Stem cell hope takes heat off embryos
The Age |
August 23, 2005
By Rick Weiss
SCIENTISTS for the first time have turned ordinary skin cells into what appear to be embryonic stem cells — without having to use human eggs or make new human embryos in the process, as previously required.
The new technique, announced by a Harvard research team in the US, uses laboratory grown human embryonic stem cells to "reprogram" the genes in a person's skin cell, turning that skin cell into an embryonic stem cell itself. Since the new stem cells made this way are essentially rejuvenated versions of a person's own skin cells, the DNA in those new stem cells matches the DNA of the person who provided the skin cells.
In theory at least, this means that any tissues grown from those newly minted stem cells could be transplanted into the person to treat a disease without much risk that they would be rejected, since they would constitute an exact genetic match.
Until now, the only way to turn a person's ordinary cell into a "personalised" stem cell such as this was to turn that ordinary cell into an embryo first and later destroy the embryo to retrieve the new stem cells growing inside — a process called therapeutic cloning.
That prospect, like others in the promising arena of human embryonic stem cell research, has stirred strong emotions among those who believe that days-old human embryos should not be intentionally destroyed.
The new approach, which is to be published later this week in the journal Science but was made public on the journal's website on Sunday, could offer an end to the heated social and religious debate that has for years overshadowed the field of human embryonic stem cell research.
Embryonic stem cells are capable of becoming virtually any kind of cell or tissue and are being intensely studied around the world as the core of a newly emerging field of regenerative medicine, in which researchers hope to grow new tissues to revitalise ailing organs.
The latest research is likely to have an impact on Capitol Hill, where the Senate is poised to vote on legislation — already passed by the House — that would loosen US President George Bush's restrictions on human embryonic research.
Earlier this month, Republican Senate Majority Leader Bill Frist said he would break with the President and support the Senate bill, which Mr Bush promised to veto.
Some opponents of relaxing the current restrictions have argued that new techniques will soon eliminate the need to use human eggs or embryos to make cells that are, to all intents and purposes, human embryonic stem cells.
They and others have for some months predicted that if such new findings were to emerge, they could shift the balance of votes in the Senate.
The researchers emphasise in their report that the technique is still far from finding application in medicine. Most important, they note that because it involves the fusion of a stem cell and a person's ordinary skin cell, the process leads to the creation of a hybrid cell. While that cell has all the characteristics of a new embryonic stem cell, it contains the DNA of the person who donated the skin cell and also the DNA of the initial embryonic stem cell.
At some point before these hybrid cells are coaxed to grow into replacement parts to be transplanted into a person, that extra DNA must be extracted.
Several teams, including one in Illinois and another in Australia, are making progress removing stem cell DNA from such hybrid cells.