Neurobiology, said in the university's announcement. The resulting cells, called induced neural stem cells (iNSCs), can go on to form neurons.

Direct reprogramming vs the pluripotent route

The better-known way to turn an adult cell into a brain cell has two steps. First, a mix of factors turns the cell into an induced pluripotent stem cell (iPSC), a cell that can become almost any tissue. Shinya Yamanaka's discovery of this reset earned a share of the 2012 Nobel Prize in Physiology or Medicine. Second, the iPSC is guided toward a neural fate.

The pluripotent reset is known to wipe out the epigenetic marks of age, and it does so quickly. Direct conversion skips that step, so it is faster to reach a usable neural cell and avoids the pluripotent stage. For years, though, it was unclear whether directly converted cells would keep the "old" marks of their donor. Earlier research on neurons made directly from skin cells suggested that they retained age signatures. The Bonn group's 2018 paper found that its blood-derived neural stem cells instead lost much of their age-associated DNA methylation, and the new paper follows that process in detail.

What an epigenetic clock measures

An epigenetic clock does not read the DNA sequence, which barely changes over a lifetime. It reads DNA methylation: small chemical tags on specific sites in the genome that affect how often genes are used. Some of those tags shift in a predictable way as people age.

The best-known early clock, published by UCLA geneticist Steve Horvath in Genome Biology in 2013, estimates age from 353 such sites. It was built from about 8,000 samples in 82 public datasets. Horvath's paper also found that embryonic stem cells and iPSCs have a methylation age close to zero, which is why reprogramming is closely tied to the idea of "molecular rejuvenation".

When the Bonn team says an 80-year-old's cells became "under 20", it means the methylation pattern in the converted cells resembled that of a young person on these clocks. It does not mean the donor got younger, or that every feature of the cells became youthful. The press materials do not name the specific clocks used, so the paper's methods section is the place to check those details.

Key numbers from the Bonn study

Why the slow pace matters more than the 60 years

The new finding is the timing. With the two-step iPSC route, the epigenetic reset happens quickly. In the direct route, the Bonn team saw the clock move back gradually over several weeks. "In our approach, rejuvenation occurred gradually and could be tracked for over 100 days," Brüstle said in the release.

That gives researchers a window to work in. If de-aging takes weeks rather than days, scientists can sample the cells along the way, see which genes and methylation sites change first, and test drugs or genetic changes that speed up or slow down the process. Brüstle described a rejuvenation lasting this long as "ideal as an experimental model", according to Nautilus.

A 2022 University of Bonn doctoral thesis by Lea Jessica Berg, first author of the new paper, reported that the rejuvenation in this system is protracted and probably does not depend on cell division. Il Sole 24 Ore also reports that the change continued after the cells stopped dividing. If confirmed, that matters: it would suggest that rejuvenation is not simply a by-product of cells copying themselves many times in culture.

Matteo Pardini, a neurologist at the University of Genoa who was not involved, made the same point to Il Sole 24 Ore: "The most interesting finding is not the sixty years gained, but the slow pace at which they are gained."

What the study does not show

• No human treatment. All of the work was done on cells in culture. Nothing was given to patients, and ScienceDaily notes that the result does not establish a way to reverse ageing in people.
• Clock age is not whole-cell age. Methylation clocks are statistical estimators. A young clock reading is strong evidence of epigenetic resetting, but it is only one view of how a cell functions. Brüstle said in the release that the rejuvenated cells behave like young cells. The press materials give few functional details, so the full paper is the place to judge that claim.
• Safety questions. c-MYC is a known cancer-related gene, so Il Sole 24 Ore points out that any clinical use would need extensive safety testing.
• Earlier transplant work was in mice. The group previously showed that neurons made this way formed connections with existing neurons after transplantation into mouse brains. That result comes from earlier work, not from this paper.
• Alzheimer's is a motivation, not a result. The study does not test any treatment for dementia.

Why it matters for Alzheimer's disease research

"After all, age is the most important risk factor for neurodegenerative diseases such as Alzheimer's!" Brüstle said. The World Health Organization's dementia fact sheet makes the same point: age is the strongest known risk factor. It estimates that 57 million people were living with dementia in 2021, with nearly 10 million new cases each year. Alzheimer's disease accounts for 60–70% of cases.

Lab models of brain disease have a well-known weakness. Neurons made through iPSCs tend to look young, because the reset erases age marks. That can hide the age-related processes that may drive late-onset disease. The Bonn system offers a way to study both sides. It lets researchers watch age marks disappear step by step and identify what controls them, which could also help design better "aged" cell models.

Pardini also cautioned against simple promises of brain repair: "Alzheimer's is not a localised lesion that can be repaired with a graft," he told Il Sole 24 Ore. In other words, the most realistic near-term use is as a research tool rather than as replacement tissue. For context on how complex neurological diagnosis can be, see our explainer on how common multiple sclerosis misdiagnosis is.

What it means

The Bonn study adds to evidence that a cell's epigenetic age can be reset without taking it all the way back to a pluripotent state, using only a patient's blood as the starting point. Its practical contribution is a slow, measurable rejuvenation process that runs over more than 100 days and that scientists can now probe for causes, speed controls and side effects.

Readers should treat "60 years younger" as a description of a methylation clock reading in lab-grown cells, not as a sign that human ageing can be reversed. The next things to watch are independent replication, functional comparisons with young donor cells, and studies that use the model to find what drives brain-cell ageing. More coverage is in our science news section.

Sources

• University of Bonn: Researchers transform old blood cells into young brain cells (9 October 2026)
• Berg L. J. et al., "Protracted Fate Acquisition and Epigenetic De-Aging During Induced Neural Stem Cell Conversion of Human Blood Cells", Aging Cell 25(10): e70751
• ScienceDaily: summary of the University of Bonn study
• Newswise: Researchers transform old blood cells into young brain cells
• Nautilus: Blood cells from an 80-year-old transformed into young brain cells
• Il Sole 24 Ore: Sixty years and 50 days (study details and comment from Matteo Pardini)
• Sheng C. et al. (2018), Nature Communications 9: 4047, blood-derived induced neural stem cells
• Horvath S. (2013), DNA methylation age of human tissues and cell types, Genome Biology
• World Health Organization: Dementia fact sheet
• The Nobel Prize in Physiology or Medicine 2012