UConn scientists create stem cells from cloned cattle
It is the first time scientists have been able to grow stable stem cell lines from a large mammal. They've done this only with mice or monkeys until now.
"So many people have tried to do this for so many years," said Dr. Xiangzhong Yang, director of UConn's Center for Regenerative Biology and an acknowledged expert on cloning. "We didn't think we could do it."
The results of the UConn team's research, led by Dr. Cindy Tian, an assistant professor at the center, Yang and Dr. Enkui Duan of the Institute of Zoology of the Chinese Academy of Sciences in Beijing, has been published in the March 2005 edition of the Journal of Reproduction.
Embryonic stem cells are the cluster of cells that form shortly after a sperm fertilizes an egg. These cells have the ability to grow into all the different types of tissue and organs in the body: skin, hair, bones, brain tissue, internal organs.
In recent years, scientists have become excited by the potential of these cells. There is hope that if researchers learn how to manipulate them, stem cells can be used to heal damaged organs and to cure chronic neurological diseases like Parkinson's disease.
"We might be able to cure Type I diabetes by using stem cells to repair the pancreas," said Dr. Thomas Wagner, a professor of molecular biology and director of oncology research at Clemson University's Greenville Hospital System in Greenville, S.C. "In the last 25 years, we've learned more about the human system than we had in the whole history of mankind."
But in the United States, President Bush has limited federal funding for this research to 60 existing embryonic stem cells. To allow new lines to be created, he has argued, would mean using more human embryos for research, which goes against his beliefs.
With federal funding not keeping pace with research, and with most of those 60 federally approved lines contaminated, individual states have pledged to begin their own stem cell research initiatives. Connecticut may spend $10 million to $20 million to support such research.
The state also created the Center for Regenerative Biology at UConn, headed by Yang, who in the 1990s was the first researcher to produce a cloned bull, as well as the first cow cloned from farm animals.
The center created one of its embryonic stem cell lines through in-vitro fertilization, letting sperm impregnate an egg in a petri dish. The center created the other two lines through cloning. It removed the nuclei from unfertilized eggs and replaced them with DNA from a cell taken elsewhere from the animal - in this case, the skin -and induced the eggs to begin dividing.
The three colonies have been producing new cells for over a year. These cells have enough similarities to human embryonic stems cells that they may be better models for study than mouse cells, Yang said.
Cattle are large mammals, like humans, and the growth patterns of cow embryos closely resemble ours.
"It takes a cow about nine months to produce a calf, like a human," said Clemson's Wagner. "A mouse has a fetus in 10 days. It's a much faster, more concentrated process."
These cells thus might prove important now, as humans begin to understand how stem cells work and how they might be used to cure injury and disease.
"We will need different animal models," Yang said. "That's what makes this so exciting."
Another reason for the scientific enthusiasm about UConn's work is that it produced two of the lines through cloning.
Cloning is a loaded word; for many people it brings forth the image of people asexually producing exact duplicates of themselves.
But therapeutic cloning has different implications. It could mean that researchers could take a few skin cells from a human and create a line of embryonic stem cells that carry that person's DNA. They could then manipulate the cells to produce cells to repair a specific organ. Unlike the organ transplants of today, there would be no worries about rejection - the cells and organs would carry the patients' genetic code.
"That's why therapeutic cloning is so important," Yang said..
"No one is talking about creating new people," Wagner said. "This therapeutic cloning. Jerry Yang has show the safety of his techniques in this. He's a brilliant man."
What the UConn team has not been able to do at this point is to use enzymes to break up the bovine stem cells colonies into new colonies - something researchers have done with monkey and mouse stem cell colonies.
"That's our next step," Yang said. "This is a new field."
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