Clinical and ethical issues in reproductive technology Viewpoint from embryologist - PowerPoint PPT Presentation

Loading...

PPT – Clinical and ethical issues in reproductive technology Viewpoint from embryologist PowerPoint presentation | free to download - id: 7ee5d-ZjY5N



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Clinical and ethical issues in reproductive technology Viewpoint from embryologist

Description:

Clinical and ethical issues in reproductive technology - Viewpoint from embryologist ... Department of Obstetrics and Gynaecology, University of Hong Kong. scientist ... – PowerPoint PPT presentation

Number of Views:685
Avg rating:3.0/5.0
Slides: 24
Provided by: O792
Learn more at: http://www.ogshk.org
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Clinical and ethical issues in reproductive technology Viewpoint from embryologist


1
Clinical and ethical issues in reproductive
technology -Viewpoint from embryologist
scientist
  • W.S.B. Yeung
  • Department of Obstetrics and Gynaecology,
  • University of Hong Kong

2
First test tube baby
18 July 1978
3
Ethical issues from IVF
  • IVF
  • Family structure, surrogacy
  • Cryopreservation
  • Posthumous baby
  • Preimplantation genetic diagnosis
  • Desinger baby
  • Selection of embryos for HLA

4
New reproductive technologies
  • Human embryonic stem cells
  • Somatic nuclear transfer
  • patient-specific embryonic stem cells
  • human-animals hybrid embryos

5
Human embryonic stem cells
Cell replacement therapy
ES cells
Thomson et al., 1998 Science. 2821145-7
6
Human embryonic stem cells
  • Ethical issues
  • Killing of embryos
  • Creation of embryos
  • Potential in regenerative medicine
  • Source of embryos
  • Supernumerary embryos (Hong Kong)
  • Creation of embryos (Mainland China, United
    Kingdom)

7
Creation of embryos NOT for infertility treatment
  • FIGO Committee for the Study of Ethical Aspects
    of Human Reproduction and Womens Health
  • Allowed if data cannot be obtained using
    supernumerary embryos
  • Nuclear reprogramming by oocytes
  • Patient specific stem cells
  • Women should not be unduly induced for donating
    oocytes

8
Embryonic stem cells without immunorejection is
required
  • Embryonic stem cell lines with different HLA ?
    immunorejection
  • Embryonic stem cells for cell therapy
  • Production of stem cells with different HLA
  • Somatic nuclear transfer
  • Induced pluripotent stem cells

9
Somatic nuclear transfer
Normal oocyte
277 nuclear transferred 29
implanted 1 live birth
Somatic cell
Enucleated oocyte
Cloning
10
Cloning in reproductive medicine
  • Natural cloning more often after assisted
    reproduction (monozygotic twins)
  • Reproductive cloning is not allowed in most
    countries
  • Therapeutic cloning

11
Therapeutic cloning
No rejection
12
Patient-specific embryonic stem cells
  • Evidence of a Pluripotent Human Embryonic Stem
    Cell Line Derived from a Cloned Blastocyst
  • Science (2004), 303 1669

Fabricated data Both papers were retracted
Patient-Specific Embryonic Stem Cells Derived
from Human SCNT Blastocysts Science. (2005)
3081777-83
13
Therapeutic cloning
  • Prohibitions in Hong Kong
  • to bring about the creation of a human embryo
    for the purpose of embryo research
  • to replace the nucleus of a cell of an embryo
    with a nucleus taken from any other cell
  • to clone any embryo

14
Treatment of cytoplasmic defectby somatic
nuclear transfer
Defective embryo
Nucleus
Normal oocyte
Enucleated oocyte
15
Somatic nuclear transfer
  • Low success rate, a high miscarriage rate, and
    complications.
  • Research should continue as a tool for studying
  • Nuclear-cytoplasmic interaction
  • Nuclear reprogramming
  • Genetic disorder

16
Human-animal hybrid embryos
  • Human oocytes are limited
  • Animal oocytes readily available
  • Interspecies embryos possible
  • Cloning endangered gray wolves (Canis lupus)
    from somatic cells collected postmortem.
  • Oh HJ et al. Theriogenology. 2008 Jun 3. Epub
    ahead of print

17
Embryonic stem cells generated by nuclear
transfer of human somatic nuclei into rabbit
oocytes
  • Chen Y, He ZX, Liu A, et al
  • Cell Research (2003) 13, 251263.
  • The derived ntES cells are human based on
    karyotype, . The ntES cells maintain the
    capability of sustained growth in an
    undifferentiated state, and form embryoid bodies,
    which, on further induction, give rise to cell
    types that express markers representative of
    all three germ layers.

18
Human-animal hybrid embryos
  • No shortage of animal oocytes
  • Provide experimental model on studying nuclear
    reprogramming
  • Alternative source of patient-specific stem cells
  • Hong Kong combine human and non-human gametes
    or embryos or any part thereof such as to give
    rise to a two-cell zygote for research is
    prohibited

19
Induced pluripotent stem cells
  • Induction of pluripotent stem cells from mouse
    embryonic and adult fibroblast cultures by
    defined factors.
  • Takahashi K, Yamanaka S. (2006) Cell 126663-76.
  • Repeated in human fibroblasts
  • Takahashi et al. (2007) Cell 131861-72.
  • Yu et al. (2007) Science 3181917-20.

Sciences Breakthrough of 2007
20
Induced pluripotent stem cells
  • Transfection of 4 transcriptional factors
  • ? stem cell-like
  • Treatment of Sickle Cell Anemia Mouse Model with
    iPS Cells Generated from Autologous Skin
  • Hanna J, Wernig M, Markoulaki S, Sun CW,
    Meissner A, Cassady JP, Beard C, Brambrink T, Wu
    LC, Townes TM, Jaenisch R (2007) Science 318
    1920-1923

21
Induced pluripotent stem cells ? embryonic stem
cells
  • global gene-expression patterns
  • DNA methylation (Oct3/4 and Nanog, H19 and Igf2r)
  • Tumor formation rate

Researches on embryonic stem cells need to be
continued
22
Summary
  • New reproductive techniques give rise to ethical
    issues.
  • Ethics vs Benefit
  • Prohibition vs Regulation

23
Thank you
About PowerShow.com