Tuesday, February 07, 2006
Stem Cell Test Tried on Mice Saves Embryo
by Nicholas Wade
Scientists have devised two new techniques to derive embryonic stem cells in mice, one of which avoids the destruction of the embryo, a development that could have the potential to shift the grounds of the longstanding political debate about human stem cell research.
A New Way to Create Embryonic Stem Cells - Embryonic Cells, No Embryo Needed: Hunting for Ways Out of an Impasse (October 11, 2005) - Forum: Bioethics
Rick Friedman for The New York Times
Robert Lanza and colleagues have experimented with mice to develop a technique to generate stem cells but leave the embryo viable. The destruction of embryos is a principal objection of anti-abortion advocates who have strenuously opposed federal financing of the research.
The second new technique manipulates embryos so they are inherently incapable of implanting in the uterus, what some see as a possible ethical advantage in the proposed therapy, which converts a patient's skin cell into embryonic cells and then new tissues to repair the body. Both methods are described in today's online edition of Nature.
The technique for making embryonic stem cells without compromising the embryo has yet to be adapted to people, but the two species are very similar at this level of embryonic development. "I can't think of a reason why the technique would not theoretically work in humans," said Brigid L. M. Hogan, an embryologist at Duke University.
If it does work in people, which could take many months to find out, the technique might divide the anti-abortion movement into those who accept or reject in vitro fertilization, because the objection to deriving human embryonic stem cells would come to rest on creating the embryos in the first place, not on their destruction.
"This gets around all of the ethical arguments, except for that small minority of the pro-life community that doesn't even support in vitro fertilization," said Representative Roscoe G. Bartlett, Republican of Maryland, whose Web site describes him as "a pro-life legislator."
Until now the only way of deriving human embryonic stem cells has been to break open the embryo before it implants in the uterus, a stage at which it is called a blastocyst, and take out the inner cell mass, whose cells form all the tissues in a human body.
Although the blastocysts used in the procedure are ones that fertility clinics have rejected for implantation, many opponents of abortion say the destruction of any embryo is wrong. Congress has forbidden the use of federal money for any such research, and federally supported scientists can work with only a small number of existing lines of embryonic stem cells that have been exempted by President Bush.
Robert Lanza and colleagues at Advanced Cell Technology, a biotechnology company in Worcester, Mass., have developed an alternative way of generating embryonic stem cells that leaves the embryo viable.
They let a fertilized mouse egg divide three times until it contained eight cells, a stage just before the embryo becomes a blastocyst. Removing one of these cells, they then coaxed it into growing in glassware and forming cells that have all the same essential properties as embryonic stem cells derived from the inner cell mass, Dr. Lanza's team reports.
The seven-cell embryo was implanted in the mouse uterus and grew successfully to term. This part of the procedure is known to work with humans too, because it is the basis of a well-established test known as preimplantation genetic diagnosis. In the test, one cell is removed from each of a set of embryos and tested for any of 150 genetic defects, giving the parents the choice of implanting an embryo that is disease free.
Dr. Lanza's technique is likely to be welcomed by many in the middle of the debate, although it has not won over the United States Conference of Catholic Bishops. Richard M. Doerflinger, its deputy director for pro-life activities, dismissed the technique, saying that preimplantation genetic diagnosis itself is unethical.
The technique "is done chiefly to select out genetically imperfect embryos for discarding, and poses unknown risks of future harm even to the child allowed to be born," Mr. Doerflinger said in an e-mail message.
Only a procedure that generated embryonic stem cells without creating or destroying embryos "would address the Catholic Church's most fundamental moral objection to embryonic stem cell research as now pursued," Mr. Doerflinger said in testimony last December to the President's Council on Bioethics.
Senator Sam Brownback, a Kansas Republican and a leading pro-life advocate did not return a call to his office. Edmund D. Pellegrino, the new chairman of the President's Council on Bioethics, said through a spokeswoman that he had no comment.
But Markus Grompe, a leading stem cell scientist and a Roman Catholic who supports the church's teaching on the unacceptability of destroying embryos, praised the Lanza approach, provided that the extracted cell could not develop into an embryo by itself. "I find it clearly less objectionable than the outright destruction of the embryo," said Dr. Grompe, who studies liver stem cells at the Oregon Health and Science University.
In response to Dr. Grompe's reservation, Dr. Lanza said individual human blastomeres, as the cells are known at this stage, had never been shown to create viable embryos.
If Dr. Lanza's technique proves to work in humans, it could do more than just provide researchers with a new source of cells. It might allow every child born through preimplantation genetic testing to have its own line of embryonic cells stored for the future. The blastomere removed at the eight-cell stage could be allowed to divide, with one cell being used for genetic testing and the other for growing a culture of perfectly matching embryonic stem cells.
