the VOA Special English Health Report.
experts predict that doctors will someday use stem cells to treat many
different diseases. Yet so far there has been less progress in stem cell
therapies than many had hoped.
years, scientists have studied stem-cell treatment of cancer. Doctors now use
stem cells in therapies for several forms of the disease. But at the same time,
researchers increasingly are examining a possible connection between stem cells
number of researchers now point to stem cells as a possible cause of solid
tumors. Studies have reported identifying cancer stem cells.
can develop into any kind of cell, like skin, blood or brain cells. Embryos
have more stem cells than adults. Embryonic stem cells can develop into all the
many different tissues that form the body.
there are stem cells that remain throughout a person's life to replace cells
that become damaged. When a stem cell divides, one of the two cells remains a
stem cell. The other becomes a specialized cell.
questions remain to be answered. But the general thinking seems to be that
cancer stem cells represent a small population of the cells in a tumor. Some
researchers think these cancer stem cells have the ability to divide and change
into other types of cells. As a result, they think the stem cells help the
cancer to metastasize, or spread to other organs.
researchers also think cancer stem cells are able to repair and feed tumors so
they continue to grow. They suspect that the cells are even able to repair
damage from radiation treatment and form new tumors. This could explain why
some cancers resist drug therapies.
the research into cancer stem cells is being done in California and Canada.
Last week, Canadian Health Minister Tony Clement and California Governor Arnold
Schwarzenegger announced joint efforts. Their governments agreed to provide one
hundred million dollars each over the next three years for research into cancer
California company says it is close to tests in humans of a drug that would
directly target cancer stem cells. Two scientists who led the discovery of cancer
stem cells in solid tumors, Michael Clarke and Max Wicha, started OncoMed
Pharmaceuticals four years ago. OncoMed has signed an agreement with a major
drug company, GlaxoSmithKline, to work on the experimental treatment.
that's the VOA Special English Health Report, written by Caty Weaver. I'm Steve Ember.