There's been a lot of fuss about the incredible effects young blood has on old mice. After initial hype debate emerged over whether one protein, GDF-11, was behind the claims - but a Harvard team is now suggesting that it really is the real deal.
So what is GDF-11?
Scientists began reporting astonishing effects when old mice were first hooked up to young blood, and others quickly scurried about trying to find what was in the blood that had such an effect. They stumbled across a protein called GDF-11, which appeared to be reduced in older mice. To test this theory, various groups have infused GDF-11 into mice by itself. What happened? It appeared to rejuvenate muscles, the brain and reversed age-related thickening of the heart.
But it wasn't all good news
In 2014 another group led by Novartis challenged the results with a study claiming that the prior research was detecting another protein called myostatin (also GDF-8) at the same time, compromising the results. When they conducted their own study, they stated GDF-11 levels actually rise with age, and inhibit muscle regeneration! We've discussed the debate around GDF-11 in an article before, but it's all very confusing.
To add to the confusion, a Harvard team has now added to the debate again, claiming that the Novartis group's detection was also flawed and was picking up a protein called immunoglobulin that does rise with age. As more papers have racked up the positive support for GDF-11, it was odd that one result should be so different, so this could explain the anomalies.
“They actually had very consistent findings to ours with respect to the blood levels of GDF11/8 with the antibody we all used, but their interpretation was confused by this case of mistaken identity.”
The Harvard research also explained that GDF-11 used in studies was often purchased, and has some differences to 'natural' GDF-11. Knowing this, they repeated experiments again and found that GDF-11 injections do indeed shrink heart muscle in aging mice and help with weight loss too. The results also suggested a narrow therapeutic window, which means it only has positive effects at a certain level. If too much GDF-11 is used, it may hinder muscles instead of helping them.
There is still much more to be unraveled in the debate, but it's looking more likely that GDF-11 could be a good candidate to add to the list of longevity factors. It's still too early to confirm, but hopefully additional efforts will iron out exactly what's in young blood that gives new life to the elderly.
Read more at Science Mag