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Bioethical Considerations Related to the Use of Human Embryonic Stem Cells

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Title: Bioethical Considerations Related to the Use of Human Embryonic Stem Cells


1
Consortium on Law and Values in Law, Health and
the Life Sciences University of Minnesota Law
School
Bioethical Considerations Related to the Use of
Human Embryonic Stem Cells
Janet D. Rowley, M.D.
2
SOURCES OF STEM CELLS
  • Oocytes/Embryos
  • Fetal Ovaries
  • Adult
  • Umbilical cord blood
  • Bone marrow and other tissues

3
History of Federal Bioethical Committees
  • Roe vs. Wade
  • National Commission for the Protection of Human
    Subjects of Biomedical
  • and Behavioral Research set guidelines for
    human fetal and embryo research
  • National Ethics Advisory Board (HHS) (expired
    1980)
  • Birth of first child using IVF
  • Human Embryo Research Panel (NIH)
  • -Create embryos for research up to 14 days
    (overruled by Clinton)
  • -Do research on unneeded embryos (banned by
    Congress in 1996)
  • Birth of Dolly - sheep cloned from adult cell
  • NIH Panel set guidelines for use of unneeded
    embryos that would be
  • eligible for federal funding (Bush put on hold)
  • 2001 (Aug) President Bush approved use of
    existing embryonic stem cell lines for
  • federally funded research

4
NAS Scientific Panels on Stem Cells
  • Stem Cells and the Future of Regenerative
    Medicine
  • Stem Cells have great potential
  • Develop new embryonic stem cell lines
  • Somatic cell nuclear transfer may help avoid
    immune rejection
  • Need federal funding for research
  • Critical review for compliance with
    federally-mandated ethical guidelines
  • Establish a broadly representative national
    oversight group at NIH
  • 2002 Reproductive Cloning
  • Confirmed the clear therapeutic potential for
    stem cells including those derived from somatic
    cell nuclear transfer
  • Reproductive cloning should be banned on grounds
    of safety (at least for 5 years)
  • Establish a national advisory board at NIH to
    review future developments

2004. Workshop to Establish Guidelines
5
WHAT ARE THE ISSUES?
Human Oocytes 1. Must be obtained from women who
receive high doses of hormones that induce
release of multiple oocytes with retrieval
by laparoscopy. Risks to individual? 2. Replace
nucleus of oocyte with nucleus of donor
(SCNT) 3. Activate oocyte to obtain embryos that
provide cell lines to be used for
research. Human Embryos 1. Dissociate cells to
develop cell lines
At present, either process is inefficient (lt1 to
20). In either case, one Is destroying a cell or
group of cells that has the potential to become a
human being. For some people, this is
murder. For some people, the cell or embryo
merits special respect, but the potential benefit
to many thousands of individuals with
life-threatening diseases tips the balance of
competing goods toward using embryonic stem cells
for therapeutic purposes.
6
(No Transcript)
7
Efficiency of Cloning from Adult, Fetal and
Embryonic Cells In Six Species
Sheep
Cattle
Mouse
Goat
Pig
Monkey
Embryos created
3156
7413
6468
428
1185
78
Embryos developed into morula/blastocyst
625
1940
2736
246
589
59
Embryos transferred
570
738
2647
182
511
29
Fetuses after embryo transfer
116
244
440
29
10
3
Live births
50
78
62
9
6
2
Offspring alive at time of publication
24
51
49
6
8
2
8
Human embryogenesis is also a very wasteful
process in nature. Only 1/4 to 1/3 of
fertilized oocytes result in a baby
9
NIH APPROVED CELL LINES
CURRENT
  • About 20 cell lines available that were developed
    before August 2001
  • No cell lines at NIH
  • Only partly characterized
  • Cost money (5000/vial)
  • MTA Restrictions

NEEDS
  • More genetic diversity
  • More reliable in culture
  • No contact with animal cells
  • Free
  • Minimal restrictions (MTA)
  • Central ES cell bank

10
NEW EMBRYONIC STEM CELL LINES
Criterion for Embryo Donors - Unneeded human
embryos (IVF) - Given by parents for
research no money
  • Human Embryos (all frozen)
  • 286 embryos (6-12 cell - 97 inner cell masses -
    12 cell lines)
  • 58 blastocysts - (5 cell lines)
  • Culture
  • Mouse embryonic fibroblast feeder layer
  • Growth factors
  • Weened to trypsin disaggregation
  • Tolerant of antibiotics
  • 17 Cell Lines
  • Derived after August 2001
  • Stable - more than 150 doublings
  • Normal karyotype for early culture (12 later
    common in other laboratories shorter doubling
    time)
  • Form multiple cell types, ectoderm, mesoderm,
    endoderm, in vitro
  • Form teratocarcinoma in nude mice (in vivo)

