A technique to eliminate potentially lethal side effects of stem cell therapy has been developed by researchers at the Stanford University School of Medicine.
With the right combination of growth factors, skill and patience, a laboratory tissue culture dish promises to yield therapeutic wonders.
But within these batches of newly generated cells lurks a big potential problem: Any remaining embryonic stem cells - those that haven't differentiated into the desired tissue - can go on to become dangerous tumours called teratomas when transplanted into patients.
Now, the Stanford University researchers have found the way to remove these pluripotent human embryonic stem cells from their progeny before the differentiated cells are used in humans. ("Pluripotent" describes cells that are able to become all types of adult tissue.)
"The ability to do regenerative medicine requires the complete removal of tumour-forming cells from any culture that began with pluripotent cells," said Irving Weissman, MD, director of the Stanford Institute for Stem Cell Biology and Regenerative Medicine.
"We've used a combination of antibodies to weed out the few undifferentiated cells that could be left in the 10 or 100 million differentiated cells that make up a therapeutic dose," he stated.
The scientists believe the technique could also be used to remove residual tumour-initiating cells from populations of cells derived from induced pluripotent stem, or iPS, cells.
These cells may also be useful for therapy but, unlike embryonic stem cells, iPS cells are created in the laboratory from adult tissue.
The researchers found that combining antibody anti-SSEA-5 with two other antibodies known to bind to pluripotent cells completely separated the pluripotent from the differentiated cells, although they did see some smaller, less-diverse growths in some cases.
The study was published online Aug. 14 in Nature Biotechnology.