Stem Cell Research
To inform people the significance of Stem Cell Research.
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19.05.2009, Cody P, 0 Comments
The history of stem cell research had a benign, embryonic beginning in the mid 1800's with the discovery that some cells could generate other cells. Now stem cell research is embroiled in a controversy over the use of human embryonic stem cells for research. In the early 1900's the first real stem cells were discovered when it was found that some cells generate blood cells.
The history of stem cell research includes work with both animal and human stem cells. Stem cells can be classified into three broad categories, based on their ability to differentiate. Totipotent stem cells are found only in early embryos. Each cell can form a complete organism (e.g., identical twins). Pluripotent stem cells exist in the undifferentiated inner cell mass of the blastocyst and can form any of the over 200 different cell types found in the body. Multipotent stem cells are derived from fetal tissue, cord blood, and adult stem cells. Although their ability to differentiate is more limited than pluripotent stem cells, they already have a track record of success in cell-based therapies.
A prominent application of stem cell research has been bone marrow transplants using adult stem cells. In the early 1900's physicians administered bone marrow by mouth to patients with anemia and leukemia. Although such therapy was unsuccessful, laboratory experiments eventually demonstrated that mice with defective marrow could be restored to health with infusions into the blood stream of marrow taken from other mice. This caused physicians to speculate whether it was feasible to transplant bone marrow from one human to another (allogeneic transplant). Among early attempts to do this were several transplants carried out in France following a radiation accident in the late 1950's. Performing marrow transplants in humans was not attempted on a larger scale until a French medical researcher made a critical medical discovery about the human immune system. In 1958 Jean Dausset identified the first of many human histocompatibility antigens. These proteins, found on the surface of most cells in the body, are called human leukocyte antigens, or HLA antigens. These HLA antigens give the body's immune system the ability to determine what belongs in the body and what does not belong. Whenever the body does not recognize the series of antigens on the cell walls, it creates antibodies and other substances to destroy the cell.
A bone marrow transplant between identical twins guarantees complete HLA compatibility between donor and recipient. These were the first kinds of transplants in humans. It was not until the 1960's that physicians knew enough about HLA compatibility to perform transplants between siblings who were not identical twins. In 1973 a team of physicians performed the first unrelated bone marrow transplant. It required 7 transplants to be successful. In 1984 Congress passed the National Organ Transplant Act, which among other things, included language to evaluate unrelated marrow transplantation and the feasibility of establishing a national donor registry. This led ultimately to National Marrow Donor Program (NDWP) a separate non-profit organization that took over the administration of the database needed for donors in 1990. The 1990's saw rapid expansion and success of the bone marrow program with more than 16,000 transplants to date for the treatment of immunodeficiencies and leukemia. Adult stem cells also have shown great promise in other areas. These cells have shown the potential to form many different kinds of cell types and tissues, including functional hepatocyte-like (liver) cells. Such cells might be useful in repairing organs ravaged by diseases.
In 1998, James Thompson (University of Wisconsin - Madison) isolated cells from the inner cell mass of early embryos, and developed the first embryonic stem cell lines. In the same year, John Gearhart (Johns Hopkins University) derived germ cells from cells in fetal gonadal tissue (primordial germ cells). Pluripotent stem cell "lines" were developed from both sources. The blastocysts used for human stem cell research typically come from in vitro fertilization (IVF) procedures. The ethical concerns over this type of embryonic stem cell research has been expressed in the following US legal regulations:
In 1973 a moratorium was placed on government funding for human embryo research. In 1988 a NIH panel voted 19 to 2 in favor of government funding. In 1990, Congress voted to override the moratorium on government funding of embryonic stem cell research, which was vetoed by President George Bush. President Clinton lifted the ban, but changed his mind the following year after public outcry. Congress banned federal funding in 1995. In 1998 DHHS Secretary Sullivan extended the moratorium. In 2000, President Bill Clinton allowed funding of research on cells derived from aborted human fetuses, but not from embryonic cells. On August 9, 2001, President George W. Bush announced his decision to allow Federal funding of research only on existing human embryonic stem cell lines created prior to his announcement. His concern was to not foster the continued destruction of living human embryos. In 2004, both houses of Congress have asked President George W. Bush to review his policy on embryonic stem cell research. President George W. Bush released a statement reiterating his moral qualms about creating human embryos to destroy them, and refused to reverse the federal policy banning government funding of ESC research (other than for ESC lines established before the funding ban).
