Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Tissue Engineering & Regenerative Medicine > Intro & Methods > Flashcards

Intro & Methods Flashcards

1
Q

Define morphogens

A

Inductive signals (e.g. growth factors) which initiate/govern tissue morphogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define stem cells

A

Primordial progenitors

Have enormous potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are biomaterial scaffolds?

A

They mimic ECM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are major prostheses used for?

A
  • load transmission (e.g. tendon/ligament replacements)
  • bearing surfaces (total joint replacement)
  • controlling fluid flow (heart/vascular/urethral replacements, ventricles valves for CSF control)
  • passive space filling (cosmetic/rhinoplasty)
  • functional space filling (cranial plates to protect the brain)
  • generation/application of external stimuli (pacemakers)
  • light transmission (intra-ocular prostheses)
  • sound transmission (ossicular replacement)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Requirements for biomaterials

A
  • non-toxic/bioinert/biostable

- bioactive/biodegradable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens if a biomaterial is not bioinert/biostable?

A

Toxic -> inflammation when implanted -> repair -> restimulation of inflammation -> resorption + cell necrosis + de-differentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How do biomaterials become bioactive/biodegradable?

A
  • form chemical bonds with tissue stabilizing them
  • get resorped in the body when no longer required (sutures, drug capsules)
  • use biological components (cells/biomolecules) within implants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Limitations of transplantation

A 
Donor shortage
Immunological rejection
Ethical issues
Not available for all tissues/organs
Transmissible infective agents in animals and humans
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the difference between tissue engineering and tissue regeneration?

A

Tissue Engineering = in vitro (outside)

Tissue Regeneration = in vivo (inside the organism)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 3 aims of tissue engineering?

A

To repair, replace and regenerate tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do we mean by tissue repair?

A

Manipulate

Deliver cells/materials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What do we mean by replacing tissues?

A

Transplantation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What do we mean by tissue regeneration?

A

Stimulating new growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the principle steps of tissue engineering?

A 
1 - cell isolation from a source
2 - cultivate in 2D
3 - seeding in 3D porous scaffold
4 - tissue organization
5 - engineered tissue transplantation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the pros of using isolated cells or cell substitutes?

A
  • avoids surgery
  • allows replacement of only those required functional cells
  • allows manipulation of cells before infusion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the cons of using isolated cells or cell substitutes?

A
  • failure of infused cells to maintain their function in the recipient
  • immunological rejection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the pros of tissue inducing substances?

A
  • development of methods to target molecules
  • large scale production of signal molecules
  • purification of signal molecules such as growth factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the pros of cell seeded on or in scaffolds?

A
  • open or closed systems
  • natural materials such as collagen and/or synthetic materials
  • immunological acceptance with use of immuno-suppressive drugs or autologous cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a tissue engineered biological substitute comprised of?

A
  • cells
  • ECM
  • scaffold
  • signals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are some issues with cells?

A
  • finite lifespan then expire
  • they generate newly differentiated cells through multi-step lineage pathways
  • newly differentiated cells replace expired ones
  • they then fabricate ECM and new tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What do we need to consider when choosing a cell type?

A

Availability of cells:

  • embryonic stem cells? (but a lot of ethical issues)
  • autologous (donor to donor)
  • allogenic (donor to recipient)

Cell Phenotype
Cell capacity to redifferentiate and produce ECM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How is cell signalling a challenge?

A
  • cells exchange mechanical and chemical signals
  • these are essential in determining cell fate/phenotype and tissue homeostasis
  • the signals are mediated by cell surface molecules
  • cell surface molecules transduce them across compartments of the cell
  • communication between cells and ECM (scaffold) needs to facilitate this and consider how porosity and diffusion will play a part
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How can scaffolds control cell signalling?

A

Can be engineering to be a source of signaling molecules promoting cell differentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are some features of intelligent scaffolds?

A
  • hold/attract cells
  • influence cell development
  • reserve space for regeneration
  • inhibit inflammation events/immunoprotective
  • breakdown into active factors
  • encapsulate morphogens, cytokines and MMPs
  • provide mechanical stability
  • facilitate integration
  • contribute to final events
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are some challenges with scaffolds?

A
  • porosity is essential for repair/regeneration

- 3D is essential to allow cellular function without compromising mechanical integrity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are some examples of scaffolds?

