Links for Keyword: Stem Cells

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Eyes Are the Windows to the Soul; Skin Is a Window to the Brain

by Valerie Ross Some might call skin the unsung hero of organs. It provides waterproofing, mediates sensation, guards against germs, and—as if that’s not enough—now researchers believe it may serve as a valuable repository of brain cells. Last spring, scientists at the Salk Institute in California announced the creation of a technique for transforming simple skin cells scraped from patients with schizophrenia into functional neurons, a major step toward more personalized, noninvasive approaches to drug testing. “Psychiatrists give patients first line, second line, third line drugs, hoping that one will work,” says Salk neuroscientist Fred Gage, who led the research. Pre-screening drugs on patient-derived cells could increase the odds of picking the right drug from the beginning. After collecting skin cells from people with and without schizophrenia, Gage and team genetically reprogrammed the cells to become pluripotent stem cells, with the youthful ability to give rise to any of the more than 200 cell types in the body. From there, the blank-slate cells were bathed in a biochemical solution designed to mimic the developmental conditions of a brain cell. A month later, the cells from the healthy volunteers looked nearly identical to conventional brain cells, while the cells from the schizophrenic patients were smaller and formed fewer connections, hinting at the physical root of the disease. In further tests, the diseased neurons responded in petri dishes to five schizophrenia drugs. One common medication, loxapine, boosted the number of connections among the cells, providing a window into how the medication might work in the brain. © 2011, Kalmbach Publishing Co.

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 4: Development of the Brain; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 15955 - Posted: 10.27.2011

How to make a human neuron

Ewen Callaway By transforming cells from human skin into working nerve cells, researchers may have come up with a model for nervous-system diseases and perhaps even regenerative therapies based on cell transplants. The achievement, reported online today in Nature1, is the latest in a fast-moving field called transdifferentiation, in which cells are forced to adopt new identities. In the past year, researchers have converted connective tissue cells found in skin into heart cells2, blood cells3 and liver cells4. Transdifferentiation is an alternative to the cellular reprogramming that involves converting a mature cell into a pluripotent stem cell — one capable of becoming many types of cell — then coaxing the pluripotent cell into becoming a particular type of cell, such as neurons. Marius Wernig, a stem-cell researcher at Stanford University in California, and the leader of the study, says that skipping the pluripotency step could avoid some of the problems of making tissues from these induced pluripotent stem cells (iPSCs). The pluripotency technique can also take months to complete. Wernig's team sparked the imaginations of cellular reprogrammers last year, when it transformed cells taken from the tip of a mouse's tail into working nerve cells5. That feat of cellular alchemy took just three foreign genes – delivered into tail cells with a virus – and less than two weeks. "We thought that as it worked so great for the mouse, it should be no problem to work it out in humans," Wernig says. "That turned out to be wrong." © 2011 Nature Publishing Group,

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 4: Development of the Brain; Chapter 5: The Sensorimotor System
Link ID: 15377 - Posted: 05.28.2011

Stem cells were God’s will, says first recipient of treatment

By Rob Stein, CHATOM, Ala. — When Timothy J. Atchison regained consciousness, he was drenched in blood and pinned in his car on the side of a dark rural road. “I was just pouring blood,” said Atchison, 21, who said he recoiled in pain when he tried to drag himself through a window of the wrecked Pontiac, a high-school graduation gift. “I didn’t know if I was going to bleed to death or not.” Then, Atchison said, he realized that his legs felt strangely huge — and completely numb. He was paralyzed from the chest down. “I was just praying — asking for forgiveness and thanking God for keeping me alive,” said Atchison, who was trapped for at least an hour before rescuers freed him. “I said, ‘From here on out, I’m going to live for you and nothing else.’ I never got down after that. I figure that’s what must have kept me up — God keeping me up.” That sense of destiny propelled Atchison when he faced another shock just seven days later: Doctors asked him to volunteer to be the first person to have an experimental drug made from human embryonic stem cells injected into his body. “We were just stunned,” said Atchison, who was with his mother and grandfather when researchers approached him. “We were like, ‘Whoa, really?’ We were all just kind of in awe.” Atchison, known to friends and family as T.J., described the events during an interview Tuesday with The Washington Post — his first detailed account since disclosing his carefully guarded identity to The Post. Atchison’s story reveals provocative insights into one of the most closely watched medical experiments, including what some might see as irony: that a treatment condemned on moral and religious grounds is viewed by the first person to pioneer the therapy, and by his family, as part of God’s plan.