In the November 2004 election, California had a Stem Cell Research Funding authorization initiative on the ballot that won by a 60% to 40% margin. It established the "California Institute for Regenerative Medicine" to regulate stem cell research and research facilities. It authorizes issuance of general obligation bonds to finance institute activities up to $3 billion dollars subject to an annual limit of $350 million.
The history of stem cell research includes work with both animal and human stem cells. Stem cells can be classified into three broad categories, based on their ability to differentiate. Totipotent stem cells are found only in early embryos. Each cell can form a complete organism (e.g., identical twins). Pluripotent stem cells exist in the undifferentiated inner cell mass of the blastocyst and can form any of the over 200 different cell types found in the body. Multipotent stem cells are derived from fetal tissue, cord blood, and adult stem cells. Although their ability to differentiate is more limited than pluripotent stem cells, they already have a track record of success in cell-based therapies.
A prominent application of stem cell research has been bone marrow transplants using adult stem cells. In the early 1900's physicians administered bone marrow by mouth to patients with anemia and leukemia. Although such therapy was unsuccessful, laboratory experiments eventually demonstrated that mice with defective marrow could be restored to health with infusions into the blood stream of marrow taken from other mice. This caused physicians to speculate whether it was feasible to transplant bone marrow from one human to another (allogeneic transplant). Among early attempts to do this were several transplants carried out in France following a radiation accident in the late 1950's. Performing marrow transplants in humans was not attempted on a larger scale until a French medical researcher made a critical medical discovery about the human immune system. In 1958 Jean Dausset identified the first of many human histocompatibility antigens. These proteins, found on the surface of most cells in the body, are called human leukocyte antigens, or HLA antigens. These HLA antigens give the body's immune system the ability to determine what belongs in the body and what does not belong. Whenever the body does not recognize the series of antigens on the cell walls, it creates antibodies and other substances to destroy the cell.
A bone marrow transplant between identical twins guarantees complete HLA compatibility between donor and recipient. These were the first kinds of transplants in humans. It was not until the 1960's that physicians knew enough about HLA compatibility to perform transplants between siblings who were not identical twins. In 1973 a team of physicians performed the first unrelated bone marrow transplant. It required 7 transplants to be successful. In 1984 Congress passed the National Organ Transplant Act, which among other things, included language to evaluate unrelated marrow transplantation and the feasibility of establishing a national donor registry. This led ultimately to National Marrow Donor Program (NDWP) a separate non-profit organization that took over the administration of the database needed for donors in 1990. The 1990's saw rapid expansion and success of the bone marrow program with more than 16,000 transplants to date for the treatment of immunodeficiencies and leukemia. Adult stem cells also have shown great promise in other areas. These cells have shown the potential to form many different kinds of cell types and tissues, including functional hepatocyte-like (liver) cells. Such cells might be useful in repairing organs ravaged by diseases.
In 1998, James Thompson (University of Wisconsin - Madison) isolated cells from the inner cell mass of early embryos, and developed the first embryonic stem cell lines. In the same year, John Gearhart (Johns Hopkins University) derived germ cells from cells in fetal gonadal tissue (primordial germ cells). Pluripotent stem cell "lines" were developed from both sources. The blastocysts used for human stem cell research typically come from in vitro fertilization (IVF) procedures. The ethical concerns over this type of embryonic stem cell research has been expressed in the following US legal regulations:
In 1973 a moratorium was placed on government funding for human embryo research. In 1988 a NIH panel voted 19 to 2 in favor of government funding. In 1990, Congress voted to override the moratorium on government funding of embryonic stem cell research, which was vetoed by President George Bush. President Clinton lifted the ban, but changed his mind the following year after public outcry. Congress banned federal funding in 1995. In 1998 DHHS Secretary Sullivan extended the moratorium. In 2000, President Bill Clinton allowed funding of research on cells derived from aborted human fetuses, but not from embryonic cells. On August 9, 2001, President George W. Bush announced his decision to allow Federal funding of research only on existing human embryonic stem cell lines created prior to his announcement. His concern was to not foster the continued destruction of living human embryos. In 2004, both houses of Congress have asked President George W. Bush to review his policy on embryonic stem cell research. President George W. Bush released a statement reiterating his moral qualms about creating human embryos to destroy them, and refused to reverse the federal policy banning government funding of ESC research (other than for ESC lines established before the funding ban).
