minden pookie's study guide 2

types of stem cells (ES cells)

- embryonic stem cells [ES cells]

- adult stem cells

- fetal stem cells

- umbilical cord stem cells

- somatic cell nuclear transfer [SCNT] stem cells

- induced pluripotent stem cells [iPS cells]

- parthenogenetic stem cells

- neural stem cells

ES stem cells review

- derived from blastocyst [early embryo]

- pluripotent

adult stem cells

- found in many of out developed tissues

- usually multipotent

- sometimes unipotent

main categories of adult stem cells

- true adult stem cells

- multipotent stromal cells

- progenitor cells

true adult stem cells/tissue stem cells

- capable of long-term self-renewal

- maintain specific tissue for life

- can generate multiple cell types within that tissue

- ex: hematopoietic stem cells

Hematopoietic stem cells (HSCs)

- stem cell found in red bone marrow

- true stem cells

- produce blood cells and immune cells

- they differentiate into myeloid progenitor cells and lymphoid progenitor cells, which then differentiate further

multipotent stromal cells/mesenchymal stem cells; MSCs

- connective tissue-associated cells

- show multipotent differentiation in vitro

- often function through signaling and tissue support

mesenchymal stem cells

- found in yellow marrow [stromal region]

- can form bone, cartilage, muscle in vitro

- secrete factors that are important for tissue repair and immune regulation

MUSE cells [multi-lineage differentiating stress enduring cells]

- subset of MSCs [1-2%]

- potentially higher therapeutic value than MSCs

- can be recognized by specific surface markers

progenitor cells

- more differentiated than true stem cells

- limited self-renewal

- committed to a specific lineage

- ex: endothelial progenitor cells [EPCs]

Question: MSCs are present in the __________ bone marrow

- yellow

skin basal layer

- the deepest layer

- contains epidermal stem cells

epidermal stem cells

- migrate upwards as they differentiate into keratinocytes

keratinocytes

- replace the outer layer, which contains dead keratinocytes, once it becomes damaged or flaking occurs

intestine is made up of

- crypts

crypts contain

- stem cells

- these stem cells give rise to intestinal epithelial cells, like enterocytes and other cell types in the intestine

other examples of adult stem cells

- spermatogonial stem cells

- hair follicle stem cells

- muscle stem cells [MuSCs]

Spermatogonial stem cells

- giver rise to sperm

- unipotent

hair follicle stem cells

- give rise to cells tat form the hair shaft

- multipotent

- give rise to multiple cell types of the hair shaft

muscle stem cells

- aka skeletal muscle satellite cells

- give rise to muscle cells; important for muscle repair

- unipotent

Question: Adult stem cells of the intestine are located in the:

A. Crypt

B. Paneth

C. Top of the villi

D. Lumen

E. None of the above

A. Crypt

Question: The type of cell in the outermost layer of the skin are the:

A. Epithelial cells

B. Basal cells

C. Keratinocytes

D. Enterocytes

E. Crypt cells

C. Keratinocytes

fetal stem cells

- found in fetal tissues in the first trimester

- usually multipotent

- fetal cells grow rapidly, and are associated with rapid growth of the fetus

- fetal cells are generally a mix of stem and progenitor cells

ex use for disease and research of fetal stem cells

- dopamine neurons in Parkinson's disease research and potential treatment

source of HSCs

- cord blood

source of MSCs

- Wharton's jelly

source of endothelial progenitor cells

- cord vein

storage and use of umbilical cord stem cells

- can be stored in blood banks

Question: The type of gel-like connective tissue found in the umbilical cord

is called ___________ jelly

- Wharton

SCNT step 1

- the nucleus from the somatic cell is transferred to an enucleated [nucleus removed] egg cell

SCNT step 2

- this egg is activated [artificially without sperm] and develops into a blastocyst

SCNT step 3

- blastocyst is used as a source of embryonic stem cells

SCNT step 4

- if implanted into a female [originally this was done in sheep], the embryo develops into a cloned baby

SCNT step 5

- this cloned baby animal will contain the genetic information from the original somatic cell

SCNT step 6

- these methods all involve cloning techniques, as the original somatic cell is cloned

types of cloning

- therapeutic and reproductive

therapeutic cloning

- stem cells

reproductive cloning

- whole organism

- Dolly the Sheep

SCNT developments

- this method has been used to clone multiple types of animals, including farm animals and pets, including primates

- making adults SCNTs has been challenging and also controversial

- scientists have, however, found that adult human cells can be used to produce blastocysts using therapeutic cloning

why are SCNTs promising

- research models for disease

- possibility of autologous stem cell therapy

autologous stem cell therapy

- patient's own cells are used to make the stem cells, so the genetic match is perfect

telomeres

- found at the ends of chromosomes

- prevent the coding regions of DNA from losing material

- shorten with each cell division

- older individuals have shorter ones than younger individuals

telomeres and SCNT cells

- telomeres may be restored/lengthened in SCNT cells

- this is an advantage, especially when using somatic cells from older individuals