Harvard - HHMI - JDF effort Cowan, et al.
(Melton) NEJM 350 1353, 2004.
11
Cloned Embryonic Stem Cell Line Hwang et al.,
Science 303 1669,2004 South Korea
  • Starting Material
  • 242 Oocytes from 16 volunteers appropriate
    informed
  • consent, not paid
  • 176 Oocytes used for autologous SCNT
  • Nucleus squeezed from oocyte (confirmed with
    FISH) and replaced
  • with a nucleus from an ovarian cumulus
    cell of the donor
  • Chemical activation to stimulate mitosis
  • Results
  • 30 SCNT derived blastocysts gt 20 Inner Cell Mass
  • 1 Cell line derived expressing ES cell markers
  • Stable, more than 70 passages
  • Normal female karyotype
  • Can produce ectoderm, mesoderm, endoderm, and
    multiple
  • tissue types
  • Heterozygous (maternal and paternal) DNA markers
    so
  • unlikely that it contains original oocyte
    nucleus
  • Develop teratoma in SCID mice

12
Treatment Results
  • None in Humans
  • A few in animals
  • Some in humans with fetal cells with
  • widely varying results.

13
Current Issues with Human Embryonic Stem Cells
SAFETY
  • Infections
  • Grown on mouse feeder layers
  • also express unique murine
    glycoproteins
  • Quality Control
  • Impeccable cell culture conditions
  • Good Manufacturing Practices (FDA)
  • Traceability of cells from donor to
    final cell
  • preparation used in human trials. Can
    current lines
  • meet these criteria?
  • Genetic Disorders
  • What are the risks of transferring cells with a
    genetic
  • disease?
  • What tests should be done?
  • Need family medical histories of donors.

Dawson, et al. Safety Issues in Cell-based
Intervention Trials Fertil Steril 80 1077, 2003
14
Current Issues with Human Embryonic Stem Cells
PRECLINICAL TESTING
  • Do cells misdifferentiate or become malignant?
  • 2. Do cells go to wrong target?
  • 3. Are cells rejected through immune responses?

Problem Cannot answer these questions based
only on animal data. Do the cells behave
similarly in humans? Ethical Issue Wait
until cells can be modified to carry a reliable
suicide gene?
Dawson, et al. Safety Issues in Cell-based
Intervention Trials Fertil Steril 80 1077, 2003
15
Current Issues with Human Embryonic Stem Cells
CLINICAL TESTING
  • Typical three-phase strategy for drug testing
  • may not be an appropriate model for
    oncology.
  • Use patients with no alternative therapy.
  • Ethical objections include concern that long
    term follow-up may not be possible. Therefore,
    late side effects would not be detected.

Dawson, et al. Safety Issues in Cell-based
Intervention Trials Fertil Steril 80 1077, 2003
16
Current Issues with Human Embryonic Stem Cells
ETHICAL ISSUES
  • Should not expose humans to non-human infectious
    agents, so dont use current cell lines.
  • Risk of infection is small and destruction of
    more embryos is a greater evil.
  • If wait and use new lines, then clinical trials
    are only
  • possible with private (foundation or
    commercial) support.
  • No or reduced federal oversight.
  • Traceability of cells back to donor?

Dawson, et al. Safety Issues in Cell-based
Intervention Trials Fertil Steril 80 1077, 2003
17
THERAPEUTIC CLONING IN THE USA
National 1. No Federal laws prohibiting human
embryonic stem cell research 2. Strict Federal
laws prohibiting Federal funding of research on
human embryos or embryonic
stem cell lines developed after Aug. 2001 3.
About 20 characterized human embryonic stem cell
lines are available for federally funded
research 4. No restrictions on study of adult
human or animal stem cell lines
States
  • California (2004) encourages stem cell research
    and allocated 3 billion in bonds for stem cell
    research over 10 years
  • New Jersey (2004) 50 million (state). NJ Stem
    Cell Research Institute with additional private
    funds.
  • Banned or restricted - Iowa, Arkansas, Michigan,
    North Dakota.
  • Permissive legislation pending - Illinois,
    Connecticut, Maryland, Massachusetts, Minnesota,
    New York, Pennsylvania, Rhode Island, Tennessee,
    Washington.
  • Illinois State Comptroller Daniel Hynes has
    proposed a bond issue for 500 million.

