Post by Salem6 on Feb 12, 2004 12:28:57 GMT
By Jonathan Amos
BBC News Online science staff, in Seattle
Human embryo clones: 'The most advanced yet produced'
South Korean scientists have cloned 30 human embryos to obtain cells they hope could one day be used to treat disease.
Seoul National University's Woo Suk Hwang, and colleagues, took the genetic material from normal cells in women donors and combined it with their eggs.
The resulting embryos were then grown up to produce so-called stem cells that can divide into any tissue in the body.
The aim is to use the cells to replace ones that have failed in patients with problems such as Alzheimer's disease.
"Because these cells carry the nuclear genome of the individual, after differentiation they could be expected to be transplanted without immune rejection for treatment of degenerative disorders," said Professor Hwang.
"Our approach opens the door for the use of these specially developed cells in transplantation medicine."
Details of the research are published online by the journal Science, on its Science Express website, and are to be discussed here on Thursday at the American Association for the Advancement of Science's annual meeting.
Mice proof
There have been claims in the past for the creation of human embryo clones to study so-called stem cells - many of them disputed.
The method used to empty the eggs is said to be critical
But no group has reported producing so many early-stage clones and seen their development progress to such an advanced stage.
The work has also been subjected to the rigorous scrutiny of independent scientists before publication in a major journal.
"These are the most advanced human embryo clones yet produced," Professor Hwang told BBC News Online.
The team says it sought approval for its work from an ethical review board and obtained informed consent from its women donors before proceeding with the work.
Thirty embryos
The team tells Science Express how it used 242 eggs in its experiments taken from 16 women.
In each case, material was transferred from the nucleus of a non-reproductive (somatic) cell, containing the woman's genetic blueprint, into a nucleus-free egg from the same donor.
Following this transfer, factors within the host egg's exterior, or cytoplasm, are believed to have reprogrammed the new nuclear contents by activating versatile embryonic genes, while silencing the more limited adult somatic cell genes.
In total, 30 embryos - exact genetic copies of their female donors - were then cultured to the so-called blastocyst stage at which stem cells could be extracted.
Stem cell guide:
What are stem cells and what might they be used for?
These special cells were seen to divide into all three of the main tissue types found in the human body, the researchers report.
The cells were even transplanted into mice to show they could differentiate into still more specific cell types, offering further proof of their "pluripotency".
The stated intention is to study human embryonic stem cells to see how they could be used as a therapeutic tool to treat disorders, such as diabetes, osteoarthritis, and Parkinson's disease, among others, in which tissues in the body have begun to fail.
Non-egg future
Editor-in-chief of the journal Science, Donald Kennedy, said: "The potential for embryonic stem cells is enormous, but researchers still must overcome significant scientific hurdles."
And he added: "These results seem promising. But, it's important to remember that cell and tissue transplantation and gene therapy are still emerging technologies, and it may be years yet before embryonic stem cells can be used in transplantation medicine."
Addressing ethical concerns, he also called for a worldwide ban on activities which would seek to use this technology to create living children.
Professor Hwang, whose expertise has been developed in animal cloning, said any attempt to produce a baby would be "crazy".
"We will never try to produce cloned human beings," he said.
" During animal cloning, we experienced so many difficulties and dangers with deformities, especially in the internal organs."
Commenting on the Korean work, Roger Pedersen, professor of regenerative medicine, at the University of Cambridge, UK, told BBC News Online: "The present work has substantially advanced the cause of generating transplantable tissues that exactly match the patient's own immune system.
"These researchers' findings also make it possible to learn how to reprogramme the human genome to an embryonic state.
"This will likely accelerate the development of alternative ways of reprogramming human cells, which could in the future diminish the need to use human eggs for this purpose."
Video:-
The BBC's Christine McGourty
"This represents an important step forward for modern medicine"news.bbc.co.uk/media/video/39849000/rm/_39849619_cloning06_mcgourty_vi.ram
What are stem cells?
Stem cells are the body's "master" cells.
A growing embryo must produce all the different cells that make up the human body.
It contains stem cells - cells which have the ability to be transformed into any cell needed for blood, bone or the brain.
Scientists believe that this ability of stem cells could be harnessed to provide medical treatments.
Stem cell uses
In some diseases, cells are lost or damaged.
Researchers are exploring ways of using stem cells to produce cells which could replace these.
Much research is currently focused on using new heart muscle cells to help heart failure patients, and on producing new brain neurons to treat people with Parkinson's or Alzheimer's diseases.
Stem cell sources
The most obvious source of stem cells is from embryos, just a few days after conception.
An embryo's centre is made up of a bundle of stem cells which can be extracted.
Stem cells which are more differentiated and therefore closer in form to specific cells - such as blood or brain cells - can be found in older foetuses.
Adult stem cells
The use of embryonic and foetal stem cells is controversial - many people believe that the early embryo is sacrosanct.
An alternative might be to find a source of stem cells in adults.
Scientists have found that certain bone marrow cells behave very like embryonic cells and can be transformed into different types of cell.
Stem cell potential
There are still many technological obstacles and ethical considerations to be overcome before stem cell therapy could be routinely used.
But there is potential for stem cells to be used to treat a wide variety of conditions - from diabetes, to strokes, to blindness.
