Engineering Cartilage

Question 1

Why engineering cartilage?

Answer 1

1) essential for good quality of life

2) it has little/no capacity for effective self repair

Question 2

What is cartilage?

Answer 2

connective tissue

• has a supporting role in the body
• composed of cell (chondrocytes) embedded in an ECM

Question 3

What is the extracellular matrix?

Answer 3

1) non cellular component present within all tissues and organs
- a collection of extracellular molecules secreted by cells
- provides structural and biochemical support to the surrounding cells

Functions:

• essential physical scaffolding for cellular components
• initiates crucial biochemical and biomechanical cue required for tissue morphogeneis, differentiation and homeostasis

Question 4

What is the ECM composed of?

Answer 4

1) fibres: collagen

2) ground substance: semi-solid gel through which metabolites can diffuse

Question 5

What is the ECM ground substance?

Answer 5

semi-solid gel
made up of proteins and fluid
many ECM proteins are a complex mixture of long chain molcules (polypeptide chain) with side chains (polysaccharide chains) - absorbs large amount of water: turns water into structural material (shock absorption)
water in between layers of cartilage = lubricant

Question 6

What is the ECM ground substance made up of?

Answer 6

proteoglycans*
glycoproteins*
long carbohydrate chains***

Question 7

What are the four types of cartilage?

Answer 7

hyaline
fibrous/elastic
elastic
hypertrophic

Question 8

What is hyaline cartilage?

Answer 8

very dense, matric of collagen fibres and ground substance
mainly collagen II fibres in ECM
relatively large amount of ground substance
aggrecan is the predominant proteglycan

Question 9

Where is hyaline cartilage found?

Answer 9

joint surfaces

costal cartilage

Question 10

What is fibrocartilage?

Answer 10

thick interlaced collagen fibres and less ground substance

Question 11

Where is fibrocartilage found?

Answer 11

found in areas of high impact

Question 12

What is elastic cartilage?

Answer 12

elastin and collagen fibres and some ground substance

Question 13

Where is elastic cartilage found?

Answer 13

provides rigid structure - elastic framework (ears, nose)

Question 14

What is hypertrophic cartilage?

Answer 14

most bones in the body are formed from a intermediate cartilage template
(remodelled into bone via endochondral ossification)

Question 15

Where is hypertrophic cartilage found?

Answer 15

growth plate and during repairing bone fracture

Question 16

Where is hypertrophic cartilage found?

Answer 16

growth plate, during repairing bone fracture

Question 17

Why does orthopaedics support the idea of engineering cartilage?

Answer 17

potential for regenerative cell therapies and tissue engineering for cartilage regeneration

Question 18

Where is the research focused for engineering cartilage?

Answer 18

cartilage regenerative cell therapies and TE focused on repair of articular cartilage lesions

Question 19

What is the structure of normal articular structure?

Answer 19

1) superficial zone
2) deep zone
3) calcified cartilage
4) subchondral bone

Question 20

What is the main function of cartilage?

Answer 20

biological shock absorber

forms an almost frictionless surface needed for joint movement

Question 21

What is the cell type in cartilage?

Answer 21

chondrocyte

Question 22

What is the intercellular matrix?

Answer 22

ECM between cells
rich in collagen II
proteoglycan (aggrecan)
**

Question 23

How does the lack of blood supple affects cartilage repair?

Answer 23

means it cant repair

mineralises instead

Question 24

Why is cartilage considered a shock absorber?

Answer 24

proteoglycans (aggrecan) molecules bind through a special linking protein to hyaluronic acid = large aggregates which can bind lots of water

Question 25

How does articular cartilage become dmagaed?

Answer 25

trauma | disease

Question 26

Cartilage facts...

Answer 26

10,000 cartilage injuries /year warrant surgical intervention injuries to ligements -> joint misalignment -> osteoarthritis

Question 27

What are OA risk factor?

Answer 27

obesity

Question 28

Why is full function repair of OA important?

Answer 28

OA is common

Question 29

What is OA?

Answer 29

degenerative joint disease | causes pain

Question 30

What is OA?

Answer 30

``` degenerative joint disease causes pain, loss of joint function - joint mobility joint swelling joint deformity stiffness impaired quality of life no cure (symptomatic relief) =major clinical challenge ```

Question 31

Where are the common sites of osteoarthritis?

Answer 31

knees hands hips spine

Question 32

Where are the common sites of osteoarthritis?

Answer 32

knees hands/fingers (extremities) hips spine

Question 33

What are signs of OA in x ray?

Answer 33

bone spurs | loss of tissue

Question 34

What is OA pathology?

Answer 34

has a persistent inflammation component - often low grade inflammation, - acute synovitis - overexpression of pro-inflammatory cytokines chemokines, neuropeptides. irreversible erosion of articular component

Question 35

What are the classical approaches to articular cartilage repair?

Answer 35

1) joint washout and debridement - removes loose tissue debris, symptomatic relief (no effect on OA progression) 2) surface abrasion and microfracture - symptomatic relief, fibrocartilage formation (no effect on OA progression) 3) total joint replacement

Question 36

What is total joint replacement?

Answer 36

one of the most successful operation

Question 37

What are the problems of total joint replacement?

Answer 37

``` prosthetic loosening (5% may need revision surgery) revision surgery more of problem in younger patients (below 60 years of age) limited lifespan of prosthesis (shorter than life expectancy) ```

Question 38

Degeneration of IVD (DDD) a problem?

Answer 38

IVD- discs of fibrocartilage, mainly collagen I in AF and collagen II in NP ***************

Question 39

What is the need for effective regeneration of cartilage damaged by trauma and early osteoarthritis problems?

Answer 39

cartilage has limited ability to repair itself

Question 40

Why are faces important?

Answer 40

sense of identity important in communication disfigurement = loss of self esteem **************

Question 41

What are the current methods for facial surgical reconstruction?

Answer 41

1) customised soft tissue prosthesis (silicone polymers) 2) surgical interventions - tissue grafts need a good blood supply

Question 42

Why is it important to repair the trachea?

Answer 42

causes difficulty in breathing (stenosis in trachea and bronchi)

Question 43

What are the tissue components of the trachea?

Answer 43

1) cartilage rings = keeps trachea open | 2) epithilium

Question 44

Where has the tissue engineered trachea gone wrong?

Answer 44

surgeon scientific fraud 1) switch from decellularized human tissue to synthetic biomaterial scaffold appears to have been a factor in some cases 2) was this work human experimentation without consent