IN A reversal of fortune for biomedical researchers in the US, President Bush
announced last week that he will allow federal funding for limited research on
stem cells taken from human embryos.
Embryonic stem cells (ESCs) have the ability to develop into any type of cell
in the body, something scientists hope will allow them to grow replacement
tissues for transplants, and treat diseases such as Alzheimer鈥檚, Parkinson鈥檚 and
diabetes. The US government will now support research on ESCs, but only ones
from existing cultures.
In Britain, it is legal to extract ESCs from discarded IVF embryos and use
them for research into fertility or treatments for disease, or to take them from
embryos made for therapeutic cloning research. The same work is legal in the US
if it鈥檚 privately funded. But critics find this kind of research morally
repugnant because it involves destroying human embryos.
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During his election campaign, Bush promised to ban government funding for ESC
research. His hard-line attitude drew criticism from patients suffering from
diseases that ESCs may some day treat. Bush says he has tried to balance all
these concerns in his decision. 鈥淚 have concluded that we should allow federal
funds to be used for research on these existing stem cell lines where the
life-and-death decision has already been made,鈥� he said.
The move has met with a mixed response from researchers. 鈥淭he proposed
compromise will slow the research,鈥� says James Thomson of the University of
Wisconsin in Madison, whose team pioneered the extraction of human ESCs. 鈥淏ut
the compromise is better than halting the research entirely.鈥�
Experts disagree over how many lines there are and how long they will retain
their ability to transform into other cell types. Some scientists argue that the
60 existing cell lines that Bush cited are insufficient.
Others say genetic differences could mean some embryos are more suitable
sources of stem cells for research than others. Diane Krause, a stem cell
researcher at Yale University, adds that limiting the genetic diversity of the
stem cells available could hamper work on treatments for certain diseases.
鈥淲e need to see a variety of these in order to fully understand the
applications to multiple different diseases,鈥� Krause says. 鈥淚t will be good
enough for some purposes, but it will be limited.鈥�
Despite all these reservations, some researchers welcomed Bush鈥檚 change of
heart. 鈥淚鈥檓 enormously relieved,鈥� says George Daley, a stem cell researcher at
the Whitehead Institute in Cambridge, Massachusetts. 鈥淭his will energise the
scientific community. It鈥檚 about as good an outcome as we could have
补苍迟颈肠颈辫补迟别诲.鈥