A few clinical trials have already been carried out in humans.
BBC News Online science staff, in Seattle
Human embryo clones: 'The most advanced yet produced'
South Korean scientists have cloned 30 human embryos to obtain cells they hope could one day be used to treat disease.
Seoul National University's Woo Suk Hwang, and colleagues, took the genetic material from normal cells in women donors and combined it with their eggs.
The resulting embryos were then grown up to produce so-called stem cells that can divide into any tissue in the body.
The aim is to use the cells to replace ones that have failed in patients with problems such as Alzheimer's disease.
"Because these cells carry the nuclear genome of the individual, after differentiation they could be expected to be transplanted without immune rejection for treatment of degenerative disorders," said Professor Hwang.
"Our approach opens the door for the use of these specially developed cells in transplantation medicine."
Details of the research are published online by the journal Science, on its Science Express website, and are to be discussed here on Thursday at the American Association for the Advancement of Science's annual meeting.
Mice proof
There have been claims in the past for the creation of human embryo clones to study so-called stem cells - many of them disputed.
The method used to empty the eggs is said to be critical
But no group has reported producing so many early-stage clones and seen their development progress to such an advanced stage.
The work has also been subjected to the rigorous scrutiny of independent scientists before publication in a major journal.
"These are the most advanced human embryo clones yet produced," Professor Hwang told BBC News Online.
The team says it sought approval for its work from an ethical review board and obtained informed consent from its women donors before proceeding with the work.
Thirty embryos
The team tells Science Express how it used 242 eggs in its experiments taken from 16 women.
In each case, material was transferred from the nucleus of a non-reproductive (somatic) cell, containing the woman's genetic blueprint, into a nucleus-free egg from the same donor.
Following this transfer, factors within the host egg's exterior, or cytoplasm, are believed to have reprogrammed the new nuclear contents by activating versatile embryonic genes, while silencing the more limited adult somatic cell genes.
In total, 30 embryos - exact genetic copies of their female donors - were then cultured to the so-called blastocyst stage at which stem cells could be extracted.
Stem cell guide:
What are stem cells and what might they be used for?
These special cells were seen to divide into all three of the main tissue types found in the human body, the researchers report.
The cells were even transplanted into mice to show they could differentiate into still more specific cell types, offering further proof of their "pluripotency".
The stated intention is to study human embryonic stem cells to see how they could be used as a therapeutic tool to treat disorders, such as diabetes, osteoarthritis, and Parkinson's disease, among others, in which tissues in the body have begun to fail.
Non-egg future
Editor-in-chief of the journal Science, Donald Kennedy, said: "The potential for embryonic stem cells is enormous, but researchers still must overcome significant scientific hurdles."
And he added: "These results seem promising. But, it's important to remember that cell and tissue transplantation and gene therapy are still emerging technologies, and it may be years yet before embryonic stem cells can be used in transplantation medicine."
Addressing ethical concerns, he also called for a worldwide ban on activities which would seek to use this technology to create living children.
Professor Hwang, whose expertise has been developed in animal cloning, said any attempt to produce a baby would be "crazy".
"We will never try to produce cloned human beings," he said.
" During animal cloning, we experienced so many difficulties and dangers with deformities, especially in the internal organs."
Commenting on the Korean work, Roger Pedersen, professor of regenerative medicine, at the University of Cambridge, UK, told BBC News Online: "The present work has substantially advanced the cause of generating transplantable tissues that exactly match the patient's own immune system.
"These researchers' findings also make it possible to learn how to reprogramme the human genome to an embryonic state.
"This will likely accelerate the development of alternative ways of reprogramming human cells, which could in the future diminish the need to use human eggs for this purpose."
Video:-
The BBC's Christine McGourty
"This represents an important step forward for modern medicine"news.bbc.co.uk/media/video/39849000/rm/_39849619_cloning06_mcgourty_vi.ram
What are stem cells?
Stem cells are the body's "master" cells.
A growing embryo must produce all the different cells that make up the human body.
It contains stem cells - cells which have the ability to be transformed into any cell needed for blood, bone or the brain.
Scientists believe that this ability of stem cells could be harnessed to provide medical treatments.
Stem cell uses
In some diseases, cells are lost or damaged.
Researchers are exploring ways of using stem cells to produce cells which could replace these.
Much research is currently focused on using new heart muscle cells to help heart failure patients, and on producing new brain neurons to treat people with Parkinson's or Alzheimer's diseases.
Stem cell sources
The most obvious source of stem cells is from embryos, just a few days after conception.
An embryo's centre is made up of a bundle of stem cells which can be extracted.
Stem cells which are more differentiated and therefore closer in form to specific cells - such as blood or brain cells - can be found in older foetuses.
Adult stem cells
The use of embryonic and foetal stem cells is controversial - many people believe that the early embryo is sacrosanct.
An alternative might be to find a source of stem cells in adults.
Scientists have found that certain bone marrow cells behave very like embryonic cells and can be transformed into different types of cell.
Stem cell potential
There are still many technological obstacles and ethical considerations to be overcome before stem cell therapy could be routinely used.
But there is potential for stem cells to be used to treat a wide variety of conditions - from diabetes, to strokes, to blindness.
A few clinical trials have already been carried out in humans.