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 4: Development of the Brain; Chapter 5: The Sensorimotor System
Link ID: 15228 - Posted: 04.16.2011

Human brain stem cells grown in rats

by Andy Coghlan STEM cells from the human brain that were transplanted into the brains of newborn rats have matured and are able to function just like native rat cells. The breakthrough demonstrates the potential for people with brain damage, caused by epilepsy or Parkinson's for example, to use their own brain stem cells as a treatment. The key finding was that the adult stem cells had the ability to turn into all types of brain tissue in the rats. This includes the neocortex, which deals with higher processing, and the hippocampus, involved in memory and spatial awareness. "We're showing the most dramatic integration of human adult neurons into rat brains," says Steven Roper of the University of Florida in Gainesville, who carried out the work. Roper extracted the adult stem cells from tissue he had taken from a teenage girl's brain as part of standard epilepsy surgery. He and his colleague Dennis Steindler multiplied the cells in the lab, then genetically engineered them so that they would glow green under ultraviolet light. Next, they injected groups of the cells into the brains of newborn rats. Three weeks later, they examined the rats' brains and found green cells throughout. "The cells matured into neurons appropriate for each part of the brain they reached," says Roper. © Copyright Reed Business Information Ltd.

5 Questions for the Stem-Cell Maestro

by Amy Barth As a chemical engineering grad student at Caltech, Sarah Heilshorn could not make up her mind: “One day I wanted to work on green chemistry; then I’d meet someone working on solar cells and think that was the specialty for me.” Clarity came after she heard a talk by David Tirrell, a Caltech engineer who designed synthetic biomolecules. Soon he became Heilshorn’s mentor. “I was fascinated by the idea that engineers could program organisms to create new materials for medicine,” she explains. Now head of her own lab at Stanford, Heilshorn engineers proteins to aid neural stem cells in healing injured brains and spines. If I cut my hand, it heals on its own. Why is it so much harder to heal spinal cord injuries? Peripheral nerves like the ones in your hand regenerate well. Nerves in the spinal cord and brain do not. This might have to do with the blood-brain barrier, which protects the central nervous system but also makes drug delivery difficult. In addition, spine injuries are often caused by a crushing or twisting motion, so there may be bone fragments floating around and compromised blood flow to the region. You engineer proteins to help stem cells regenerate neurons. How does that work? Proteins are made of smaller molecules called amino acids, which combine to form modules. Some modules make a protein act like a spring; others help it bind to cells. I mix modules in new ways to create novel proteins with new functions, and then I mass-produce them [in the machine at right]. Copyright © 2010, Kalmbach Publishing Co.

Stem cells could help blind patients to see within six weeks

By Steve Connor, Science Editor Blind patients suffering from a type of eye disease that strikes in childhood will become the second group of people in the world to receive stem cells derived from spare IVF embryos left over from fertility treatment. The US Food and Drug Administration (FDA) has given the go-ahead for the controversial transplant of embryonic stem cells into the eyes of patients with Stargardt's macular degeneration, where the light-sensitive retina cells at the back of eye are destroyed. The announcement follows the first injection of embryonic stem cells into a patient in the US who is partially paralysed as a result of a spinal cord injury. Last October, a US biotechnology company, Geron, announced the start of the first clinical trial of embryonic stem cells with the hope of repairing damaged nerves. Another US biotechnology firm, Advanced Cell Technology, has now been given approval for a second clinical trial involving the injection of thousands of embryonic stem cells into the eyes of a dozen adult patients with a juvenile form of macular degeneration. Robert Lanza, the company's chief scientific officer, said that the first patient could receive the stem cell transplants early in the new year and although the trial is designed primarily to assess safety, the first signs of visual improvement may be apparent within weeks. "Talking to the clinicians, we could see something in six weeks, that's when we think we may see some improvements. It really depends on individual patients but that's a reasonable time frame when something may start to happen," Dr Lanza said. ©independent.co.uk

