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Promises, Premises, and Published Data… |
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Claims unsubstantiated for embryonic stem cells |
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Current or potential embryonic stem cell
problems: |
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Difficult to establish and maintain |
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Difficulty in obtaining pure cultures in the
dish |
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Potential for tumor formation and tissue
destruction
*Wakitani S et al.; “Embryonic stem cells injected
into the mouse knee joint form teratomas and subsequently destroy the
joint”; Rheumatology 42, 162-165; January 2003 |
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Questions regarding functional
differentiation
*Hansson M et al., “Artifactual insulin release
from differentiated embryonic stem cells”, Diabetes 53, 2603-2609, October
2004
*Sipione S et al., “Insulin expressing cells from
differentiated embryonic stem cells are not beta cells”, Diabetologia 47,
499-508, 2004 (published online 14 Feb 2004)
*Rajagopal J et al.;
“Insulin staining of ES cell progeny from insulin uptake”; Science 299, 363; 17 Jan 2003
*Zhang
YM et al.; “Stem cell-derived cardiomyocytes demonstrate arrhythmic
potential”; Circulation 106, 1294-1299; 3 September 2002 |
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Problem of immune rejection |
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Genomic instability
*Cowan CA et al.,
“Derivation of embryonic stem-cell lines from human blastocysts”, New
England Journal of Medicine 350, 13; published online 3 March 2004
*Draper JS et
al., “Recurrent gain of chromosomes 17q and 12 in cultured human embryonic
stem cells”, Nature Biotechnology 22, 53-54; January 2004
*Humpherys D et
al.; “Epigenetic instability in ES cells and cloned mice”; Science 293,
95-97; 6 July 2001 |
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Few and modest successes in animals, no clinical
treatments |
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Ethically contentious |
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Cloning is unsafe for the clone and surrogate
mother |
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The numbers are against survival |
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Dolly the sheep, first cloned mammal: 1 live birth out of 277 cloned
embryos (0.4%) |
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Cloned mice: 5 live births out of 613 cloned embryos (0.8%)
5 live births out of 314
cloned embryos implanted (1.6%) (0.3%; 1 survived)
26 live births out of 312
cloned embryos implanted (8.3%) (4.2%; 13 survived) |
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Cloned pigs: 5 live births out of 72 cloned embryos implanted (7%) |
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Cloned goats: 3 live births out of 85 cloned embryos implanted (3.5%) |
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Cloned cattle: 30 live births out of 496 cloned embryos implanted (6%)
(4.8%; 24 survived) |
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Cloned cat: 1 live birth out of 188 cloned embryos (0.5%); of 87 embryos implanted (1.1%) |
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Cloned gaur: 1 live birth out of 692 cloned
embryos (81 blastocysts) (0.1%) (0%; 0 survived) |
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Cloned rabbits: 6 live births out of 1852 cloned
embryos (0.3%) (0.2%; 4 survived) |
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Cloned banteng: 2 live births out of 30 cloned
embryos implanted (6.7%) (3.3%; 1 survived) |
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Cloned mule (fetal cells): 3 live births out of
334 cloned embryos (0.9%) |
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Cloned horse: 1 live birth out of 841 cloned
embryos (0.1%) |
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Cloned rats: 3 live births out of 129 cloned embryos implanted (2.3%)
(1.6%; 2 survived) |
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Even apparently healthy clones have gene
expression abnormalities.
*Humpherys D et al.; “Epigenetic
instability in ES cells and cloned mice”; Science 293, 95-97; 6 July
2001
*Humpherys D et al.; “Abnormal gene expression in cloned mice
derived from embryonic stem cell and cumulus cell nuclei”; Proc. Natl.
Acad. Sci. USA 99, 12889-12894; 1 October 2002 |
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A review of all the world’s cloned animals
suggests that every one of them is defective.
Ian Wilmut: “There
is abundant evidence that cloning can and does go wrong and no
justification for believing that this will not happen with humans.”
“Gene
defects emerge in all animal clones”, Sunday Times of London, April 28,
2002 |
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Health risk for the surrogate mother—“large
offspring syndrome” |
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Clones may need to be gestated to
“harvest”already-differentiated tissues
*R Lanza et al.;
“Generation of histocompatible tissue using nuclear transplantation,” Nature
Biotechnology 20, 689-696; July 2002 (published online 3 June 2002)
*R
Lanza et al., “Regeneration of the infarcted heart with stem cells derived
by nuclear transplantation,” Circulation Research 94, 820-827, April 2004
(published online 10 Feb 2004) |
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Current Clinical Uses of Adult Stem Cells |
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Cancers—Lymphomas, multiple myeloma, leukemias,
breast cancer, neuroblastoma, renal cell carcinoma, ovarian cancer |
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Autoimmune diseases—multiple sclerosis, systemic
lupus, rheumatoid arthritis, scleroderma, scleromyxedema, Crohn’s disease |
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Anemias (incl. sickle cell anemia) |
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Immunodeficiencies—including human gene therapy |
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Bone/cartilage deformities—children with
osteogenesis imperfecta |
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Corneal scarring-generation of new corneas to
restore sight |
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Stroke—neural cell implants in clinical trials |
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Repairing cardiac tissue after heart attack—bone
marrow or muscle stem cells from patient |
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Parkinson’s—retinal stem cells, patient’s own
neural stem cells, injected growth factors |
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Growth of new blood vessels—e.g., preventing
gangrene |
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Gastrointestinal epithelia—regenerate damaged
ulcerous tissue |
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Skin—grafts grown from hair follicle stem cells,
after plucking a few hairs from patient |
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Wound healing—bone marrow stem cells stimulated
skin healing |
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Spinal cord injury—clinical trials currently in
Portugal, Italy, S. Korea |
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Ethical Questions about Embryo Research |
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Unethical? |
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to destroy human embryos |
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to destroy human embryos for stem cells if there
is a viable alternative |
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to experiment with humans before work is
verified in animals |
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because embryonic stem cells pose significant
risks |
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Tumors |
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Transplant rejection |
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Instability in gene expression |
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because it would divert limited funds to less
promising research and potentially delay cures |
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Problems Regarding Human Cloning |
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Any evidence that cloning is necessary or useful
for medical treatments? |
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Will cloning research divert resources and delay
cures? |
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Is banning implantation unenforceable? |
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Possible reproduction of living or deceased
persons without knowledge or consent? |
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Confusion—kinship, parent-child identity,
parental expectations? |
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Creating a class of humans who exist only as a
means to achieve the ends of others? |
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Risking health and exploitation of women? |
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Leading to commercialization of human life? |
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Gateway to genetic manipulation and control of
human beings? |
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Unsafe, Unethical, Unnecessary |
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Euthanasia |
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Actively committing or encouraging the taking of
human life. |
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“Noble” death, or getting rid of unwanted
burdens? |
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Utilitarian, considering vulnerable people as
things, of lesser value, less than fully human. |
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Compassion for pain and suffering. |
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What does it mean to be human? |
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Person or property? |
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To whom do we choose to assign value? |
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Who will benefit? Who will decide? |
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슬라이드 노트