1.5: stem cells

Question 1

properties of a stem cell

Answer 1

1. unspecialised: no tissue-specific structures for specific functions
2. long term self renewal: symmetrical/asymmetrical division
3. can differentiate: differential gene expression (to assist regeneration)

Question 2

what can totipotent stem cells differentiate into

Answer 2

• any cell in the adult body
• including extraembryonic membrane (placenta)

Question 3

where can totipotent stem cells be found

Answer 3

zygote

up to 8-cell stage of embryonic development

Question 4

what can pluripotent stem cells differentiate into

Answer 4

3 germ layers: mesoderm, endoderm, ectoderm

NOT extraembryonic membrane

Question 5

where can pluripotent stem cells be found

Answer 5

inner cell mass of blastocyst

Question 6

what can multipotent stem cells differentiate into

Answer 6

multiple but limited types of related cell types
eg haematopoietic (only blood)

Question 7

potency of ZSC

Answer 7

totipotent

Question 8

potency of ESCs

Answer 8

totipotent

Question 9

potency of ASCs

Answer 9

multipotent

Question 10

sources of ESCs

Answer 10

1. in-vitro fertilisation
2. somatic cell nuclear transfer

Question 11

pros of ESCs

Answer 11

1. divide indefinitely
2. differentiate into wide range of cell types
3. relatively easily accessible (infertility treatments)

Question 12

cons of ESCs

Answer 12

1. ethic issues
2. potential rejection by patient’s immune system
3. cannot control what types of differentiation ESC will undergo

Question 13

source of ASCs

Answer 13

1. umbilical cord
2. specialised tissues and organs (eg bone marrow, brain, liver, skin)

Question 14

pros of ASCs

Answer 14

1. less ethical controversy
2. ASCs will produce specific cell types of tissues (multipotent)
3. lowered risk of immune rejection (own body)

Question 15

cons of ASCs

Answer 15

1. limited quantities
2. limited ability to differentiate
3. cannot divide indefinitely

Question 16

concerns: hESCs

Answer 16

1. ethical: destruction of embryo/intentionally making embryos
   2: donate vs destroy anyways

Question 17

concerns: SCNT

Answer 17

risk of reproductive cloning

Question 18

what are iPSCs

Answer 18

induced pluripotent stem cells

somatic cells reprogrammed via chemical env -> stem cells

unlimited self renewal

pluripotent

can replace ESCs (ethics)

Question 19

applications of iPSCs

Answer 19

1. regenerative medicine
2. disease modelling

Question 20

pros of iPSCs

Answer 20

1. reduce risk of immune rejection
2. almost unlimited supply
3. ethical concerns solved

Question 21

cons of iPSCs

Answer 21

1. low efficiency and partial programming of cells
2. risk of tumorigenesis