19.2 Pluripotent Stem Cells, Cellular Reprogramming and Regenerative Medicine

Question 1

() can be grown indefinitely as pure stem cell populations that have pluripotency

Answer 1

embryonic stem cells

Question 2

the capacity to develop into all of the different types of cells in adult tissues

Answer 2

pluripotency

Question 3

embryonic stem cells are important experimental tools because:

Answer 3

1. they can be used to introduce altered genes into mice
2. they provide an outstanding model system for studying molecular and cellular events associated with embryonic cell differentiation

Question 4

experiments by Martin and colleagues found that embryonic cells could be directed to differentiate along specific pathways by the () to an embryonic stem cell culture

Answer 4

addition of the appropriate growth factors or small molecules (e.g. retinoic acid)

Question 5

mouse embryonic cells are grown in a growth factor called () to maintain the cells in the undifferentiated state

Answer 5

leukemia inhibitory factor (LIF)

Question 6

removal of LIF from mouse embryonic cell culture causes the cells to aggregate into () and differentiate

Answer 6

embryoid bodies

Question 7

transplantation of a nucleus of one cell (e.g. mammary epithelial cell) into an unfertilized egg in place of a normal egg nucleus

Answer 7

somatic cell nuclear transfer

Question 8

what are the main issues of somatic cell nuclear transfer

Answer 8

1. it is an extremely inefficient procedure in mammals
2. the small number of cloned animals that survive birth suffer various abnormalities and have short life spans

Question 9

a nucleus from an adult human cell is transferred to an enucleated (nucleus removed) egg, which would then be used to produce an early embryo in culture

Answer 9

therapeutic cloning

Question 10

what are the main benefits of therapeutic cloning

Answer 10

1. resulting embryo could produce differentiated cells for transplantation therapy
2. because the embryo would come from the patient’s nucleus and cells, this could bypass the problem of tissue rejection

Question 11

major obstacles to therapeutic cloning

Answer 11

1. . low efficiency of generating embryos by somatic cell nuclear transfer
2. ethical concerns with respect to the possibility of cloning human beings (reproductive cloning) and with respect to the destruction of embryos

Question 12

() can be directly converted to pluripotent stem cells in culture

Answer 12

adult somatic cells

Question 13

() arise by reprogramming somatic cells by the action of only 4 transcription factors → results in cells resembling embryonic stem cells

Answer 13

induced pluripotent stem cells

Question 14

the 4 transcription factors used to make induced pluripotent stem cells

Answer 14

1. Oct4
2. Sox2
3. Klf4
4. c-Myc

Question 15

to make induced pluripotent stem cells, transcription factors were introduced via ()

Answer 15

infection with retroviral vectors

Question 16

the ff. 3 transcription factors activate a transcriptional program that is also expressed in embryonic cells

Answer 16

1. Oct4
2. Sox2
3. Nanog

Question 17

Oct4, Sox2, and Nanog form an autoregulatory loop → ()

Answer 17

they act together to positively regulate each other’s expression

Question 18

activation of Oct4, Sox2, and Nanog results in the activation of genes that () and repression of genes that ()

Answer 18

1. maintain the pluripotent state
2. enable differentiation

Question 19

reprograming somatic cells into other types of differentiated cells (e.g. fibroblasts to muscle cells or neurons)

Answer 19

transdifferentiation

Question 20

mouse fibroblasts have already been converted into heart muscle cells using only 3 transcription factors

Answer 20

Gata4, Mef2c, Tbx5

Question 21

mouse fibroblasts have already been converted into nerve cells using only 3 transcription factors

Answer 21

Ascl1, Brn2, Myt1l