A 
Gel
Sponges
Fibres
Natural (collagen, fibrin)
Synthetic (PEG)
Carbohydrate based (PLA, PLGA, agarose, alginate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does is it mean to model something?

A

To test this prostheses/material onto something

  • this may be in vivo or in vitro
  • may be on a organ-on-a-chip
  • may be on an animal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are some challenges with modelling?

A
  • in vivo or in vitro
  • need to maintain cell viability via GF
  • may get large necrotic regions as there is limited transport in the centre of 3D scaffolds
  • need to enhance mass transport with mechanical conditions and creating fluid environments in a bioreactor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are bioreactors?

A

Establish and maintain 3D culture
Provide mechanical conditioning
Enhance tissue regeneration
Provide transport system for nutrients to cells
Allow withdrawal of toxic/inhibitory metabolic products
Allow mechanical conditions to a 3D scaffold
Enhance cell differentiation and tissue development

30
Q

What are some mechanical challenges?

A
  • little is known about mechanical forces required to maximally stimulate matrix formation
  • complexity of mechanobiology
  • effects of mechanical signals on matrix synthesis will vary greatly with each different scaffold system
31
Q

What do manufacturing processes require?

A
  • tested cells from working cell banks
  • automatic injection into tissue bioreactors
  • computerized system to monitor growth and conditions
  • frozen tissue
  • quality control for cells and matrix
  • processed in bioreactors until clinical use
32
Q

Define tissue engineering

A

In vitro

Seed cells into a biomaterial, grow matrix and then implant into body/model

33
Q

Define regenerative medicine

A

In vivo

Implant biomaterial matrix with or without seeded cells into body to facilitate regeneration of the tissue

34
Q

What are the key principles in tissue engineering?

A

Cells + biomaterial + bioreactors + factors ->
Engineered tissue ->
Transplantation

35
Q

What are some general considerations when choosing tissue engineering methods?

A
  • choice of cells/starting material (do you need to make some genetic modifications? do you need to isolate and purify?)
  • choice of culture media
  • phenotypic characterisation
  • seeding logistics
  • growth conditions (static on a plate or dynamic with a bioreactor)
  • 2D vs 3D models
36
Q

What are simple tissue types?

A

FLUID

  • bone
  • bone marrow
37
Q

What are complex tissue types?

A

Not fluid => TISSUE

38
Q

What are some conditions for growth?

A
  • serum
  • vitamins
  • glucose
  • glutamine, methionine, serine
  • antibiotics
39
Q

What is a primary culture?

A

Coming from a living organism (e.g. adult, embryo, gametes)

40
Q

What are some methods for cell isolation from a primary culture?

A
  • you have your primary culture
  • aim is end up with single stem cells to grow on a dish
  • may do this by mechanical dissection to break up major tissue organisation so you can get the cells you want (hepatocytes from a liver)
  • rendering cells from soft tissue
  • rendering specific cells non soft tissues is more complex
  • then finally compose growth media (micronutrients + serum/serum free)
41
Q

Pros of autologous cells

A
  • promote tissue regeneration
  • no inflammation/immunogenic response
  • 10 fold expansion with primary cells
42
Q

Cons of autologous cells

A
  • limited availability
  • low yield (cell concentration)
  • further expansion without reprogramming is difficult
43
Q

Pros of allogenic cells

A
  • potentially more cells at isolation
  • could be used to treat more than 1 patient (cell bank)
  • 10 fold expansion (even more with reprogramming)
44
Q

Cons of allogenic cells

A
  • inflammation

- immunogenecity failure

45
Q

What does anchorage independent cells mean?

A
  • are anchored to a culture for example (haematopoietic cells are expanded in suspension culture)
  • vs. anchorage dependent are cultured in monolayer (most human cells)
46
Q

What are the 3 phases during growth in a monolayer

A

1) Lag phase
2) Exponential (log) phase
3) Plateau phase

47
Q

What happens during the lag phase?

A
  • adhesion to the surface
  • recovery from isolation/subculture
    SO NEED TO
  • precoat to enhance adhesion
  • gentle subculture
48
Q

What happens during the exponential (log) phase?

A
  • rapid division
    SO NEED TO
  • feed regularly
49
Q

What happens during the plateau phase?

A
  • primary cells have finite life span
  • division slows/stops after 50 divisions when you reach the Hayflick limit or if there is contact inhibition
  • cells start to show transformation
    SO NEED TO
  • subculture
50
Q

What are some properties of transformed cells?