In the November 2004 election, California had a Stem Cell Research Funding authorization initiative on the ballot that won by a 60% to 40% margin. It established the "California Institute for Regenerative Medicine" to regulate stem cell research and research facilities. It authorizes issuance of general obligation bonds to finance institute activities up to $3 billion dollars subject to an annual limit of $350 million.
08.05.2009, Cody P, 0 Comments
Embryonic Stem Cell Science Requires Human Eggs…and you don’t just pick them up at the store. Some scientists insist the best opportunity to cure diseases like diabetes will come from embryonic stem cell research (ESCR) and Somatic Cell Nuclear Transfer (SCNT), another name for human cloning. But these techniques require human eggs that can only come from women.
Go to my files located on the top of my magazine and click the file that is titled "Embryonic Stem Cells Research, Human Cloning and the Exploitation of Women" for an explanation from Ethicist Pia de Solenni, Ph.D. who presents the facts on how hundreds of millions of poor, disadvantaged women could be exploited in the process.
Go to my files located on the top of my magazine and click the file that is titled "Embryonic Stem Cells Research, Human Cloning and the Exploitation of Women" for an explanation from Ethicist Pia de Solenni, Ph.D. who presents the facts on how hundreds of millions of poor, disadvantaged women could be exploited in the process.
01.04.2009, Cody P, 0 Comments
Not a matter to ignore or to weigh in light scales. Any serious injury to the spines can lead to permanent damage. The motor functions of various body parts becomes irrecoverable.
But relax! Scientists are struggling hard to obtain a fruitful solution to the problem.In fact partial success has been achieved.
A team of researchers at Keio University has succeeded in improving spinal cord damage in mice by transplanting into them neural stem cells produced with human induced pluripotent stem cells.
This transplantation is noteworthy because this is the first time in which human iPS cells have been used. The iPS cells are known to get converted into other types of body cells.
This study result is expected to pave the way for treatment of human beings with similar kind of injuries.
www.arbiteronline.com (source)
Personally when i read this article at (http://stemcell.taragana.net/category/spinal-injury/) i got a little excited about the situation. It is something that will take time and in hope of this to keep funds continuing. And one day be able to help the people in need. Technology is amazing anymore, impressed!
But relax! Scientists are struggling hard to obtain a fruitful solution to the problem.In fact partial success has been achieved.
A team of researchers at Keio University has succeeded in improving spinal cord damage in mice by transplanting into them neural stem cells produced with human induced pluripotent stem cells.
This transplantation is noteworthy because this is the first time in which human iPS cells have been used. The iPS cells are known to get converted into other types of body cells.
This study result is expected to pave the way for treatment of human beings with similar kind of injuries.
www.arbiteronline.com (source)
Personally when i read this article at (http://stemcell.taragana.net/category/spinal-injury/) i got a little excited about the situation. It is something that will take time and in hope of this to keep funds continuing. And one day be able to help the people in need. Technology is amazing anymore, impressed!
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Stem Cell Research Facts
08.05.2009, Cody P, 0 Comments
As widespread interest in stem cell research increases, so do the number of news articles and reports. It is an unfortunate fact that several misconceptions and distortions have taken hold within the secular media. Ten such “Media Myths” are addressed below.
Myth 1. Stem cells can only come from embryos. In fact stem cells can be taken from umbilical cords, the placenta, amniotic fluid, adult tissues and organs such as bone marrow, fat from liposuction, regions of the nose, and even from cadavers up to 20 hours after death.
