German scientists said yesterday that they have created cells similar to embryonic stem cells without using embryos, suggesting a way that stem cell research might advance without the controversy that has surrounded it.
The team of scientists removed sperm-producing stem cells from mice and transformed them into cells that appear to be identical to embryonic stem cells, which can become any type of cell in the body and which lead to new treatments for a variety of diseases.
If the same technique can be adapted to human cells, scientists would not need to use frozen embryos to create the equivalent of embryonic stem cells, and they would not need to clone stem cells -- the two approaches most scientists have been investigating.
Scientists have suggested other ways of avoiding the ethical controversy around embryonic stem cell research. But the new results electrified the scientific community yesterday because the results provided the most convincing evidence yet that doctors may be able to take cells from a patient and turn them into any tissue their body needs, without creating or destroying an embryo.
''This is a very exciting opportunity," said Dr. Christopher E. Shaw, a stem cell researcher at King's College London who was not involved in the research. ''A lot of people are going to be trying to replicate this now."
One prominent critic of embryonic stem cell research predicted that the advance, to be published in the journal Nature next week, would be widely hailed by those who oppose the destruction of human embryos in scientific research.
''This is a big step in the right direction," said the Rev. Tadeusz Pacholczyk, director of education for the National Catholic
Critics of the research believe an embryo is a human life.
Today, embryonic stem cells are typically created using frozen embryos that fertility clinics plan to discard. The embryos are microscopic, balls of several hundred cells. These embryos are placed in a laboratory dish and pulled apart. A stem cell derived this way does not exactly match the patients cells, limiting its potential medical applications.
Another approach involves creating embryonic stem cells by cloning a patient's own cells, which also requires the destruction of an embryo. This creates stem cells that are genetically identical to a patient, allowing scientists to study diseases the patient has, and perhaps, one day to grow replacement cells that will not be rejected by the patient's immune system. To create embryonic stem cells identically matched to a female patient, researchers would not be able to use the new technique, and would still have to use cloning.
Stem cell scientists yesterday cautioned that it is still not known if the new technique will work in humans. First, they said, the procedure will have to be verified by other laboratories. (A number of dramatic claims by stem cell scientists in South Korea collapsed recently when other researchers scrutinized the findings.) Next, researchers will have to adapt the process to humans. The biology of mice and humans is quite close, but technical problems often emerge when techniques that work in mice are attempted in humans.
The Nature report provides evidence that the stem cells created from testicular cells can become any other types of cell, but there are even more stringent tests that do not seem to have been done yet, according to Dr. George Q. Daley, a stem cell scientist at Children's Hospital in Boston and Harvard Medical School. The new cells are clearly stem cells, but they may prove to be more difficult to work with than embryonic stem cells, or less able to form particular types of tissue, he said.
''A lot of work remains to be done before we can believe that these will be as useful as embryonic stem cells," Daley said. ''If this turns out to be true, it will be an exciting advance."
The team, led by Dr. Gerd Hasenfuss, a scientist at the Georg-August-University of Goettingen in Germany, began with tissue taken from the testicle of a mouse, according to the report in Nature. They then isolated spermatogonial stem cells, which churn out sperm throughout the life of a male. The scientists then found a growth medium that pushed the cells to have the same potential as embryonic stem cells, according to the paper.
The key advances over previous work are their approach to purifying the sperm stem cells -- which were known to exist -- and the discovery of a medium that transformed the cells, leaving them capable of producing any kind of tissue.
The team did a number of tests to show that the new cells, called ''multipotent adult germline stem cells" or ''maGSCs," were able to form a wide range of tissues, not just sperm cells. In one experiment, a handful of maGSCs were placed into an early male mouse embryo. The maGSCs went on to form a wide variety of tissues in living mice. Using sperm from 15 mice, the team was able to establish four viable batches of the cells, according to the Nature report.
To harvest sperm, fertility doctors commonly remove the type of testicular tissue that would be needed to conduct similar work in humans, and the procedure is considered very safe, according to Douglas Powers, chief scientific officer of Boston IVF, a fertility clinic. Fertility clinics use the needle biopsy to draw out sperm, but it could also be used to draw out the sperm-generating stem cells needed for the technique. Hasenfuss told the Associated Press that he is optimistic about finding similar cells in humans.
Gareth Cook can be reached at firstname.lastname@example.org.