Vascular Tisse Engineering

Question 1

Define artery functions

Answer 1

carrys blood away from the heart

Question 2

Define a veins function

Answer 2

carrys blood towards the heart

Question 3

Give some functions of blood

Answer 3

• body heat
• coagulation
  -gas exchange
• hormone transport

Question 4

What are the 3 layers of a blood vessel?

Answer 4

• Tunica Adventitia
• Tunica Media
• Tunica Intima

Question 5

Describe the Tunica Adventitia

Answer 5

-The outermost layer of the blood vessel.
-Houses the vasa vasorum (vessels) and the nevi vasorum (nerves) that supply the cells of the wall of the vessel itself.
-Collagen in the externa anchors the vessel to nearby structures and tissue

Question 6

Describe the Tunica Media

Answer 6

• The middle layer of the vessel wall.
  -Contains transversely arranged smooth muscle cells that are capable of changing the diameter of the vessel lumen
• contains elastic lamellae

Question 7

Describe the tunica intima

Answer 7

• innermost layer
  -Exposed to the luminal contents.
  -A single layer of simple squamous endothelial cells supported by a basal lamina. Separated from the media by elastic fibres.
  -Thickest in the arterial system and thin throughout the entire venous system

Question 8

Describe the endothelial cells in the vascular system

Answer 8

• grow in sheets & line entire system
• monolayer = one cell thick
• semipermeable barrier controls passage of water & substances

Question 9

Roughly describe the size of the endothelium

Answer 9

0.2 um thick

Question 10

Define angiogenesis

Answer 10

• formation of new blood vessels from existing ones

Question 11

Define Vasculogenesis

Answer 11

• generation of new blood vessels ‘from scratch’ via differentiation of endothelial progenitor/stem cells

Question 12

What does vascular damage expose?

Answer 12

• sub endothelial collagen which acts as a substrate for platelet adhesion & sunsequent activation

Question 13

Define Extravastion

Answer 13

• process of any substance or cell leaving a blood vessel

Question 14

What is leukocyte extravasation?

Answer 14

• highly regulated series of events involving interaction of receptors on the surface of leukocytes with molecules on surface of endothelial cells

Question 15

What can happens if leukocyte ‘leak’ out of a blood vessel ?

Answer 15

• can result in chronic inflammation due to unrestricted passage of inflammatory cells into tissues around the vessel

Question 16

Define Aneurysm

Answer 16

• bulging of a blood vessel caused by a weakness in its wall
• if the bulge ruptures = incredibly serious & can be fatal

Question 17

Define Atherosclerosis

Answer 17

• build up of lipid plaque in walls of an artery
• causes them to harden & narrow

Question 18

What is a common histological feature of aneurysm ?

Answer 18

-medial degeneration

Question 19

Describe the inflammatory cell role in atherosclerosis plaque deposition

Answer 19

• complex infiltration of inflammatory cells
• macrophages laden with lipids become ‘foam cells’

Question 20

What are the most commonly used biomaterial to augment dieased vascular tissue?

Answer 20

stents

Question 21

Describe a stent

Answer 21

• tubular, usually metal, cage like device
• used as a scaffold to restore normal diameter to an occluded blood vessel

Question 22

When is a stent fitted?

Answer 22

During an angioplasty

Question 23

Describe an angioplasty

Answer 23

• stent is directed via guide wire using medical imaging
• stent driven into defect in collapsed state, with a small balloon inside
• when it gets to target vessel the balloon is inflated, opening & expanding the stent
• balloon removed & stent remains

Question 24

What can cause a stents diameter to decrease over time?

Answer 24

• cellular process called neointimal hyperplasia

Question 25

Define Restenosis

Answer 25

-process of a vessel becoming occluded again after a stent has been inserted

Question 26

What is an 'bare metal stent'?

Answer 26

- purely metallic stent

Question 27

What are 'drug eluting stents'?

Answer 27

- stent coated with a polymer, with a predictable degradation profile, that can be used to release a drug into the tissue surrounding the implant - goal of drug is to minimise restenosis

Question 28

What drugs are typically used in stents?

Answer 28

- tend to be anti-proliferative agents - example = sirolimus