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 4: Development of the Brain
Link ID: 14699 - Posted: 11.22.2010

Stem cells used in stroke trial

By Pallab Ghosh Doctors in Glasgow have injected stem cells into the brain of a stroke patient in an effort to find a new treatment for the condition. The elderly man is the first person in the world to receive this treatment - the start of a regulated trial at Southern General Hospital. He was given very low doses over the weekend and has since been discharged - and his doctors say he is doing well. Critics object as brain cells from foetuses were used to create the cells. The patient received a very low dose of stem cells in an initial trial to assess the safety of the procedure. Over the next year, up to 12 more patients will be given progressively higher doses - again primarily to assess safety - but doctors will be looking closely to see if the stem cells have begun to repair their brains and if their condition has improved. The company making the stem cells says the trial has ethical approval from the medicine's regulator. BBC © MMX

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 4: Development of the Brain
Link ID: 14679 - Posted: 11.16.2010

First patient treated in stem cell study

By Rob Stein Doctors have injected millions of human embryonic stem cells into a patient partially paralyzed by a spinal cord injury, marking the beginning of the first carefully designed attempt to test the promising but controversial therapy, officials announced Monday. The patient was treated Friday at the Shepherd Center, a 132-bed hospital in Atlanta that specializes in spinal cord and brain injuries, according to announcement by the hospital and Geron Corp. of Menlo Park, Calif., which is sponsoring the research. The hospital is one of seven sites participating in the study, which is primarily aimed at testing whether the therapy is safe. Doctors will also conduct tests to see whether the treatment restores sensation or enables the patient to regain movement. No additional information about the first patient was released. The milestone was welcomed by scientists eager to finally move the research from the laboratory to the clinic, as well as by advocates for patients and by patients hoping for cures. Although the cells have been tested in animals, and some clinics around the world claim to offer therapies using human embryonic stem cells, the trial is the first to have been vetted by a government entity and aimed at carefully evaluating the strategy. After repeated delays, the Food and Drug Administration gave the go-ahead in July. But the move was criticized by those with moral objections to any research using cells from human embryos, and it is raising concern even among many proponents. Some argue that the experiments are premature, others question whether they are ethical, and many fear that the trials risk disaster for the field if anything goes awry. © 2010 The Washington Post Company

Related chapters from BN: Chapter 11: Motor Control and Plasticity; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 4: Development of the Brain
Link ID: 14549 - Posted: 10.12.2010

Paralysed man is first to be treated with stem cells from embryo

By Steve Connor, Science Editor A patient who was partially paralysed as a result of an injury to the spinal cord has become the first person to be injected with millions of stem cells derived from early human embryos created by IVF. Geron Corporation, based in Menlo Park, California, said that it has enrolled the first of several patients in a pioneering study of embryonic stem cells. The phase one clinical trial will attempt to assess whether the novel treatment is safe, rather than effective. Embryonic stem cells have the proven ability to develop into any of the 200 or more specialised tissues of the body, from insulin-making pancreatic cells to the nerve cells of the brain. Scientists believe they could be used to treat many incurable conditions, from spinal injury to Parkinson's disease. However, there are concerns that the reality may not live up to the hype. As yet, there has been little clinical demonstration that human embryonic stem cells are safe, let alone effective, with concerns that they may lead to cancerous tumours. Early in 2009, Geron was given a licence by the US Food and Drug Administration (FDA) to carry out the first clinical trial on spinal cord patients. But later in the year the company had to carry out further tests when the FDA became concerned about the growth of cysts in some laboratory animals injected with embryonic stem cells. ©independent.co.uk

