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COD Matrix biology Flashcards

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1
Q

Describe the ECM

A

Highly specialised
Composed of fibrillar and non-fibrillar molecules
Reciprocally influences cellular function
Modulates normal tissue homeostasis and progression of disease

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2
Q

Give an example of some molecules found in the ECM

A 
Collagens
Structural proteins
Proteoglycans
Glycosaminoglycans
Glycoproteins
Proteinases
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3
Q

Describe collagens

A

Most abundant and widespread distribution in tissues
28 different collagen types
Construct fibers, networks and filaments in the ECM
Formed from polypeptide alpha chains
These create homo or hetero trimeric triple helices
Typical collagenous domains within alpha chains consist of repeat triplets of amino acids Gly-X-Y
Fibrillar is the most common
FACIT and MACIT
Anchoring and Beaded fillaments are self assembled forming

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4
Q

What are MACIT and FACIT collagens?

A

MACIT - membrane associated collagens with interrupted triple helices
FACIT - Fibril associated collagens with interrupted triple helices

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5
Q

What are some subclasses of collagen types?

A 
Fibrillar
Network forming
FACIT
MACIT
Anchoring filaments
Beaded filaments
Multiplexin
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6
Q

What are heterotypic fibrils

A

A mixture of different collagen types
Dermis, tendon and bone - Type I,III,V
Cartilage and Vitreous - Type II,IX,XI

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7
Q

What is Elastin used for?

A

Structural protein

Lends elasticity and resilience to tissues

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8
Q

What are laminins used for?

A

Structural protein

Cell-cell assembly

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9
Q

What are fibronectins used for?

A

Structural protein

A receptor that binds to other ECM molecules

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10
Q

What are the 4 types of glycosaminoglycans?

A 
Carbohydrate attached to a protein core
Chondroitin sulphate
Dermatan sulphate
Heparan sulphate
Keratan sulphate
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11
Q

Describe the glycosaminoglycan Hyaluronan

A

Synthesised and assembled on the plasma membrane
Non-Sulphated
Not attached to a protein core
Found in joint synovial fluids to facilitate joint movement

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12
Q

Describe the glycosaminoglycan Heparin

A

Prevents clotting
Synthesised and stored in mast cells
Used as an anticoagulant in medicine

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13
Q

Describe glycoproteins

A

Non structural
Modulate cell function
By interacting with cell surface receptors, hormones, proteases, structural matrix proteins (collagens)

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14
Q

What are some enzyme components of the ECM?

eg heparanases

A 
Matrix Metalloproteinases (MMP)
ADAM and ADAMTS proteinases
Serine proteases
Cathepsins
HA-degrading enzymes (Hyaluronidases)
Heparanases
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15
Q

Tissues requiring high tensile strength are enriched in what?

A

Fibrillar collagens eg tendons, bone, ligaments

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16
Q

Tissues requiring compressive properties are enriched in what?

A

Proteoglycans and hyaluronan eg cartilage

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17
Q

Tissues requiring elastic properties and recoil are enriched in what?

A

Elastin, eg skin, ligaments, connective tissue of lungs/blood vessels

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18
Q

Matrix stored chemical signals include what?

A

Growth factors

Cytokines

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19
Q

Where is the mutation in Ehlers-Danlos Syndrome?

A

Collagen
MMP gene that play key roles in regulating
collagen organization

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20
Q

Describe Ehlers-Danlos Syndrome

A

Elastic skin
Hyper flexible joints
Valvular heart disease

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21
Q

Invertebral disc disease IVD is a disorder of aging. What impact does this have and what is it attributed to?

A 
Impacts mobility
Decreased workplace productivity
Attributed to loss of glycosaminoglycans through the loss of aggrecan
Decreased hydration
Reduced compressibility
Increased risk of disc herniation
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22
Q

What are the changes in cell behaviour in IVD disease?

A

Hypoxia (O2)
Inflammation
Autophagy (Self eating)

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23
Q

Describe fibrosis

A

Damaging
Can occur as a result of excess formation of
connective tissue in response to injury
Due to a combination of factors such as a disproportionate activity of
matrix enzymes responsible for matrix degradation and reorganization
Hyperactive ligand-mediated receptor signaling via TGF-ß
Activity of mesenchymal cells

