South Korean scientists have created 30 human embryo clones. BBC News Online looks at the significance of the announcement.
What have the Seoul researchers done?
Professor Woo Suk Hwang and colleagues created embryos that were the exact genetic copies of the women who donated the eggs and cells to make them.
They produced 30 embryo clones that divided over several days to a stage where special cells known as embryonic stem cells could be extracted.
How credible is the research?
Several groups have made claims in the past for similar work.
In some cases, no evidence was presented to back up the assertions. In others, where supporting data was published, the embryos stopped dividing at a very early stage.
The Koreans, on the other hand, have shown their embryos to be long lasting. What is more, they have subjected their work to independent scrutiny and a paper detailing their experiments has been published by the international journal Science.
What made the Koreans successful?
The researchers have a proven track record in animal cloning. Indeed, one of the critical steps credited with making these embryos was developed in the field of cattle cloning.
The South Korean team also credits its success to the use of extremely fresh donor eggs, and a special method for emptying the eggs prior to injecting them with the genetic material to be copied.
That genetic material came from the nuclei of cumulus cells. These are tiny clouds of support cells that surround and nourish a developing egg in a woman’s ovaries. Cumulus cells were used to produce the world’s first cloned mouse in 1998.
What is the point of the research?
The Koreans extracted embryonic stem cells from their embryos – “master” cells that can divide into virtually any of the body’s tissues.
The team demonstrated the beginnings of this differentiation and saw it progress still further when the cells were transplanted into mice.
The eventual aim is to use such cells to replace those that have failed in patients with degenerative diseases, such as some heart conditions and Parkinson’s, or in spinal cord injuries.
This is known as therapeutic cloning. The Korean researchers see it as very different from reproductive cloning – attempting to bring about the birth of a cloned baby. How far away is therapeutic cloning?
Experts believe it will be many years before stem cell treatments based on cloning technology are available.
If the cells come from a cloned embryo they should not be rejected by the patient because they match exactly that individual’s genetic make-up.
At the moment, patients have to take powerful drugs to prevent their body’s immune system from attacking tissues transplanted from another person.
Are there not ethical concerns here?
All embryo research draws the criticism that it is tampering with cells which have the potential to be human beings.
The Korean experiments were given approval by an ethical review board and all the women who donated cells and eggs gave informed consent – but this will mean nothing to those who are uncomfortable with this kind of science.
Could this latest work bring a cloned baby closer?
Scientists have been struggling to clone monkeys. It is clear there are particular difficulties involved in making genetic copies of primates.
The Korean research shows some of these technical hurdles can be overcome and those minded to produce cloned babies will attempt to use the new information to make children.