Scientists overcome hurdles to stem cell alternatives

By Rob Stein Scientists have invented an efficient way to produce apparently safe alternatives to human embryonic stem cells without destroying embryos, a long-sought step toward bypassing the moral morass surrounding one of the most promising fields in medicine. A team of researchers at the Harvard Stem Cell Institute in Boston published a series of experiments Thursday showing that synthetic biological signals can quickly reprogram ordinary skin cells into entities that appear virtually identical to embryonic stem cells. Moreover, the same strategy can then turn those cells into ones that could be used for transplants. "This is going to be very exciting to the research community," said Derrick J. Rossi of the Children's Hospital Boston, who led the research published in the journal Cell Stem Cell. "We now have an experimental paradigm for generating patient-specific cells highly efficiently and safely and also taking those cells to clinically useful cell types." Scientists hope stem cells will lead to cures for diabetes, Alzheimer's disease, spinal cord injuries, heart attacks and many other ailments because they can turn into almost any tissue in the body, potentially providing an invaluable source of cells to replace those damaged by disease or injury. But the cells can be obtained only by destroying days-old embryos. © 2010 The Washington Post Company

Imperfect Mimics: Reprogramming may not produce exact embryonic stem cell replicas

By Tina Hesman Saey Pod people may look a lot like the real thing, but — as the fictional town of Santa Mira finds out in Invasion of the Body Snatchers — they are disastrously different. The same may be true for reprogrammed stem cells. These cells are designed to mimic embryonic stem cells and are grown in lab dishes by researchers, not pods by aliens. But scientists now worry that reprogrammed cells, like the duplicates that invaded Santa Mira, may not be wholly satisfactory replacements. New research suggests that important differences may separate the two kinds of cells. Such differences could impair the ability of reprogrammed cells to make other cell types, which doctors hope to use to repair diseased and damaged tissues. Other limitations of the reprogramming process could leave transplanted cells more susceptible to diseases such as cancer, some scientists fear. Every lab has its own recipe to convert mature skin and blood cells to a reprogrammed state — and comparisons show that some of these procedures work better than others. Time and patience, one study finds, may help erase lingering differences between the superbly flexible embryonic stem cells and their lab-made substitutes. Embryonic stem cells are pluripotent, meaning they can become any type of cell. But isolating stem cells destroys the embryo from which they come, raising ethical concerns and funding barriers. © Society for Science & the Public 2000 - 2010

Mice testicles yield 'ethical' stem cells

Andy Coghlan Men’s testicles may provide an “ethical” source of embryonic stem cells (ESCs), suggest new experiments in mice. A team in Germany has successfully grown mouse ESC-like cells from spermatagonial stem cells which normally turn into sperm. The ESC-like cells can be grown into all tissues of the mouse body, suggesting that if the same could be done in men, it would provide patients with a source of tissue-matched cells for repairing any damaged organs or tissue. So far, all existing colonies of human ESCs have been derived from surplus human embryos, leftover from infertility treatments. Because a human embryo is sacrificed in the process, many religious groups oppose such research, especially in the US where President George W Bush has placed heavy restrictions on federal stem cell researchers. The discovery that cells which behave like ESCs can now be obtained from adult mice may now open up the possibility of a similar “ethical” source from grown men. “We’re in the process of doing this in humans, and we’re optimistic,” says Gerd Hasenfuss of the Georg-August University of Göttingen, Germany, and head of the team which pioneered the breakthrough. © Copyright Reed Business Information Ltd.

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 4: Development of the Brain; Chapter 15: Language and Lateralization
Link ID: 8706 - Posted: 06.24.2010

Hey presto! Brain cells from mouse tails

by Ewen Callaway In a feat of cellular alchemy, connective tissue from a mouse's tail has been transformed directly into working brain cells. Ordinarily, so drastic a makeover would require the creation of so-called induced pluripotent stem (iPS) cells and then turning these into neurons, an inefficient process that can take weeks. Marius Wernig and colleagues at Stanford University in California discovered that inserting a cocktail of three genes into fibroblasts turns them directly into neurons in just days. "The real surprise was that this conversion is extremely efficient," he says. By many indications, these neurons are the real deal. Under a microscope, they look like a kind of mouse brain cell found in the cortex and they can form synapses to send and receive signals from others. Wernig expects that the cells will integrate into a mouse's brain - an experiment that's in the works. If they do, cells produced using a similar process might one day be used to treat conditions such as Parkinson's disease in humans. Because such cells are derived from adult cells, not pluripotent cells – which have the potential to form a kind of tumour called a teratoma – they might be safer than iPS cells. © Copyright Reed Business Information Ltd.