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24
Q

Name some common diseases that exhibit fibrosis

A

Pulmonary fibrosis
Hepatic fibrosis
Renal scarring

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25
Describe osteoarthritis
Bone ends rub together | Thinned cartilage
26
Describe rheumatoid arthritis
Bone erosion | Swollen inflamed synovial membrane
27
What is the structure of the knee joint?
``` Synovial membrane Articular cartilage Fibrous joint capsule Joint cavity filled with synovial fluid Ligaments ```
28
Describe the bio mechanical function of articular cartilage
Composite of collagens, proteoglycans and water Allows tissue to withstand load Provides a near frictionless surface for joint articulation Tension, compression, shear, lubrication
29
What is the morphology of articular cartilage?
``` No lymphatics Avascular Aneural Hypocellular No basement membrane ```
30
Articular cartilage is highly hydrated with water accounting for WHAT% of its wet weight
65 - 85%
31
What are chondrocytes?
Resident cells | Produce collagen, proteogylcans and enzymes
32
What are type II collagens?
Major collagen | Provides a cartilaginous framework and tensile strenght
33
What proteoglycans? | eg aggrecan
Major proteoglycan | Gives cartilage compressive stiffness
34
What is the chondrocyte morphology? | eg what are the zones
Superficial zone Middle (intermediate) zone Deep zone Calcified zone
35
Describe the zones of chondrocytes | eg superficial, intermediate, deep, calcified
Superficial - 600um. Cells flat, collagen Fibrils parallel to articular surface Intermediate - 1500um. Cells round, collagen fibrils diagonal to articular surface Deep - Cells round, collagen fibrils perpendicular to articular surfaces Calcified - 300um, cells round, collagen fibrils perpendicular to articular surface
36
What are aggrecan aggregates composed of?
``` 30-50 aggrecan monomers 1 Hyaluronan Glycosaminoglycan 30 - 50 Link proteins that stabilise the aggrecan interactions All of these interactions are non-covalent ```
37
Describe the glycosaminoglycans charge
Negative charges Create strong charge repulsive forces Charge repulsion stiffens proteoglycans in the collagen network And give cartilage compressive stiffness
38
Load bearing properties of cartilage are provided by the tensile properties of WHAT?
Of the collagen fiber network and | The osmotic swelling pressure of the high concentration of aggrecan
39
Aggrecan is immobolised within the matrix by forming WHAT aggrecates with hyaluronan and link protein?
Supramolecular
40
What 2 phases are there in the biomechanical behaviour of cartilage?
Fluid and solid phase
41
Describe the fluid phase in the biomechanical behaviour of cartilage
Is under high interstitial fluid pressurisation | Allows for the transmission of load in cartilage
42
Describe the solid phase in the biomechanical behaviour of cartilage
Low permeability This is because the proteoglycans PGs resist fluid flow They are also restricted by the collagen fibril network
43
WHAT are the major proteinases responsible for matrix turnover in cartilage?
Metalloproteinases
44
Is cartilage turnover relatively slow or fast in adults?
Slow
45
MMP (Metalloproteinases) and ADAMTS (A Disintegrin And Metalloproteinase with ThromboSpondin motif) are enzymes that require what for their activity?
Zinc OR Calcium (metal ions)
46
True or false | Matrix proteinases are proteolytic enzymes
True
47
Collagenases (MMPs) and gelatinases (MMPs) degrade WHAT
The collagen fibers
48
Aggrecanases (ADAMTS4 and ADAMTS5) degrade WHAT
Aggrecan
49
Stromelysins (MMP3 and MMP10) degrade WHAT
Non- collagenous matrix proteins
50
Collagenases (MMP-1 & MMP-13) - degrade WHAT Gelatinases (MMP-2 & MMP-9) - degrade WHAT Stromelysins (MMP-3 & MMP-10)-degrade WHAT
triple helical collagens denatured collagens non-collagenous matrix proteins (not aggrecan)
51
What are the 2 classifications of OA?
Primary | Secondary
52
Describe primary OA
Idiopathic (no known cause)
53
Describe secondary OA
``` Post traumatic Metabolic Endocrine disorders Congenital (present at birth) Malposition ```
54
What are some risk factors associated with OA?
``` Age Sex Hereditary Ethnicity Overweight Lifestyle Post menopausal Resective joint surgery ```
55
What are symptoms of OA?
Limited movement Pain Crepitation (crackling/rattling sound) Sensitivity to damp or cold
56
How do you diagnose OA?
X-ray
57
What is the main hallmark of OA?
Matrix degradation of the articular cartilage | Results in loss of tissue function
58
In OA, chondrocyte metabolism is altered. Explain how
Mechanical forces (through mechano and osmo sensors embedded in the chrondrocyte plasma membrane) Inflammatory mediators (cytokines, chemokines, reactive oxygen species, nitric oxide) Increased synthesis and activation of aggrecanases and MMP through NF kappa signalling pathway Increased degradation of aggrecan and collagen
59
What is catabolism?
