Novel Sources of Stem Cells/Biomedical Ethics

embryonic stem cells characteristics

• not found in adult body

• able to self-renew + differentiate

• located + originated in inner cell mass of blastocyst

• pluripotent

• provoke immune response

• function to build an adult organism

adult stem cells characteristics

• found in adult body

• able to self-renew + differentiate

• originate in specialized adult tissues

• located in various adult tissues (bone marrow, hippocampus, skin, subgranular zone

• multipotent

• function for maintenance + repair

somatic cell nuclear transfer

de-differentiates cells:

1. take nucleus from differentiated somatic body cell w/desired genes

2. remove nucleus from egg + somatic body cell

3. put somatic cell nucleus in egg cytoplasm → reprogramming

reprogramming

• regulatory transcription factors: Oct4, Sox2, Klf4 Myc, Nanog, Lin28

• regulate these genes:

  • HATs + HDACs

  • chromatin remodelers

  • proteins that erase methyl groups

induced pluripotent stem cells (iPSCs) characeristics

• not found in adult body

• able to self-renew + differentiate

• originate in differentiated cells in the body

• pluripotent

• function to create patient-specific pluripotent stem cells for potential use in regenerative medicine

• can help diabetes, stroke, macular degeneration + de-differentiates cells

obstacles/complications of iPSCs

• tumorgenicity (cancer-causing)

• immune responses

• long-term viability

• overcoming genetic abnormalities (may need to rely on donor cells to treat genetic disorders)

• differentiation to the correct cell identity (in vivo or in vitro)

physiological definitions of beginning of human life

• fertilization (Day 0)

• gastrulation (Day 14)

• human-like brain activity (24 weeks)

• birth and/or ability to survive outside the mother (22-23 weeks, but low survival at that point)

how to determine if biomedical research is ethical

• autonomy

• nonmaleficence

• beneficence

• justice

biomedical ethics: autonomy

• patients/participants must have ability to give informed consent before receiving therapeutic treatment/participating in research study

• must be able to weigh pros + cons independently + w/o coercion

biomedical ethics: nonmaleficence

procedures/research studies involving patients must minimize harm in every way possible

biomedical ethics: beneficence

• procedures/research studies w/human subjects must be carrier out w/good of subject in mind

• must strive for net benefit for subject

biomedical ethics: justice

• burden + benefit of any new medical tech must be distributed fairly among all members of a community

• no one group should benefit/suffer disproportionally