Hold the Embryos: Genes turn skin into stem cells

Patrick Barry In an advance that could solve many of the ethical and technical issues involved in stem cell research, two groups of scientists have independently converted human skin cells directly into stem cells without creating or destroying embryos. "We are now in a position to be able to generate patient- and disease-specific stem cells without using human eggs or embryos," Shinya Yamanaka, leader of one of the research teams at Kyoto University in Japan, said in an e-mail interview. Preliminary tests show that the newly created cells can develop into nerve cells, heart cells, or any other kind of cell in the body. Previously, only stem cells taken from early embryos had this kind of flexibility, called pluripotency. Scientists have suggested that such embryonic stem cells could be used for learning about genetic diseases, testing new drugs on cells grown in the lab, or growing healthy cells for therapeutic transplantation. Producing embryonic stem cells has become controversial, however, because the process destroys the embryo. "[Our] whole procedure doesn't involve any embryo," says Junying Yu, leader of the other research group, at the University of Wisconsin–Madison. "This approach is certainly going to get rid of this [ethical] problem." ©2007 Science Service.

'Trojan cells' treat brain diseases from the inside

Scientists have managed to protect and regenerate the part of the brain that is damaged in Parkinson’s disease, by genetically engineering cells to bypass the blood-brain barrier. The study was conducted in animals, but the approach could one day be used to treat brain conditions in humans, the researchers say. The blood-brain barrier protects the brain from harmful substances, but also prevents drugs from entering, so experimental treatments have involved injecting drugs directly into the brain. Now Clive Svensden at the University of Wisconsin-Madison, US, and colleagues have devised an alternative – implanting cells that act as a Trojan horse, churning out the drug from inside the brain’s fortress. The team took human neural progenitor cells (hNPCs) from fetal tissue at 10 to 15 weeks’ gestation. These have a lot in common with stem cells, though they have already differentiated into specific neural cells. The researchers genetically modified the cells to produce a growth molecule called glial cell line-derived neurotrophic factor (GDNF). This is produced naturally by the brain at around eight weeks’ gestation in humans, but by 20 weeks it has all gone. Previous studies show that GDNF increases the survival and function of dopamine-producing cells, which are progressively destroyed in Parkinson’s disease. © Copyright Reed Business Information Ltd.

Markers of brain cell development may help success of stem cell transplants

Four sugar-coated faces made by stem cells as they differentiate into brain cells during development have been identified by scientists. These unique expressions of sugar on the cell surface may one day enable stem cell therapy to repair brain injury or disease by helping stem cells navigate the relative “jungle” of the adult brain, says Dr. Robert K. Yu, director of the Institute of Neuroscience and the Institute for Molecular Medicine and Genetics at the Medical College of Georgia. “These glycoconjugate markers are like specific addresses that characterize the cell at that particular moment. We call them stage-specific embryonic antigens,” says Dr. Yu of recognition molecules that assist in the unbelievably rapid assemblage of 100 billion to 200 billion cells into a brain in nine months. The four compounds – two glycolipids, GD3 and O-acetylated GD3, and two glycoproteins, Stage-specific Embryonic Antigen-1 and Human Natural Killer Cell Antigen 1 – were known, but their role in helping cells migrate where and when needed was unknown. Copyright 2005 Medical College of Georgia

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 4: Development of the Brain
Link ID: 7858 - Posted: 06.24.2010

Neural crest stem cells in skin could provide alternative to embryonic stem cell use

