Embryonic stem cell lines that have been federally approved for
research may be contaminated by the animal cells used to culture
them, according to a study released last week.
These contaminated stem cell lines, 22 in total, cannot be
applied therapeutically because the foreign particles would trigger
rejection by the human immune system.
The findings, published by scientists from UC San Diego and the
Salk Institute for Biological Studies in La Jolla, Calif.,
confirmed the belief of many stem cell researchers that culture
techniques may provide obstacles to clinical use of the current
federally approved lines.
Embryonic stem cells are cultured in media and nutrients derived
from mice, calves and other animals.
Therapeutic application of embryonic stem cells, however, is
still several years of research away.
“It isn’t surprising that there would be some issues
with the existing lines in terms of their clinical utility,”
said Jerome Zack, a professor of microbiology, immunology and
molecular genetics and associate director of the UCLA AIDS
Institute.
“It was pretty obvious we couldn’t use these cells
clinically even if there was a therapeutic application now,”
said Zack, who is researching the use of stem cells for HIV
treatment.
The study confirmed that human stem cells have the ability to
pick up these foreign molecules.
The current state of stem cell research, however, is far from
the point where stem cells could be injected into a human patient
for the potential treatment of diseases such as Alzheimer’s
and diabetes.
“Regulations require strict processing of all biologics
that are going to go into humans,” Zack said. “These
cells are not being cultured that way now so they would not be
useful clinically without major changes in culture
procedures.”
“The reality of it is it really doesn’t affect the
man on the street because these cells are not ready for clinical
use,” Zack said. “In the grand scheme of things there
isn’t a net loss to the potential for stem cells, we just
have to rethink whether the presidential approved lines would be
suitable use for humans,” he added, referring to the
federally approved lines.
Currently, over 60 researchers at UCLA are investigating the
potential of stem cells to treat neurological disorders, regenerate
tissue, and treat other diseases.
“Right now the majority of UCLA researchers doing stem
cell research are interested in fundamental issues rather than
carrying into treatment,” said Harley Kornblum, an assistant
professor in molecular and medical pharmacology and pediatrics in
the UCLA School of Medicine.
Kornblum is currently investigating the use of neural stem cells
in neurological repair and regeneration, and has been an active
supporter of stem cell research on the UCLA campus.
“I think there will be very little impact of this work on
UCLA research except to underscore the need for the development of
new lines,” Kornblum said.
The foreign animal molecules can be eliminated from already
contaminated cell lines if they are cultured under careful
conditions in human serum for several weeks.