stem cells

Question 1

define totipotent, pluripotent, unipotent and multipotent

Answer 1

totipotent: the potential of a cell to develop into a total organism

pluripotent: a cell’s capacity to give rise to all cell types in the body but not to supporting structures (placenta, chorion, amnion) that are needed in development
* embryonic stem cells
* induced pluripotent stem cells (iPS) –> engineered cells derived from somatic cells that resemble ES cells

unipotent: cell can give rise to one type of cell

multipotent: cell can give rise to a small number of different cell types
* tissue specific stem cells
ex: bone marrow

Question 2

Definition of stem cell

Answer 2

o Cells that Persist for the Lifetime of the Organism
o Continues to Reproduce Itself
o Generates Differentiated Progeny (Involves Transit Amplifying Cells).
o Inner cell mass in blastocyst gives rise to ES cells.

Question 3

Somatic cell nuclear transfer (SCNT)

Answer 3

• Nucleus from Somatic Cell Transferred into Enucleated Eggs.
• Early Embryo Can Be Used to Create Embryonic Stem Cells (Genetic Match to Donor).
• Offers Pathway to Therapeutic Cloning or Propagation of Livestock

labor intensive and inefficient. IVF is preferred

Question 4

In vitro fertilization

Answer 4

• In vitro fertilization for reproductive purposes→ eggs from donor fertilized & allowed to develop in vitro (in culture)
• Fertilized eggs implanted into mother in fertility clinics
• Extra embryos frozen →excess embryos that can be used to harvest ES cells
• Inner cell mass harvested from blastocyst (30 cells) → cultured with feeder cells
• Feeder cells provide matrix for attachment & nutrients
• Feeder cells can contaminate ES cells with viruses or other molecules (safety issues in patient transplantation)

Question 5

advantages of iPS cell lines

Answer 5

• Differentiated cells will be a perfect immunological match to the donor, permitting grafting back without the use of immunosuppressive drugs.
• Permits treatment of genetic diseases or cancers (e.g., repopulation of bone marrow).
• Tumor formation represents major concern due to mechanisms of viral gene insertion (introduction of pluripotency genes). Host genes may be interrupted. In addition, silenced genes (which occur during passage) may be reactivated.
• need to be able to make the cell, get into tissue, graft successfully and prevent rejection

potentials:

1. form beta cells in vitro and then lodge into liver (where can respond to signal) for treatment in type I diabetes
   - limited because doesn’t get rid of the immune attack that destroys the beta cells
2. parkinson’s: problems: difficulty in grafts forming proper neuronal connections, tumor formation?, alternate therapies may be more effective
3. spinal repair: goal: re-myelinating cells after trauma. tumor risk

Question 6

hematopoietic stem cell transplantation; HSCT

Answer 6

• 50,000 HSCTs carried out yearly with 10% mortality rate (includes bone marrow and stem cells from non-marrow sources (e.g., peripheral blood or umbilical cord blood).
• Radiation preferentially kills dividing cells, where hematopoietic tissue of bone is most sensitive.
• Following repopulation from donor there is immune cell reprograming and a transfer of tolerance.
• Matching of host and donor lymphocytes [requires a good human leukocyte antigen (HLA) match].
• Current practice involves incomplete destruction of host cells, and uses graft-versus-leukemia effect to destroy tumor cells.

hematopoietic stem cells grafts can repopulate the marrow

UCB (umbilical cord blood) =focus=source of stem cells. –> unfit because low stem cell count
–> dmPGE2 to help with the formation of graft?

Question 7

hematopoietic stem cell transplantation; HSCT

Answer 7

• 50,000 HSCTs carried out yearly with 10% mortality rate (includes bone marrow and stem cells from non-marrow sources (e.g., peripheral blood or umbilical cord blood).
• Radiation preferentially kills dividing cells, where hematopoietic tissue of bone is most sensitive.
• Following repopulation from donor there is immune cell reprograming and a transfer of tolerance.
• Matching of host and donor lymphocytes [requires a good human leukocyte antigen (HLA) match].
• Current practice involves incomplete destruction of host cells, and uses graft-versus-leukemia effect to destroy tumor cells.

hematopoietic stem cells grafts can repopulate the marrow

UCB (umbilical cord blood) =focus=source of stem cells. –> unfit because low stem cell count
–> dmPGE2 to help with the formation of graft?