BioWorld International Correspondent
LONDON - The announcement last week by a South Korean team that they cloned human embryos to provide embryonic stem cell lines should have far-reaching implications for medical research.
The breakthrough could hasten the day that people can donate cells to repair their own damaged organs, perhaps after the cells have undergone gene therapy in a test tube.
A UK team reported almost simultaneously that they, too, had cloned a human embryo.
Woo Suk Hwang, professor of veterinary medicine at Seoul University in South Korea, told a packed press conference in London: "This report brings science a giant step forward toward the day when some of humankind's most devastating diseases and injuries can be effectively treated through the use of therapeutic stem cells."
The South Korean team's paper was published on the Sciencexpress website on May 19, 2005. Its title: "Patient-Specific Embryonic Stem Cells Derived from Human SCNT Blastocysts."
The UK team's paper, titled "Derivation of a human blastocyst after heterologous nuclear transfer to donated oocytes," is being refereed by the journal Reproductive Biomedicine Online, although an abstract is available on the journal's website.
Hwang's group denied that the latest advances would speed up progress toward reproductive cloning. Speakers at the press conference called for an international ban on reproductive cloning, and said they believed it was far too dangerous to attempt.
Instead, the emphasis was on the benefits that the "extraordinary set of discoveries" reported would hold for medical research and the development of new therapies. Gerald Schatten, a professor at the University of Pittsburgh School of Medicine and an author of the Science paper, told the press conference: "I don't want to mislead you that that these are truly clinical-grade, patient-specific human stem cells - but, boy, they are real close."
The speed of progress by the South Koreans has taken the scientific community's breath away. Last year, Hwang and his colleagues reported that they had taken the nucleus of a woman's cell and transferred it into one of her own oocytes. That experiment took 242 tries before they derived a single cell line and because the donor of the nucleus and the donor of the oocyte were the same person, the scientists weren't able to tell whether the embryo that developed was entirely programmed by the "donated" nucleus.
Their latest publication demonstrated a major increase in efficiency. They now take a cell derived from a skin biopsy, and transfer the nucleus into a donated oocyte. Refinements in the technique mean that they now have to do it about only 12 times to be sure of getting a cell line. They also use a layer of the remaining cells from the skin biopsy to grow the stem cells - meaning that the only animal products remaining in the cell line are some enzymes and calf serum.
Perhaps most importantly, Hwang's team also has been able to prove that the embryonic cell lines they derived are genetically identical to the donor who supplied the nucleus. Their paper in Science described how they produced cell lines using nuclei from male and female patients, aged 2 to 56, who had spinal cord injuries, juvenile diabetes and inherited immune deficiencies.
The importance to medical research right now, Schatten said, is the ability to generate embryonic cell lines from patients with different diseases.
"This affords tremendously important research in understanding the root causes of devastating diseases," he said. "Imagine being able to take skin cells from a dozen children with autism and grow their stem cells, and differentiate them into neurons; then contrast them with a dozen other cell lines generated from their identical twin brothers or sisters who do not have autism - or schizophrenia, or asthma, or chronic obstructive pulmonary disease, or obesity, or juvenile diabetes."
Julian Savulescu, director of Oxford University's Uehiro Centre for Practical Ethics, said it was a "huge ethical step forward" that much medical research would in future be done on cells and not on people. He called for an international collaborative research effort on a scale to match that of the Human Genome Project.