James Sherley: No Path to Find Cure-All

James Sherley: No path to find cure-all

If it was wrong to clone human embryos in 2002, it is wrong today

| October 12, 2006 The Australian

IN 2002, federal parliament made a historic decision to ban cloning embryos for research or reproduction. Recognising that human embryos should be given some respect, MPs passed legislation allowing leftover human embryos to be used for research but outlawed the creation of cloned human embryos that would be destroyed for research.

Now parliament is revisiting this question with some members, who opposed cloning embryos just four years ago, adopting the surprising view that the previous law should be overturned. The public must ask those parliamentarians who propose overturning the law: "Why?"

Certainly, if it was wrong to clone human embryos in 2002, it is still wrong today. The basis for some to reverse their position and promote the use of cloned human embryos for research is their belief that embryonic stem cells produced from cloned embryos will yield an amazing medicine chest of new cures for debilitating diseases.

Nothing could be further from the truth. Cloning is the process by which a human embryo is produced artificially by putting the genetic material from an adult cell into a human egg that has had its genetic material removed. Cloned embryos can be matured to a point at which embryonic stem cells can be extracted.

This process has been successful in animal studies but has yet to be confirmed for human cells.

Previous fraudulent reports by South Korean scientists, who claimed to have succeeded, are a well- known blot on the image of human embryonic stem cell science. But even if someone achieves this feat, the cells produced will have no value for developing new cures for defects in adult tissues.

There are several reasons for this state of affairs that Australian members of parliament must consider when they exercise their conscience vote next month.

First, it is well known that cloned embryos and the stem cells derived from them have defects in their genetic program. These defects will certainly render tissues derived from them ineffective and potentially dangerous.

Second, cloned embryonic stem cells, as with embryonic stem cells in general, form tumours when transplanted into adult tissues. Though some scoff that this problem can be solved with research, it is as difficult as curing cancer.

The third reason is due to a fundamental aspect of mammalian biology. Embryonic cells cannot be used to replace adult tissues. Adult stem cells are responsible for the continuous renewal and repair of adult tissues and organs. They accomplish this by dividing to remake themselves and create new cells that mature to carry out the function of the tissue.

These mature cells have a limited lifetime and must be continuously replaced by the special division of adult stem cells. Embryonic stem cells cannot replicate in this fashion and the mature cells proposed from them are not sufficiently long-lived to allow effective cures for diseases and injuries in the tissues and organs of children and adults.

Scientists in Australia who promote research based on cloned embryos may be interested in probing living human beings at the earliest stage of life, but they are certainly not going to provide any benefit in the form of new cures.

Even the proposal to use cloned human embryos to investigate adult disease mechanisms has no scientific legs. The worth of such studies will be limited by the inherent genetic defects in cloned embryos and, fundamentally, diseases that arise in the adult are not likely to manifest until later in embryonic development, if at all before birth.

Finally, it is important for federal MPs to know that in stopping the production of cloned embryos for research, they will not deny their constituents the opportunity for new cures from advances in stem cell science.

Despite similar misinformation to the contrary, adult stem cell research is a viable and vibrant path to new medical therapies. Even calling them an alternative to embryonic stem cells misinforms the public.

Why? Because embryonic stem cells provide no path at all.

James Sherley is associate professor of biological engineering at Massachusetts Institute of Technology in Boston. He is in Australia this week as a guest of Doctors Against Cloning.