Myth 2. Christians are against stem cell research. There are four categories of stem cells: embryonic stem cells, embryonic germ cells, umbilical cord stem cells, and adult stem cells. Given that germ cells can come from miscarriages that involve no deliberate interruption of pregnancy, Christians in general oppose the use of only one of these four categories, i.e., embryonic stem cells. In other words, most Christians approve of three of the four possible types of stem cell research.
Myth 3. Embryonic stem cell research has the greatest promise. Up to now, no human being has ever been cured of a disease using embryonic stem cells. Adult stem cells, on the other hand, have already cured thousands. For example, bone marrow cells from the hipbone have repaired scar tissue on the heart after heart attacks. Research using adult cells is 20-30 years ahead of embryonic stem cells and holds greater promise. This is in part because stem cells are part of the natural repair mechanisms of an adult body, while embryonic stem cells do not belong in an adult body (where they are likely to form tumors, and to be rejected as foreign tissue by the recipient). Rather, embryonic stem cells really belong only within in the specialized microenvironment of a rapidly growing embryo, which is a radically different setting from an adult body.
Myth 4. Embryonic stem cell research is against the law. In reality, there is no law or regulation against destroying human embryos for research purposes. While President Bush has banned the use of federal funding to support research on embryonic stem cell lines created after August 2001, it is not illegal. Anyone using private funds is free to pursue it.
Myth 5. President Bush created new restrictions to federal funding of embryonic stem cell research. The 1996 Dickey Amendment prohibited the use of federal funds for research that would involve the destruction of human embryos. Bush’s decision to permit research on embryonic stem cell lines created before a certain date thus relaxes this restriction from the Clinton era.
Myth 6. Theraputic cloning and reproductive cloning are fundamentally different from each other. The creation of cloned embryos either to make a baby or to harvest cells occurs by the same series of technical steps. The only difference is what will be done with the cloned human embryo that is produced. Will it be given the protection of a woman’s womb in order to be born? Or will it be destroyed for its stem cells?
Myth 7. Somatic nuclear cell transfer is different from cloning. In fact, “somatic cell nuclear transfer” is simply cloning by a different name. The end result is still a cloned embryo.
Myth 8. By doing somatic cell nuclear transfer, we can directly produce tissues or organs without having to clone an embryo. At the present stage of research, scientists are unable to bypass the creation of an embryo in the production of tissues or organs. In the future it may be possible to inject elements from the cytoplasm of a woman’s ovum into a somatic cell to “reprogram” it into a stem cell. This is called “de-differentiation.” If so, there would be no fundamental moral objection to this approach to getting stem cells.
Myth 9. Every body cell, or somatic cell, is somehow an embryo and thus a human life. People sometimes argue: “Every cell in the body has the potential to become an embryo. Does that mean that every time we wash our hands and are shedding thousands of cells, we are killing life?” The problem is that this overlooks the basic biological difference between a regular body cell, and one whose nuclear material has been fused with an unfertilized egg cell, resulting in an embryo. A normal skin cell will only give rise to more skin cells when it divides, while an embryo will give rise to the entire adult organism. Skin cells are not potential adults. Skin cells are potentially only more skin cells. Only embryos are potential adults.
Myth 10. Because frozen embryos may one day end up being discarded by somebody, that makes it allowable, even laudable, to violate and destroy those embryos. The moral analysis of what we may permissibly do with an embryo doesn’t depend on its otherwise “going to waste,” nor on the incidental fact that those embryos are “trapped” in liquid nitrogen. Consider a radical case in which a group of children are permanently trapped in a schoolhouse through no fault of their own; that would not make it morally acceptable to send in a remote control robotic device which would harvest organs from those children and cause their demise.
Myth 1. Stem cells can only come from embryos. In fact stem cells can be taken from umbilical cords, the placenta, amniotic fluid, adult tissues and organs such as bone marrow, fat from liposuction, regions of the nose, and even from cadavers up to 20 hours after death.
Myth 2. Christians are against stem cell research. There are four categories of stem cells: embryonic stem cells, embryonic germ cells, umbilical cord stem cells, and adult stem cells. Given that germ cells can come from miscarriages that involve no deliberate interruption of pregnancy, Christians in general oppose the use of only one of these four categories, i.e., embryonic stem cells. In other words, most Christians approve of three of the four possible types of stem cell research.
