Seeking a cure in stem cell therapyOne out of every 1,000 babies born worldwide suffers from a neural tube defect, in which the spinal cord or brain has not developed properly. Methods to repair the congenital abnormality, such as surgery on the fetus, can involve daunting risks.
At the other end of the age spectrum, progressive neurological diseases that primarily affect people over the age of 50, such as Parkinson’s disease, still have no cure.
But a glimmer of hope for treating such diseases has emerged as a result of the work of a scientist who specializes in reproductive cell research.
Park Se-pill, 44, the director of Maria Biotech Co., has demonstrated for the first time the possibility of treating incurable conditions, including neural tube defect, in embryos through stem cell therapy.
Stem cells are primitive cells that have the capacity to differentiate into various cell types, and thus may be able to ameliorate or cure various diseases. Though stem cell research is in its initial stages, scientists believe it may have great potential.
“The use of embryonic stem cells will play a significant role in curing many incurable diseases in the future,” Mr. Park says. “That is why scientists around the world are involved in such research. Instead of organ transplants, now we are focusing on treating the damaged parts of an organ by injecting stem cells.”
Recently, a team at Inha University’s medical school said it injected stem cells extracted from the bone marrow of patients with spinal paralysis into the damaged areas of the patients’ spinal cords and found that their condition improved.
Last month, Maria Biotech, a research institution established by Maria Infertility Hospital and Seoul National University Children’s Hospital, said Mr. Park and Wang Kyu-chang, a professor of neurosurgery and dean of the university’s medical school, succeeded in resealing open neural tubes of chicken embryos by injecting them with human embryonic stem cells.
In a normally developing embryo, the neural tube fuses to produce the brain and spinal cord.
The Maria Biotech researchers cracked the shells of three-day-old fertilized chicken eggs and opened the embryos’ neural tubes. They then transplanted embryonic stem cells into the amniotic cavity and observed whether the neural tube cells reproduced in the proper form. After seven days, the amniotic cavity had nearly disappeared, indicating a fusing of the tube. According to Mr. Park, this is the first stem cell therapy research conducted on animals.
A four-year project
This was the result of a four-year research project that began in December 2001, initiated by the Health Ministry to develop organic tissue regeneration technology.
Mr. Park’s relationship with stem cell research began when he was in a veterinary medicine doctoral degree program at Konkuk University. His professor suggested he specialize in reproductive cell study, Mr. Park says. “That was the time when interest in cloning was growing,” he adds.
He then did postdoctoral study in the life science department of the University of Wisconsin.
In August 2000, Mr. Park was the first in Korea to succeed in producing embryonic stem cells, derived from five-year-old frozen human embryos. This followed similar experiments in the United States and by a group of researchers from China and Australia.
Another breakthrough in research on stem cell therapy came last year, when Mr. Park successfully transplanted genetically modified stem cells into the brain of a mouse with Parkinson’s disease and cured it.
Despite the worldwide interest in stem cell research, producing stem cells from an embryo is not an easy task. “If there is too much nutrition, stem cells will differentiate and will no longer be considered stem cells, but if nutrition is insufficient, stem cells will die,” he says.
The experiments encountered difficulties, but the biggest problem was dealing with ethical issues. Since Mr. Park succeeded in producing stem cells from human embryos, his work was considered unethical by some. “I got a lot of criticism. People don’t want to look at the importance of the research, but they confront me with ethical issues,” Mr. Park says.
A couple of years later, Mr. Park experienced another setback that almost cost him his job.
In spring 2002, he was doing research aimed at generating human embryonic stem cells from an embryo created by inserting human genetic material into a “hollowed-out” cow egg. But dozens of protesters denounced Mr. Park for interspecies cloning, which they believed could create a half-human, half-cow species.
“It was a difficult time,” Mr. Park says. Protests mainly came from religious groups, who wrote letters to newspapers and posted messages on the Internet. But, he says, “Creating a species by interspecies cloning is impossible.”
The work was put on hold because of the protests. But while the research was suspended here, China succeeded in breeding stem cells from an interspecies embryo created by fusing a human cell nucleus with a hollowed-out rabbit egg.
“Cloning and stem cell research in China has developed rapidly due to strong backing by the communist government,” Mr. Park says.
Because of ethical concerns, Mr. Park has not yet cloned a human embryo, though he said the same methods used in cloning a cow embryo could be used in the human case. Early this year, Hwang Woo-suk, a professor of veterinary medicine at Seoul National University, and a team of researchers there said they suceeded in growing stem cells from a cloned human embryo.
The government has passed a law that will allow stem cell and cloning research for therapeutic purposes, using only five-year-old frozen embryos that are ready to be discarded. It will take effect next year.
“The situation has improved greatly,” Mr. Park says. “I am glad the government passed the ethics law on cloning.”
One reason Mr. Park tried to clone an embryo with cow eggs is the difficulty in obtaining enough human eggs. “Most women who come to Maria Infertility Hospital for artificial insemination don’t want their eggs used in stem cell research even after they succeed in getting pregnant and giving birth to a baby,” Mr. Park says. “They say they want their unfertilized eggs destroyed instead.”
Asked how Korea has achieved its current position in cloning and stem cell research, Mr. Park says, “A lot of basic research has been done [here].”
What is the next step? Continuing his research on transplanting stem cells into chicken embryos, Mr. Park has been studying whether the treated embryos can develop normally into fully grown chickens. While declining to discuss the project in detail, he says, “The results have been positive.”
by Limb Jae-un
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