Baltimore, MD (4/2/99)- The dream that adult stem cells could be used
to create organs and to treat cancer, heart disease and other disorders appears
to be a step closer to reality. New research confirms that the necessary cells
can be isolated from bone marrow and have the capability to form structural
and connective tissues.
For the first time, researchers have been able to isolate a particularly
rare cell in human bone marrow, the mesenchymal stem cell. These cells can
replicate as undifferentiated cells and have the remarkable ability to differentiate
into different kinds of tissues including bone, cartilage, fat, tendon, muscle,
and marrow stroma. After isolating the cells from donor bone marrow, the researchers
accomplished another first, encouraging the stem cells to differentiate into
colonies of fat, cartilage and bone cells.
"When we saw that human adult stem cells could be expanded from a single
cell that would differentiate to all three lineages, that really clinched
it. Each of the lineages that we reported in Science has important
health implications associated with them, ranging from the direct regeneration
of bone and cartilage injuries, to the treatment of osteoporosis, osteoarthritis
and obesity," said Mark F. Pittenger, Ph.D., associate director, Muscle Research
and Cell Biology, Osiris Therapeutics.
left Isolated marrow-derived stem cells differentiate in vitro to multiple
lineages appropriately to the adipogenic (Adipo), chondrogenic (Chondro),
and osteogenic (Osteo) lineages.
Adult mesenchymal stem cells go through a sequence of proliferation, commitment
(deciding which cell type to be), differentiation (forming the cells) and
maturation- the creation of healthy tissue. In a healthy human, these cells
take care of the replacement and regeneration of human connective tissues.
How these cells are stimulated to proliferate and differentiate is not well
understood. The growth and differentiation conditions for each lineage, such
as bone, cartilage and fat, are quite different, involving a combination of
growth factors, nutrients, spatial organization and mechanical forces. The
new research findings will provide researchers with a way to study these processes
outside of the body.
Until this point, stem cell research has concentrated on the potential of
hematopoeietic stem cells derived from embyronic tissues. The current research
with mesenchymal progenitors marks a new direction in stem cell research and
could offer a way around ethical concerns (and federal regulations) on the
use of stem cells derived from embryos.
It is exciting to think of growing stem cells to produce complex tissues
and organs for the restoration of damaged or diseased tissue. However, much
research remains to be done to establish the safety and reliability of such
The research appears in the April 2, 1999 issue of the journal Science.
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