Lecture 4 Flashcards
(15 cards)
What is the function of a bioscaffold
To mimic the form and function of the ECM
- multiple components and tissue specific
What are the 5 functions of ECM?
- Structural support & physical environment for cells to grow
- Structural/Mechanical properties
- Provision of bioactive cues (cellular allignment)
- Act as a reservoir of growth factors
- Provides a changeable environment to allow remodelling & revascularisation
What are the 4 scaffold properties?
- Architecture
- Tissue Compatibility
- Bioactivity
- Mechanical Properties
Scaffold Architecture
- Void volume (vascularisation & new tissue formation)
- Porous (metabolite and nutrient transport)
- Biodegradable (degradation rate matching neo-tissue formation)
Scaffold Tissue Compatibility
- Cells must be able to grown upon it & differentiate
- Scaffold & its breakdown products must be non-toxic
Scaffold Bioactivity
- Able to interact with cells to regulate activities
Scaffold Mechanical Properties
- Provide shape & stability to tissue defect
- Could be similar to that of host tissue
- Important for cell differentiation
What are the 4 main approaches to scaffold design?
- Porous scaffold
- Decellularise ECM
- Cell sheets w secreted ECM
- Cells encapsulated in self assembled hydrogel
Porous scaffold
- NATURAL (derived from biological material- silk, collagen)
o Autogeneic/Autologous: from patient
o Allogeneic/Homogenic: same species
o Xenogeneic: different species
Adv = excellent biocompatability
Dis = limited physical & mechanical stability - SYNTHETIC (non-biological - ceramics, glass)
o greater control over physical and
mechanical properties
o Inorganic (glass/ceramic) v Organice (nylon,
teflon)
manufacture of porous scaffold (4)
- Process of manufacture will determine the final properties of the bioscaffold
o Electrospinning: high pot. volt
o Casting: porous
o Nanoweaving: motorbike gear, superman cost
o 3D Weaving: Make abnormal structures
Decellularised ECM scaffold
- derived from allograft or xenograft
- all cellular components removed
- left with ECM - ECM components well conserved between species
Adv = properties matched to homologous function
excellent biocompatability
Dis = poor cell distribution when seeding
possible imm. reaction in not properly
decellularised
Cell Sheet Scaffolds
Cell Sheet Scaffolds
- cells grown on specialised surface
- secrete their own ECM
- Cells _ ECM removed from culture surface as single sheet
- can be stacked into multiple layers
Adv = cells secret own ECM
rapid neovascularisation
no sutures to keep in place
Dis = Limited thickness
Not good for load bearing tissue
Cell Encapsulation scaffold
- Entrapment of living cells within a homogenous solid mass
- can suspend in liquid and inject into defect
Adv = good for irregular shaped defects
Dis = not good for load bearing tissue
Combination Scaffolds
- Utilise the best qualities from two or more devices
- Custom to suit purpose
e.g. silk fibroin
Silk Fibrion
- from silkworms or spiders
1. Fibroin (structural)
2. Sericin (glue-like) - biocompatability, bidegradability, strong mechanical propoerties & diverse morphologies
