Stem cells

What are the abilities of stem cells?

• self renewal: can continuously divide by asymmetric replication

• Potency: can differentiate into specialised cells

What can unipotent stem cells differentiate into?

1 cell type that have the property of cell renewal

Eg. Adult stem cells

What can multipotent stem cells differentiate into?

A family of cells in a tissue

Eg. Cord blood (umbilical) stem cells (rich in mesenchymal + hematopoietic stem cells)

What can pluripotent stem cells differentiate into?

the cells of the germ later (any cell apart from the placenta)

Eg. embryonic stem cells + induced pluripotent stem cells

What can totipotent stem cells differentiate into?

Embryonic and extra embryonic cells

What type of stem cells are found in the bone marrow? Give examples

Multipotent stem cells

• haematopoietic: RBC + inflammatory cells

• Mesenchymal: fibre breasts, cartilage, muscle, fat, bone

• Endothelial progenitor cell

What are the different types of cells? Give examples

labile - divide constantly e.g. skin epithelia, GI tract

Stable - Can divide, but don’t do it (at G0) constantly e.g. hepatocytes, osteoblast, fibroblast

Permanent - Unable to divide eg. RBC, Neuron, cardiac cmyocytes

What do epidermal growth factors do?

Mitogenic (induces mitosis) for epithelial cells and fibroblasts

What do vascular endothelial growth factors do?

Induce angiogenesis

What do platelet derived growth factors do?

Cause migration and proliferation of fibroblasts

What do tumor necrosis factors do?

Induced fibroblast migration, proliferation and collagenase secretion

What stimulates regeneration and repair?

Growth factors

Stimulate transcription of genes that regulate cell proliferation

** produced by macrophages

What inhibits regeneration and repair?

Cell-cell + cell-stroma contact → effect-contact inhibition (drops cell growth/proliferation)

What binds cells to eachother?

Cadherins and connexion

What binds cells to the ECM?

Integrins

Pros and cons of stem cells

Pro:

• medical benefits: disease curing + used in regeneration and repair

• Research for human diseases

• Drug testing

Cons:

• uncertainty of long term effects

• Potential tumour growth + tissue rejection

• Ethical + legal problems