Canadian researchers find new stem cell source
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TORONTO — A part of the umbilical cord once thought to have no value has been found to contain a rich source of stem cells, offering hope for improved success in bone-marrow transplants and tissue repair, Canadian researchers say.
The stem cells are found in the connective tissue surrounding blood vessels in the umbilical cord and can be removed and grown in a few weeks to provide an abundant number of cells, said John Davies, a professor of biomaterials at the University of Toronto and head of the team that reported its findings in the journal Stem Cells.
These stem cells, called mesenchymal progenitor cells, are those that go on to become bone, cartilage, muscle or other connective tissue.
It's long been known that blood from the umbilical cord is a source of blood-forming stem cells, and an increasing number of parents are having them frozen and stored as insurance against future diseases in their child or other family members.
"This provides another source of cells which could be stored from the umbilical cord, which is otherwise just thrown away," said Davies, whose team used cords only from full-term newborns, donated by parents specifically for research.
Davies said these stem cells could be used in transplanting bone marrow - the body's factory for stem cells that develop into the components of all the different tissues of the body, from the brain and organs to muscles and bone.
Bone-marrow transplants are often performed to treat leukemia and some other cancers, as well as immune-deficiency disorders. The transplant requires blood-forming stem cells as well as connective-tissue stem cells.
But with the difficulty of matching bone-marrow donors and recipients, more doctors are scooping stem cells from the bloodstream, growing them in the lab, then infusing them into the patient.
Davies said previous studies have suggested that adding more connective-tissue stem cells could boost the success rate of bone-marrow transplants, which currently averages about 40 per cent.
In bone marrow, connective-tissue stem cells and blood stem cells "talk to each other and depend upon each other for their survival," said Davies.
"So there's an increasing understanding out there that we may be able to radically increase the success of marrow transplants by co-infusing blood stem cells with mesenchymal cells."
Bill Stanford and his wife, who are both involved in stem-cell research, had their first child in April and decided to bank their son's blood stem cells and his mesenchymal cells.
"We were too impressed by this source of stem cells not to take advantage of this biological insurance," said Stanford, a cell biologist at the university, adding that the cells could potentially lead to treatments for a myriad of connective-tissue diseases in the future.
Among those are arthritis and osteoporosis, both common among North America's greying population.
"Mesenchymal stem cells can leave the marrow during injury and actually home (in) to the tissue which is damaged," Davies said. "This is why these cells are very important to us in an ongoing state of tissue repair throughout life."
Administering an extra dose of these connective-tissue stem cells can also help repair broken bones or build new cartilage, he said.
Dr. Allen Eaves, a senior scientist at the B.C. Cancer Institute, called the discovery of the new source for the stem cells exciting.
"The cord is normally discarded after birth and this is a non-controversial source of stem cells, and this makes it particularly attractive," Eaves said from Vancouver. Controversy has arisen over proposals to use stem cells from aborted fetuses or fetuses grown specifically for research.
"More study is really needed to try and optimize the use of these cells," said Eaves. "There's no question they have some therapeutic use."
As well, studies have shown that those stem cells that survive the deep freeze and thawing out are missing an antigen that causes transplant rejection - suggesting that these cells could be used safely in non-related people, the researchers said.
The next step for Davies and his team is to test the mesenchymal stem cells in immunologically deficient mice to see how they might develop if they were infused back into a human body.