Stem Cells

Question 1

stem cells

Answer 1

• undifferentiated and unspecialised cells
• able to differentiate to form specialised cells upon receiving molecular signals by the differential switching on and off of genes
• undergo extensive proliferation and self renewal by mitosis to maintain a constant pool of stem cells
• stem cells can be
  1. multipotent – can differentiate into a few cell types with related functions
  2. pluripotent – can differentiate into most cell types except extraembryonic tissue such as placenta
  3. totipotent – can differentiate into all cell types

Question 2

argument against the use of embryonic stem cells

Answer 2

• embryonic stem cells have the potential to develop into a human being hence has the status of one, stem cell research could be equated to murder
• using embryo is a source of spare parts
• lead to abuse in the future, once human status is denied of human status, could set a precedent for other categories of human beings such as the elderly infirm and the profoundly disabled
• possibility of unforeseen circumstances such as tumour formation and other long-term health effects
• for donors of eggs, there may be issues wrt informed consent

Question 3

arguments for using embryonic stem cells

Answer 3

• embryos are not equivalent to life, as they are not conscious, cannot feel and cannot survive outside the womb
• blastocysts are a cluster of cells, is no more human than skin cells, some believe life only begins when the heartbeat develops
• embryonic stem cells have the potential to treat a wide range of diseases, they have the potential to grow indefinitely and can differentiate into almost all cell types
• more than a third of the zygotes do not normally implant in the uterus, far more embryos are lost due to chance compared to embryonic stem cell research
• surplus embryos are beind destroyed or stored long past their viable storage life, can be used to create new stem cell lines for research

Question 4

iPSCs

Answer 4

pluripotent stem cells that can be generated directly from adult somatic cells

Question 5

advantages of iPSCs

Answer 5

• can be obtained directly from adult tissues, does not generate or destoy embryos
• adult tissue can be easily obtained from donor without risk to donor
• iPSCs derived fro a patient’s own cells will not be rejected by the immune system –> no need to use immunosuppressant drugs
• allows generation of pluripotent stem cell lines from patients with inherited diseases, to better understand why the diseases develop

Question 6

problems with iPSCs

Answer 6

• may result in genomic modifications caused by insertion of genes coding for transcription factors into the genome, can sometimes lead to cancer due to insertional mutagenesis