The long wait for forever
It might seem odd that a single protein could produce changes in several seemingly-unrelated areas, but in fact aging damage in all these areas is largely the product of a single factor -- the decline in production of new cells and, in the brain, the flexibility of the synaptic connections between them (critical to memory formation). Basically, all over the body, things are wearing out and being repaired all the time -- but as we get older, the processes which perform the repairs become less effective.
The apparent forgetfulness often observed in elderly humans is actually a problem of memory formation -- it's not that they become more inclined to lose memories, it's that their brains become less adept at creating new memories. This is why old people often can clearly remember things that happened decades ago but can't remember what you said to them a few minutes ago. So if GDF11 has the same effect in humans as it does in mice, it would get to the core of that problem.
Even if it works on humans as on mice, GDF11 will not be a magic-bullet cure for aging. Aging is too complex a phenomenon to be cured by any one therapy; in the end, it will be a whole group of therapies that address its various effects. But even if all GDF11 ultimately does is to strengthen aging hearts and muscles and restore a youthful memory capacity to aging brains, it will become an important member of that group of therapies, and all by itself it will relieve an immense amount of suffering.
Which is why it's infuriating to read, at the Harvard Gazette link, that "they expect to have GDF11 enter initial human clinical trials within three to five years."
Three to five years? And initial human clinical trials are only the beginning, not the end, of the process of making this available for general use in human patients. I know why such testing is necessary -- we need to be sure that GDF11 (a) has the same beneficial effects in humans as in mice and (b) is safe for use in humans. Rushing it into widespread use in humans without being sure of those things would be dangerous and might not even bring any benefits. But carrying out these necessary steps as fast as possible also needs to be a consideration.
During early research on treatments for AIDS, some effort was made to speed up the normally glacially-slow process of drug testing and approval, in recognition of the fact that AIDS was killing people all the time and that the risks of accelerated testing had to be balanced against the certainty that every month's delay in the final approvals would cost lives that could have been saved. But that point applies in this case, too -- on a far vaster scale. If GDF11 does work as we hope, every year's delay in its final availability means a year of additional suffering for hundreds of millions of elderly people. And tens of millions of people die of old age every year. Every year's delay in the arrival of anti-aging treatments in general will mean additional loss of life equal to the population of a good-sized country.
This, perhaps, is where international competition in science is beneficial, especially as the number of countries capable of carrying out such advanced research increases. If the testing and approval regimen in one country is too slow and rigid, another country may apply different rules. The more different balances are being struck between safety and speed, the better the chance that some country will get it right. And the country that does get it right will have a lot to gain economically -- therapy that can truly reverse even just some of the effects of aging will be well worth an intercontinental trip, for millions.
[Standard disclaimer: Pro-death clichés and negativity are not welcome here. Before posting comments of that kind, please get up to speed on the issues.]