South Korean scientists have surmounted a key hurdle in stem-cell research, reporting Thursday that they have produced 11 human embryo clones of injured or sick patients and harvested individualized stem cells – a template for creating therapeutic cells for anyone.
The experiment involved both male and female patients ranging in age from 2 to 56 and produced stem cells much more efficiently than before, validating the technology’s medical feasibility.
The findings were reported by the same team that produced the first human embryo clones last year.
Scientists said that if the process can be replicated in other labs, they could create individualized lines of stem cells to produce tissues suitable for transplants without running the risk of rejection.
Patient-specific lines of embryonic stem cells could be created to produce new heart muscle to repair the damage from a heart attack, for instance, or fresh brain tissue to treat stroke victims.
Researchers also could develop cell lines to study different types of cancer and genetic diseases, such as Alzheimer’s, Parkinson’s and juvenile diabetes.
“It just opens a floodgate of possibilities,” said Fred Gage, a professor of genetics at the Salk Institute in La Jolla, Calif.
The researchers, who published their work in the online edition of the journal Science, insisted that their progress in cloning human embryos will not make things easier for anyone attempting to create a cloned baby, which they believe is impossible in any event.
“Reproductive cloning is not our goal,” said Woo Suk Hwang, the lead researcher from Seoul National University. “Reproductive cloning is unsafe and unethical, and so it shouldn’t be done in any country.”
Hwang created human embryo clones last year using eggs and DNA from the same donors, all healthy women.
This time, the donor eggs were mixed and matched with unrelated DNA from patients.
Tests verified that the stem cells were able to multiply as well as differentiate into neurons, muscle, bone, cartilage, and respiratory and islet cells, among others.
Ian Wilmut, the Scottish scientist who led the team that cloned Dolly the sheep in 1996, called this a “remarkable improvement in efficiency” that marks “a very significant step forward.”
Scientists also said it was significant that the South Koreans were able largely to overcome a persistent problem with contamination that plagues stem-cell lines.
A study earlier this year by Gage and others found that human stem cells nourished by tissue from mice, calves and other animals have incorporated a type of acid that would trigger a harmful immune response if transplanted into humans.
Each of the advances reported in the paper is considered crucial to achieving the ultimate goal of customizing stem cells to treat individual patients, said Gerald Schatten, a biomedical researcher at the University of Pittsburgh and a co-author of the study.
Researchers strongly suspect that tissues made from stem cells containing a patient’s own genetic material are most likely to succeed in a transplant because there would be little danger of tissue rejection or other complications.
“This may be nature’s best repair kit,” said Schatten, who leads the Pittsburgh Development Center, a biology research institute.
But there is a range of genetic diseases that can’t be solved by simply growing new tissue from stem cells because they would contain the same defects that caused the disease.
Scientists, however, believe stem cells still could be used to research other cures by illuminating “the cellular mechanisms that cause these diseases to occur,” Gage said.
Although 60 percent of Americans support embryonic stem- cell research, according to a poll conducted this month by Gallup, they remain uncomfortable with the idea of human cloning, with 87 percent of respondents calling it “morally wrong.”
David Magnus, the director of the Stanford Center for Biomedical Ethics and the author of an article accompanying the Science study, said Hwang’s approach largely avoids serious ethical complications. Scientists say the cloned embryos are incapable of growing into healthy babies because they don’t go through all the steps that normally follow fertilization of an egg by a sperm.
He said embryos produced through cloning have fewer ethical strings attached than embryos discarded from in vitro fertilization clinics, which do have the potential to become babies.
