Researchers have drawn on an odd experimental technique invented more than a century ago, in order to make an important anti-ageing wellness discovery. Heterochronic parabiosis involves opening a flap of skin on the side of two mice and stitching the two together so that the same blood pumps through both creatures.
Stem cell biologist Amy Wagers and cardiologist Richard Lee, both of the Harvard Stem Cell Institute, wondered if any of the circulating factors in young blood, such as hormones, might affect ageing hearts. Therefore, they and their team yoked together five two-year-old mice (which is downright ancient in mouse years) with two-month-old counterparts, using parabiosis. They also had a control group of 12 pairs of old mice paired together with 10 pairs of young mice.
Lee, who also practices at Brigham and Women’s Hospital in Boston, commented that the first result was ‘obviously positive’; the old mice’s heart tissue had thinned and softened – looking just as spry and supple as the 2-month-olds’ – after just four weeks of being connected. The old mice now had young hearts, while the young mice’s hearts stayed strong, but the team spent years trying to figure out why.
Less explained, ‘There have been factors found that are suggested to be ageing factors, but there has not been identification of a circulating factor that can go the other way, of turning the old tissue into younger tissue.’ SomaLogic, a protein-analysis company in Boulder, Colorado, finally helped the team to make a breakthrough, narrowing down the likely suspects to only 13 factors.
One of the suspects, growth differentiation factor 11, or GDF-11, appeared to explain the miraculous heart rejuvenation. The researchers report online in Cell that old mice injected with this protein for 30 days developed younger, stronger heart tissue. Lee noted, ‘It’s conceivable that this is just an interesting mouse story, but we’re hoping to get data that might tell us that it pertains to humans.’
According to cardiologist Deepak Srivastava of the Gladstone Institute of Cardiovascular Disease in San Francisco, California, who was not involved in the work, ‘This is probably the first handle we have on what makes the heart young and what makes it old.’ However, cardiologist Gerald Dorn of Washington University in St. Louis, says the use of the parabiosis lends the research a gothic, macabre flavour, adding, ‘I was looking to see whether Tim Burton or Vincent Price were a part of the experimental design.’
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