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 evidence concerns the heart: when researchers supplemented GDF11 in old mice to the levels found in young mice, age-related thickening of the heart clearly decreased. The heart muscle cells became smaller and the molecular composition shifted towards that of a younger heart. This effect occurred 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 indications are more preliminary. In mice, it was reported 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 clusters and better spatial memory. Whether GDF11 itself is the cause of that improvement, or merely an accompanying marker, has not been proven.

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

There is therefore no practical guidance to offer. GDF11 supplements for humans have not been tested for safety or efficacy. The translation of mouse results to humans is far from straightforward in this type of research. There is no basis for acting on this now: it has been studied too little to make any recommendation.