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by Nicholas Wade
Scientists have devised two new techniques to derive embryonic stem cells in mice, one of which avoids the destruction of the embryo, a development that could have the potential to shift the grounds of the longstanding political debate about human stem cell research.
A New Way to Create Embryonic Stem Cells - Embryonic Cells, No Embryo Needed: Hunting for Ways Out of an Impasse (October 11, 2005) - Forum: Bioethics
Rick Friedman for The New York Times
Robert Lanza and colleagues have experimented with mice to develop a technique to generate stem cells but leave the embryo viable. The destruction of embryos is a principal objection of anti-abortion advocates who have strenuously opposed federal financing of the research.
The second new technique manipulates embryos so they are inherently incapable of implanting in the uterus, what some see as a possible ethical advantage in the proposed therapy, which converts a patient's skin cell into embryonic cells and then new tissues to repair the body. Both methods are described in today's online edition of Nature.
The technique for making embryonic stem cells without compromising the embryo has yet to be adapted to people, but the two species are very similar at this level of embryonic development. "I can't think of a reason why the technique would not theoretically work in humans," said Brigid L. M. Hogan, an embryologist at Duke University.
If it does work in people, which could take many months to find out, the technique might divide the anti-abortion movement into those who accept or reject in vitro fertilization, because the objection to deriving human embryonic stem cells would come to rest on creating the embryos in the first place, not on their destruction.
"This gets around all of the ethical arguments, except for that small minority of the pro-life community that doesn't even support in vitro fertilization," said Representative Roscoe G. Bartlett, Republican of Maryland, whose Web site describes him as "a pro-life legislator."
Until now the only way of deriving human embryonic stem cells has been to break open the embryo before it implants in the uterus, a stage at which it is called a blastocyst, and take out the inner cell mass, whose cells form all the tissues in a human body.
Although the blastocysts used in the procedure are ones that fertility clinics have rejected for implantation, many opponents of abortion say the destruction of any embryo is wrong. Congress has forbidden the use of federal money for any such research, and federally supported scientists can work with only a small number of existing lines of embryonic stem cells that have been exempted by President Bush.
Robert Lanza and colleagues at Advanced Cell Technology, a biotechnology company in Worcester, Mass., have developed an alternative way of generating embryonic stem cells that leaves the embryo viable.
They let a fertilized mouse egg divide three times until it contained eight cells, a stage just before the embryo becomes a blastocyst. Removing one of these cells, they then coaxed it into growing in glassware and forming cells that have all the same essential properties as embryonic stem cells derived from the inner cell mass, Dr. Lanza's team reports.
The seven-cell embryo was implanted in the mouse uterus and grew successfully to term. This part of the procedure is known to work with humans too, because it is the basis of a well-established test known as preimplantation genetic diagnosis. In the test, one cell is removed from each of a set of embryos and tested for any of 150 genetic defects, giving the parents the choice of implanting an embryo that is disease free.
Dr. Lanza's technique is likely to be welcomed by many in the middle of the debate, although it has not won over the United States Conference of Catholic Bishops. Richard M. Doerflinger, its deputy director for pro-life activities, dismissed the technique, saying that preimplantation genetic diagnosis itself is unethical.
The technique "is done chiefly to select out genetically imperfect embryos for discarding, and poses unknown risks of future harm even to the child allowed to be born," Mr. Doerflinger said in an e-mail message.
Only a procedure that generated embryonic stem cells without creating or destroying embryos "would address the Catholic Church's most fundamental moral objection to embryonic stem cell research as now pursued," Mr. Doerflinger said in testimony last December to the President's Council on Bioethics.
Senator Sam Brownback, a Kansas Republican and a leading pro-life advocate did not return a call to his office. Edmund D. Pellegrino, the new chairman of the President's Council on Bioethics, said through a spokeswoman that he had no comment.
But Markus Grompe, a leading stem cell scientist and a Roman Catholic who supports the church's teaching on the unacceptability of destroying embryos, praised the Lanza approach, provided that the extracted cell could not develop into an embryo by itself. "I find it clearly less objectionable than the outright destruction of the embryo," said Dr. Grompe, who studies liver stem cells at the Oregon Health and Science University.
In response to Dr. Grompe's reservation, Dr. Lanza said individual human blastomeres, as the cells are known at this stage, had never been shown to create viable embryos.
If Dr. Lanza's technique proves to work in humans, it could do more than just provide researchers with a new source of cells. It might allow every child born through preimplantation genetic testing to have its own line of embryonic cells stored for the future. The blastomere removed at the eight-cell stage could be allowed to divide, with one cell being used for genetic testing and the other for growing a culture of perfectly matching embryonic stem cells.
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