Word: stems
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Dates: during 1990-1999
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...keep our batteries from winding down. Scientists may also learn to repair our telo meres, the tiny ties at the ends of each chromosome that help hold our genetic bundles together but fray with age. Researchers may even learn to grow whole new hearts and livers from stem cells, a prospect I find slightly dispiriting. Will we walk off the stage at last elaborately disguised, a living prosthesis--false teeth, false eyes, false taste buds, false everything...
...Parkinson's and Alzheimer's, as well as brain damage caused by strokes and head injuries. Even a year ago, such a sweeping claim might have been dismissed as nonsense. But that was before last fall's discovery that the fetal human brain contains master cells (called neural stem cells) that can grow into any kind of brain cell. Snyder extracted these cells and "mass-produced" them in the lab. His hope is that the cells, when injected into a damaged adult brain, will turn themselves into replacements for cells that are dead or diseased...
Different kinds of blood cells, red and white, come from a single kind of stem cell in bone marrow. These chameleon-like stem cells transform themselves into whatever kind of blood cells the body needs. The skin and liver have their own stem cells. "Maybe there is a brain stem cell, a mother cell that gives rise to all types of brain cell," Snyder says he wondered. "I wanted to find this cell and harness it to repair injured brains...
...grown them in a culture. Snyder then teamed up with Dr. Jeff Macklis, a colleague at Harvard Medical School who had engineered a strain of mouse whose neurons died off in a tiny region of the cortex where cells were not known to regenerate. Snyder injected the stem cells into the mice. Like heat-seeking missiles, the cells rapidly sought out the injured part of the cortex and transformed themselves into healthy neurons. "That's the beauty of stem cells," says Snyder. "You don't have to find the injury--the stem cells do it for you. They instinctively home...
Gage's finding--coupled with Snyder's report that same month of stem cells in the fetal human brain--has stood neuroscience on its head, so to speak. As has the latest finding, announced last month by researchers at Princeton, that adult macaque monkeys are constantly growing new cells in the highest and most complex area of the brain, the cerebral cortex. Snyder is now flush with confidence that neuroscience will ultimately cure many, if not all, diseases of the human brain. "By the year 2020 I hope we will have an active way of treating damaged brains...