25. Cardiac Prostheses Flashcards
What are the three types of cardiovascular diseases?
Vacular related diseases
Valve related diseases
Muscle related diseases
What are some examples of vascular related diseases?
Atherosclerosis
Aneurisms
What are some examples of valve related diseases?
Incompetence
Stenosis
What are some muscle related diseases?
Muscle failure
Aneurisms
Septal defects
What are the two types of “cardiac prostheses” available (sources)?
Mechanical/synthetic substitutes
Biological subtitutes
What are some types of mechanical cardiac prostheses?
Coronry artery substitutes
Patch material
Heart valves
What are some biological cardiac prostheses?
Cardiovascular patches (pericardium) Vascular conduits (aorta, coronary arteries) Heart valves
What are some advantages of mechanic/synthetic prostheses?
Availability
Durability
Variety
What are the advantages of biological prostheses?
Availability
Physiological flow
Variety
What are the disadvantages of mechanical cardiac prostheses?
Thromboembolic (clots form)
Coagulation
Haemolytic (burst blood vessels)
What are the disadvantages of biological cardiac prostheses?
Calcification
Degeneration
Cannot resist wear and tear - need to provide a scaffold that can serve as a framework for regeneration
What does tissue engineering mean?
Manipulation of biological molecules and cells for the purpose of creating new structures capable of normal physiological activities
What goes into a viable prosthesis?
Donor cells
Scaffold
What are the cell sources of tissue engineered prostheses?
Vascular endothelial cells Vascular interstitial cells Arterial myofibroblasts Venous myofibroblasts Mesenchymal stem cells
What cardiovascular structures can you tissue engineer?
Biomaterials
Heart valves
Blood vessels
Myocardium
What are the ideal cardiovascular prostheses qualities?
1) Readily available
2) Hemodynamic flow properties
3) Biocompatible
4) Regenerate/growth
5) Viable
How is the scaffold prepared?
Decellularised Removal of antigenicity Stabilisation of matrix Growth activation Sterilisation
How is the scaffold decellularised?
Surfactants
Freezing/thawing
Sodium hydroxide
How is the antigenicity of the scaffold removed?
Surfactant
Nucleases
Crosslinking
Sodium hydroxide
How is a scaffolds matrix stabilised?
Cross linking
Polymer incorporation
How is growth activation achieved on scaffold?
Growth factors
Protein incorporation
Amino acid supplementation
Physical activation (signalling from surrounding tissue)
How is a scaffold sterilized?
Chemicals (prop oxide, aldehydes, peracetic acid)
Physical (heat, radiation, gas)
Combination
What are the 3 scaffold models?
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
Can you crosslink a decellularised allograft/xenograft?
Yes with carbodiimides
What is an example of a synthetic biodegradable scaffold?
Polyglycolic acid (PGA) and poly-L-lactic acid (PLLA) fibers (Purac)
Valve
Seeded with sheep mesenchymal stem cells
What are the advantages of a biodegradable scaffold?
Easily replaced
Pliable
What are the disadvantages of a biodegradable scaffold?
Toxic (polymers)
Unpredictable
Immunogenic
What are the advantages of a non-biodegradable scaffold?
Durable
Non - immunogenic
Pliable
What are the disadvantages of a non-biodegradable scaffold?
No- replacement
No - remodeling
Foreign body response
What can you make a matrix patch scaffold from?
Pericardium (bovine, Ovine, porcine, Human)
Extracted collagen (sheet or Gel) - xenogeneic
Polymers
What you make a heart valve scaffold from?
Pericardium (bovine, ovine, procine, human)
Heart valve structure - xenogeneic / human
Polymers
What can you make a blood vessel scaffold from?
Artery from bovine, ovine, porcine, kangaroo, human
Vein from bovine, ovine, porcine, kangaroo, human
Polymers
How can you make myocardium matrix?
“Muscle flap” augmentation
Stem cells (injection)
Stem cell vehicle
What occurs in the tissue regeneration cascade?
1) Cell seeding (in vitro) / infiltration (host tissue)
2) Cell duplication (“Growth”)
3) Cell trans-differentiation (“Transformation”)
4) Remodeling (neo-collagen, neo-capillaries etc)
What factors affect tissue remodeling?
Physical stimuli (movement, pressure, pH)
Degeneration (“Wear and tear”, enzymatic)
Cell type (growth factors)
Chemical stimuli
What is the process for placing human cells on animal scaffold in vitro?
Harvest fibroblasts from Human Saphenous vein
Establish fibroblast cell line
Confirm cell type
What are the requirements of a bioreactor?
Isolated Temperature controlled Flow (physiological) Gas Exchange Media Exchange
What are the 3 types of bioreactors?
Pulsatile
Laminar
Forward flow
What are some advantages associated with bioreactors?
Visible observations
Adjust PH levels
Study Morphology
Temp, gas exchange, growth factors all adjustable
What are the disadvantages of a bioreactor?
Sterility Synchronisation Cost Technical failure Limited time
