A new study, conducted by Dr. Jerry L. Hall, examines a technique that could create stem cells that could turn into nerve cells without the requirement for human fetuses.
The study was performed on mice and explored the usefulness of asexual reproduction towards the goal of producing stem cells.
Dr. Jerry L. Hall is an embryologist at the Institute for Reproductive Medicine and Genetic Testing, a fertility clinic in Maryland. He discovered a method, using chemicals, by which he could coax an egg cell to begin to develop without fertilization by a sperm cell. Embryos produced in this manner would not be able to develop into a child, even if they were implanted in a womb. They do live long enough, however, to produce viable stem cells in the laboratory.
Stem cells are extremely useful to scientists, both for analytical and clinical applications because they are undifferentiated cells, which under the right conditions, can be directed to develop into virtually any other type of cell in the body. This could prove clinically useful by providing a means for creating replacement cells that could be transplanted into the patients.
Currently stem cells are stirring up quite a lot of ethical controversy because they can only be obtained by destroying deceased human fetuses.
Dr. Hall argues that if an "embryo" were not formed by conception and would not be able to turn into a child, that might make stem cell work more acceptable.
This research study may provide an alternative means to obtaining the stem cells needed for scientific research without the need to destroy embryos.
"We feel that this really could circumvent a lot of ethical concerns," said Dr. Hall.
The techniques utilizes the ability, called Parthenogenesis, of some species of flowers, insects, lizards and snakes, to reproduce asexually, without the requirement for the female egg to be fertilized by male sperm.
This phenomenon has been known to science for many years, and scientist have known how to trick the eggs of mice, mice, rabbits and other mammals into developing as if they had been fertilized by subjecting the eggs to various chemicals or to temperature changes, needle pricks or electrical shocks.
In normal reproduction the egg cell must eject half of its chromosomal DNA in order to accept the half that comes from the male sperm. The technique described in this study involves the suppression of the DNA ejection from the egg, so that the egg will develop with a full compliment of DNA.
Dr. Hall claims that the embryo developed in this way would not be a clone of the mother, because the chromosomal DNA in the egg is slightly different than the woman's DNA. However, he also says that the egg's DNA would be close enough to the mother that re-implantation would be possible.
However, much concern still surrounds the ethical questions concerning stem cell research.
Richard M. Doerflinger of the United States Conference of Catholic Bishops, said the technique was unlikely to end the opposition the Roman Catholic Church has to embryonic stem cell work.
"The fact that these beings would not survive to birth does not answer the question," Doerflinger said, "Our teaching about the embryo does not rely on it having been created by fertilization."
Numerous questions about the practicality of the experiment, which has yet to be published in a scientific journal, resound, concerning whether the stem cells could turn into other types of cells, or even if the nerve cells produced would be like normal nerve cells.
Dr. Azim Surani, a professor of biology at Cambridge University, said that it was unclear how many other types of cells could be created this way. "They don't form muscle cells very easily," he said.
Dr. Surani also said the parthenotes and any tissues derived from them might be abnormal. That is because in normal embryo development, certain genes from the father but not the mother, or vice versa, are turned on. But parthenotes don't have genes from the father, so this process, called imprinting, would go awry. Lack of imprinting is also probably the reason that parthenotes do not develop into babies, he said.
However, Dr. West said it might be possible one day to produce human babies through parthenogenesis. Male parthenotes could be created, too, he said, by replacing the DNA in an egg with the DNA from two of a male's sperm cells.
Dr. West said that if this process could be used to produce live offspring it would open up vast new reproductive possibilities. A woman could give birth by herself. Or two men may be able to each contribute one sperm to have a baby together.
Dr. Hall, who's research has so-far been limited to mice studies, says that he has not yet tried to derive human stems in this manner. The University of Massachusetts, working in conjunction with Advanced Cell Technology, a stem cell and cloning company in Worcester, Mass, has applied for a patent on using the technique to derive stem cells from primates, including humans.
Scientist ts the university and company were able to derive a line of stem cells from monkeys using the technique, which can be maintained for months and directed towards development of any type of cell. In fact, the cells from this stem cell line spontaneously began to develop into a variety of specialized cells such as beating heart cells.
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