- NEW YORK (Reuters) - The technology used to make three generations of
cloned mice might lead to a cure for cancer, make possible organ farms
for transplants and offer new ways to make valuable drugs, scientists say.
Some of the world's top experts on cloning, including the researchers who
cloned more than 50 mice using a new technique, gathered Wednesday to explain
the possibilities the technology offers. They said the work by Teruhiko
Wakayama and Ryuzo Yanagimachi proved that adult animals could be cloned
routinely. And because the University of Hawaii team used mice, the new
clones could be bred quickly and tested and retested. Clones are made from
cells that have been tricked into acting as if they were newly fertilized
egg cells. Instead of splitting into skin cells or brain cells, they regain
the potential for growing into a complete animal. When the cells are tricked,
they are taken off the usual path toward programmed cell death, or apoptosis.
All cells eventually die. But in cancer, something goes wrong and they
do not. Instead they multiply out of control and become a tumor. Yanagimachi
said the cloned cells could become cancerous but did not. ``Can we bring
a cancer cell back to normal using this knowledge?'' he asked. James Robl
of the University of Massachusetts said cloning technology offered ways
to retrain cells. It might be possible, for example, to grow brain cells
to use to treat patients with Parkinson's disease, he said.
- The brains of Parkinson's patients no
longer produce a very important chemical known as dopamine. Victims get
tremors, develop problems moving and eventually die. Brain cells from human
fetuses, injected into the brains of Parkinson's patients, have been shown
to help the brains produce dopamine and seem to reduce symptoms. ``But
human fetal cells are not readily available, and there are lots of problems
with using human fetal cells,'' Robl said. So perhaps another animal species
could be used, one that has been genetically modified, perhaps to make
human dopamine. ``The ultimate would be if these cells could come from
the patient,'' he said.
- Robl and colleagues have helped start
a company, Advanced Cell Technology Inc., and are breeding cloned cattle
they hope may be used some day in this and other ways. The makers of Dolly,
the world's first cloned adult mammal, started out with the idea of making
animals that produce human proteins. Their genetically engineered sheep
produce a human protein, alpha-1-antitrypsin, that is used to treat cystic
fibrosis patients, for example. But Alan Colman of PPL Therapeutics Plc.,
the company set up to develop the animals commercially, said the technology
was still hit-and-miss and cloning could make it more consistent. ``Traditional
methods for making transgenic animals cannot control where in a cell the
gene takes up residence,'' he said. Usually, he said, the gene doesn't
take at all. But with cloning, scientists could make one good genetically
engineered animal and then clone it. ``We have referred to the idea of
having instant flocks,'' Colman said. ``With nuclear transfer, you can
make all your animals in one go.''
- Perhaps cows could be bred that lacked
the gene that makes them susceptible to mad cow disease, he added. Sheep
could be bred that could not develop scrapie, their own version of the
brain-destroying disease, he said. Colman also said that cows could be
created that produced huge amounts of human antibodies in their milk. Colman
said his dream would to be to take an adult cell and trick it into becoming
another type of cell. Yanagimachi has a similar hope of one day growing
vats of skin for grafts or of kidneys for transplant.
- ``This is a dream now, just a mere fantasy,''
Yanagimachi said. ``But it's not an impossible dream. Maybe in the 21st
century we can learn to use cloning technology wisely.'' One thing the
scientists agree on is that the world is not ready for a human clone. ``To
my view, the immorality of human cloning is that to refine the technique,
we would have to make many embryos,'' Colman said. ``The expense of becoming
refined would require a number of deformed babies. ... It will always be
immoral, in my view ... because it would have such a history of misery
associated with it.''