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Stem Cell and Regenerative Medicine > Biomaterials and scaffolds > Flashcards

Biomaterials and scaffolds Flashcards

1
Q

what is biomaterials?

A
  • a nonviable material used in a medical device, intended to interact with biological systems.
  • a material intended to interface with biological systems to evaluate, treat augment or replace any tissue, organ of function of the body.
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2
Q

what are the 4 main types of biomaterials?

A
  • polymers
  • cermaics
  • semiconductor materials
  • metals
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3
Q

what are polymers used for?

A
  • skin/catrilage
  • ocular implants
  • drug delivery devices
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4
Q

what are ceramics used for?

A
  • bone replacements
  • heart valves
  • dental implants
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5
Q

what are semiconductor materials used for?

A
  • biosensors

- implantable microelectrodes

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6
Q

what are metals used for?

A
  • dental implants

- orthopedic scres/fixation

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7
Q

what is the most common polymer used for drug delivery?

A

polyethylglycol

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8
Q

why are biosensor development needed?

A

want sensors that can detect changes in the environment which are coated in a good material that allows diffusion but prevents accumulation

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9
Q

why is titanium used in bone?

A

bioactive- bone will grow onto the surface of it

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10
Q

what are the 4 main things that need to be considered during biomaterial selection?

A
  • mechanical
  • biological
  • chemical
  • optical/electrical
  • regulatory constraints
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11
Q

give 6 material selection parameters

A
  • mechanical
  • biocompatibility
  • water absorption
  • diffusion
  • biostability
  • degradation properites
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12
Q

what are the 3 main polymers used and why?

A

PLLA, PGA and PCL- they have FDA approval

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13
Q

what is a problem with PCL?

A

doesn’t degrade very well- hydrophobic

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14
Q

what is wrong with the 3 polymers that are used most?

A

they dont degrade in a linear way- get rapid transfer of mechanical load onto th new tissue. You also get a lot of debris- sterile inflammation

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15
Q

what are some simple biological parameters can control what happens in the cell?

A
  • the surface roughness can determine how stem cells differentiate
  • surface charge
  • stiffness
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16
Q

why do we need scaffolds in biotechnology ? (4)

A
  • Protect the cells.
  • Enable delivery of cells to the area of need: gels maybe
  • Retain the cells in the area of need.
  • Modulate the cellular response.
17
Q

what is the basic principle of tissue engineering? what is the potential problem with this model?

A
  • cells from a biopsy
  • monolayer cell culture
  • expanded cells
  • culture of a 3D polymeric scaffold
  • generation of a graft

(can be too expensive and time consuming)

18
Q

what are the three elements of tissue engineering/ regenerative medicine?

A

scaffold: porous, absorbable synthetic and natural biomaterials (collagen bs polygylocolic acid)
- cells (autologous or allogenic): differentiates cells of same type as tissue, stem cells
regulators: growth factors or their genes, mechanical loading, static versus dynamic culture

19
Q

how can scaffolds be involved in matrix?

A

before it is absorbed a scaffold can serve as a matrix for cell adhesion to facilitate/“regulate” certain unit cell processes (e.g., mitosis, synthesis, migration) of cells in vivo or for cells seeded in vitro.
– the biomaterial may have ligands for cell receptors (integrins)
– the biomaterial may selectively adsorb adhesion proteins to which cells can bind

20
Q

what are the 7 main roles of a scaffold?

A
  • the scaffold serves as a framework to support cell migration into the defect from surrounding tissues; especially important when a fibrin clot is absent.
  • serves as a delivery vehicle for exogenous cells, growth factors, and genes; large surface area.
  • before it is absorbed a scaffold can serve as a matrix for cell adhesion to facilitate/“regulate” certain unit cell processes
  • may structurally reinforce the defect to maintain the shape of the defect and prevent distortion of surrounding tissue.
  • serves as a barrier to prevent the infiltration of surrounding tissue that may impede the process of regeneration
  • Thescaffoldsmayservetosupport/carrycells grown ex vivo back into the implant site to migrate off the implant. Or:
  • To entice cells from the surrounding tissues onto the scaffold to fill the defect.
21
Q

what factors prevent regeneration?

A
  • size of the defect: large bone defects will not regenerate easilyy
  • collapse of the surrounding tissue into the defect: periodontal defects. solution is membranes for guided tissue regeneration- keep soft tissue out of the way while the bone comes back
  • excessive strains in the reparative tissue- unstable structures that require fixation
22
Q

what are 3 synthetic scaffold materials?

A

– Hydroxyapatite
– Calcium carbonate
– Calcium phosphate

23
Q

what is a scaffold material used that is natural?

A

natural bone mineral - HA

24
Q

what is a sinus lift? what is the problem with the granules here?

A

lift gum up- put an implant of lots of material such as synthetic or natural granules (bone chip maybe) and after 6 month hopefully the bone will grow in and you can put an implant in. They take up lot of room in the implant

25
Q

what makes a polymer non degradable?

A

The construction of a polymer with a C-C backbone tends to confer chemical stability to the polymer- non susceptible to hydrolysis

26
Q

what makes a polymer degradable?

A

Heteroatom-containing polymer backbones confer biodegradability

27
Q

what are polymers used for?

A
  • sutures
  • cell seeded implants
  • cell seeded implants for teeth- put cells (dental pulp)
28
Q

what is injection moulding?

A

have a mould and put plastic in with high turn over- but you can’t put a molecule in there because thermosensitive

29
Q

what is electrospinning?

A

take dilute solution polymer and apply a potential difference between two points and you get a dire mat forming- good for encapulsation of drugs within these fibres-

30
Q

what is the problem with electropsinning?

A
  • Residual solvent

• Need to undertake rigorous quality control methods to determine that solvent levels are below acceptable limits.

31
Q

what are naturally derived scaffolds?

A
  • naturally derived heart valve ( can also be made by electropsinning too to get combination of strong synthetic and biologcial functionality)
  • decal re-cel stuff: break down cells and just get collagen skeleton which you can recel
32
Q

what was their group looking at?

A

small intestine submucosa- decell- want to maintain the architecture and some of the growthh factors potentially- can eectropsin onto the outside.

33
Q

what is the role of a sinus lift?

A

a sinus lift involves placing bone chips into the region of the jaw when the tooth is missing from in an attempt to prevent the collapse of this region and maximise the space of the implant along with encouraging osteointegration of the implanted tooth

34
Q

how can you use compressed collagen?

A

you can use it to patch a heart that has suffered cardiac infarct to promote regeneration

Stem Cell and Regenerative Medicine (17 decks)

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