CPPS 325 Midterm 2 Exam Questions
With Answers
What are stem cells? - Answer - unspecialized cells from which differentiated cells
develop
- capacity to both self-renew and give rise to differentiated cells
- help us to understand adult tissue homeostasis and disease biology
How were hematopoietic stem cells discovered? - Answer 1) lethal radiation to recipient
mouse bone marrow to kill all bone marrow cells
2) transfer of bone marrow from donor mouse to radiated mouse
3) sub-lethal radiation to recipient cells to induce unique chromosomal mutations in
individual cells (each cell has unique mutation = marker)
4) cell colonies that share a common mutation indicates they originated from a single
cell (hematopoietic stem cell)
potency of stem cells - Answer - defined as the ability of cells to differentiate into
different cell lineages
- can be totipotent, pluripotent, multipotent, or unipotent
- the inner cell mass is totipotent and can differentiate into every cell type (except
placenta)
Examples of stem cells and their potency - Answer - Embryonic stem cells (ESCs) :
Pluripotent (can form all cell types except trophectoderm).
- Hematopoietic stem cells (HSCs) : Multipotent (blood cells and immune cells).
- Mesenchymal stem cells (MSCs) : Multipotent (bone, cartilage and fat).
- Intestinal stem cells (ISCs): Multipotent (different types of cells in the intestine).
- Epidermal stem cells: Bipotent, keratinocytes and Merkel cells).
-Spermatogonial stem cells (SSCs): Unipotent (sperm cells only).
Features of stem cells - Answer - self-renew to make copies of themselves (cell
division)
- generate transit amplifying cells (in transition between stem cells and differentiated
cells)
- persist for long periods of time
, - regulated by their closer environment (niche environment)
asymmetric stem cell division - Answer - maintains the pool of stem cells
- steady state maintenance of stem cells and differentiated cells
- The balance between the symmetric and asymmetric divisions of stem cells is
influenced by tissue requirements and is controlled by the stem cell environment (stem
cell niche)
Symmetric stem cell division - Answer - expansion of amplifying cells: tissue growth and
repair
- expansion of stem cells: maintains stem cell reserve
Why do stem cells persist for long periods of time? - Answer - Stem cells have sufficient
telomerase enzyme (preserves the length of telomeres)
- Stem cells have a low turnover rate. (divide less frequently than regular cells)
stem cell niche - Answer - an area of a tissue that provides a specific microenvironment,
in which stem cells are present in an undifferentiated and self-renewable state.
- Cells of the stem-cell niche interact with the stem cells to maintain them or promote
their differentiation.
- external stimuli (ex: hormones, oxygen content, lipids) promote the differentiation of
cells
Stem cell niche: small intestine - Answer - Wnt and EGF from paneth cells and wnt and
R-spondin from mesenchymal cells are essential for stemness of the intestinal stem
cells
hematopoietic stem cells (HSC) - Answer - cells in the bone marrow that gives rise to all
types of blood cells and immune cells
- multipotent stem cell
- two progenitor cells (lymphoid and myeloid)
hematopoietic stem cell markers - Answer - specific proteins attached to a cell that can
be used to identify the cell
- most of the markers expressed in the HSCs are also expressed in the progenitor cells
- all the hematopoietic cell types express CD34+
- HSCs are distinguished based on overlapping markers
Stem cell sorting method - Answer - A mixed population of cells (HSCs/progenitor cells)
are stained with Fluorescent- tagged antibodies against surface antigens expressed on
the cells.
- Fluorescent activated cell sorter (FACS) machine will sort and purify cells based on
cell fluorescence (colour)
HSC characterization experiment - Answer In vivo transplantation:
With Answers
What are stem cells? - Answer - unspecialized cells from which differentiated cells
develop
- capacity to both self-renew and give rise to differentiated cells
- help us to understand adult tissue homeostasis and disease biology
How were hematopoietic stem cells discovered? - Answer 1) lethal radiation to recipient
mouse bone marrow to kill all bone marrow cells
2) transfer of bone marrow from donor mouse to radiated mouse
3) sub-lethal radiation to recipient cells to induce unique chromosomal mutations in
individual cells (each cell has unique mutation = marker)
4) cell colonies that share a common mutation indicates they originated from a single
cell (hematopoietic stem cell)
potency of stem cells - Answer - defined as the ability of cells to differentiate into
different cell lineages
- can be totipotent, pluripotent, multipotent, or unipotent
- the inner cell mass is totipotent and can differentiate into every cell type (except
placenta)
Examples of stem cells and their potency - Answer - Embryonic stem cells (ESCs) :
Pluripotent (can form all cell types except trophectoderm).
- Hematopoietic stem cells (HSCs) : Multipotent (blood cells and immune cells).
- Mesenchymal stem cells (MSCs) : Multipotent (bone, cartilage and fat).
- Intestinal stem cells (ISCs): Multipotent (different types of cells in the intestine).
- Epidermal stem cells: Bipotent, keratinocytes and Merkel cells).
-Spermatogonial stem cells (SSCs): Unipotent (sperm cells only).
Features of stem cells - Answer - self-renew to make copies of themselves (cell
division)
- generate transit amplifying cells (in transition between stem cells and differentiated
cells)
- persist for long periods of time
, - regulated by their closer environment (niche environment)
asymmetric stem cell division - Answer - maintains the pool of stem cells
- steady state maintenance of stem cells and differentiated cells
- The balance between the symmetric and asymmetric divisions of stem cells is
influenced by tissue requirements and is controlled by the stem cell environment (stem
cell niche)
Symmetric stem cell division - Answer - expansion of amplifying cells: tissue growth and
repair
- expansion of stem cells: maintains stem cell reserve
Why do stem cells persist for long periods of time? - Answer - Stem cells have sufficient
telomerase enzyme (preserves the length of telomeres)
- Stem cells have a low turnover rate. (divide less frequently than regular cells)
stem cell niche - Answer - an area of a tissue that provides a specific microenvironment,
in which stem cells are present in an undifferentiated and self-renewable state.
- Cells of the stem-cell niche interact with the stem cells to maintain them or promote
their differentiation.
- external stimuli (ex: hormones, oxygen content, lipids) promote the differentiation of
cells
Stem cell niche: small intestine - Answer - Wnt and EGF from paneth cells and wnt and
R-spondin from mesenchymal cells are essential for stemness of the intestinal stem
cells
hematopoietic stem cells (HSC) - Answer - cells in the bone marrow that gives rise to all
types of blood cells and immune cells
- multipotent stem cell
- two progenitor cells (lymphoid and myeloid)
hematopoietic stem cell markers - Answer - specific proteins attached to a cell that can
be used to identify the cell
- most of the markers expressed in the HSCs are also expressed in the progenitor cells
- all the hematopoietic cell types express CD34+
- HSCs are distinguished based on overlapping markers
Stem cell sorting method - Answer - A mixed population of cells (HSCs/progenitor cells)
are stained with Fluorescent- tagged antibodies against surface antigens expressed on
the cells.
- Fluorescent activated cell sorter (FACS) machine will sort and purify cells based on
cell fluorescence (colour)
HSC characterization experiment - Answer In vivo transplantation:
