South Korean scientists said Thursday that they had developed a more efficient way to produce cloned pigs suitable for organ transplants for humans.
Unlike the traditional cloning method using somatic cells, the scientists said they had used stem cells extracted from pigs' bone marrow to obtain cloned embryos -- much improving the success rate.
The scientists wanted to clone smaller-than-normal pigs weighing between 60-80 kilogrammes (132-176 pounds) when adult, since their organs would be a similar size to human ones.
They said it was the first time such pigs had been cloned using stem cells.
"This is a highly efficient method to produce cloned mini-pigs," said Seong Hwan-Hoo, a senior researcher with the National Institute of Animal Science.
Embryos cloned using somatic cells have only a one to five percent chance of survival, the team said. Using stem cells, this can be increased to 20 percent.
Four baby pigs cloned through stem cells were born on December 3. One was killed for DNA analysis, one was crushed to death while feeding and the remaining two are growing well.
"This technology will be useful to produce mini-pigs with modified genes, whose organs may cause little resistance when transplanted into human beings," Seong told AFP.
South Korea's bio-engineering industry suffered a setback after a much-touted achievement by cloning expert Hwang Woo-Suk turned out to have been faked.
Hwang, who is on trial for fraud, embezzlement, ethical breaches and other charges, has been banned from research using human eggs after his claims that he created the first human stem cells through cloning were ruled to be bogus.