L5.StemCells

Question 1

What are the two requirements for a cell to be a STEM CELL?

Answer 1

1. Renew - Duplicate into an identical Stem Cell

2. Differentiate - Specialize

Question 2

Define each type of Stem Cell & give examples/where they can be found:

1. Totipotent
2. Pluripotent
3. Multipotent

Answer 2

1. Totipotent cells are able to differentiate into anything human. Found in Zygote.
2. Pluripotent cells are able to differentiate into any of the three germ layers. Embryonic stem cells found in Blastocyst (starting at day 5)
3. Multipotent are stem cells limited in their ability to differentiate. Postnatal Stem Cells. Many different forms. Found throughout the body.

Question 3

How do adult and embryonic stem cells differ in their ability to Renew?

Answer 3

Embryonic stem cells have near endless self renewal abilities.
Adult stem cells have a LIMITED renewal capacity

Question 4

When a stem cell differentiates what is the required middle step b/t stem cells and specialized cells? Describe

Answer 4

Committed Progenitors = Transient amplifying cell

• Multipotent
• Divide rapidly
• No self renewal

Question 5

Where are Hematopoietic Stem Cells derived from? Describe their specialization pathway.

Answer 5

Hematopoietic stem cells are found in bone marrow.
HSC –> Multipotential SC (=committed progenitor) –> Lymphoid Progenitor OR Myeloid Progenitor cell.
-Lymphoid Progenitor –> NK cells & T & B lymphocytes
-Myeloid Progenitor –> White & red blood cells & platelets

Question 6

What are Stromal/Mesenchymal stem cells?

Answer 6

Stromal/Mesenchymal are HETEROGENOUS SCs that exist in nearly ALL tissues of the body. They are the fibroblast like cells that form bone, skin, cartilage, etc..

Question 7

What are 3 examples of Oral MSC that were discussed in class? Think of the studies presented

Answer 7

1. SHED = Baby teeth (Human Exfoliated Deciduous Teeth)
2. DPSC = Dental Pulp
3. PDLSC = periodontal ligament
   Note: Also Gingival and apical papillary SC found

Question 8

What is necessary for a stem cell niche?

Answer 8

A stem cell niche is the microenvironment around stem cells that provides support and signal regulating self-renewal and differentiation. Can be through…

• Direct Contact (Junctions, ECM, Basement Mem)
• Soluble Factors (signal transduction pathways)
• Intermediate cells

Question 9

A hair follicle niche for SC is located in the bulge, which is located app halfway b/t the hair follicle and the epidermis. What does the SC differentiate into? 2 things

Answer 9

1. Permanent segment towards the epidermis

2. Cycling segment down towards the hair follicle and incorporated into hair at the dermal papilla

Question 10

Is it possible to transform Adult/somatic stem cells into Pluripotent stem cells (iPS)?

Answer 10

Yes, the signaling is not entirely understood but pathways and specific signalers have been isolated that control this.