A
  • altered morphology
  • loss of contact inhibition (cells grow over each other)
  • proliferate with attachment (anchorage independent)
  • proliferate indefinitely (immortalisation)
  • reduced requirement for mitogenic GF
  • tumorigenicity
51
Q

What culture conditions are key for tissue engineering?

A
  • defined culture media (induce differentiation of progenitor stem cells)
  • biomaterial scaffolds (provide 3D cell culture environment + influence mechanical properties of engineered tissue)
  • bioreactor systems (promote spatially uniform cell seeding, mass transport, biophysical stimulation)
52
Q

What culture conditions determine cell fate?

A 
Physiological = temp, pH, osmolarity, oxygen, 3D environment, cell to cell contact
Biochemical = nutrients, small molecules, GF, nanoparticles
Physical = compression, tension, hydrostatic pressure
53
Q

List some scaffold requirments

A
  • stability (size, shape, biomechanics)
  • porosity
  • biodegradable/remodellable
  • absorbable
  • biocompatible
  • cell attachment
  • bioactive/gene delivery
  • surgical application
54
Q

Which scaffold materials have the highest (+ lowest) structure stability?

A

Hydrogel (high)
Woven Mesh (intermediate)
Sponge (medium)
Non-woven mesh (low)

55
Q

Which scaffold materials have the highest (+ lowest) porosity?

A

Non-woven mesh (high)
Woven mesh (intermediate)
Hydrogel + Sponge (low)

56
Q

Which scaffold materials are naturally absorbable?

A
  • agarose
  • alginate
  • hyaluronic acid
57
Q

Which scaffold materials are biodegradable/synthetic?

A
  • polyglycolic acid

- PLGA

58
Q

Which scaffold materials are remodelable?

A

Calcium phosphate

59
Q

Advantages of biopolymers

A
  • similar size to proteins
  • large SA with functional groups/ligands
  • rapid absorption and release behaviour
  • rapid diffusion and volume change
  • tuneable degradation kinetics and mechanical properties
60
Q

What do innovative 3D models for cell culture involve?

A
  • microfabrication techniques

- microfluidics (deliver nutrients/agents, generate dynamic fluid flows)

61
Q

What are the 3 principles of tissue engineering?

A

CELL TYPE
SCAFFOLD
MECHANICS

62
Q

What is a rocking bioreactor?

A

Automated
Just need to provide nutrients and chemicals
Load cells and culture medium into cellbag bioreactor via ports on bag surface
Motorized base, rocking motion induces waves in cell culture for efficient mixing and gas transfer to respiring cells
Also want them to respond to changes (e.g. give more glucose when cells are producing lots of lactic acid due to respiration for example)

63
Q

What are some examples of mechanics?

A

Compression -> dynamic and static
Dynamic is better to create
Then
Intermittent dynamic or continuous dynamic
Need to determine which is best for the type of tissue you are using.

64
Q

What molecules can we use to influence cells?

A 
GF
Chemokines
Cytokines
Hormones
(can cause growth, be protective etc.)
65
Q

What is the effect of passage?

A

Also called splitting, method of culturing to keep cells alive…. BUT:

  • cells change morphologically
  • adhesion rate increases
  • cell proliferation reduces
  • collagen, proteoglycan and mRNA content is reduced
66
Q

What does cell immortalisation mean?

A

Keep expanding + passaging indefinitely until eventually passaged so many times that morphology is very different

67
Q

What is confluency?

A

When cells proliferate to cover 70% of the plate

68
Q

How do we culture cells?

A
  • isolate cells in a plate with culture medium (allows them to grow)
  • cells expand
  • cells reach a state of confluence
  • need to split the cells into separate plates using trypsin
  • cells now float up into the culture medium
  • spin the cell population down and culture them
  • continue to passage them forming 2 cell populations
69
Q

What does trypsin do?

A

Breaks down integrins which make up the receptors allowing the cells adhering to each other and the plate

70
Q

What phase do we want the cells to be in, to work best at?

A

Exponential Phase

71
Q

What are the affects of cell passaging?

A
  • increases cell concentration

- negatively affects cell’s ability to maintain phenotype

72
Q

What type of model is best to maintain cell phenotype?

A

3D model!

Tissue Engineering & Regenerative Medicine (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions