Fusion might end need for embryo cells

1st step reported

decade of development forecast

August 23, 2005|By Jonathan Bor and Dennis O'Brien | Jonathan Bor and Dennis O'Brien,SUN STAFF

A Harvard scientist who led experiments that transformed skin cells into stem cells said yesterday that the technique could lead to ways to dispense altogether with the use of human embryos - but it could take a decade to accomplish.

When embryonic stem cells were fused with adult skin cells, the stem cells, in effect, taught the more mature cells to act just like them.

"This set back the clock of these cells to their embryonic state," said Dr. Kevin Eggan, lead author of the study scheduled to appear Thursday in the online journal Science.

FOR THE RECORD - An Aug. 23 article mischaracterized Richard Doerflinger's position on the importance of therapeutic cloning. Doerflinger, deputy director of the Secretariat for Pro-Life Activities for the U.S. Conference of Catholic Bishops, said he considers cloning immoral and unlikely to produce health benefits and believes money should not be spent on it.
The Sun regrets the error.

The goal, said Eggan, is to decipher the mechanism used by the embryonic stem cells - gathered from laboratory cultures - in reprogramming the skin cells. Such know-how might give scientists the ability to transform the adult cells directly, without relying on cells taken from human embryos.

"For those who have fundamental objections to the destruction of embryos, this experiment still carries the same moral burden," Eggan said of the fusion approach.

Embryonic stem cells are the master cells that produce every tissue type in the human body, including bone, skin, muscle and brain. Since scientists in 1998 found ways to isolate them and culture them in the lab, they have became a fertile but controversial tool for research into treatments and cures.

While scientists are searching for a path that does not require embryos, they could employ the fusion method to produce large colonies of stem cells to replace the abnormal cells of patients suffering from Parkinson's, diabetes and other ailments.

That faces technical hurdles, too.

Foremost is that the fusion of two cells results in a hybrid carrying twice the DNA of a normal cell. To avoid safety problems before use in human therapies, scientists must find a way to remove unwanted DNA before or after the fusion occurs.

Ultimately, the technique could provide an alternative to therapeutic cloning, a method tried successfully by Korean scientists. In that method, scientists rid a human egg of its genetic material and replace it with DNA plucked from an adult cell. This turns the egg into an embryo that produces a pocket of stem cells that can be extracted and multiplied in lab dishes.

For both techniques, a patient requiring treatment would supply tissue used to generate the replacement cells. Consequently, the resulting stem cells would stand little chance of being rejected once transplanted into the patient, scientists say.

The fusion technique does not create a new embryo that would soon be destroyed. That could help surmount objections of those who argue that stem cell research involves the destruction of potential life, but only if scientists can avoid using embryos to start with.

Richard Doerflinger, deputy director of pro-life activities for the U.S. Conference of Catholic Bishops, said he considers the findings a positive step because they might lead to scientific advances that could end the practice of using embryos.

But he said other approaches such as research using umbilical cord blood should also be pursued. "In science, there's always more than one way to skin a cat. We want those ways found without skinning human embryos," he said.

Doerflinger said the findings undercut support for therapeutic cloning because they show the potential for creating healthy cells tailored to individual patients without cloning.

"The idea that we need to do cloning to come up with cells that are an identical match for a patient seeking treatment may be superseded by this," he said. However, he added that therapeutic cloning remains an important avenue for research.

The findings, Eggan said, do nothing to reduce the need for new stem cell lines beyond the limited number that President Bush made available for federal funding in a policy announced in August 2001. The rule has frustrated scientists and advocates for research into Alzheimer's, cancer and other diseases.

A bill to ease those restrictions passed the House in May, and Senate approval is expected after Labor Day. Bush is expected to veto the measure.

Daniel Perry, president of an advocacy group that has lobbied for the bill's approval, said the Harvard experiments do not diminish the need for easing restrictions on federal funding.

"This is a time for making regulations and guidelines less restrictive, more flexible and to be supporting science," said Perry, who leads the Coalition for the Advancement of Medical Research. "This is not the whole game. It's very preliminary."

Dr. Judith Swain, dean of translational medicine at University of California San Diego medical school and an expert on stem cell research, said the Harvard team's work could eventually help avoid the emotionally charged issue of embryo destruction.

She warned against being overly optimistic, however, noting that some once-promising discoveries relating to bone marrow cells and gene therapies have yet to translate into therapies.

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