Cell replacement therapy offers a novel and powerful medical technology. A type of embryonic stem cell, called a neural crest stem cell, that persists into adulthood in hair follicles was recently discovered by Maya Sieber-Blum, Ph.D., of the Medical College of Wisconsin, Milos Grim, MD Ph.D., of Charles University Prague, and their collaborators. The discovery – reported recently in Developmental Dynamics, a journal of the American Association of Anatomists published by John Wiley & Sons, Inc. – may in many instances provide a non-controversial substitute for embryonic stem cells. Embryonic stem cells are unique, because they can differentiate into any cell type of the body. Their use, however, raises ethical concerns because embryos are being destroyed in the process. In contrast, neural crest stem cells from adults have several advantages: similar to embryonic stem cells, they have the innate ability to differentiate into many diverse cell types; they are easily accessible in the skin of adults; and the patient's own neural crest stem cells could be used for cell therapy. The latter avoids both rejection of the implant and graft-versus-host disease. Studies in the mouse showed that neural crest stem cells from adult hair follicles are able to differentiate into neurons, nerve supporting cells, cartilage/bone cells, smooth muscle cells, and pigment cells. Preliminary data indicate that equivalent stem cells reside in human hair follicles.

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 4: Development of the Brain
Link ID: 6564 - Posted: 06.24.2010

Fetal tissue graft restores lost sight

Three years ago Elisabeth Bryant believed she would be blind for the rest of her life. “I couldn’t see anything,” she says. Now, although her vision is not perfect, she can see well enough to read, play computer games and check emails. Bryant has retinitis pigmentosa, an eye disease that has blinded four generations of her family. What has saved the sight in one of her eyes is a transplant of a sheet of retinal cells. The vision in this eye has improved from 20:800 to 20:84 in the two-and-a-half years since the transplant – a remarkable transformation. So far, six patients with either advanced retinitis pigmentosa or macular degeneration have had similar transplants. Together, these degenerative diseases are the biggest cause of blindness in rich countries, affecting tens of millions of people. While Bryant’s improvement is the most dramatic, four other patients have also had good results. When New Scientist print edition (1 February, 2003) reported the initial results of these retinal transplants, experts cautioned that the results could be due to the rescue effect: a short-term improvement triggered by the release of growth factors after eye surgery. That appears increasingly unlikely, because the rescue effect usually lasts only months. © Copyright Reed Business Information Ltd.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 6339 - Posted: 06.24.2010

UCSF finding advances insight into adult stem cells in human brain

UCSF researchers have made a notable advance in the effort to illuminate the existence of adult stem cells in the human brain, identifying a ribbon of stem cells that potentially could be used to develop strategies for regenerating damaged brain tissue - and that could offer new insight into the most common type of brain tumor. The study, conducted by investigators in the UCSF Department of Neurological Surgery, is the cover story in the Feb. 19 issue of Nature. The researchers conducted their study on brain specimens (from neurological resections and autopsies) containing the lining of the brain's fluid-filled cavity, a region known as the subventricular zone. There, they discovered a sheet of the brain's most ubiquitous cell, the astrocyte - traditionally thought of as a supportive cell for neurons in the adult brain – and determined in cell culture studies that the cell has the capacity to function as a neural stem cell. They also detected fresh, young neurons within the astrocytic region that likely are the progeny of these stem cells, the researchers say

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 4: Development of the Brain
Link ID: 5003 - Posted: 06.24.2010

Neurologists create a font of human nerve cells

Scientists have created an unlimited supply of a type of nerve cell found in the spinal cord – a self-renewing cell line that offers a limitless supply of human nerve cells in the laboratory. Such a supply has long been one goal of neurologists anxious to replace dead or dying cells with healthy ones in a host of neurological diseases. In this study, appearing in the March issue of Nature Biotechnology, the scientists then used the cells to partially repair damaged spinal cords in laboratory animals, re-growing small sections of the spinal cord that had been damaged. Doctors emphasize that tests in people with damaged spinal cords or other neurological conditions are a long ways off. The researchers, led by neurologist Steven Goldman, M.D., Ph.D., of the University of Rochester Medical Center, created the unique cells by introducing a gene called telomerase, which is responsible for the ability of stem cells to live indefinitely, into more specialized "progenitor" cells. In normal development, these progenitor cells give rise to very specific types of spinal neurons, but they do so for only short periods of time, because they lack the ability to continuously divide. With the newly added telomerase gene, the spinal progenitor cells were able to continuously divide while still producing only specific types of neurons. The outcome was a line of immortal progenitor cells, capable of churning out human spinal neurons indefinitely.

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