Tumor Angiogenesis Flashcards
In which 5 situations does angiogenesis occur?
- Growth and differentiation
- Wound repair
- Endometrial and placental growth
- Retinopathies
What are the 4 major stimuli of angiogenesis?
- VEGF
- Hypoxia
- PDGF
- Angiopoietins
Which stimuli is the most potent factor?
VEGF
Where does VEGF come from?
Endothelial cells but also many others (stromal, tumors, muscle). Pretty much any cell can produce it.
What makes tissue hypoxic?
Lack of oxygen to tissues.
Where does PDGF come from?
Mainly from platelets. To a lesser extent from monocytes/macrophages.
Where do angiopoietins come from?
Endothelial cells, kidney cells, and pericytes.
What does histamine do to vessels?
Increases vascular permeability and vasodilates.
How does histamine induce vascular permeability?
Breaks adhesion junctions b/t endothelial cells.
Are angiogenic signals present in new capillary formation?
Yes.
List the steps of new capillary formation (5).
- Endothelial cells degrade the vascular basement membrane
- Endothelial cells migrate, forming tip cells, that migrate toward the stimulus
- Endothelial cell proliferation forms a lumen
- The lumen extends towards the angiogenic signals through endothelial cell division and tip cell migration
- Two “sprouts” fuse their lumens, providing a route for blood flow
How do endothelial cells degrade the vascular basement membrane?
They release metalloproteinases.
Can endothelial cells invade intact basement membranes?
No.
What is notch signaling?
When tip cells migrate first, they then recruit stock cells.
The lumen formed by endothelial cell proliferation is also called what?
Folkman’s sprout.
Arteriogenesis can alleviate what?
An occluded major artery.
In arteriogenesis, are major arterioles recruited?
No.
Signifcant vascular remodeling does what in arteriogenesis?
Thickens vascular walls and increases luminal diameter.
How is thickening of vascular walls accomplished?
MCP-1 recruits macrophages. Macrophages secrete growth factors which cause endothelial cells and smooth muscle cells to grow (1 layer of endothelium and 2-3 layers of smooth muscle).
Is arteriogenesis flow mediated?
Yes: pressure changes and shear stress response stimulate it.
What is arteriogenesis?
The expansion of the existing arterial system.
T or F. Arteriogenesis and angiogenesis both require the same growth factors and development of lumens.
T.
How does angiogenesis differ from arteriogenesis?
The presence of mural cells in angiogenesis. Mural cells are only present on capillaries and not on arteries.
Where do heparin and heparan sulfates come from?
Mast cells.
