Researchers in Germany have turned blood cells from an 80-year-old into stem cells that can make brain cells, and lab measures of aging in those cells dropped to the level of someone younger than 201. The team, at the University Hospital of Bonn and the University of Bonn, published the work in the journal Aging Cell12. All of it was done on cells in lab dishes. No person was treated.
What happened
The scientists took immature red blood cells, the early cells that later become red blood cells, and changed them directly into neural stem cells1. Neural stem cells are cells that can go on to make neurons and other cells found in the brain3.
Along the way, the markers that scientists use to estimate a cell’s age were reset2. Cells taken from an 80-year-old ended up with an age signature below 20, a drop of more than six decades on these measures1.
The study covered 15 donors, from newborns to a 101-year-old3. According to futuretimeline.net, which reviewed the paper, the newly converted stem cells had an estimated age that was on average just 13% of their donors’ real ages, and this fell to 5% when the cells were grown for longer3. Cells from even the oldest donors also lost several other features linked to aging3.
How the cells were changed, and how “age” was measured
Every cell in the body carries essentially the same genetic instructions, but cells settle into fixed jobs as they develop. Normally a blood cell cannot become a nerve cell1. Lab methods can now push past that limit using proteins called transcription factors, which control which genes are switched on1.
In this case the team used modified viruses to deliver instructions for two such proteins, called SOX2 and cMYC3. “Using this method, we have directly converted red blood cell precursors into neural stem cells,” said Prof. Dr. Oliver Brüstle, director of the Institute of Reconstructive Neurobiology at the University Hospital of Bonn1.
To measure age, the researchers used epigenetic clocks1. These read chemical tags on DNA that build up or shift as people get older. The tags do not change the DNA code itself; they affect how often certain genes are used. Because the pattern changes in a predictable way with age, it can be used to estimate how old a cell looks at the molecular level1.
Brüstle also said the reset goes beyond the clock reading. “We also know that this epigenetic rejuvenation ensures that the cells actually behave like young cells,” he said1. The sources read for this article do not describe the tests behind that statement in detail.
Why the slow pace matters
Scientists already knew that reprogramming cells can reset their age measures. But the earlier method had two steps1. First, a cell such as a blood cell was turned into a pluripotent stem cell, an all-purpose cell that can become almost any cell type in the body. Then it was guided into becoming a neural stem cell1. That route resets the clock fast, in around 20 days, which makes it hard to see each change as it happens13.
The Bonn team skipped the all-purpose stage.
“In contrast, we converted blood cells directly into neural stem cells -- that is, without first passing through the pluripotent cell stage,” said Brüstle. “In our approach, rejuvenation occurred gradually and could be tracked for over 100 days.”1
Most of the age-related changes disappeared over roughly 50 days, and the team kept following the cells for more than 100 days3. Because the reset was so slow, the researchers say it suits a closer look at how cells get younger2.
One early clue: the reset kept going even when the researchers slowed or blocked cell division3. That suggests the effect does not come simply from cells copying themselves over and over3.
What it does not show yet
- It is lab work only. Everything happened in dishes. Futuretimeline.net, an independent science blog, noted that reversing molecular aging in lab-grown cells does not yet show that whole tissues or people can be safely made younger3.
- Clock readings are estimates. Epigenetic clocks infer age from DNA tag patterns1. A younger reading in a dish is a measurement, not proof of a younger body.
- The cells changed type. The old cells did not become young blood cells. They became a different kind of cell, a brain stem cell1. This is a way to study aging, not a way to refresh blood.
- Small number of donors. The study used cells from 15 people3.
- No safety data in people. The sources describe no plan to test the method in patients.
The team had shown before that nerve cells made with this approach could connect with existing neurons after being transplanted into the brains of mice1. That was animal work, and it was not part of the age findings reported here.
Who is behind it
The work comes from the Institute of Reconstructive Neurobiology, part of the University Hospital Bonn and the University of Bonn3. Brüstle directs the institute and is also a member of the university’s Transdisciplinary Research Area Life & Health1. A figure from the paper is credited to Berg et al., Aging Cell (2026)3.
The group first showed this blood-to-brain-stem-cell technique in 2018, using blood cells from six donors aged 31 to 623. The new paper extends it to a wider age range and follows the age reset over time3.
ScienceDaily’s version of the news lists the University of Bonn as its source1. The sources read for this article do not say who paid for the study or whether any researchers have company ties.
How it fits the field
Brüstle pointed to why this matters for brain disease: “age is the most important risk factor” for conditions such as Alzheimer’s3. Many lab models of brain disease start from cells whose age has been wiped out. A slower reset could help researchers study how aging and rejuvenation work, and the university’s summary says it could help researchers better understand diseases such as Alzheimer’s1.
Other groups are chasing younger cells by different routes. In May, researchers at the Icahn School of Medicine at Mount Sinai reported that calming overactive lysosomes, the cell’s recycling centers, made old blood-forming stem cells act younger in mice4. That was an animal study published in Cell Stem Cell, and it used a drug rather than reprogramming4. Both lines of work aim to understand why cells lose youthful function, but they test very different ideas.
For a separate approach aimed at the aging brain, see our report on a pill aimed at dementia now tested at higher doses.
What to watch next
The Bonn team says the slow reset makes the process easier to study in detail2. Things to look for:
- Work that pins down which steps drive the reset, building on the finding that it continues even when cell division is slowed3.
- Whether other labs can repeat the age reset with this direct method.
- Whether these younger-acting cells are used to model age-related brain diseases such as Alzheimer’s, as the researchers hope1.
For now, the result is a measurement in lab dishes: old blood cells became brain stem cells whose DNA-based age readings fell by decades, slowly enough to watch it happen13.
