WORCESTER, Mass., Jan. 31 (UPI) -- Researchers said Thursday that they have created a renewable line of stem cells using unfertilized egg cells from a monkey.
While stem cells created without sperm had previously been produced using mouse egg cells, this is the first time it has been done in primates. Stem cells can develop into essentially any type of tissue and are thought to hold hope for the treatment of numerous diseases.
Lead researcher José B. Cibelli of Advanced Cell Technology in Worcester, Mass., told United Press International: "You can generate very nice cell lines, like this one, and they can produce all the cell types. They may have developmental problems in terms of making the whole organism, but they can certainly make the cells very easily."
Cibelli said the cells appeared to be immortal and were a renewable source of cells that can differentiate into different cell types.
"These cells will be very useful for women of reproductive age to help themselves," Cibelli told UPI.
George Daley, a stem cell researcher at the Whitehead Institute in Cambridge, Mass., told UPI: "The issue remains as to whether or not these cells will face the same transplantation barriers as any other allogenetic (same species) human tissue. I expect they will."
Daley said one advantage would be that with parthenogenesis, since the material is only coming from one individual -- the mother -- instead of two individuals, it could simplify the tissue matching process, which is the key to a successful transplant.
Should this research bear fruit and be applicable in humans, with cell lines from several hundred different types of people, a tissue bank could be developed that might be able to serve almost anyone, Daley theorized. It may be found that tissue transplants are better tolerated than organ transplants, he added.
There still are many questions about transplant compatibility of parthenogenetically derived stem cells, he added.
In the experiment, reported in this week's issue of the journal Science in a paper titled "Parthenogenetic Stem Cells in Nonhuman Primates," 77 eggs were taken from macaques, a species of monkey. After being allowed to mature in a glass container under very specific conditions for 36 hours, about one-third of the eggs were successfully tricked into thinking they had been fertilized by changing the calcium level of the fluid in which they were contained. A few of the cells then developed to what is called the blastocyst stage, which normally occurs in humans about five days after conception.
Parts of the inner portions of the cells were then removed using microsurgery techniques and put into a glass dish. After about one week, three of the cell masses that had been removed had undergone proliferation or multiplication. Of these three cell masses, one culture produced a stable line of stem cells that have now been grown for 10 months and have maintained their undifferentiated state.
Further work by the group showed the stem cells could be induced to form into nerve tissue. The undifferentiated cells also were injected into immunosuppressed mice where they formed benign tumors that consisted of the three main classes of cells, forming cartilage, muscle, bone, neurons, skin, hair, intestinal and respiratory cells.
The nerve cells were shown to secrete dopamine, raising hopes that techniques can be developed to allow tissue to be placed in the brains of Parkinson's patients to replace lost neurons. Such cells already have been developed in mice from embryonic stem cells.
The work, involving 17 researchers, was done at Advanced Cell Technology; Wake Forest University Medical School in Winston Salem, N.C.; Sloan Kettering Cancer Center in New York City; and the Mayo Clinic in Rochester, Minn.
Some scientists expressed cautious optimism. "One report doesn't necessarily make a finding that we can count on, but nevertheless it is intriguing," said Mark Frankel, director of the scientific freedom, responsibility and law program for the American Association for the Advancement of Science, based in Washington.
Asked if the parthenogenesis method might be acceptable to some people opposed to stem cells derived from fertilized eggs that have become embryos, Frankel said, "It's not an embryo in the traditional sense of having been fertilized by a sperm and for those who believe that is the moment at which life begins, that's very significant, since they may not view this 'embryo' produced by parthenogenesis in the same way that they view an embryo created by fertilization."
One molecular biologist who has studied medical ethics closely, Kevin FitzGerald of Georgetown University, said the unique development of partenotes, that is, eggs stimulated to divide without sperm, might cause some people to drop their objection to stem cells derived from human eggs.
But FitzGerald, a research associate professor in the department of oncology at Georgetown University Medical Center and the David Lauler chair for Catholic heath care ethics, raised another point.
"One thing that gets lost in the discussion about all the wonderful benefits that will come from this research, and often the justification used to go ahead with research that is controversial and ethically contentious, is that the benefits outweigh the risks," he said. "And presumably the benefits mean all these people who are going to be benefitted. And the question that seriously needs to be looked at is, 'Is it indeed true that all these people will be benefitted?'"
Many people, if not most, even in the United States, are not seeing the benefits of medical research, FitzGerald told UPI.
(Reported by Joe Grossman in Santa Cruz, Calif.)