Hallmark of OA | Loss of cartilage
60
Aggrecanase activity is defined by the specific cleavage between a Glutamate (E) and an Alanine (A) peptide bond in the WHAT of Aggrecan
Interglobular Domain (IGD)
61
The cleavage in the IGD of Aggrecan allows the WHAT attachment domains of Aggrecan to be released from the cartilage
glycosaminoglycan (GAG)
62
Loss of aggrecan results in the loss of WHAT and the ability to imbibe water Net loss of compressive properties
glycosaminoglycans
63
``` True or false Loss of collagen results in the breakdown of the framework of cartilage and the tensile strength of the tissue. Collagen loss is reversible ```
FALSE | Collagen loss is irreversible
64
Name some treatments for OA
Steroids Non steroidal anti-inflammatory drugs (NSAIDs) Anti-cytokine antibodies Neutraceuticals Joint replacement surgery Autologous chondrocyte or mesenchymal repair Future- specific drugs to target enzyme activity
65
Human adults can regenerate only some organs. Give an example
Skin | Liver
66
Give an example of human tissues that do not regenerate
Cartilage | Nerve tissue
67
What is tissue engineering?
Involves the practice of combining scaffolds, cells and biologically active molecules into functional tissues
68
``` Tissue engineering Give an example of: Structural replacement Functional replacement Wound healing ```
Cosmetic reconstruction Musculoskeletal tissues Autologous skin grafts in burn patients
69
What is regenerative medicine?
Research field that includes tissue engineering but also research on self-healing This is where the body uses its own systems, Sometimes with the help of foreign biological material To recreate cells and rebuild tissues and organs
70
What are 'key ingredients' of tissue engineering?
Cell precursors Autologous, heterologous (allogeneic) or xenogeneic cells derived from healthy or pathological tissue Source of cells (skin biopsy, bone marrow) Types/origins of cells (embryonic stem cells/mesenchymal stem cells) Bioactive molecules (enzymes, growth factors,interleukins)
71
What are cell precursors?
Produce ECM and/or synthesis and release bioactive molecules (growth factors)
72
In tissue engineering, what is used to make 'scaffolds'? | Natural products
``` Purified collagens (usually Type I) Fibronectin Fibrin Hyaluronan Silk Plant polysaccharides e.g. cellulose Animal polysaccharides e.g. Chitin ```
73
In tissue engineering, what is used to make 'scaffolds'? Synthetic biomaterials Composites
``` Polylactic acid (PLA) biodegradable • Polyglycolic acid (PGA) biodegradable • Carbon fibres • PLA/Elastin • PLGA/Hyaluronan ```
74
What are some common knee sport injuries?
Meniscal Cartilage Tears Collateral Ligament injuries Cartilage lesions- e.g.Osteochondritis Dissecans
75
Describe Osteochondritis Dissecans OCD
Inflammation of bone and cartilage Results in the formation of loose fragments Occurs in 15-29 of 100,000 patients More common in males than females ( between 2:1 and 3:1) Most common aged 10-20 Common in young athletes Idiopathic focal joint disorder affecting the subchondral bone Knee is the commonly affected joint A Fragment of cartilage and subchondral bone separates from the articular surface Due to a lack of blood supply (osteonecrosis) in the underlying bone Decalcification of the trabecular bone matrix Left untreated, OCD can lead to the development of degenerative arthritis
76
What are they symptoms of Osteochondritis Dissecans OCD?
``` Pain Inflammation Swelling Edema Soreness in the joint Catching and locking in the joint during movement Reduced range of motion Crepitus ```
77
How do you diagnose Osteochondritis Dissecans OCD?
Radiographic examination | MRI
78
Describe simply a chondrocyte transplantation in the right femoral condyle
A lesion in the right femoral condyle is made There is a biopsy of the healthy cartilage There is enzymatic digestion These are cultivated for between 11-21 days They are treated with trypsin Suspension of cells There is an injection of the cultured chondrocytes under the lap in the lesion A periosteal flap is taken from the medial tibia and sutured over the lesion
79
When doing a chondrocyte transplantation, how many mgs of cartilage is harvested from low weight bearing region?
300-500mg
80
Describe Autologous matrix-induced chondrogenesis (MACI) | eg cell precursors and scaffold
Cell precursors- bone marrow and constituents | Scaffold- hydrogel
81
Describe first generation ACI
Cell precursors- autologous chondrocytes | Scaffold-none- but use of periosteal flap/collagen membrane
82
Describe second generation ACI (also known as MACI)
Cell precursors: autologous chondrocytes | Scaffolds: hydrogels, fibrous scaffolf, decelluarised ECM
83
Describe third generation ACI
Cell precursors: allogenic stem cells, autologous stem cells Scaffolds:hydrogel, fibrous scaffold, decelluraised ECM, or composite

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