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WASHINGTON (Reuters) - Cloning technology may someday
be able to give patients "re-booted" immune systems, offering new
treatments for diseases ranging from pneumonia to multiple sclerosis,
US researchers said on Thursday.
Stem cells made from cattle traveled throughout their
blood, and out-competed the animals' older, native cells, researchers
at a Massachusetts biotechnology company told a conference.
The research has not been reviewed by other scientists,
a standard procedure in medical science, but the team at Advanced
Cell Technology has reported regularly on cloning experiments, including
the first reported attempt to clone a human embryo.
The privately held firm, which has herds of cloned
cattle, is also testing the use of so-called therapeutic cloning,
which uses cloning technology for medical experiments.
The idea is to help a patient grow new cells and tissues
using his or her own cells, eventually leading to "grow-your-own"
transplants and other treatments. But the approach is controversial
because an embryo must be created and then taken apart in the procedure.
"We used the therapeutic cloning procedure to give
old cows new immune cells," Robert Lanza, medical director at ACT,
said in an interview conducted by E-mail.
They found the oldest cattle they could and cloned
them.
"These animals were the equivalent of 70-year-old
humans," Lanza told the Third Annual Conference on Regenerative
Medicine, held in Washington this week. Cattle allowed to live natural
lives can survive 24 years and longer.
The clones were not grown to calves but instead stopped
when the embryos were just a few days old and still in the lab dish.
They were used as a source of embryonic stem cells, which have the
potential to become any kind of cell in the body.
"We gave an 1,800-pound (800 kg) animal a thimbleful
of cells," Lanza said.
It was hoped these embryonic stem cells would respond
to the body's own signals and start to produce immune system cells
as needed. Earlier experiments suggest the cells can be directed
to migrate to needed areas, producing a variety of different types
of cells.
RE-BOOTING THE IMMUNE SYSTEM
"If this approach works in humans, it could not only
be used to treat cancer and immunodeficiencies, but to 'reboot'
the immune system in patients with various autoimmune diseases,"
Lanza said.
"There are over 40 autoimmune diseases in humans,
including multiple sclerosis, rheumatoid arthritis, juvenile diabetes,
lupus, inflammatory bowel disease and dozens of others."
He said that 170 days later the injected cells had
survived and were thriving in the blood of the cattle. When put
into lab dishes, they grew abundantly, much as young fetal cells
do.
Immune cells from the bone marrow are already widely
used to treat cancer and some auto-immune diseases. But when a patient
receives these "adult" stem cells, even from a close relative, he
or she usually must take immune-suppressing drugs to keep them from
attacking the body in what is known as graft versus host disease.
Therapeutic cloning, also known as somatic cell nuclear
transfer, offers a way around this problem. "The nuclear transfer
procedure generates cells that are more youthful, and potentially
of far greater therapeutic value," Lanza said.
"The ability to regenerate an aged or defective immune
system without the need for drugs, tissue matching or the risk of
graft-versus-host disease would have important implications for
medicine. For instance, an injection of new immune cells might prevent
elderly patients from dying of pneumonia."
Lanza, along with other scientists in the field, fears
Congress may soon block the research. One of two competing bills
would ban all cloning research involving humans, while the second
would allow work such as Lanza's.
But US federal policy, backed by President Bush, is
to ban federal funding of such work, which scientists complains
slows it down.
"We're all a bit frustrated by the lack of progress--we
should be on the verge of clinical trials by now," Lanza said.
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