25. Cardiac Prostheses

Question 1

What are the three types of cardiovascular diseases?

Answer 1

Vacular related diseases
Valve related diseases
Muscle related diseases

Question 2

What are some examples of vascular related diseases?

Answer 2

Atherosclerosis

Aneurisms

Question 3

What are some examples of valve related diseases?

Answer 3

Incompetence

Stenosis

Question 4

What are some muscle related diseases?

Answer 4

Muscle failure
Aneurisms
Septal defects

Question 5

What are the two types of “cardiac prostheses” available (sources)?

Answer 5

Mechanical/synthetic substitutes

Biological subtitutes

Question 6

What are some types of mechanical cardiac prostheses?

Answer 6

Coronry artery substitutes
Patch material
Heart valves

Question 7

What are some biological cardiac prostheses?

Answer 7

Cardiovascular patches (pericardium)
Vascular conduits (aorta, coronary arteries)
Heart valves

Question 8

What are some advantages of mechanic/synthetic prostheses?

Answer 8

Availability
Durability
Variety

Question 9

What are the advantages of biological prostheses?

Answer 9

Availability
Physiological flow
Variety

Question 10

What are the disadvantages of mechanical cardiac prostheses?

Answer 10

Thromboembolic (clots form)
Coagulation
Haemolytic (burst blood vessels)

Question 11

What are the disadvantages of biological cardiac prostheses?

Answer 11

Calcification
Degeneration
Cannot resist wear and tear - need to provide a scaffold that can serve as a framework for regeneration

Question 12

What does tissue engineering mean?

Answer 12

Manipulation of biological molecules and cells for the purpose of creating new structures capable of normal physiological activities

Question 13

What goes into a viable prosthesis?

Answer 13

Donor cells

Scaffold

Question 14

What are the cell sources of tissue engineered prostheses?

Answer 14

Vascular endothelial cells
Vascular interstitial cells
Arterial myofibroblasts
Venous myofibroblasts
Mesenchymal stem cells

Question 15

What cardiovascular structures can you tissue engineer?

Answer 15

Biomaterials
Heart valves
Blood vessels
Myocardium

Question 16

What are the ideal cardiovascular prostheses qualities?

Answer 16

1) Readily available
2) Hemodynamic flow properties
3) Biocompatible
4) Regenerate/growth
5) Viable

Question 17

How is the scaffold prepared?

Answer 17

Decellularised
Removal of antigenicity
Stabilisation of matrix
Growth activation
Sterilisation

Question 18

How is the scaffold decellularised?

Answer 18

Surfactants
Freezing/thawing
Sodium hydroxide

Question 19

How is the antigenicity of the scaffold removed?

Answer 19

Surfactant
Nucleases
Crosslinking
Sodium hydroxide

Question 20

How is a scaffolds matrix stabilised?

Answer 20

Cross linking

Polymer incorporation

Question 21

How is growth activation achieved on scaffold?

Answer 21

Growth factors
Protein incorporation
Amino acid supplementation
Physical activation (signalling from surrounding tissue)

Question 22

How is a scaffold sterilized?

Answer 22

Chemicals (prop oxide, aldehydes, peracetic acid)
Physical (heat, radiation, gas)
Combination

Question 23

What are the 3 scaffold models?

Answer 23

non-biodegradable scaffold - (synthetic)
- repopulate in vitro/vivo with autogenous cells
Biodegradable scaffold - (biologic/synthetic)
-repopulate in vitro / in vivo with autogenous cells
Allograft / xenograft matrix
- repopulate in vivo with autogenous cells

Question 24

Can you crosslink a decellularised allograft/xenograft?

Answer 24

Yes with carbodiimides

Question 25

What is an example of a synthetic biodegradable scaffold?

Answer 25

Polyglycolic acid (PGA) and poly-L-lactic acid (PLLA) fibers (Purac) Valve Seeded with sheep mesenchymal stem cells

Question 26

What are the advantages of a biodegradable scaffold?

Answer 26

Easily replaced | Pliable

Question 27

What are the disadvantages of a biodegradable scaffold?

Answer 27

Toxic (polymers) Unpredictable Immunogenic

Question 28

What are the advantages of a non-biodegradable scaffold?

Answer 28

Durable Non - immunogenic Pliable

Question 29

What are the disadvantages of a non-biodegradable scaffold?

Answer 29

No- replacement No - remodeling Foreign body response

Question 30

What can you make a matrix patch scaffold from?

Answer 30

Pericardium (bovine, Ovine, porcine, Human) Extracted collagen (sheet or Gel) - xenogeneic Polymers

Question 31

What you make a heart valve scaffold from?

Answer 31

Pericardium (bovine, ovine, procine, human) Heart valve structure - xenogeneic / human Polymers

Question 32

What can you make a blood vessel scaffold from?

Answer 32

Artery from bovine, ovine, porcine, kangaroo, human Vein from bovine, ovine, porcine, kangaroo, human Polymers

Question 33

How can you make myocardium matrix?

Answer 33

"Muscle flap" augmentation Stem cells (injection) Stem cell vehicle

Question 34

What occurs in the tissue regeneration cascade?

Answer 34

1) Cell seeding (in vitro) / infiltration (host tissue) 2) Cell duplication ("Growth") 3) Cell trans-differentiation ("Transformation") 4) Remodeling (neo-collagen, neo-capillaries etc)

Question 35

What factors affect tissue remodeling?

Answer 35

Physical stimuli (movement, pressure, pH) Degeneration ("Wear and tear", enzymatic) Cell type (growth factors) Chemical stimuli

Question 36

What is the process for placing human cells on animal scaffold in vitro?

Answer 36

Harvest fibroblasts from Human Saphenous vein Establish fibroblast cell line Confirm cell type

Question 37

What are the requirements of a bioreactor?

Answer 37

``` Isolated Temperature controlled Flow (physiological) Gas Exchange Media Exchange ```

Question 38

What are the 3 types of bioreactors?

Answer 38

Pulsatile Laminar Forward flow

Question 39

What are some advantages associated with bioreactors?

Answer 39

Visible observations Adjust PH levels Study Morphology Temp, gas exchange, growth factors all adjustable

Question 40

What are the disadvantages of a bioreactor?

Answer 40

``` Sterility Synchronisation Cost Technical failure Limited time ```