Myth 3. Embryonic stem cell research has the greatest promise. Up to now, no human being has ever been cured of a disease using embryonic stem cells. Adult stem cells, on the other hand, have already cured thousands. For example, bone marrow cells from the hipbone have repaired scar tissue on the heart after heart attacks. Research using adult cells is 20-30 years ahead of embryonic stem cells and holds greater promise. This is in part because stem cells are part of the natural repair mechanisms of an adult body, while embryonic stem cells do not belong in an adult body (where they are likely to form tumors, and to be rejected as foreign tissue by the recipient). Rather, embryonic stem cells really belong only within in the specialized microenvironment of a rapidly growing embryo, which is a radically different setting from an adult body.
Myth 4. Embryonic stem cell research is against the law. In reality, there is no law or regulation against destroying human embryos for research purposes. While President Bush has banned the use of federal funding to support research on embryonic stem cell lines created after August 2001, it is not illegal. Anyone using private funds is free to pursue it.
Myth 5. President Bush created new restrictions to federal funding of embryonic stem cell research. The 1996 Dickey Amendment prohibited the use of federal funds for research that would involve the destruction of human embryos. Bush’s decision to permit research on embryonic stem cell lines created before a certain date thus relaxes this restriction from the Clinton era.
Myth 6. Theraputic cloning and reproductive cloning are fundamentally different from each other. The creation of cloned embryos either to make a baby or to harvest cells occurs by the same series of technical steps. The only difference is what will be done with the cloned human embryo that is produced. Will it be given the protection of a woman’s womb in order to be born? Or will it be destroyed for its stem cells?
Myth 7. Somatic nuclear cell transfer is different from cloning. In fact, “somatic cell nuclear transfer” is simply cloning by a different name. The end result is still a cloned embryo.
Myth 8. By doing somatic cell nuclear transfer, we can directly produce tissues or organs without having to clone an embryo. At the present stage of research, scientists are unable to bypass the creation of an embryo in the production of tissues or organs. In the future it may be possible to inject elements from the cytoplasm of a woman’s ovum into a somatic cell to “reprogram” it into a stem cell. This is called “de-differentiation.” If so, there would be no fundamental moral objection to this approach to getting stem cells.
Myth 9. Every body cell, or somatic cell, is somehow an embryo and thus a human life. People sometimes argue: “Every cell in the body has the potential to become an embryo. Does that mean that every time we wash our hands and are shedding thousands of cells, we are killing life?” The problem is that this overlooks the basic biological difference between a regular body cell, and one whose nuclear material has been fused with an unfertilized egg cell, resulting in an embryo. A normal skin cell will only give rise to more skin cells when it divides, while an embryo will give rise to the entire adult organism. Skin cells are not potential adults. Skin cells are potentially only more skin cells. Only embryos are potential adults.
Myth 10. Because frozen embryos may one day end up being discarded by somebody, that makes it allowable, even laudable, to violate and destroy those embryos. The moral analysis of what we may permissibly do with an embryo doesn’t depend on its otherwise “going to waste,” nor on the incidental fact that those embryos are “trapped” in liquid nitrogen. Consider a radical case in which a group of children are permanently trapped in a schoolhouse through no fault of their own; that would not make it morally acceptable to send in a remote control robotic device which would harvest organs from those children and cause their demise.
Spinal Cord
07.05.2009, Cody P, 0 Comments
http://www.ucdenver.edu/about/WhoWeAre/Research/Pages/spinalCordInjuries...
The link above will take you to the University of Colorado Denver, which Stephen Davies shows how he is taking part in spinal cord injuries and stem cell research. Check it out and let me know your thoughts!
There is also a little video/audio to this site that gives you an idea of what its all about for the ones who don’t like reading so much.
The link above will take you to the University of Colorado Denver, which Stephen Davies shows how he is taking part in spinal cord injuries and stem cell research. Check it out and let me know your thoughts!
There is also a little video/audio to this site that gives you an idea of what its all about for the ones who don’t like reading so much.
