Engineering Cartilage Flashcards
Why engineering cartilage?
1) essential for good quality of life
2) it has little/no capacity for effective self repair
What is cartilage?
connective tissue
- has a supporting role in the body
- composed of cell (chondrocytes) embedded in an ECM
What is the extracellular matrix?
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
What is the ECM composed of?
1) fibres: collagen
2) ground substance: semi-solid gel through which metabolites can diffuse
What is the ECM ground substance?
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
What is the ECM ground substance made up of?
proteoglycans*
glycoproteins*
long carbohydrate chains***
What are the four types of cartilage?
hyaline
fibrous/elastic
elastic
hypertrophic
What is hyaline cartilage?
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
Where is hyaline cartilage found?
joint surfaces
costal cartilage
What is fibrocartilage?
thick interlaced collagen fibres and less ground substance
Where is fibrocartilage found?
found in areas of high impact
What is elastic cartilage?
elastin and collagen fibres and some ground substance
Where is elastic cartilage found?
provides rigid structure - elastic framework (ears, nose)
What is hypertrophic cartilage?
most bones in the body are formed from a intermediate cartilage template
(remodelled into bone via endochondral ossification)
Where is hypertrophic cartilage found?
growth plate and during repairing bone fracture
Where is hypertrophic cartilage found?
growth plate, during repairing bone fracture
Why does orthopaedics support the idea of engineering cartilage?
potential for regenerative cell therapies and tissue engineering for cartilage regeneration
Where is the research focused for engineering cartilage?
cartilage regenerative cell therapies and TE focused on repair of articular cartilage lesions
What is the structure of normal articular structure?
1) superficial zone
2) deep zone
3) calcified cartilage
4) subchondral bone
What is the main function of cartilage?
biological shock absorber
forms an almost frictionless surface needed for joint movement
What is the cell type in cartilage?
chondrocyte
What is the intercellular matrix?
ECM between cells
rich in collagen II
proteoglycan (aggrecan)
**
How does the lack of blood supple affects cartilage repair?
means it cant repair
mineralises instead
Why is cartilage considered a shock absorber?
proteoglycans (aggrecan) molecules bind through a special linking protein to hyaluronic acid = large aggregates which can bind lots of water
How does articular cartilage become dmagaed?
trauma
disease
Cartilage facts…
10,000 cartilage injuries /year warrant surgical intervention
injuries to ligements -> joint misalignment -> osteoarthritis
What are OA risk factor?
obesity
Why is full function repair of OA important?
OA is common
What is OA?
degenerative joint disease
causes pain
What is OA?
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
Where are the common sites of osteoarthritis?
knees
hands
hips
spine
Where are the common sites of osteoarthritis?
knees
hands/fingers (extremities)
hips
spine
What are signs of OA in x ray?
bone spurs
loss of tissue
What is OA pathology?
has a persistent inflammation component
- often low grade inflammation,
- acute synovitis
- overexpression of pro-inflammatory cytokines
chemokines, neuropeptides.
irreversible erosion of articular component
What are the classical approaches to articular cartilage repair?
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
What is total joint replacement?
one of the most successful operation
What are the problems of total joint replacement?
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)
Degeneration of IVD (DDD) a problem?
IVD- discs of fibrocartilage, mainly collagen I in AF and collagen II in NP
*******
What is the need for effective regeneration of cartilage damaged by trauma and early osteoarthritis problems?
cartilage has limited ability to repair itself
Why are faces important?
sense of identity
important in communication
disfigurement = loss of self esteem
****
What are the current methods for facial surgical reconstruction?
1) customised soft tissue prosthesis
(silicone polymers)
2) surgical interventions
- tissue grafts need a good blood supply
Why is it important to repair the trachea?
causes difficulty in breathing (stenosis in trachea and bronchi)
What are the tissue components of the trachea?
1) cartilage rings = keeps trachea open
2) epithilium
Where has the tissue engineered trachea gone wrong?
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
