Back in 2005, Drs. Irina and Michael Conboy showed that joining the circulatory systems of young and old mice together in a procedure called parabiosis could rejuvenate aged tissues and reverse some aspects of aging in old mice.

Following this discovery, many researchers concluded that there must be something special in young blood that was able to spur rejuvenation in aged animals, and various companies have been trying to find out what. Indeed, we recently reported that researchers were apparently successful in halving the epigenetic age of old rats by treating them with Elixir, a proprietary mix of pro-youthful factors normally found in young blood.

However, a question still remains: was the rejuvenation the result of there being something beneficial in the young blood, or is it more a case of dilution of the harmful factors present in old blood?