Tissue engineering Flashcards
What is Tissue Engineering?
The goal of tissue engineering is to
• replace or even improve biological tissues that have a problem (doesn’t work well and can’t get any other tissue due to grafting or rejected)
• and their functions by the use of engineering methods and life sciences
What are the Four important factors in Tissue Engineering?
- The right cell to do the job
- The right environment – scaffold
- The right biomolecules like GF
- Physical and mechanical forces
What are the basic principles of tissue engineering?
- Monolayer cell – cells grown in 2D and give them GF, nutrients so that you maintain ph environment so they grow
- Scaffold – give them something to grow on which will help them get that 3D structure
- Generate graft that you are interested in
• Remove cells from the body
o stem cells/ functionally differentiated cells)
• Cell expansion in culture
• Seed the cultured cells on nanofibrous scaffolds in culture media
o supplemented with growth factors
• Leave in culture to form functional tissue
• Re-implant the engineered cell-scaffold construct to the injury site for repair
What are the main features required for nanomaterials for scaffolds?
• Biocompatibility, biodegradability, and low immunogenicity – because if you are growing that organ in the scaffold – don’t want any problems or side effect.
What are the basic principles of nanomaterials for scaffolds?
- A scaffold composed of nanoscaled fibers (nanoscale range) provides excellent cellular interactions as well as tissue compatibility (help the cell grow and attach to the scaffold as well as biocompatibility)
- One important feature of these fibrous biomaterials is the increased ratio of surface area to volume (volume to surface area ratio is large – helps cell grow and differentiate as you have a wide area for them to grow – that helps for complex tissues in terms of how they are formed and what they also contain).
- Improved mimicking of the extracellular environment
- Be used to engineer more complex tissues/organs when compared to traditional biomaterials
What are the basic design considerations of nanomaterials?
- Porosity (can get cells coming in and out) and surface features contribute to tissue repair in terms of cell– material interactions – helps the cell grow and helps interactions (So start replicating and differentiating e.g.)
Biodegradability and biocompatability:
• To increase the success rate of implantation of a construct
• To avoid additional surgical procedures and adverse side effects
Scaffold needs to be able to degrade
Degradation of these materials must also be considered, since it can be
• Employed as an additional infiltration path for cells or as a release mechanism for bioactive molecules stored within the scaffold (once 3D structure formed, don’t need scaffold anymore as it will also inhibit the growth)
Proper cell infiltration is vital (within scaffold)
• For cell migration, proliferation, and differentiation within the scaffold. (Don’t want scaffold to be prohibiting so need scaffold to be promoting proliferation and help them grow)
• The scaffold should also:
o Support cells
o Regulate the extracellular environment to enhance tissue alignment and cell–cell interactions
• These features lead to sufficient neovascularisation, adequate oxygen supply, and a mechanism for waste disposal
What are the advantages of metallic nanostructures?
Optical adjustability, electrical conductivity (i.e. for heart conductivity, neurons), surface chemistry (change surface if you need to), ease of fabrication
What are the properties of metallic nanostructures for treating damaged heart tissue?
- Produced by seeding heart cells within three-dimensional porous biomaterial scaffolds
- The scaffold usually made of either biological polymers such as alginate or synthetic polymers such as poly(lactic acid) (PLA), help cells organize into functioning tissues
- BUT poor conductivity of these materials limits the ability of the patch to contract strongly as a unit (Having a 3D structure lost their conductivity).
• They then incorporated Gold nanowires within alginate scaffolds have been shown:
o To bridge the electrically resistant pore walls of alginate (so help it with electrical conductivity)
o To improve electrical communication between adjacent cardiac cells
o The gold nanowires have also enhanced the tissue thickness and alignment (how cell aligns)
They found out that the
Give an example of where gold is used in tissue engineering
Nanorods for chemica and biological sensor
Nanowires in aliginate scaffold for cardiac patches
Give an example of where silver is used in tissue engineering
Silver nanoparticle containing gelatin nanofibers for wound healing
Give an example of where titanium is used in tissue engineering
Nanopowder in ompacts for bone regeneration
Why are CNT used in tissue engineering?
o Because they are highly compatible with blood
o They are chemically inert and do not wear out
• Integrating CNTs into polyurethane has significantly enhanced its tensile strength and elongation capability
• CNTs have significantly improved the anticoagulant properties of polyurethane
• Potential for the use of carbon nanotube-based materials in other blood-contacting applications
• Due to their superior electrical conductivity, CNTs have been applied in neuronal tissue regeneration
• People have used them as a substrate for cultured neurons, CNTs have promoted the neurite outgrowth and the branching of neurons (to find other neurons)
They have been reported to promote neuron attachment, growth, differentiation, and long-term survival
What is and why is cell encapsulation used?
• Immobilization of the cells within a polymeric semipermeable membrane
• Membrane permits the bidirectional diffusion of molecules such as the influx of oxygen, nutrients, growth factor
• But the semi-permeable membrane prevents immune cells and antibodies from destroying the encapsulated cells
• Why cell encapsulation?
o To overcome the existing problem of graft rejection in tissue engineering applications
o Reduce the need for long-term use of immunosuppressive drugs after an organ transplant to control side effects
Why is collagen used as a scaffold in tissue engineering?
• A major protein component of the extracellular matrix (always need for 3D structure).
• Most abundant protein in mammals, making up from 25% to 35% of the whole-body protein content
• Support tissues like skin, cartilage, bones, blood vessels and ligaments
• Can be used as a model scaffold or matrix for tissue engineering
• Why?
o Biocompatibility
o Biodegradability – gives the support and gives support for extracellular matrix, once you grafting them, as biodegradable
o Ability to promote cell binding
What is advantageous about 3D Bioprinting?
• Compared with non-biological printing, 3D bio-printing involves additional complexities such as:
• The choice of materials,
o Cell types
o Cell growth and differentiation factors