27.04.2009, Cody P, 0 Comments
Stem Cell Treatment Heals Spinal Cord Injuries In Mice.
Not a matter to ignore or to weigh in light scales. Any serious injury to the spines can lead to permanent damage. The motor functions of various body parts becomes irrecoverable.
But relax! Scientists are struggling hard to obtain a fruitful solution to the problem.In fact partial success has been achieved.
A team of researchers at Keio University has succeeded in improving spinal cord damage in mice by transplanting into them neural stem cells produced with human induced pluripotent stem cells.
This transplantation is noteworthy because this is the first time in which human iPS cells have been used. The iPS cells are known to get converted into other types of body cells.
This study result is expected to pave the way for treatment of human beings with similar kind of injuries.
www.arbiteronline.com (source)
Personally when i read this article at (http://stemcell.taragana.net/category/spinal-injury/) i got a little excited about the situation. It is something that will take time and in hope of this to keep funds continuing. And one day be able to help the people in need. Technology is amazing anymore, impressed!
Not a matter to ignore or to weigh in light scales. Any serious injury to the spines can lead to permanent damage. The motor functions of various body parts becomes irrecoverable.
But relax! Scientists are struggling hard to obtain a fruitful solution to the problem.In fact partial success has been achieved.
A team of researchers at Keio University has succeeded in improving spinal cord damage in mice by transplanting into them neural stem cells produced with human induced pluripotent stem cells.
This transplantation is noteworthy because this is the first time in which human iPS cells have been used. The iPS cells are known to get converted into other types of body cells.
This study result is expected to pave the way for treatment of human beings with similar kind of injuries.
www.arbiteronline.com (source)
Personally when i read this article at (http://stemcell.taragana.net/category/spinal-injury/) i got a little excited about the situation. It is something that will take time and in hope of this to keep funds continuing. And one day be able to help the people in need. Technology is amazing anymore, impressed!
27.04.2009, Cody P, 0 Comments
With the increasing number of research programs focusing on stem cell research and their application to brain injury and spinal cord injury, today’s facts will help you understand why they are so useful.
Stem cells are basically blank cells that, in most cases, have the ability to become a variety of other cells. They are found in bone marrow, blood, the brain, skeletal muscle, fat and even the skin. While the main controversy exists over embryonic stem cells as they have the ability to become just about any cell, we are still able to utilize adult stem cells in a handful of useful ways.
The idea is that scientists can, with the right research, learn to program stem cells to become new spinal cord tissue or new brain tissue, repairing damage that right now, is irreversible. With more studies coming to light regarding the useful application of adult stem cells, we will hopefully see a day when researchers and anti-stem cell research advocates can find a common ground. In the meantime, keep reading. New applications are being discovered all the time!
Stem cells are basically blank cells that, in most cases, have the ability to become a variety of other cells. They are found in bone marrow, blood, the brain, skeletal muscle, fat and even the skin. While the main controversy exists over embryonic stem cells as they have the ability to become just about any cell, we are still able to utilize adult stem cells in a handful of useful ways.
The idea is that scientists can, with the right research, learn to program stem cells to become new spinal cord tissue or new brain tissue, repairing damage that right now, is irreversible. With more studies coming to light regarding the useful application of adult stem cells, we will hopefully see a day when researchers and anti-stem cell research advocates can find a common ground. In the meantime, keep reading. New applications are being discovered all the time!
02.04.2009, Cody P, 0 Comments
The work is by Konstantinos Meletis, a postdoctoral fellow at the Picower Institute, and colleagues at the Karolinska Institute in Sweden. Their results could lead to drugs that might restore some degree of mobility to the 30,000 people worldwide afflicted each year with spinal-cord injuries.
In a developing embryo, stem cells differentiate into all the specialized tissues of the body. In adults, stem cells act as a repair system, replenishing specialized cells, but also maintaining the normal turnover of regenerative organs such as blood, skin or intestinal tissues.
The tiny number of stem cells in the adult spinal cord proliferate slowly or rarely, and fail to promote regeneration on their own. But recent experiments show that these same cells, grown in the lab and returned to the injury site, can restore some function in paralyzed rodents and primates.
