Researchers Find a Type of Stem Cell May Have the Ability to Repair the Brain

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http://www.nytimes.com/2004/02/20/science/20CELL.htmlNYT:20, 2004Researchers Find a Type of Stem Cell May Have the Ability to Repair theBrainBy SANDRA BLAKESLEEtype of self-renewing cell found in the adult human brain may have thepotential to repair brain damage or disease, scientists reported yesterday.The cells, neural stem cells, have been known about for some time. But theirfunction has been a mystery. Researchers theorized that the cells, as inrats and monkeys, generated new neurons that migrated to olfactory regions,helping maintain the sense of smell.But the study, reported yesterday in Nature, indicates that in humans, thestem cells behave differently. They form ribbons that produce differenttypes of brain cells, including neurons. The new neurons do not migrate toolfactory regions, and they are not involved in the human capacity forsmell, the study found.Dr. Nader Sanai, a resident neurosurgeon at the University of California atSan Francisco School of Medicine and the study's lead author, said muchremained to be learned before scientists knew whether the cells could beharnessed to regenerate or replace tissue lost to disease or injury."First we need to understand the biology of these cells," Dr. Sanai said."We don't know enough to predict their usefulness."One possibility, he said, is that the cells, found in the lining of twofluid-filled pockets near the front of the head, will turn out to serve nopurpose. Or they may migrate to other parts of the brain to carry outrepairs.Dr. Pasko Rakic of Yale, a leading expert on stem cells who was not involvedin the research, called the study "important and interesting." The bigchallenge, Dr. Rakic said, remains to find a way to induce the potentialneuronal stem cells to migrate into the right positions and replace lost ordamaged neurons.Researchers are keenly interested in the cells because they do not poseethical questions raised by stem cells drawn from embryos. Many tissues inthe body produce localized stem cells that presumably exist to replenishlost cells throughout a person's lifetime.The study was conducted in the laboratory of its senior author, Dr. ArturoAlvarez-Buylla, a professor of neurological surgery at San Francisco. Tolearn more about human brain stem cells, the researchers collected targettissue from 65 people who had brain surgery and from 45 autopsied brains.The researchers were struck by the fact that the tissue, when stained,contained ribbons of astrocytes, a kind of brain cell known to support manyaspects of brain function."We immediately knew we had to investigate them further," Dr. Sanai said.When the researchers added growth factors to the ribbons in a culture dish,tiny spherical balls appeared. Those balls in turn gave rise to neurons,other astrocytes and a kind of cell that insulates neurons.In a second experiment, the scientists placed individual ribbon astrocyteson a warm layer of ordinary astrocytes. Again, the ribbon astrocytesproduced new neurons and two types of helper cells.Copyright 2004 The New York Times Company | Home | Privacy Policy | Search |Corrections | Help | Back to Top