Stem Cell Treatment for Leukemia Improved
Transplant Technique Speeds Immune System Recovery
Jan. 19, 2010 -- Leukemia patients who receive stem cell transplants from the umbilical cord blood of newborns are usually vulnerable to life-threatening infections for at least a month as their immune systems recover.
Now researchers from Seattle’s Fred Hutchinson Cancer Center may have found a way to dramatically shorten this recovery period and reduce infection-related deaths.
In a small, early study, the researchers were able to successfully manipulate umbilical cord-derived stem cells to speed the production of infection-fighting white blood cells.
It took about two weeks for the transplanted cells to start making white blood cells on their own -- a process known as engraftment -- compared to a month when patients got the non-manipulated cord blood.
The research appears in the Jan. 17 issue of the journal Nature Medicine.
“If we really can make stem cell sources better, this may mean we would have donors for pretty much everyone who needs a transplant,” study researcher Colleen Delaney, MD, tells WebMD.
Many Patients Can’t Find Matches
Stem cell transplants are performed in some patients with leukemia and other blood cancers to help the body make new blood cells after its own blood cells have been destroyed by disease or cancer treatments.
But cord blood contains only about one-tenth of the stem cells found in bone marrow, and this is why cord blood transplants usually take so much longer to engraft.
The advantage of cord blood transplants is that they do not need to be as perfectly matched to the patient as bone marrow transplants.
Close to one in three patients -- and as many as 95% of non-white patients -- who could benefit from a stem cell transplant never find a suitable match.
Researchers have long sought ways to increase the number of stem cells in cord blood in an effort to speed the production of infection-fighting white blood cells.
In the new research, the Fred Hutchinson researchers manipulated a system known as the Notch signaling pathway, which is involved in embryonic development.
By engineering a protein that activated the pathway, the researchers were able to expand the number of stem cells in a single unit of cord blood about 164-fold -- from 200,000 stem cells per kilogram of body weight to 6 million.
In a phase I study, 10 leukemia patients were treated with one unit of non-manipulated cord blood and one unit manipulated in the lab.
It took 14 days for the manipulated stem cells to engraft versus four weeks for the non-manipulated cells.
“We have shown that we can decrease the time to engraftment,” Delaney says. “Now we have to show a clinical benefit to the patient.”