The researchers at MIT and the Karolinska Institute found that neural stem cells in the adult spinal cord are limited to a layer of cube- or column-shaped, cilia-covered cells called ependymal cells. These cells make up the thin membrane lining the inner-brain ventricles and the connecting central column of the spinal cord.
"We have been able to genetically mark this neural stem cell population and then follow their behavior," Meletis said. "We find that these cells proliferate upon spinal cord injury, migrate toward the injury site and differentiate over several months."
The study uncovers the molecular mechanism underlying the tantalizing results of the rodent and primate and goes one step further: By identifying for the first time where this subpopulation of cells is found, they pave a path toward manipulating them with drugs to boost their inborn ability to repair damaged nerve cells.
"The ependymal cells' ability to turn into several different cell types upon injury makes them very interesting from an intervention aspect: Imagine if we could regulate the behavior of this stem cell population to repair damaged nerve cells," Meletis said.
Upon injury, ependymal cells proliferate and migrate to the injured area, producing a mass of scar-forming cells, plus fewer cells called oligodendrocytes. The oligodendrocytes restore the myelin, or coating, on nerve cells' long, slender, electrical impulse-carrying projections called axons. Myelin is like the layer of plastic insulation on an electrical wire; without it, nerve cells don't function properly.
"The limited functional recovery typically associated with central nervous system injuries is in part due to the failure of severed axons to regrow and reconnect with their target cells in the peripheral nervous system that extends to our arms, hands, legs and feet," Meletis said. "The function of axons that remain intact after injury in humans is often compromised without insulating sheaths of myelin."
If scientists could genetically manipulate ependymal cells to produce more myelin and less scar tissue after a spinal cord injury, they could potentially avoid or reverse many of the debilitating effects of this type of injury, the researchers said.
article found at:
(http://www.sciencedaily.com/releases/2008/07/080721223346.htm)
In a developing embryo, stem cells differentiate into all the specialized tissues of the body. In adults, stem cells act as a repair system, replenishing specialized cells, but also maintaining the normal turnover of regenerative organs such as blood, skin or intestinal tissues.
The tiny number of stem cells in the adult spinal cord proliferate slowly or rarely, and fail to promote regeneration on their own. But recent experiments show that these same cells, grown in the lab and returned to the injury site, can restore some function in paralyzed rodents and primates.
The researchers at MIT and the Karolinska Institute found that neural stem cells in the adult spinal cord are limited to a layer of cube- or column-shaped, cilia-covered cells called ependymal cells. These cells make up the thin membrane lining the inner-brain ventricles and the connecting central column of the spinal cord.
"We have been able to genetically mark this neural stem cell population and then follow their behavior," Meletis said. "We find that these cells proliferate upon spinal cord injury, migrate toward the injury site and differentiate over several months."
The study uncovers the molecular mechanism underlying the tantalizing results of the rodent and primate and goes one step further: By identifying for the first time where this subpopulation of cells is found, they pave a path toward manipulating them with drugs to boost their inborn ability to repair damaged nerve cells.
"The ependymal cells' ability to turn into several different cell types upon injury makes them very interesting from an intervention aspect: Imagine if we could regulate the behavior of this stem cell population to repair damaged nerve cells," Meletis said.
Upon injury, ependymal cells proliferate and migrate to the injured area, producing a mass of scar-forming cells, plus fewer cells called oligodendrocytes. The oligodendrocytes restore the myelin, or coating, on nerve cells' long, slender, electrical impulse-carrying projections called axons. Myelin is like the layer of plastic insulation on an electrical wire; without it, nerve cells don't function properly.
"The limited functional recovery typically associated with central nervous system injuries is in part due to the failure of severed axons to regrow and reconnect with their target cells in the peripheral nervous system that extends to our arms, hands, legs and feet," Meletis said. "The function of axons that remain intact after injury in humans is often compromised without insulating sheaths of myelin."
If scientists could genetically manipulate ependymal cells to produce more myelin and less scar tissue after a spinal cord injury, they could potentially avoid or reverse many of the debilitating effects of this type of injury, the researchers said.
article found at:
(http://www.sciencedaily.com/releases/2008/07/080721223346.htm)