- promising, but results have been variable in different studies

risks and issues regarding SCNTs

- ethical concerns [involves embryo destruction]

- some health problems that have appeared in cloned cells may have some abnormalities

what are induced pluripotent stem cells [iPS cells]

- adult cells reprogrammed to take on characteristics of pluripotent stem cells

- were originally made by retroviral infection of 4 genes into somatic skin cells

- later, it was shown to be more effective if 6 genes were used

retroviral infection

- used as a method to introduce genes into the cells

four original genes used to make iPS cells

- Oct3/4

- Sox2

- C-Myc

- Klf4

two additional genes shown to be effective in iPS cells

- nanog

- Lin28

Oct3/4

- a transcription factor that is associated with many target genes implicated in maintenance of pluripotency

Sox2

- a transcription factor necessary for embryonic development and for preventing ES cell differentiation

C-Myc

- a transcription factor with many cellular functions

- important for proliferation, oncogenic

Klf4

- transcription factor

- its overexpression inhibits differentiation of ES cells

Nanog

- a transcription factor, normal found in ES cells

- has a role in promoting pluripotency

Lin28

- an mRNA binding protein found in ES cells that has a role in both pluripotency and differentiation

advantages of using iPS cells

- no embryos needed

- personalized medicine and autologous therapy is a possibility

- reduced risk of immune rejection due to the ability to use genetically matched cells

challenges of using iPS cells

- cancer risk; especially because of the use of c-Myc and use of retroviral infection

- sometimes the developed cells exhibit low growth

- takes time to develop the cells

- sometimes, cells have been shown to develop mutations over time

use of iPS cells

- mostly research

- disease modeling

- drug testing

Question: Which of the following best describes induced pluripotent stem (iPS) cells?

A. They are derived from embryos and can only form extraembryonic tissues

B. They are differentiated adult cells that have been reprogrammed to a pluripotent state

C. They are naturally occurring stem cells found only in bone marrow

D. They are formed by fusion of sperm and egg cells

B. They are differentiated adult cells that have been reprogrammed to a pluripotent state

parthenogenetic stem cells definition

- stem cells from activation of unfertilized eggs

parthenogenetic stem cells methods

- eggs are activated artificially [chemicals and electricity]

- activated egg develops into a blastocyst but cannot develop into embryo

- stem cells can still be derived from this blastocyst

neural stem cells (NSCs) definition

- cells that differentiate into neurons

neural stem cells (NSCs) sources

- iPS cells that are differentiated into neurons in vitro

- ES cells that are differentiated into neurons in vitro

- MSCSs that are differentiated into neurons in vitro

- fetal stem cells from the fetal nervous system

- a small number of NSCs are also present naturally in the brain throughout life [adult stem cells]. They give rise to olfactory neurons and some granule cells

Question: Isolation of some types of adult stem cells requires isolation of cells from a blastocyst.

True/False

- False

Question: The type of stem cells that are derived from the developing brain of a fetus are called:

A. Embryonic stem cells

B. Fetal stem cells

C. Hematopoietic stem cells

D. Parthenogenetic stem cells

E. B or C

B. Fetal stem cells

Question: Why might scientists use somatic cell nuclear transfer (SCNT) to generate stem cells?

A. To produce stem cells that genetically matched to the donor, thus reducing the risk of rejection by the immune system.

B. To create genetically modified animals for agricultural purposes.

C. To generate hybrid cells with traits from multiple species.

D. To induce spontaneous differentiation of adult cells without the need to use an embryo.

E. To increase the lifespan of aging somatic cells.

A. To produce stem cells that genetically matched to the donor, thus reducing the risk of rejection by the immune system.

Question: In the intestine, stem cells are located in the:

A. Crypt

B. Paneth cells

C. Enterocytes

D. Basal layer

E. Keratinocyte layer

A. Crypt

Question: Which of the following best describes cells generated by somatic cell nuclear transfer (SCNT)?

A. They are genetically identical to the oocyte donor

B. They are genetically identical to the somatic cell donor

C. They are genetically identical to both the somatic cell donor and the oocyte donor

D. They are haploid cells that require fertilization to develop further

E. They are the same as parthenogenetic stem cells

B. They are genetically identical to the somatic cell donor

Question: What is the key differences between therapeutic cloning and reproductive

cloning?

A. Therapeutic cloning is used to generate stem cells for research or treatment, while

reproductive cloning aims to produce a whole organism

B. Therapeutic cloning requires fertilization, while reproductive cloning does not

C. Therapeutic cloning produces haploid cells, while reproductive cloning produces diploid organisms

D. Therapeutic cloning can only be carried out with human cells, where reproductive cloning can be carried out using any cell types

A. Therapeutic cloning is used to generate stem cells for research or treatment, while

reproductive cloning aims to produce a whole organism

Question: A type of stem cells that are formed from artificial egg activation and that results in haploid cells are called ____________ stem cells

- parthenogenetic stem cells