A protein can make the hearts of aging mice appear to be more youthful, it can also improve brain and skeletal muscle function.

Injections of the protein, dubbed GDF11, improved exercise capability and function of the olfactory region of the brain in mice equivalent in age to a 70 year-old human, a Harvard University news release reported. The mice could detect the same smells as younger rodents.

The research team tested the protein's effects by creating a parabiotic system in which two mice are surgically joined so the blood of the younger one circulates through the other. They also injected older mice with GDF11.

"[I couldn't] recall a more exciting finding to come from stem cell science and clever experiments. This should give us all hope for a healthier future. We all wonder why we were stronger and mentally more agile when young, and these two unusually exciting papers actually point to a possible answer: the higher levels of the protein GDF11 we have when young. There seems to be little question that, at least in animals, GDF11 has an amazing capacity to restore aging muscle and brain function," Doug Melton, co-chair of Harvard's Department of Stem Cell and Regenerative Biology (HSCRB) and co-director of Harvard Stem Cell Institute (HSCI)  said in the news release.

The protein is found in both mice and humans, and could be tested in clinical trials within the next five years.

"It isn't out of question that GDF11," or a drug developed from it, "might be capable of slowing some of the cognitive defects associated with Alzheimer's Disease, a disorder whose main risk factor is aging itself," Lee Rubin of HSCRB, said in the news release.

The researchers are working to obtain funding in hopes of moving the possible treatment to clinical trials.

"I would wager that the results of this work, together with the other work, will translate into a clinical trial and a treatment," said the stem cell biologist. "but of course that's just a wager," Rubin said.