Human-cloning claim creates controversy.

Public relations ploy or scientific breakthrough? That's one of the questions swirling around a biotech firm's disclosure this week that it has cloned human embryos, although they never grew larger than a few cells.

The goal of these experiments is not to create a cloned person but to grow such embryos long enough that stem cells can be harvested, say scientists at Advanced Cell Technology (ACT), the Worcester, Mass., company that did the work. ACT investigators and other researchers contend that human embryonic stem cells, immortal cells that can develop into any cell type in the body, will one day help treat a wide range of medical conditions (SN: 11/7/98, p. 293).

However, scientists fear that a patient's immune system may reject stem cells unless they are genetically identical to the patient's other cells. ACT says that cloning technology can produce such individually matched stem cells.

This latest embryo research "represents the dawn of a new age in medicine by demonstrating that the goal of therapeutic cloning is within reach," ACT president Michael West and his colleagues write in the January 2002 SCIENTIFIC AMERICAN.

The ACT scientists stripped the DNA from 19 human eggs and implanted in each a DNA-containing nucleus from an other person's cell. They then applied chemicals to trigger the eggs to begin dividing as if they had been fertilized by a sperm.

Only 3 of the 19 eggs undergoing this procedure actually started to divide. One reached the two-cell stage, another the four-cell stage, and the third egg developed into six cells.

The company's work drew predictable outrage from political and religious leaders who find such human-embryo research immoral, but the experiments also drew criticism from biologists who were less than impressed.

"Scientifically, in terms of a breakthrough, it's a very minimal one," says developmental biologist Brigid L. M. Hogan of Vanderbilt University in Nashville. "It's obviously a publicity stunt."

Hogan and other researchers contend that ACT's work offers little scientific information about the feasibility of human cloning, whether intended to produce a person or stem cells. The egg would have to develop into a ball of about 100 cells before researchers could harvest stem cells or implant the embryo in a woman's uterus.

The cloned embryos didn't even survive to the eight-cell stage, in which they would have started to make use of genes. That fact suggests that the DNA transfers performed by the ACT scientists were a failure, says Hogan.

William A. Haseltine, editor of the JOURNAL OF REGENERATIVE MEDICINE, the peer-reviewed publication in which ACT details its experiments, defends the work as the beginning of a long-term effort to make replacement cells and tissues for people. "This is not a big step, but it's the first step," he says.

Not surprisingly, that step has reinvigorated a debate in Congress over whether or not to ban all or some types of human cloning. The House of Representatives has already approved a full ban, but the Senate has yet to act.

The work by ACT researchers "activates the debate again, but it would have been nice to do that with good science," says Hogan, who sits on a National Academy of Sciences panel that has been considering the merits of human cloning (SN: 10/20/01, p. 250). The panel's report, due out soon, is widely expected to recommend a ban on cloning intended to create a person.