Lecture 14 - Ethical Issues about Stem Cell Research Flashcards
Types of pluripotent stem cells
Embryonic
Somatic cell nuclear transfer (SCNT)
Induced pluripotent stem cells (iPS)
Where are embryonic stem cells derived from?
Inner cell mass of blastocyst (day 6).
Embryo destroyed in extraction process.
SCNT
Somatic cell nuclear transfer.
Technique for creating a viable embryo from a somatic cell and an enucleated oocyte.
Therapeutic cloning of somatic cell nucleus put into oocyte. Blastocyst is formed, embryonic stem cells taken from inner cell mass of blastocyst.
Issues with SCNT
Creation of a foetus for destruction
Where to get oocytes. Need to be harvested from a women in an invasive procedure.
Can clone humans.
How was Dolly the sheep cloned?
Somatic cell nuclear transfer
iPS cells
Induced pluripotent stem cells.
Take a skin biopsy, overexpress certain genes in vitro.
This makes patient-specific iPS cells.
How could iPS or SCNT be used to model disease?
Take cells from patient with disease (EG: motor neurone disease).
Create stem cells, make them differentiate into neurons, see if there is a developmental defect (compare to healthy neurons)
Why mightn’t iPS be an ‘ethical alternative’ to SCNT?
SCNT requires high tech materials, oocytes to perform.
iPS could be performed anywhere, used to clone humans, etc.
Why can’t iPS clones fertile?
They are tetraploid. They can have a mock pregnancy, but can’t have viable offspring.
How can you clone with iPS?
1)
2)
3)
1) Fuse two gametes to form a tetraploid blastocyst.
2) iPS cells are injected into blastocyst, direct development.
3) Developing embryo is implanted into surrogate mother.
Does iPS cloning have a very high success rate?
No. ~1-3% success rate.
Australian law about stem cell research.
Embryonic stem cell use is very tightly-regulated. Need a license, ethics approval.
Donor stem cells regulated.
Autologous stem cells are relatively unregulated.
Aspect of Australian law that limits use of SCNT stem cells
Clause that requires justification as to why a particular approach is used when another might be more ethical.
SCNT and iPS can serve similar roles
How is an ethics license and NHMRC approval given for embryonic stem cell research?
1)
2)
3)
Project-by-project basis
1) How consent will be obtained
2) Likelihood of significant advancement in knowledge or improvements in infertility treatment
3) Number of embryos required to reach project goals
Approval required to genetically-modify human tissue samples in Australia
Office of Gene Transfer Technology
