Scientists Made an 80-Year-Old’s Cells Look 19 Years Old. Could It Mean Aging Is Reversible?

The human body contains more than 200 major cell types, but all of those differing cells—whether blood cells, brain cells, muscle cells, and on and on and on—originate from just one fertilized zygote. In other words, dig deep into any cell’s past and it was once an undifferentiated stem cell.

The trillions of cells that make up the body aren’t terribly unlike the billions of people who make up human civilization. In a perfect society, children would be free to develop into a supportive role that enhances a healthy civilization, and in a similar sense, stem cells also hold this differentiating potential, as they can form virtually every cell in the body. Now, a new study led by scientists at the University of Bonn in Germany finds that if red blood cell precursors undergo some “job retraining” (continuing with our civilization-focused analogy), then, perplexingly, they can also rewind their molecular clock by more than 60 years. The results of the study were published in the journal Aging Cell.

In a previous 2024 study, University of Bonn neurobiologist Oliver Brüstle and his team used transcription factors (proteins that operate “on” and “off” switches for gene expression) to create induced neural stem cells (iNSC) from blood cells and found that they successfully matured within the organism. However, in this new study, Brüstle wanted to focus closer on a strange quirk of these cells.

“In our current study, however, we focused on a different phenomenon: namely, the observation that cells become significantly rejuvenated during reprogramming,” Brüstle, who is senior author of the new paper, said in a press statement. “We also know that this epigenetic rejuvenation ensures that the cells actually behave like young cells.”

Using a molecular clock which tracks DNA modifications that are closely linked to aging, the new study showed that blood cell precursors from an 80-year-old exhibited a molecular age of less than 20 years old after reprogramming. Typically, these cells are reprogrammed by first converting cells into pluripotent stem cells and then developing into iNSCs. This time around, however, authors skipped that middle step and used a virus to deliver two transcription factors. After 12 days, the precursor blood cells began to resemble iNSCs, and by using DNA methylation and RNA sequencing, the team could track aging effects on the cell.

“In contrast, we converted blood cells directly into neural stem cells—that is, without first passing through the pluripotent cell stage,” Brüstle said in a press statement. “In our approach, rejuvenation occurred gradually and could be tracked for over 100 days.”

This slow rejuvenation process is key because in the typical, two-step process, changes occur very quickly, but this longer period of rejuvenation allows scientists to investigate what exactly drives these changes. Using that benefit, the authors tracked the cells getting progressively younger until they reached roughly 60 years younger across just 50 days. As Science Alert notes, the cells also acted their (youthful) age by displaying less mitochondrial toxicity, and their de-aging occurred even when cell proliferation was inhibited. And it doesn’t take an adventurous imagination to see how turning old cells into young neural cells could have huge benefits, especially as many neurodegenerative diseases are linked to aging.

It might be true that you can’t teach an old dog new tricks, but that long-held maxim doesn’t quite hold up in the cellular world.