According to their research that will be published Friday in the journal Science, the scientists produced 11 human stem cell batches, or lines, that are genetic matches of 11 patients age 2 to 56.
The patients — six adults and three children — have spinal cord injuries, juvenile diabetes and a rare immune disorder.
Although the patients whose cells were copied do not stand to benefit at this time, the researchers hope to study the cells to understand their conditions better, according to Reuters.
The research team, led by Dr. Woo Suk Hwang and Dr. Shin Yong Moon of Seoul National University, announced in February 2004 that it had produced a single stem cell line from a cloned embryo.
The team’s latest research, incorporating several technical improvements, demonstrated a more efficient method of culling master cells, therefore, making the pursuit of therapeutic cloning more practical.
Therapeutic cloning produces stem cells — universal cells that are extracted from embryos, destroying the embryos in the process — that can, in theory, be directed to grow into any of the body’s cell types.
Since the stem cells came from embryos that are cloned from individuals, they should be exact genetic matches and, therefore, can be used to study the origin of diseases and develop replacement cells identical to the ones a patient has lost, reported The New York Times.
“I didn’t think they would be at this stage for decades, let alone within a year,” said Dr. Gerald Schatten of the University of Pittsburgh, who served as an adviser for the Korean lab in analyzing its data, quoted the Associated Press.
“It is a tremendous advance,” said Dr. Leonard Zon, a stem cell researcher at Harvard Medical School and president of the International Society for Stem Cell Research, who was not involved in the research, the Times reported.
The work, carefully regulated by the South Korean government, is still controversial in the United States, where the House and Senate are considering rival bills that would either ban the research outright or encourage it with more federal funding.
Currently, federal funding of stem cell research in the United States is strictly limited, but researchers may use private funding as they wish.