The research, led by Prof. Dr. Oliver Brüstle of the University Hospital of Bonn and the University of Bonn, used cellular reprogramming to directly convert immature red blood cells into neural stem cells. Unlike conventional methods that pass through a pluripotent intermediate stage, this approach bypassed that step, allowing rejuvenation to occur gradually over more than 100 days.
"Using this method, we have directly converted red blood cell precursors into neural stem cells," said Brüstle. He noted that earlier experiments had already shown that nerve cells generated this way could connect with existing neurons in mouse brains.
The team measured biological age using epigenetic clocks, which analyze chemical modifications to DNA. After 50 days, cells from an 80-year-old donor displayed molecular age signatures corresponding to someone younger than 20. "We also know that this epigenetic rejuvenation ensures that the cells actually behave like young cells," Brüstle added.
Because the rejuvenation unfolded slowly, researchers could track changes over time. "In our approach, rejuvenation occurred gradually and could be tracked for over 100 days," said Brüstle. This extended timeline makes it possible to investigate which factors and substances accelerate or slow down the process.
The findings are particularly relevant to neuroscience, as age is the most important risk factor for neurodegenerative conditions such as Alzheimer's disease. However, the work does not establish a treatment capable of reversing aging in humans; it provides a laboratory model to study how cells regain youthful characteristics.
The study was conducted in collaboration with RWTH Aachen University and funded by the EU's Horizon 2020 program, the German Research Foundation, and the Federal Ministry of Research, Technology, and Space.