Wednesday, Oct. 23, 2002
United Press International
Scientists said Tuesday they can increase the number of stem cells derived from umbilical cord blood significantly by exposing the blood to a particular molecule. The finding could have important implications for stem cell research.
Dr. Irwin Bernstein, a pediatric oncologist at Fred Hutchinson Cancer Center and the University of Washington, in Seattle, led a research team to determine how best to use stem cells that can be derived from umbilical cord blood.
To do so, they exposed cord blood in the laboratory to a protein molecule called Delta-1. Although it remains unclear exactly how the molecule works, it somehow increased the number of immature stem cells in a sample of cord blood 100-fold.
It also increased the number of hematopoeitic stem cells, which are cells that can evolve into any type of cell found in blood.
As reported in the Oct. 22 issue of the Journal of Clinical Investigation, the researchers next tested their newly harvested cells in mice with deficient immune systems. The animals' immune systems resembled those of leukemia patients who have undergone radiation therapy before a bone marrow transplant.
Such patients are left with collapsed immune systems, making them vulnerable to infection.
Study results showed the enhanced stem cells were more potent in the mice compared with non-cultured stem cells or stem cells not exposed to Delta-1. This finding is critical, the researchers said, because it helps scientists overcome a major obstacle in the transplantation of cells into adults.
When cells are transplanted, the body typically recognizes them as foreign and attempts to reject them.
"What we're interested in and what we're trying to understand is what makes a stem cell renew," Bernstein told United Press International. "We're only beginning to learn about hematopoeitic stem cells."
Scientists are studying stem cells because they can be developed into a variety of mature cells, involving the immune system, blood or different types of tissue.
The ability to regenerate tissues could have major implications for the treatment of many diseases, such as Alzheimer's, Parkinson's and cancer.
So far, however, such efforts have been difficult, Bernstein said, because stem cells behave differently in the body, their natural environment, than in the laboratory.
The finding that certain stem cells behave differently when exposed to Delta-1 could improve the ability to control stem development, he explained.
"We can use this information to begin to engineer so we can grow these stem cells in vitro and use them for therapeutic value," Bernstein said. "It used to be thought this [stem cell differentiation] was all random, but it isn't."
Alternative to Killing Human Embryos
Stem cells from umbilical cord blood also might be an ideal alternative to embryonic stem cells, which remain highly controversial because to harvest them human embryos must be destroyed.
"To me, cord blood seems to be best alternative" source of stem cells, David Harris, director of the Cord Blood Registry Stem Cell Bank in Tucson, Ariz., told UPI. It offers the same advantages as embryonic stem cells without the ethical problems, he said.
Harris, a professor of immunology at the University of Arizona, said researchers have known since the 1960s umbilical cord blood was a rich source of stem cells.
He called Bernstein's findings "very promising. The sooner it gets into clinical trials, the better.
"Newborn stem cells don't have those emotional, moral problems that
fetal stem cells have," Harris said.
© Copyright 2002 by United Press International