Scientists Welcome Tetra – First Monkey Cloned Through Embryo Splitting

Scientists from Oregon Regional Primate Research Center, Portland, US, have pioneered the first successful cloning of a monkey. "Tetra is the world's first monkey cloned by embryo splitting," says a proud Gerald Shatten, of the Oregon Regional Primate Research Center.

Tetra was created from splitting the embryo or fertilized egg, of a Rhesus monkey.

The procedure is not unique- similar clones of cows and mice have been created before. Yet what makes scientists elated is that this is the first time a monkey, the closest genetic relative of the human, has been cloned. They hope this step will now bring them closer towards cures for ‘incurable’ and terrible diseases, as identical monkeys will be the best models for studying human diseases.

"The potential to understand the genetic basis for disease in a close animal relative may lead to life-saving cures faster," says Shatten. At the same time, this experiment is completely different from the cloning of Dolly the sheep. The latter involved a procedure called nuclear transfer.

Yet, these two experiments have something in common: both have stirred up hornets’ nests of controversies surrounding the ethics of cloning.

The procedure -embryo splitting basically involves splitting of an eight-celled embryo into four identical parts. This is what the body does naturally when it produces triplets, quadruplets etc.

It is for this very reason that fears of technology being rushed in to answer problems of human infertility, and permit human clones have risen.

"There's always been a discussion about using this technology for increasing the number of embryos for couples in infertility treatments. To my knowledge it hasn't been demonstrated yet in humans but there's clearly that potential there," says Dr. John Gearhart of Johns Hopkins University.

Another concern is ‘ enraged animal activists’. "Monkeys are just much more sympathetic creatures than lab mice or rats," says Tom Murray of the Hastings Center.

The Oregon researchers have also revealed that they have successfully made stem cells from these embryos. These could be transformed into heart and nerve tissue, they say.

If so, this would be a laboratory milestone that could clear the way for similar work in human beings.

The study also resurrects hope that a similar process using cloned human embryos could create transplant tissue genetically matched to patients. This would help to thus avoid the risk of rejection.

Until the early release of the study, originally slated for publication in the British scientific journal Nature on Nov. 22, scientists had all but given up hope that it would ever be possible to clone the embryos of primates. This biological order includes monkeys, apes and human beings.

In 2005, South Korean researchers had claimed to have created stem cells from cloned human embryos. Yet, this highly publicized effort turned out to be one of science’s greatest hoaxes.

Meanwhile, the path is now open once again for cloning of human embryos. "I'm quite sure it will work in humans", lead investigator Shoukhrat Mitalipov says.

Human embryonic stem cells are created shortly after a fertilized egg begins to grow. They have the potential to become virtually any organ or tissue under the right conditions. This is what makes them alike the Holy Grail of stem cell researchers. Stem cells made from such embryos could be chemically coaxed to make a new heart for a dying child, to help cement a severed spinal cord of someone paralyzed in an accident, etc., or serve as reservoirs of human part replacements.

Mitalipov's ultimate goal is to clone a living rhesus monkey, and produce copies of the clone with genes removed or "knocked out”, so that human diseases can be mimicked. Researchers are currently limited to the use of such genetically engineered mice to study human diseases in the lab. Yet, the greatest constraint is that mice are biologically quite different from humans.

Mitalipov says he has no interest in cloning a human being - a feat that would be more complex technologically and, scientists agree, ethically indefensible.

Yet, scientists hope they can adapt the latest techniques to produce human embryos for the harvest of stem cells for therapeutic cloning. President Bush has banned the use of federal funds for such research, yet it could be resurrected by a $3 billion stem cell initiative approved by California voters in 2005.

Source-Medindia
ANN/P