May 19, 2005
WASHINGTON - South Korean scientists have created the world's first human embryonic stem cells that are customized to injured or sick patients, a major step in the quest to grow patients' own replacement tissue to treat diseases.
These same scientists last year became the first to clone a human embryo, sparking international clamor. But those cloned stem cells - the building blocks that give rise to every tissue in the body- were a genetic match to a healthy woman, not a sick person. And it wasn't easy: It took 242 donated human eggs to grow just one batch.
Now the Seoul scientists have cloned patient-specific stem cells, important if doctors are to develop cell-based therapies that won't be rejected by the body's immune system. The technique worked with males and females, as young as 2 and as old as 56 - all suffering either spinal cord injuries, diabetes or a genetic immune disease, the researchers report in Friday's edition of the journal Science.
And the Korean lab found faster and safer ways to cull stem cells, using far fewer donated eggs - about 20 per try. They also eliminated use of mouse "feeder cells" that have been used to nourish most human stem-cell lines, thus easing concerns about contamination.
Any therapy is still years away from being tested in people.
"Therapeutic cloning has tremendous, tremendous healing potential, but we have to open so many doors before human trials," lead researcher Hwang Woo-suk of Seoul National University said in a telephone interview. "Our work reveals the possibility that this technology could be applied in the patient himself in the future."
Stem-cell specialists called the research remarkable.
"This is a very important advance," said Dr. Janet Rowley of the University of Chicago, a genetics specialist who helped co-author recent ethics guidelines on stem-cell research from the Institute of Medicine. "It's surprising to me the amount of progress they've made in basically a year's time."
"This paper will be of major impact," said stem-cell researcher Dr. Rudolph Jaenisch of the Whitehead Institute for Biomedical Research in Cambridge, Mass. "The argument that it will not work in humans will not be tenable after this."
The work marks "a gigantic advance" for another reason, said neuroscientist Fred Gage of the Salk Institute for Biological Studies in San Diego. By cloning stem cells from sick patients, scientists can watch, in a test tube, the very earliest origins of diseases like Alzheimer's, insight that could point to other ways to prevent and treat illness, explained Gage, who plans to do some of that work.
The Korean research "will be a tremendous boon to the investigation of the nature and biology of human disease," he said.
It's also sure to revive international controversy over whether to ban all forms of human cloning, as the Bush administration wants - or to allow cloning for medical research, so-called therapeutic cloning that South Korea has committed by law to pursue.
Culling stem cells destroys the days-old embryo harboring them, regardless of whether that embryo was cloned or left over in a fertility clinic. Because opponents argue that is the same as destroying life, President Bush has banned federally funded research on all but a handful of old embryonic stem-cell lines - and the South Korean work spotlights the frustration many U.S. scientists felt at being left behind.
"It's just going to highlight the tragedy of our current situation in America where there are technologies that are promising that are not being pursued by talented American scientists because of ideologic constraints," Rowley said.
The Seoul researchers collected eggs donated by 18 unpaid volunteers and removed the gene-containing nucleus from them. They inserted into those eggs DNA from skin cells of 11 people who had spinal cord injuries, Type 1 diabetes or a congenital immune disease.
Chemicals jump-started cellular division, and 31 blastocysts - early-stage embryos - successfully grew. From those, the scientists were able to harvest 11 colonies, or "lines," of stem cells, each one a genetic match to the patient who had donated a skin snippet.
The scientists were careful to explain to the research participants that getting medicine made from their stem cells is a long shot. They don't yet know how to control which types of tissues - brain cells, bones, muscles, etc. - the stem cells form, something the Korean lab is studying next.
"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 acted as an adviser to the Korean lab in analyzing its data for U.S. publication. "All of us in the biomedical communities owe our colleagues in Korea a tremendous debt of gratitude."
The work raises ethical concerns, cautioned Stanford University bioethicists David Magnus and Mildred Cho. Scientists must ensure that women understand they get no benefit and can be put at some risk when they agree to donate eggs for medical research - and that patients who volunteer also understand that it's unlikely they'll benefit from any stem cells they help to clone because so many years of research are yet required, they wrote.