Stem Cells 1

Stem cells

Cells that self renew and give rise to differentiated cells

What does stem cell knowledge help with

Development biology

Help use understand adult tissue homeostasis

Understand disease biology

Serve as therapeutic agents

Hematoppietic stem cells

Used for treating blood cancers and disorders affecting the blood and immune system

Prochymal

Example of a stem cell product in Canada

Mesenchymal cells Indicated for Graft vs Host Disease

Lifespan of RBC, platelets, and WBC

RBC - 120 days

Platelets - 8 - 10 days

WBC - 2-3 weeks

When do stem cells become totipotent cells?

8 - 16 cell stage

Blastocyst inner cell mas vs trophectoderm

Inner cell mass - pluripotent (capable of giving rise to different types of cells)

Trophectoderm - turn to extra-embryonic tissue

Totipotent cells

cells that are able to develop into any type of cell found in the body.

Top of the heiracrchy

Heirachy of potency

Totipotent

Pluripotent

Multipotent

Differentiated cells

What can pluripotent cells turn into

Mesnechymal cells

Hematopoietic cells

Intestinal stemm cells

WBC

RBC

platelets

embryonic stem cells

Pluripotent (can form all cell types except tropghectoderm)

Hematopoetic stem cells

Multipotent (blood cells and immune cells)

Mesenchymal stem cells

Multipotent (bone, cartilage and fat)

Intestinal stem cells

Multipotent (different types of cells in the intestine)

Epidermal stem cells

Bipotent (identified as unipotent in some literature; forms keratinocytes and merkel cells

Spermatogonial stem cells

Unipotent (sperm cells)

Salient features of stem cells

Self-renew themselves to make thier own copy

Generate trasnit amplifying cells

Persist a long time

Regulated by their closer environment

What type of division can stem cells perfomr

asymmetric + symmetric division

True or False: Transit cells undergo only a few rounds of division before their final differentiation into mature cells

False

They undergo multiple

What does assymetric division of one stem cell give rise to

A transit cell

A stem cell

What does the balance between symmetric and asymmetric division of stem cells depend on

Dependent on the tissue requirment and controlled by stem cell environment

What does Asymmetric division Symmetric division favour

Asymmetric division - tissue growth/repair

Symmetric division - steady state maintenance, stem cell reserve

Potential reasons for the long-term survival of stem cells

They express high levels of telomerase and perserve telomere length

Stem cells generally have a low turnover rate

Telomeres

At end of chromosomes

Doesnt get copied during cell division - shortens in every cell division

Why do stem cells overexpress the telomerase enzyme complex

Preserve telomere length using telomerase, thus escaping senscence

Whats the stem cell niche concept

Stem cells are regulated by their closer environment which influence the fate of stem cells

Crypt

Stem cell source in the small intestine

Fill in the blank: ISC derived cells migrate from ____ to the ____, ____

Crypt to the villus tip, maturing along the way

What is needed for the intestinal stem cell formation

Wnt, R-spondin, and EGF signals from Paneth and Mesenchymal cells

What is secreted from sertoli cells to support spermatogonial stem cells

Secrete glial cell-derived neurotrophic factor (GDNF) and FGF to support SSC

Leydic cells provide ____ to support their self-renewal

Colony-stimulating factor (CSF)