Lec 2 (What are stem cells?)

What are stem cells?

• Undifferentiated cells

• Capable of differentiating into a number of other cell types

• Self-renewing properties; but many bone and nerve cells are NOT replaced!

What are the self-renewing properties of stem cells?

• Mitosis through asymmetrical division

• Daughter remains a stem cell (keeps replicating)

What type of cell is made from single-cell asymmetry of stem cells?

Committed cell

What are committed stem cells?

does not mean it is differentiated but it will be differentiating

What 2 cell types are made from single cell asymmetry?

another stem cell and a cell committed to differentiation

Symmetrical cell division results in either:

• 2 stem cells

• 2 committed cells

What are Totipotent stem cells?

able to give rise to all embryonic and adult lineages (Ex. Zygote)

• Source: Zygote

What are Pluripotent stem cells?

able to give rise to all cell types in an adult (Ex. Embryonic stem cells)

• Source: Blastocyst

What are Multipotent stem cells?

able to give rise to multiple cells within a lineage (Ex. Neuronal stem cells)

• Source: Embryo or adult

What are Unipotent stem cells?

capable to give rise to single cell within lineage (Ex. Spermatozoa, epidermal stem cells)

• Source: Adult

What type of stem cells line our intestine?

Unipotent

• old cells shed into gut lumen to maintain gut health

• Cells from basal layer are unipotent stem cells

What are blood forming stem cells called?

Hematopoietic

• formed in human bone marrow

• produce more HSCs

• daughter cells capable to come a range of other cell types

What is BrdU?

• thymidine analogue

• actively dividing cells incorporate BrdU

What 4 features can be seen with in situ hybridization (ISH)?

1. spatial resolution of gene expression

2. temporal resolution of gene expression

3. genetic interactions of genes, gene relationships in specific diseases, genes as tissue markers

4. activity of specific alleles

What method can be used to visualize gene expression patterns in cells and tissues?

In situ hybridization (ISH)

What is ISH?

a technique that allows for precise localization of a specific segment of nucleic acid within a histologic section

What is the 4 steps for ISH?

1. Probe: Synthesized RNA with antisense sequence of target - DIG

2. Target - mRNA

3. Antibody - detects DIG, is conjugated with AP

4. Colour reaction