X-Message-Number: 18186 From: "Mark Plus" <> Subject: "Apostle of Regenerative Medicine Foresees Longer Health and Life" Date: Wed, 19 Dec 2001 08:53:04 -0800 http://www.nytimes.com/2001/12/18/health/genetics/18HASE.html?pagewanted=print December 18, 2001 Apostle of Regenerative Medicine Foresees Longer Health and Life By NICHOLAS WADE Regenerative medicine is the concept of repairing the body by developing new tissues and organs as the old ones wear out. The idea, though futuristic, is rooted in practices like growing new skin for burn victims and has acquired new plausibility with the decoding of the human genome and the growth of knowledge about stem cells, the powerful agents that generate and regenerate the body. But regenerative medicine is not around the corner. Stem cells, a principal component, are only beginning to be understood. Still, there are obvious attractions in the idea of establishing a new and gentler form of medicine, based on the body's own repair systems rather on the surgeon's knife or the pharmacist's potent chemicals. A principal apostle of regenerative medicine is Dr. William A. Haseltine. As chief executive of Human Genome Sciences, a biotechnology company in Rockville, Md., he is perhaps freer to speculate about the future of medicine than are many academic biologists. And his own company's program of developing some of the components of regenerative medicine gives him special insights as well as a keen interest in the field. Over coffee in the lobby of his New York base, the Pierre hotel, Dr. Haseltine expounded recently on his hopes for regenerative medicine and its powers to prolong health and life. The body, he noted, is constantly renewed throughout a person's life. The skin is replaced every two weeks. Red blood cells last about two months. The skeleton is replaced every seven years or so. Even in the brain, it now seems, new cells are constantly being generated to replace at least some kinds of neuron. So if the cells are in a state of continual flux, with one new body gradually replacing another throughout a person's life, why doesn't this process continue indefinitely? Dr. Haseltine suggests that the stem cells that generate new body tissues may themselves wear out. "It's a reasonable conjecture that we age because our stem cells age, and that if we were able to replace them with new and younger cells, we could continue a young healthy life in perpetuity that is the new dream," he said. Life in perpetuity will be secured by what Dr. Haseltine calls rejuvenative medicine. But first comes regenerative medicine, which leads in its advanced stages to the rejuvenative kind. Dr. Haseltine sees regenerative medicine unfolding in four phases. First is the use of the body's own signaling factors to stimulate healing processes. Amgen's erythropoietin, a hormone that stimulates red blood cell formation, is used in dialysis patients. Human Genome Sciences has discovered a wound-healing factor, known as keratinocyte growth factor-2, which is in now in clinical trials for its ability to heal venous ulcers. The factor is a high-level organizer of tissue repair. It causes three layers of skin to form, it regenerates the connective tissues and it induces new blood vessels to grow into the healed area. "You would have guessed that would take a whole series of factors, but the body seems to be programmed to heal itself," Dr. Haseltine said. Study of the human genome should bring to light more of these high-level organizing factors, as well as the signals that control stem cell behavior and force the development of mature cells. "What we can do now for a few cells we foresee doing for almost any cell in the body at almost any stage of its differentiation, whether as a stem cell or any stage along the way," Dr. Haseltine said. The second phase of regenerative medicine, in his view, "kicks in when the body is injured beyond the point of repair, at which point you want to put in a new organ," he said. Tissue engineers have already learned to grow sheets of skin and have started to produce three-dimensional structures, like bladders and blood vessels. These are constructed outside the body, with mature cells grown on special matrices. Further in the future, he believes, biologists may learn how to fashion new organs outside the body from adult stem cells, the body's guardians and regenerator of adult tissues. These would be taken from the patient's body so as to avoid problems of immune rejection. The use of embryonic stem cells, the all- purpose cells from which in principle any desired tissue can be fashioned, will be the third phase of regenerative medicine. This, he says, is the point at which regenerative medicine merges into rejuvenative medicine. Most stem cell biologists talk of using human embryonic cells for specific tasks, like replacing the cells lost in Parkinson's disease or growing new pancreatic islets for diabetics. Dr. Haseltine's vision includes those tasks and the more general idea of replacing all the body's adult stem cells as their powers start to fade. "Since we are a self-replacing entity, and do so reasonably well for many decades, there is no reason we can't go on forever," Dr. Haseltine said. Though mature cells and even adult stem cells eventually age, a special group of human cells never grows old. For these cells, the sperm and eggs, biological time stands still. Whatever the parents' age, the cells of a newborn all have clocks set to zero. "It's drawing on that miracle that an older person gives rise to a baby," Dr. Haseltine said. "We now, for the first time, may have the power to control that fundamental generative property. Five years ago, such ideas got very short shrift. Five years from now, it will be a common goal of many young scientists." In the fourth phase of regenerative medicine, according to Dr. Haseltine's timetable, nanotechnology microscopic-scale mechanical devices will merge with biological systems. Humans are already becoming partly inorganic when they receive organ- mimicking machines like the AbioCor artificial heart. Artificial devices are likely to improve to the point that they will eventually interface with evolution's form of engineering. Some people find immortality disturbing, seeing it as transgressing the line that separates people from gods. Dr. Haseltine sees it as an inherent property of life. "What distinguishes life from other forms of matter is that it is immortal we are a 3.5-billion-year-old molecule," he said, referring to the time when life on earth began. "If it were ever mortal, we would not be here. The fundamental property of DNA is its immortality. The problem is to connect that immortality with human immortality and, for the first time, we see how that may be possible." Copyright 2001 The New York Times Company | Privacy Information _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=18186