Updated December. 27, 2007 03:01
A group of Korean scientists successfully cloned a pig using stem cells for the first time in the world. Roh Gyu-gin, a professor at the veterinary college in Gyeongsang National University, said yesterday that he created a cloned pig using stem cells extracted from pigs in partnership with the National Livestock Research Institute in Gyeonggi Province, along with Professors Lee Eun-song of Kangwon University, Professor Hyeon Sang-hwan of Chungbuk University and Dr. Seong Hwan-hoo of the National Institute of Animal Science.
Pigs are similar to humans anatomically and biologically, and their organs are also similar to those of humans. The team thinks the technology used to create the cloned pig will be used to enhance efficiency when producing cloned pigs for organ transplants. Until now, somatic cells have been used to clone animals.
Professor Roh said, Cloning somatic cells stood at around 1-5% in terms of production efficiency because it posed the risk of deformities, premature births and deaths, stillbirths, miscarriages, and the death of fertilized eggs. By using stem cells that are less specialized than somatic cells, the efficiency level can be elevated to 20%.
The team extracted mesenchymal stem cells from the bone marrow of around 70kg-heavy female mini pigs, which have a similar organ size with adult humans. Mesenchymal stem cells are a kind of adult stem cells that are in the early stages of specialization, which makes it harder to extract, cultures and store them than somatic cells. The team removed a nucleus from an egg and replaced it with mesenchymal stem cells, which then were electrically shock fused to create a cloned fertilized egg. Around 100 of these eggs were implanted on the uterine wall of five female pigs (surrogates).
One out of five gave birth to four baby cloned pigs on December 3. One piglet weighed 400g and the rest weighed 800g. The 400g-heavy piglet was used for research; the other one was squeezed to death while suckling the breast of the mother; and the other two are healthy.
Two more surrogates are expecting birth. Professor Roh said, Mice and cows were cloned using stem cells in Japan, but pigs were cloned for the first time here. In the future, clone technology, in which genes with a modified immune system are inserted into stem cells, will enable the creation of different organs that cause no immune resistance for transplantation.
The team is currently writing a paper to publish its findings in an international journal. The research was conducted with funding from the Bio Organ Project of the Rural Development Administration.