Lecture 18 - Tissue engineering: novel materials Flashcards Preview

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Flashcards in Lecture 18 - Tissue engineering: novel materials Deck (16):
1

What are the 3 key hurdles that we need to consider for TE success?

technical - what will talk about mostly. Suitable biomaterials, BS to 3d structures, delivery of biological signals, infection control

Commercial - can you get the funding? Financial problems

Regulatory - need to regulate, can be difficult, uncertainty in the field

2

The tradition Te approach of placing cells and growth factors into a matrix, and forming tissue does or doesn't work?

Doesn't work - body doesn't respond well to a large foreign object placed in it, so the bio material being used is the hurdle

3

In vitro constructs is feasible for...

avascular, small or 2 dimensional tissues

so cartilage, skin have worked - no need to worry about blood supply

4

What is a n in vivo bioreactor?

allows construct develop concurrently with vascularisation

surgeons place a blood vessel loop in the side of the developing tissue

5

So the technical challenges are...

Suitable biomaterials,
BS to 3d structures,
delivery of biological signals, infection control

6

What is the role of the biomaterial used?

sacaffolds, surfaces and microenvironments for cell growth

ideally mimic native tissue ECM

provide space and biochemical environment to allow new tissue to grow

mechanics important as well as chemical and biochemical interactions

7

many criteria for good biomaterial apply, but good design may require..

compromise/optimisation

depending on the type of tissue, will determine what is prioritised

8

bicompatability is very...

specific, depends on application. Not appropriate as a broad descritpion

9

So what are the criteria for biomaterials in TE?

biocompatiblity

mechanical properties

biodegradability profile (time, strength and by-products)

suitable in vivo responses (e.g inflammation)

Ability to be fabricated into desired structures

cost-effective, available, regulatory approval

ability to be sterilised safely

adequate stability and shelf-life

promote desired cellular responses - proliferation, differentiation, gene expression

10

what are the limitations of the biomaterial in TE?

foreign body reaction, acid release, toxicity, supply, cost and reproducibility

lack of knowledge of design criteria - how quickly will the tissue grown how quickly will it degrade

lack of predictability of in vivo behavior and responses

11

Foregin body reactions, what are the steps?

1 Surgeon impants biomaterial

2. the biomaterial absorbs a layer of proteins

3. cell (neutrophils and macrophages) interrogate the biomaterial

4. cells fuse to form giant cells and secrete cytokines

5. In response to the cytokines, fibroblasts arrive and begin synthesising collagen

6. The biomaterial is encapsulated in an acellular collagenous bag - need to avoid this

12

Layer-by-layer (lbl) assemblies - involves adding what to the polymer surface?

poly-electrolites

turns off macrophage interaction

13

combining inkjetting with thermally induced phase separation is beneficial as

Get even droplets of polymer solution

by shooting them into liquid nitrogen, freeze very quickly before they can join together

Can then coat with growth factors - gets a good slow release, suitable for delivering in a tissue engineering construct

14

Alpha-MSH is an anti-inflammatory peptide. How does it interact/ whats it's significance?

a-MSH bnds strongly to hydrophobic surface

Good thing to coat the polymer microspheres with - reduces reaction with macrophages

15

The rate of release of growth factor (bFGF) and a-MSH can be independently controlled because

they vary in size

a_MSH = 13 residues

bFGF (growth factor) = 154 residues

16

Antimicrobial composites are also key in..

reducing the amount of bacteria which attach to the implant