Here's Why

Young Blood for Old Mice

Scientific vampirism with glow-in-the-dark mice at Stanford University, has given elderly mice the ability to recover their youth. Professor Thomas Rando's team have discovered that young blood from young mice will rejuvenate old mice. All they had to do was hook up their blood circulation together. In a process called "heterochronic parabiosis", the old mouse and the young mouse were circulating the same blood. One of the biggest differences between young people and old people is that young people's injuries heal fast, and old people's injuries don't heal well, and often don't heal at all. It turns out that your body's natural healing processes are regulated by signals communicated from the injury site to specialized stem cells. They're told to migrate towards the injury and turn into the cells needed to heal. These specialized "progenitor" stem cells are still present in old people and they are still listening for the signal, its just that they're not being broadcast the instruction to heal anymore. Unlike embryonic stem cells, which could become anything, progenitor cells have begun the path to specialization. Progenitor cells are committed stem cells, that will only become one kind of cell when given the right signal. These progenitor cells hang out as satellite cells in the body's organs. Our bone marrow is full of blood progenitor cells, which are stimulated by the recombinant protein erythropoietin to make billions of new blood cells every day. Inflammation is part of the body's response to injury. Progenitor cells are involved in keeping inflammation of the damaged area under control, making sure the body's arteries run smoothly. Inflammation is a key part of atherosclerosis, the disease that causes fatty deposits to build up in the lining of arteries. Its also a large part of arthritis, another disease of old age. It may be that the inflammation goes out of control in these diseases because of a failure of communication of the right signals to the progenitor cells from old blood. If you give old mice young blood, by hooking up their veins with a young mouse in a "parabiotic pairing" for five weeks, then their muscle and liver injuries heal just as fast as the young mice. The difference is due to signaling chemicals in the young blood. Muscle progenitor cells have a protein switch on their surface called "Notch". Injured muscles make a signal chemical "Delta", and this activates "Notch", telling the cells to heal the injury. Older mice had less "Delta" in their injured muscles than young mice, until they were sharing the young blood. And it wasn't just muscles that benefited from the young blood, liver injuries healed in the old mice as well. The Brm protein develops in old livers and seems to block the E2F hormone signal that tells the liver progenitor cells to heal the liver. This is reversed when the young blood is circulated. In his 1941 novel "Methuselah's Children", Robert Heinlein's future rejuvenation treatment is mainly about replacing all of the old blood tisssue in an old person with new, young blood. So how did they know that the rejuvenation was caused by factors in the blood, and not by young cells from the young mice, transplanting themselves through the common blood supply, into the old mice? Well, they genetically engineered the young mice to have cells that glow in ultra-violet light. The old mice, had non-glowing cells. So when the old mice became youthful, all they had to do was shine ultra-violet light on them to see if the healed injuries glowed. None of the old mice glowed, so the researchers were certain that only the young blood was causing the fast healing in the old mice. Hormones are the chemical communications system of the body. It seems to be that the young hormones are not being produced as much in the older animals. This may tie in with those people who are changing their hormonal balance with caloric restriction diets. They eat less calories than normal, and their body chemistry changes in a way that has proved to cause mice to live longer. People who have tried this have found that so many hormonal systems change, that women have to change back to a normal diet if they want to have children. Unethically, you could imagine the Red Cross putting the AGE of the donor on the bottle with the blood type, and there being a whole international black market in young blood. The hope for effective and ethical treatment lies in synthetic hormones. Blood tissue is very complex, with thousands of sugars and proteins and hormones, it may take some time to isolate which hormones are sending the signals for healing and rejuvenation. They know that Delta will rejuvenate muscle, E2F will rejuvenate livers, they just have to identify the signals for brain, bone and other cells. They have already developed and tested a Delta-mimicking drug that rejuvenates mice muscle cells, and it should work equally well in humans. How can the old recover the powers of the youth? Its all about communication! So old mice vampires using the signals in the blood of glow-in-the-dark, young mice, may help elderly people recover from disease and injury just like young people. References: Giving new life to old muscles Scientists closer to identifying cells that could rebuild muscle Hormone could be the elixir of youth Young Blood Found To Revive Aging Muscles Age-related muscle loss linked to protein interplay Young Blood Revives Aging Muscles, Stanford Researchers Find Progenitor Cells Can Have Protective Effect Against Brain Trauma HUMAN EMBRYONIC STEM CELLS: A PRIMER SOLVO Biotechnology Glossary Lousy Habits, Long Life. Why?

About the author: Ian Woolf lives in Sydney, has a degree in Applied Science, worked as a solar astronomer, software engineer, systems programmer, webmaster, research assistant, Cisco CCNA tutor, Physics laboratory demonstrator, Computational Theory lecturer, and subject coordinator; while changing his career to freelance writing and broadcasting. Listen to Ian on the Diffusion radio science show on radio 2SER 107.3FM Monday at 6:30pm in Sydney or streaming audio on www.2ser.com, or listen to the Diffusion podcasts. You should follow me on twitter, here

Posted by iwoolf at September 20, 2005 3:53 PM