Does the protein GDF11 rejuvenate old cells?

GDF11 is a protein that occurs at higher concentrations in the blood of young mice than in old mice. The most robust effect has been found in the heart: when GDF11 was supplemented in old mice to the level found in young mice, age-related thickening of the heart clearly decreased. The heart muscle cells became smaller and their molecular composition shifted in the direction of a younger heart. This effect was seen both through parabiosis (in which the blood circulation of a young and an old mouse was surgically connected) and through direct administration of the protein.

For the brain, the evidence is more preliminary. It has been reported in mice that GDF11 promotes the formation of new neurons in an ageing brain, but exactly how this works and how large the effect is remains unclear. In a separate mouse study on Alzheimer's disease, higher GDF11 levels were associated with less accumulation of harmful protein clumps and better spatial memory. Whether GDF11 itself causes that improvement, or is merely an accompanying marker, has not been proven.

The broader idea that blood-borne factors from young animals can simultaneously rejuvenate multiple ageing organs such as the liver, muscle and brain has been investigated in animal research and yields promising but preliminary results. Reviewers surveying this field explicitly caution that it is too early to identify any single protein as a universal remedy against ageing. All findings to date come from animal research; whether and how this applies to humans has not yet been demonstrated.

A practical takeaway does not yet exist. GDF11 supplements for humans have not been tested for safety or efficacy, and the translation of mouse results to humans is far from straightforward in this type of research.