Adult Stem Cell Research More Successful Than Embryonic
by Do No Harm
Source: Do No Harm; March 8, 20002

[Pro-Life Infonet Note: Do No Harm: The Coalition of Americans for
Research Ethics is a national coalition of researchers, health care
professionals, bioethicists, legal professionals, and others dedicated to
the promotion of scientific research and health care which does not harm
human life.]

A report today in the journal Cell, announced by the Associated Press,
purports to use "therapeutic" cloning to partially correct a genetic based
immune system defect in mice.

However, this report comes years after "remedied" adult stem cells - not
embryonic stem cells - were used to cure human infants of severe combined
immunodeficiency syndrome, in the first successful clinical trials in
human gene therapy.

In the cloning experiments, performed by researchers at the Whitehead
Institute (W.M. Rideout et al., "Correction of a genetic defect by nuclear
transplantation and combined cell and gene therapy," Cell Immediate Early
Publication, published online March 8, 2002) mice with an immune defect
causing some white blood cells to be missing were cloned, and the cloned
mouse embryos were destroyed for their stem cells. Since the embryonic
stem cells were genetically identical to the mice (supposedly to prevent
transplant rejection), they carried the same genetic defect. The
researchers used gene therapy to fix the defective gene in the embryonic
stem cells.

Several different attempts were then made to correct the immune defect in
the mice using these stem cells.

In one experiment, the "repaired" embryonic stem cells were differentiated
in culture into blood-forming cells and these were transplanted into the
defective mice. The authors note that this showed little to no success
(though the data are not shown in the paper).

Next they tried reducing the number of those cells in the recipient mice
that were blocking successful transplant. Again, this approach was
essentially negative (again, the data are not shown in the paper).

Finally, the researchers transplanted the "repaired" blood-forming cells
into a different mutant mouse that had the same genetic defect, but also
lacked the cells that had been destroying the transplanted cells. This
situation resulted in a modest restoration of the missing blood cells, but
at less than one-tenth the amounts in normal mice.

However, the researchers were able to restore normal levels of the missing
blood cells by first using the "repaired" embryonic stem cells to grow
born mice, then using the bone marrow stem cells or blood stem cells
(similar to umbilical cord blood) of those born mice for the transplant.
In other words, the researchers were most successful when they resorted to
using adult stem cells.

The published scientific paper actually shows that the "repaired"
embryonic stem cells from cloned embryos were unsuccessful in treating the
gene defect in the mice that provided the donor cells for cloning. The
authors note: "Our results raise the provocative possibility that even
genetically matched cells derived by therapeutic cloning may still face
barriers to effective transplantation for some disorders."

This study also bears out the enormous global risk to women's health
entailed in the speculative idea of "therapeutic cloning" to treat
diseases in humans. Only 1 embryonic stem cell line was successfully
cultured, starting with 202 cloning attempts. Even if the experiment had
been successful, the number of human eggs needed for such treatments would
translate to 303 million human eggs needed to treat the 1.5 million
Parkinson's patients in the U.S., and over 3.2 billion human eggs needed
to treat the 16 million diabetes patients in the U.S.

Far from being a step forward, this report shows that cloning is years
behind the far more successful advances using adult stem cells, including
their use to reverse immune deficiencies in humans.

As reported in April 2000 in the journal Science, French scientists
restored the immune systems of 3 infants with severe combined
immunodeficiency (the "bubble boy syndrome") using gene therapy with the
patients' own bone marrow stem cells. Researchers removed stem cells from
the infants' bone marrow, added a working copy of the gene to the cells'
DNA, and injected the repaired stem cells back into the infants. Since
the procedure used the patients' own cells, there was no problem of
transplant rejection. After treatment, the numbers and function of the
patients' immune cells were restored to normal levels, and the children
were living at home and developing normally with no further treatment (M.
Cavazzana-Calvo, et al., "Gene Therapy of Human Severe Combined
Immunodeficiency (SCID)-X1 Disease," Science 288, 669-672, April 28,
2000).

Far from showing the supposedly superior benefits of stem cells from
cloned embryos, the new study shows that this approach continues to lag
behind adult stem cell advances - even in mice, where embryonic stem cell
research has been pursued for over twenty years. Adult stem cells are
successfully treating real human children with serious diseases.