Who needs psychedelics when things are moving this fast? There was a report
in last week's New Scientist Magazine that we NOW have the ability to alter
the HUMAN GERM LINE. As of last week. As I was reading the report I was
sitting on the bus looking looking at out the window in a state of shock.
And I couldn't tell anyone. People in general just don't get it. The report
of course says that no one in their right mind would want to do it, but I
guess that rules out the sanity of most of the participants on this list
<smile>. Now that we can alter the germ line what genes would you add? Or
remove? Obviously we only know a little as of yet, but there are still some
interesting things we could try. Weren't their some interesting breeding
experiments with fruit flies increasing the amount of an antioxidant they
produced that dramatically increased their lifespans? Has this research
been tried out in mammals? If you could dramatically increase the lifespan
of your child wouldn't that be the trully ethical thing to do. To be frank
my aliegnece is to kith-and-kin and not to abitrary bodies whether this be
governments or homo sapiens. Perhaps we really are in the last days of our
race...
best, patrick
=============================================================================
>From New Scientist, 19 July 1997
A REAL CULTURE SHOCK
Steven Dickman
Human embryos carrying altered genes could become a
possibility sooner than anyone thought. For the first time, a biologist
claims to have grown long-lived cultures of human embryonic cells that
have the capacity to develop into a wide range of tissues. The cells
could find important medical applications. However, in theory, they
could also be used to create genetically engineered humans.
In mice, similar cultures have allowed scientists to make genetically
engineered animals with unprecedented precision. The key is that the
cells are "pluripotent"--they can divide and differentiate to form any
tissue type. Working with a culture of these "embryonic stem cells" held
in an undifferentiated state, geneticists can target genetic
manipulations with much greater precision than would be possible by the
haphazard injection of genes into newly fertilised mouse eggs. They can
then inject the genetically engineered stem cells into an early mouse
embryo. This develops into a "chimeric" mouse in which a proportion of
cells in most or all of its tissues carry the altered genes.
Because those tissues can include the cells that give rise to sperm and
eggs, repeating these experiments in humans would break the biggest
taboo in modern genetics: manipulating the human germline to induce
genetic changes that can be passed down the generations.
The researcher who created the human cell cultures, John Gearhart of
Johns Hopkins University in Baltimore, Maryland, stresses that altering
the germline is not his goal. He hopes that the cells will find a use in
conventional gene therapy, in which the altered genes cannot be
inherited, or in creating tissues that could be used for grafts without
the need for drugs to combat rejection. "I believe what comes out will
be extremely beneficial," he says.
Last week, at the 13th International Congress of Developmental Biology
in Snowbird, Utah, Gearhart revealed that he now has seven separate cell
lines growing in culture.
To create the cultures, Gearhart took cells from fetuses roughly eight
weeks into gestation, which had been aborted at a clinic in Baltimore.
The cells came from a structure called the gonadal ridge, which would
have developed into reproductive organs. As such, they are different
from most of the embryonic stem cells used by mouse geneticists, which
usually come from earlier embryos. However, Gearhart believes his cells
have many of the same properties.
One possibility, however, is that Gearhart's cells grow in culture in an
undifferentiated state not because they are pluripotent, but because
they are cancerous. But Gearhart notes that "marker" proteins carried on
the surface of his cells suggest that they are pluripotent. They can
also form clumps of cells that, in mouse cell cultures, are precursors
to further development.
The ultimate test of pluripotency would be to inject the cells into an
early human embryo and show that a healthy human chimera develops--an
experiment that few scientists would regard as ethical. In the absence
of these data, however, other scientists say they are inclined to
believe Gearhart's claim. "The science is solid and the chromosomes look
fine," says Peter Gruss, a developmental biologist at the Max Planck
Institute for Biophysical Chemistry in Göttingen, Germany.
Gearhart's cells could find applications in conventional gene therapy.
Gruss says that experiments with mouse embryonic stem cells show that
they can differentiate into the tissues that give rise to blood cells.
If the same is true for Gearhart's human cells, it may be possible to
use them to treat people with genetic diseases of the blood.
Gearhart's main goal is to create cells that could be grown to form
tissues suitable for grafts. If the cells were manipulated to remove
genes of the major histocompatibility complex, which play a central role
in the recognition of foreign tissue by the immune system, this would
help solve the problem of rejection. "These cells would be the best
donors," he claims. But at the back of people's minds is the possibility
that human embryonic cells could be used to manipulate the germline.
This would raise serious ethical concerns, says David Shapiro of the
Nuffield Council on Bioethics in London, as genetic changes would be
passed down to future generations without their consent.
However, Anne McLaren of the Wellcome Cancer Research Campaign Institute
in Cambridge, who attended the Utah meeting, questions whether anyone
would attempt human germline manipulation. "No one in their right mind
would want to do it," she says. McLaren notes that couples carrying
genetic diseases can instead have their embryos screened through
pre-implantation diagnosis and select a healthy embryo to take to term.
Mario Capecchi of the University of Utah in Salt Lake City, who
pioneered the use of embryonic stem cells to create genetically
engineered mice, says that using genetic manipulation to develop cells
for transplantation would be acceptable. "But as soon as you do it to
create a human being, you've crossed the line."
© Copyright New Scientist, IPC Magazines Limited 1997