(NaturalNews) In unrelated studies all published on May 4, researchers from two separate universities have shown that infusions of blood from younger mice may actually reverse the effects of aging in older mice. Older mice who received "young blood" exhibited increases in muscle strength and endurance; their brains grew new nerve cells, and they became better at cognitive tests.
If replicated in humans, the findings may suggest a relatively simple treatment for currently incurable conditions such as Alzheimer's disease and other forms of dementia.
Blood transfusion, memory boost
In one study, conducted by researchers from Stanford University and published in the journal Nature Medicine, researchers injected blood from young mice into older mice.
Following the transfusions, the older mice began performing better at a test in which they had to locate a submerged platform in a container filled with water. Their brains also became more adept at forming connections, and old nerve cells became active again, particularly in the hippocampus -- a region of the brain associated with memory formation, particularly memories related to spatial patterns. The hippocampus is particularly susceptible to deteriorating with age and is among the brain regions hardest hit by dementia.
"It was as if these old brains were recharged by young blood," senior author Tony Wyss-Coray, PhD, said.
Notably, the researchers found that the reverse effect also occurred. When young mice were injected with blood from old mice, the ability of their brains to grow new nerve cells decreased, and they began performing more poorly on the spatial test.
Specific protein implicated
The other studies were conducted by researchers from the Harvard Stem Cell Institute and published in the journal Science. To start, the researchers used a method called parabiosis, in which two genetically identical mice have small flaps of skin in their sides cut open and sewn together. The healing of these wounds causes the animals' circulatory systems to fuse, so they share a blood supply.
When a young and an old mouse were combined in such a fashion, the nerve and muscle stem cells in the older mouse appeared to be rejuvenated, increasing in activity and producing more nerve and muscle tissue in just four weeks. After four to five weeks, the muscle stem cells in the conjoined older mice showed significantly less DNA damage than the cells in control mice. Blood flow to the brain also increased. In the younger conjoined mice, all of these changes occurred in reverse -- increased DNA damage, lessened stem cell activity and less blood flow to the brain.
The researchers then followed up by directly injecting older mice with the protein growth differentiation factor 11 (GDF11), which circulates at high levels in the blood of young mice and declines dramatically with age. A prior study had already shown that GDF11 injections led to a youthening of heart muscle in older mice.
Consistent with these findings, the Harvard researchers found that GDF11 injections increased the number of muscle stem cells and increased the number of blood vessels in the brain. Mice given the injections navigated mazes faster, ran longer on treadmills and performed higher on strength tests than control mice.
The same effects were seen in old mice given whole-blood transfusions from young mice.
"It could have appeared that the GDF11 effects were limited to the heart," researcher Amy Wagers said. "These new studies extend the impact to other types of tissues."
The Stanford researchers have already formed a company, Alkahest, that is planning a clinical trial in which older Alzheimer's patients will be given blood transfusions from people in their 20s.
"Right now we can't do anything for Alzheimer's patients, and this seems so easy and simple," Wyss-Coray said.