9. Scaffolds for Biological Tissue Reconstruction Flashcards

1
Q

What is the tissue engineering triad?

A

Bioscaffolds + cells + growth stimulating signals

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2
Q

What is the function of bioscaffolds?

A

To mimic ECM

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3
Q

What are the 5 broad functions of ECM?

A

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

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4
Q

What are the three layers of ECM?

A

Fibrous layer
Cellular layer
Dense layer

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5
Q

What are the 4 important scaffold properties?

A

1) Architecture
2) Tissue compatibility
3) Bio-activity
4) Mechanical properties

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6
Q

What does architecture encapsulate?

A

Void volume
Porous
Biodegradable (degradation matching neo tissue formation)

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7
Q

What characteristics of tissue compatibility does a scaffold need to exhibit?

A

Cells need to grow and differentiate

Scaffold and products must be non-toxic

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8
Q

What characteristics of bio-activity does a scaffold need to exhibit?

A

Able to interact with cells to regulate activities

-Via topography or exogenous molecules

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9
Q

What mechanical properties does a scaffold need to exhibit?

A

Shape and stability

Similarity to host tissue
- Important for cell differentiation

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10
Q

What are the 4 main approaches to scaffold design?

A
  1. Pre-made porous scaffolds for cell seeding
  2. Decellularised ECM
  3. Cell sheets with secreted ECM
  4. Cells encapsulated in self assembled hydrogel
  5. Combination Scaffolds
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11
Q

What are the two “sources” of porous scaffolds?

A

a. Natural

b. Synthetic

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12
Q

What are the 3 main sources of natural scaffolds?

A

Autogenic

Allogenic

Xenogenic (different species)

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13
Q

What are the advantages of natural scaffolds?

A

Excellent biocompatability

Good cell attachment

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14
Q

What are the disadvantages of natural scaffolds?

A

Limited physical and mechanical stability

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15
Q

What are some sources of synthetic scaffolds?

A

Inorganic - Glass + ceramics etc

Organic - Polypropylene, nylon, teflon, polymethylmethacrylate

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16
Q

What process determines the final properties of the bioscaffold?

A

Manufacture

17
Q

How can bioscaffolds be manufactured?

A

Electrospinning

Casting

Nanoweaving

3D printing

18
Q

What is decellularised ECM?

A

Derived from allograft or xenograft

Cells removed

Left with ECM

ECM conserved between species

19
Q

What are the advantages of decellularised ECM?

A

Perfect properties for homologous functions

Useful for non-homologous functions if properties similar

Excellent biocompatability

20
Q

What are the disadvantages of decellularised ECM?

A

Poor distribution of cells when seeding

Possible immune reactions if not properly decellularised

21
Q

What are cell sheets with secreted ECM?

A

Cells grown on specialised surface until confluent
Secrete own ECM
Cells + ECM removed as single sheet
Stacked into multiple layers

22
Q

What are the advantages of cell sheets?

A

Secrete own ECM
Rapid neovascularization
No sutures to keep in place

23
Q

What are the disadvantages of cell sheets?

A

Limited thickness

Not good for load bearing tissue

24
Q

What is cell encapsulation in self assembled hydrogel?

A

Entrapment of living cells within a homogenous solid mass

Suspend cells and inject into defect

25
Q

What are the advantages of cell encapsulation?

A

Good for irregularly shaped defects

26
Q

What are the disadvantages of cell encapsulation?

A

Not good for load bearing tissues

27
Q

What are combination scaffolds?

A

Utilise the best qualities from two or more devices

28
Q

What is the glue like substance in silk-fibroin?

A

Seracin