Key to Growing New Human Stem Cells Found
Scientists at Duke University Medical Center have demonstrated they can grow
human stem cells in the laboratory by blocking an enzyme that naturally
triggers stem cells to mature and differentiate into specialized cells.
The discovery may enable scientists to rapidly grow stem cells and transplant
them into patients with blood disorders, immune defects, and select genetic
diseases, said the researchers.
Stem cells are the most flexible cells in the body, continually dividing into
new stem cells or into specialized cells that carry out specific roles in the
body. But little is known about how stem cells choose their fate. The Duke
team focused on hematopoietic stem cells.
In their study, published on line and in the upcoming August 1, 2006, issue
of the PNAS, the investigators discovered that an enzyme, aldehyde
dehydrogenase (ALDH), stimulates hematopoietic stem cells to differentiate
into blood or immune cells. They inhibited this enzyme in stem cell cultures
and successfully increased the number of stem cells by 3.4 fold. Moreover,
they demonstrated the new stem cells were capable of fully rebuilding the
blood-forming and immune systems of immune-deficient mice.
Our ability to treat human diseases is limited by our knowledge of how human
stem cells determine their fate that is, whether they maintain theirability
to self-renew or whether they go on to become specialized cells, said John
Chute, M.D., associate professor of medicine in the Duke adult bone marrow and
stem cell transplant program and the lead author of the study. Unraveling the
pathways that regulate self-renewal or differentiation in human stem cells can
facilitate our ability to expand the growth of human stem cells for therapeutic uses.