X-Message-Number: 8152 From: (Randy) Subject: CRYONICS Repair/regrowth of body parts Date: Tue, 29 Apr 1997 22:41:46 GMT Here are a couple of excerpts from an article By Nigel Hawkes, the Times of London about how some scientists are working on genetic switches that may give us the ability to regrow/replace missing/damaged body parts. If a small breakthrough in this area were to occur, it may help people see the potential of cryonics by pointing the way to possible revival scenarios. Excerpt 1: >> Lose an arm and you'll never grow another one. That may seem obvious, but all the original genes which instructed the first arm to grow are=20 still there and, in theory, available for service. Turning them on again and enabling the body to rebuild itself after=20 accident or disease has become the target of ambitious developmental=20 biologists. They dream of reconstructing bones damaged by osteoporosis,=20 or persuading the heart to build new muscle after a heart attack. "The whole circuitry is there, ready to go," says Dr. Doros Platika,=20 president and chief executive of Ontogeny, a biotech company in=20 Cambridge, Massachusetts >> excerpt 2 >> "What we are aiming to do=20 is to revive capabilities that are lying dormant. If we can, we should be able to treat a number of degenerative diseases, from osteoporosis to=20 Alzheimer's." Dr. Platika's optimism is based on the huge progress made=20 in the past ten years in understanding the process by which the single cell of a fertilised egg develops into the multiplicity of organs of the=20 human body. This process, akin to a miracle, appears to use exactly the=20 same mechanisms required in adults for growth, tissue regeneration and repair. The trouble, explains Dr. Platika, is that as we age, we lose the=20 capability to turn on repair mechanisms. Operations on adults generally=20 leave a scar, but operations carried out in the womb heal so perfectly that it is impossible to tell they have taken place. In adults, the ability to regenerate organs is not lost: blood, bone,=20 and many other organs are constantly being remade. The process is not=20 universal, however. When a coronary artery is blocked, the body does not=20 have the ability to create another one. But when a solid tumour develops=20 anywhere in the body, it needs blood vessels to feed it, and they are=20 created in great numbers. This shows, says Dr. Platika, that the ability=20 to create new organs is not lost in adults, but merely latent. Provide the right circumstances and it can be triggered back to life. That answer, Ontogeny believes, is based on a family of proteins called=20 Hedgehog. >> excerpt 3 >> Since then, several more Hedgehog genes have been found. Dr. Philip=20 Ingham, of Sheffield University and a member of Ontogeny's scientific=20 advisory board, was responsible with others for showing that higher=20 animals have three Hedgehogs, called equally quaintly Sonic hedgehog,=20 Indian hedgehog, and Desert hedgehog. (Conventionally, genes are given italics to distinguish them from the proteins they make, which are=20 printed in roman script.) Sonic hedgehog has several roles, including the creation of cells in the=20 brain and central nervous system. Indian hedgehog is expressed in the=20 limbs, directing the development of bone and cartilege, while Desert=20 hedgehog drives the development of male sperm. The belief is that there=20 are limited numbers of Hedgehogs -- probably no more than three or four=20 in humans, in which case it is possible that all of them have been=20 discovered. >> excerpt 4 >> The embryologist Professor Lewis Wolpert, of University College London,=20 is sceptical that things will prove as simple as Ontogeny and its=20 partners hope. He suspects that clinical applications remain a long way=20 off, if only because the process of signalling involves not just the=20 Hedgehogs, but many other "inducing molecules" that are triggered in a cascade. Hedgehogs are signalling molecules," he says, "but I would be very=20 surprised if the problem in most diseases is in the signal, rather than=20 the response. My reason for believing that is quite simple. If diseases=20 were caused by deficiencies in Hedgehog, then you wouldn't expect just one thing to go wrong, but lots of things." Dr. Platika acknowledges that there may be dozens of genes orchestrated=20 by Hedgehog, and the company has developed a neat system for discovering=20 them. The ability of geneticists to identify genes has outstripped their=20 ability to discover exactly what they do. Ontogeny has developed a=20 screening system, which enables candidate genes to be tested, and to=20 discover if they have any function in the development process. >> end of excerpt 4 Randy =20 Cryonics: Gateway to the Future? http://members.wbs.net/homepages/c/r/y/cryofan1.html =20 *********************************** Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=8152