The procedure is called parabiosis, which is Latin for “living beside.” We’ve written about it before, and in fact there was a lot of buzz about it several years ago. Some doctors enthused that it could lead to a fountain of youth.
Parabiosis-related therapies do not seem to be very popular at the moment, as far as I can gather from attending the meetings of the American Academy of Anti-Aging Medicine, a group consisting of thousands of doctors who focus on reversing the aging process.
But even though it may not be ready for prime time, there’s still something to it.
Recently, the pairing of a young mouse with an elderly mouse brought remarkable results. The elderly rodent, now getting a share of blood from the young mouse, was rejuvenated. The old mouse grew stronger, smarter and healthier.
Perhaps most exciting, the new research reveals that people can achieve similar youthful regeneration without the parabiosis procedure.
Let’s take a closer look...
In 2005, scientists at the University of California, Berkeley, discovered that parabiosis could reverse many of the signs of aging. In mouse experiments, they conjoined an old mouse with a young mouse and the old mouse experienced overall health improvements.
Animal rights advocates may be outraged at the cruelty of the experiment, and I can’t say I like it much myself. But let’s soldier on and see if we can learn anything...
Other studies followed confirming that after parabiosis old mice had better health and repair of tissues such as cartilage, muscle, skin, and even major organs such as the liver, brain, and kidneys. Even skeletal structures such as bones and the spinal cord were in better repair.
Then, scientists decided to try a new technique. Instead of parabiosis, they merely transfused young blood into elderly mice. They found the procedure rejuvenated muscle and liver tissues, but the transfusion of young blood did not have the same effect of regenerating brain tissues.
Parabiosis was clearly superior for rejuvenation purposes, and the scientific community was keen to establish what factors in the blood of the young animals brought this about.
Professor Irina Conboy, lead author of the original laboratory experiment, explained, "There are two main interpretations... The first is that...rejuvenation was due to young blood and young proteins or factors that become diminished with aging.
"But an equally possible alternative is that, with age, you have an elevation of certain proteins in the blood that become detrimental, and these were removed or neutralized by the young partners."
Rejuvenating Old Blood in Mice
To test the second hypothesis, Prof. Conboy and her team recently took a group of old mice and replaced half of their plasma -- the fluid portion of the blood, minus the blood cells -- with saline and albumin protein. The latter was simply to replace the protein that's lost when blood plasma is removed.The procedure turned out to have the same or even stronger rejuvenation effects on the brain, liver and muscles than either parabiosisor transfusion. "As our science shows," commented Prof. Conboy, "the second interpretation turns out to be correct. Young blood or factors are not needed for the rejuvenating effect; dilution of old blood is sufficient."
Now that’s news.
The big question is whether this will work in humans.
It happens that a medical procedure is already well-established called therapeutic plasma exchange (TPE) or plasmapheresis that dilutes human blood. It’s used to remove pathogenic antibodies in the treatment of various autoimmune diseases such as multiple sclerosis (MS), myasthenia gravis and Guillain-Barre Syndrome.
Pressing the Molecular Reset Button in People
During TPE, a patient's blood is removed and passed through a device that separates out and removes the plasma (which is discarded), and then the patient’s remaining red blood cells are mixed with a replacement fluid such as plasma or albumin protein and re-infused into the patient.As part of their latest experiment, the researchers studied human blood samples collected both before and after TPE from four people aged 65 to 70.
They found a number of pro-inflammatory proteins that increase with age were lowered, while more beneficial proteins, such as those that promote vascularization (growth of new blood vessels), were greatly boosted. They described TPE as acting like a molecular reset button.
Michael Conboy, fellow author and husband of Prof. Irina Conboy, explained, "A few of these proteins are of particular interest...but I would warn against silver bullets. It is very unlikely that aging could be reversed by changes in any one protein.
"In our experiment we found that we can do one procedure that is relatively simple and FDA-approved, yet it simultaneously changed levels of numerous proteins in the right direction."
Human trials are now in preparation to see if a modified form of TPE can improve the overall health of older people and treat age-associated diseases.
This is an exciting area of research indeed. I’ll keep you posted on any additional findings.
