9. Scaffolds for Biological Tissue Reconstruction Flashcards
What is the tissue engineering triad?
Bioscaffolds + cells + growth stimulating signals
What is the function of bioscaffolds?
To mimic ECM
What are the 5 broad functions of ECM?
1) Structural support and physical environment for cells to grow
2) Provides structural/mechanical properties
3) Provision of bioactive cues
4) Acts as reservoir of growth factors
5) Provides a changeable environment to allow for events such as remodeling and neovascularisation
What are the three layers of ECM?
Fibrous layer
Cellular layer
Dense layer
What are the 4 important scaffold properties?
1) Architecture
2) Tissue compatibility
3) Bio-activity
4) Mechanical properties
What does architecture encapsulate?
Void volume
Porous
Biodegradable (degradation matching neo tissue formation)
What characteristics of tissue compatibility does a scaffold need to exhibit?
Cells need to grow and differentiate
Scaffold and products must be non-toxic
What characteristics of bio-activity does a scaffold need to exhibit?
Able to interact with cells to regulate activities
-Via topography or exogenous molecules
What mechanical properties does a scaffold need to exhibit?
Shape and stability
Similarity to host tissue
- Important for cell differentiation
What are the 4 main approaches to scaffold design?
- Pre-made porous scaffolds for cell seeding
- Decellularised ECM
- Cell sheets with secreted ECM
- Cells encapsulated in self assembled hydrogel
- Combination Scaffolds
What are the two “sources” of porous scaffolds?
a. Natural
b. Synthetic
What are the 3 main sources of natural scaffolds?
Autogenic
Allogenic
Xenogenic (different species)
What are the advantages of natural scaffolds?
Excellent biocompatability
Good cell attachment
What are the disadvantages of natural scaffolds?
Limited physical and mechanical stability
What are some sources of synthetic scaffolds?
Inorganic - Glass + ceramics etc
Organic - Polypropylene, nylon, teflon, polymethylmethacrylate
What process determines the final properties of the bioscaffold?
Manufacture
How can bioscaffolds be manufactured?
Electrospinning
Casting
Nanoweaving
3D printing
What is decellularised ECM?
Derived from allograft or xenograft
Cells removed
Left with ECM
ECM conserved between species
What are the advantages of decellularised ECM?
Perfect properties for homologous functions
Useful for non-homologous functions if properties similar
Excellent biocompatability
What are the disadvantages of decellularised ECM?
Poor distribution of cells when seeding
Possible immune reactions if not properly decellularised
What are cell sheets with secreted ECM?
Cells grown on specialised surface until confluent
Secrete own ECM
Cells + ECM removed as single sheet
Stacked into multiple layers
What are the advantages of cell sheets?
Secrete own ECM
Rapid neovascularization
No sutures to keep in place
What are the disadvantages of cell sheets?
Limited thickness
Not good for load bearing tissue
What is cell encapsulation in self assembled hydrogel?
Entrapment of living cells within a homogenous solid mass
Suspend cells and inject into defect
What are the advantages of cell encapsulation?
Good for irregularly shaped defects
What are the disadvantages of cell encapsulation?
Not good for load bearing tissues
What are combination scaffolds?
Utilise the best qualities from two or more devices
What is the glue like substance in silk-fibroin?
Seracin
