Jewish World Review June 4, 2002 / 23 Sivan, 5762

Cloning used to create functioning kidney

By Steve Mitchell | (UPI) Scientists have used cloning technology to create successfully functioning kidneys and implant them into cows for the first time, a major step toward proving the potential for therapeutic cloning to generate new tissues and organs for treating disease, researchers announced Monday.

This opens the way to creating insulin-producing cells for treating diabetes, kidneys, hearts and even brain tissue, Robert Lanza, vice president of medical and scientific development at Worcester, Mass.-based Advanced Cell Technology and lead author of the research paper, told United Press International.

It has "unlimited applications," he added.

One argument against the use of therapeutic cloning -- the process of transferring DNA from a single cell of a organism into an egg cell from a donor and ultimately creating tissues and organs used to treat disease -- is that the resulting organ retains genetic material from the egg donor, which many cloning experts have thought might trigger organ rejection by the host's immune system.

Anthony Atala, director of tissue engineering at Children's Hospital in Boston and the study's senior researcher, told UPI, "The study shows nicely that rejection is not an issue."

Lanza noted there are two major problems with transplanting organs from one person to another -- immune rejection of the transplanted organ and a shortage of donor organs. "Our results suggest it may become possible to overcome both of those problems," he said.

Hans Scholer, a cloning researcher and director of the University of Pennsylvania's center for animal transgenesis and germ cell research, told UPI the results indicate "therapeutic cloning is something that is feasible. The kidney is a complex system, and if you get that worked out, I would see this as an important step," Scholer added.

Barring any legislative hurdles, Scholer said he believes the research could be applicable to humans in two or three years. The House has passed a ban on all cloning, but it is unclear whether the Senate, which is expected to take up the issue soon, would allow therapeutic cloning.

"This is one of the most exciting announcements in a long time," because it shows "the real promise of therapeutic cloning," Ron Gree, chairman of ACT's ethics advisory board, professor of religion and director of the ethics institute at Dartmouth College, told UPI. "Tissue regeneration strategies are going to be the basis of 21st-century medicine."

The ethics board, which consists of cloning and ethics experts with no financial ties to ACT, did not become heavily involved in the current research because it did not involve human cells. But Green noted that the board's general position is "the cloning of early human embryos as long as it does not go beyond 14 days is acceptable given the research promises and benefits."

Applying this cloning technique to humans would not involve the creation of embryos per se because stem cells would be harvested from the cloned cells before they ever got to a stage to be declared an embryo. But Green thinks the technique will be a "little more controversial than embryonic stem cells."

He added, "These are not embryos ... but I understand that people will be upset. I think we're gonna do our right to life debates around this issue."

Atala noted: "It's important for people to remember that the cell mass you obtain from using this technique comes from the union of a skin cell and an egg instead of a sperm cell and egg" as in the case with an embryo. "You're not sacrificing an embryo to do this."

In the study, which appears in the July issue of Nature Biotechnology, Lanza's team took DNA from a skin cell from a cow's ear and placed it inside a donor egg cell. The egg then was placed inside a surrogate mother to generate an early-stage cow embryo. In humans, this step would not be necessary, he explained, because stem cells could be harvested from the initial clone and these could then be used to generate organs and tissues.

Heart, muscle and kidney cells were harvested from the embryo and transferred to three-dimensional scaffolding to give the cells a backbone to grow around. All the tissues were implanted under the skin of the cattle from whence they came, and none showed any signs of rejection.

The kidneys, although miniature compared to adult cow kidneys and not placed in the abdominal cavity where kidneys are normally positioned, appeared to be fully functional and even produced urine, Lanza said.

The heart tissue was not grown into a fully functioning heart, but it does demonstrate how it may be possible to use this type of tissue to repair damage after a heart attack, he added. "The next step would be to engineer an entire heart ... but this is some time off," he said.

Lanza pointed out it was important to do the research in a cow to understand fully whether the cloned organ would be rejected because these animals have a sophisticated immune system similar to humans' compared with the rather primitive immune system of the more common research animal, the mouse.

"The results are encouraging in terms of proceeding with this type of research, but certainly much more research needs to be done," Atala said.

Lanza was similarly cautious. "Before you would ever apply this to a human, you'd need to very vigorously make sure this is safe in humans and everything is working fine," he said.

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© 2002, United Press International