Universities Harvard - Embarked on 100
million - Stem Cell Research Institute
18
INTERNATIONAL WORK IN THERAPEUTIC CLONING
Currently, there is active research ongoing in
the United Kingdom, South Korea, China,
Singapore, and Israel
Will the United States be left behind?
19
URGENT NEEDS
Rational national policy on human embryos and
related derivation of human embryonic stem cell
lines
Uniform ethical and scientific guidelines
Workshop on guidelines for human embryonic stem
cell research - NAS 2004-2005
20
Working Committee on Guidelines for Human
Embryonic Stem CellsNational Academies of Science
  • Preliminary Considerations for Report
  • Biological, ethical, legal issues
  • Guidelines
  • Establish a new Institutional Embryonic Stem Cell
    Research Oversight Committee
  • Procurement of material
  • Derivation of cell lines
  • Research use of cell lines
  • Banking and distribution of cell lines

21
Procurement of Embryos, Gametes or Cells
forHuman Embryonic Stem Cell Line Derivation
  • Procurement reviewed by IRB regardless of source
  • Donation of unneeded embryos at time of use from
    all involved. Cannot use if donors cannot be
    contacted
  • No financial reimbursement except actual expenses
  • Donor identity protected must be able to link
    cell lines to donors. If cell lines are used to
    treat humans, must know donor (protected)
  • Separation of IVF clinic staff from scientists
    involved in research
  • Should donor or appropriate physician be told of
    important clinical information?

22
Establish a new Institutional Embryonic Stem Cell
Research Oversight (ESCRO) Committee
  • Why do we need another Committee? Why cant the
    IRB serve this function?
  • Institutions need to know which scientists are
    doing research with hES cell lines. Document
    which cell lines are used and that they were
    derived with appropriate consent
  • Review specific research protocols, especially
    use of SCNT, culture of embryo (not after 14
    days) and development of human/non-human chimeras
  • Review banking and distribution plans
  • Need members with specialized knowledge

23
Derivation of Human Embryonic Stem Cell Lines
  • Permission to derive new cell lines granted by
    ESCRO committee requires evidence that
    procurement has been approved by IRB
  • Scientific rationale must be justified if
    involve SCNT, then strong justification required
  • Plan for characterization, storage, and
    distribution of cell lines

24
Banking and Distribution (modified from UK)
  • Central repository in a single institution
    confirms IRB approval of procurement
  • Requires a committee for management and policy
    issues
  • Effective, accurate registry of all cell lines
  • Develop uniform guidelines and quality control of
    cell culture and record keeping
  • Distribution only to qualified scientists track
    third-party transfers
  • Committee reviews intellectual property issues
  • Should there be a national repository(ies)?

25
Research use of Human Embryonic Stem Cell Lines
  • All research protocols reviewed by ESCRO
    Committee (or equivalent) protocols must be
    updated regularly
  • Registration but no review of research protocol
    if used only in in vitro experiments
  • Combining hES cells with non-human embryos,
    fetuses or adults requires approval of
    Institutional Animal Care and Use (IACUC) and
    ESCRO committees
  • Introduction of hES cells into non-human
    mammalian blastocysts permitted only under very
    special circumstances
  • No animal into which hES cells have been
    introduced at any stage should be allowed to breed

26
What about cells that will be used to treat
patients?
  • FDA involved and requires traceability of cell
    lines to donor
  • Cells must meet highest standards of culture
    throughout process (GMP)
  • Probably cannot be grown on animal cell feeder
    layers
  • Therefore virtually all present day cell lines
    are NOT suitable for therapy

27
MY RECOMMENDATIONS
  • Ban reproductive cloning.
  • Allow use of new human embryonic stem cell lines
    and encourage
  • development of additional cell lines using
    appropriate guidelines.
  • Develop new cell lines not exposed to animal
    products.
  • 4. Provide federal funding for use of all cell
    lines both embryonic and
  • adult.
  • 5. Compare use of adult and embryonic stem
    cell lines in various
  • diseases to determine which are better for
    particular diseases.
  • 6. Need a set of ethical and scientific
    guidelines that are nationally
  • accepted.
  • 7. Establish national stem cell banks.
  • 8. All aspects of research should be reviewed
    by broadly constituted
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