April 5, 2004
Stem Cells Used in Bone Marrow Research
CHICAGO --- Researchers at Northwestern University have devised
a method to induce embryonic stem cells to develop into bone marrow
and blood cells. Injecting the stem cells into the bone marrow
cavity of mice whose bone marrow cells had been depleted restored
production of blood cells, including cells of the immune system,
which normally are created in the bone marrow.
As reported by Richard K. Burt, M.D., and colleagues in April
issue of The Journal of Experimental Medicine, the method was effective
even in genetically mismatched mice.
If the same results can be produced in humans, the technique
may eventually eliminate the need to find genetically matched human
bone marrow donors for persons with leukemia, autoimmune diseases
and other immune disorders, Burt said.
Burt is associate professor of medicine and chief of immunotherapy
for autoimmune diseases at the Feinberg School of Medicine at Northwestern
University.
Embryonic stem cells, which are derived from embryos, have the
potential to grow into many different cell types. Burt and colleagues
identified the most effective mix of growth factors to induce stem
cells in culture to develop into precursor bone marrow and blood
cells. They also developed a technique to select the most viable
cells for injection.
Despite the genetic mismatch between donor and recipient mice,
the injected cells were not rejected. The injected cells matured
into a new immune system that recognized the recipient as self.
Blood or marrow
stem cells from a sibling or an unrelated or cord blood registry
often fail to develop tolerance to the recipient
or patient into which they are infused – an often-fatal complication
after bone marrow transplantation that is known as graft-versus-host
disease.
But in the
study, after embryonic stem cell transplantation the mice’s
immune response, while tolerant to self, responded to foreign
substances normally, indicating that recipients are
able to fight off infection. Although the use of human embryonic
stem cell lines is controversial, it has many advantages over the
use of donor bone marrow or blood cells, which are highly variable,
cannot be cultured in a laboratory, may cause lethal graft-versus-host
disease and are often not available to patients due to inability
to find a suitably matched donor.
Human embryonic stem cell lines can be cultured indefinitely,
providing a permanently renewable alternative marrow source that
restores blood cell production with an intact immune response without
causing graft-versus-host disease. |