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Some opponents of stem cell research argue that it offends human dignity or harms or destroys human life. Proponents argue that easing suffering and disease promotes human dignity and happiness, and that destroying a blastocyst is not the same as taking a human life.
Policies vary by country, by region and even by university. They govern whether research can be performed or funded on human embryos themselves and cells made from human embryos. Other policies also require researchers to show that certain stem cell therapies are likely to be safe before testing them in people.
That the depletion of stem cells as we age may be a consequence of DNA damage has been hinted at. New studies now show that DNA repair is needed to keep our blood stem cells in good working order as we age.
Bone marrow transplants containing blood stem cells are used routinely for blood diseases such as leukemia. Almost all stem cells currently in clinical trials are from the blood and bone marrow.
Dolly the sheep came not from the union of sperm and egg but from the mammary cell of one sheep and the unfertilized egg of another. Her birth, more than 10 years ago showed that nuclei from specialized adult cells can be reprogrammed into all the cells of an organism.
Much of the work that had previously convinced scientists that only oocytes, and not zygotes, could be used for cloning came from very careful studies by McGrath and Solter in the 1980s1,2. A few weeks before Kevin Eggan's paper3 was made public, Nature Reports Stem Cells tracked down Davor Solter to learn his thoughts.
Unfertilized eggs have long been the limiting resource for attempts to make genetically tailored human embryonic stem cells. If a new technique for cloning mice from fertilized eggs works in humans, they might not be necessary.
Findings that fertilized eggs can be used to clone mice raise an old question: how can a single cell manipulate DNA to support an entire organism's development?
Scientists should try putting human nuclei into animal eggs. These part-animal cells could produce some of the most powerful tools yet for unravelling human disease. Even if this procedure doesn't lead to embryonic stem cells, the attempt has something to teach us.