Is stem cell research bringing us closer to human cloning?

To some, stem cell research is essentially the same as cloning, while others see the relationship as merely semantic. The gulf between these outlooks is broad indeed. Yet one Stanford professor may have come up with a way to reconcile them.

In between these divergent positions stands Human Biology Prof. William Hurlbut, who sits on the President’s Council on Bioethics. Hurlbut believes that “both sides of this difficult debate are defending important human goods” — proponents of stem cell research claim to defend medicinal progress while opponents advocate the integrity of human life.

In hopes of reconciling these two viewpoints, Hurlbut has proposed a technique he calls “altered nuclear transfer,” which he described as “a way to get embryonic stem cells without creating a human organism.”

Instead of putting the full genetic code inside the egg cell, Hurlbut’s technique will delete several genes from the code before implanting it in the egg. The resultant cell will be fully capable of producing the desired stem cells, but will lack the capacity to develop as a human being.

An issue of language?

The controversy surrounding stem cell research largely derives from the confusion between two differing research techniques: “therapeutic cloning” and “reproductive cloning.”

Whereas therapeutic cloning is used to produce stem cells, reproductive cloning was used to clone Dolly the sheep and could theoretically be used to clone a human being.

But the first steps in both of these techniques are the same. These are the steps in which the incomplete set of genetic material inside a female’s egg cell is replaced with the full genetic code from a body cell such as a skin, liver or brain cell.

This similarity causes some people to confuse the two procedures, even though the latter steps are quite different.

In therapeutic cloning, once the egg cell is given the full genetic code, it is stimulated to grow into a specific kind of tissue — such as brain tissue to potentially relieve Alzheimer’s or pancreatic tissue to treat early-onset diabetes. In reproductive cloning, the egg cell is usually implanted into a womb, and thereby stimulated to grow into a whole new organism, such as a sheep named Dolly.

Laws drafted to restrict reproductive cloning have often blocked funds to therapeutic and reproductive cloning.

The Human Cloning Research Prohibition Act, which is now in Congress, seeks to prohibit all “nuclear transfer technology” — the technology that is essential to both therapeutic and reproductive cloning.

“We’ve got a really serious crisis of language here,” said Idelle Datlof, executive director of Stem Cell Action Network, a non-profit that lobbies in favor of stem cell research.

“When you talk about therapeutic cloning, the word ‘cloning’ is there and you can’t get rid of it,” Datlof said.

Datlof said that deliberate misinformation, sown largely by the religious right, has caused mass confusion in Congress on the issue of stem cells.

“My guess is that it if you gave all the Congressmen the test on what is nuclear transfer, 90 percent would fail,” she said.

Datlof said that the stigma surrounding stem cell research results from a probem of semantics.

“You hear the word ‘fetus’ used interchangeably with the word ‘embryo,’” she said, stating the opinion that an embryo, unlike a fetus, will not necessarily develop into a human life.

However, for Noelle Patno, president of Stanford Students for Life, an activist group that challenges stem cell research, there is more to the stigma than confusion about language.

Patno said she believes that the fetus, the embryo and even the single fertilized egg all deserve the same respect as a human being.

Because an egg cell modified through therapeutic cloning has the capacity to grow into a healthy human being, the resulting cell “is essentially the same as a fertilized egg,” Patno said.

It is this capacity that instills the egg cell with human dignity - the stage of development makes no difference, she added.

Nor does it matter that the modified egg cell is not inserted into a womb. “The location of the embryo does not matter,” Patno said. “Killing human embryos is wrong.”

A proposed compromise

Hurlbut said he believes egg cells that undergo altered nuclear transfer are not the same as a human embryo. He pointed out that, during the stage of development when stem cells are produced, an embryo only uses about a quarter of its genetic material. In theory, one could transfer only that quarter of the genome into an egg. The egg would still be capable of yielding stem cells, but it would be missing three quarters of the genes it takes to make a human. Because of this absence, Hurlbut said he believes that the altered cell is not equivalent to a human embryo.

“Even an egg cell with no nucleus can divide to the eight-cell stage. It appears to be a living being, but would we really call that egg cell a human organism? Of course not,” Hurlbut said.

Hurlbut’s altered nuclear transfer technique is receiving support from prominent figures in politics, science and even in the Catholic Church, which has historically opposed research on embryonic stem cells.

Archbishop William J. Levada recently wrote a letter to President George W. Bush in which he wrote, “As Chairman of the U.S. Conference of Catholic Bishops Committee on Doctrine, I want to assure you of our interest in and encouragement of Dr. Hurlbut’s proposal.”

Hurlbut outlined the technology before the President’s Council on Bioethics last month but it has yet to be put into practice.

However, the good news for Hurlbut is that MIT Biology Prof. Rudolf Jaenisch reviewed the proposal and concluded in an open letter that, “Based on current scientific evidence and reasonable expectations, the proposed approach is both technically feasible and consistent with the scientific and medical goals of embryonic stem cell research.”