Cell-substrate interactions 4 Flashcards
What do current biomaterial research look to achieve
Producing a scaffold/substrates for the cells and tissue in the body to interact with along with guidance molecules and become the replacement tissue.
This has also been used in the lab to replace this damaged tissue.
Give an example of current biomaterials
Porous hydroxyapatite or colalgen.
What is one of the main drivers for biomaterials
Lack of organ transplants
What is a bioreactor
This allows a dynamic environment for these cells to grow in instead of the traditional static environment (e.g. 37C at 5% O2)
What are the benefits of bioreactors
Can produce more cells than static culture
Can limit static environments effects on cells
Simulates the body
Still cultured on a porous scaffold
What did Holtorf et al 2005 find regarding bioreactors effects on mesenchymal stem cells
Osteopontin was used as a marker for osteoblast differentiation
The use of a biomarker and a dynamic culture showed that osteopontin levels were significantly higher with or without dexomethasone in comparison to static conditions.
How else can cell behaviour be stimulated in tissue engineering and give some examples
Growth factors -
- Transforming growth factor-beta (TGF-β)
- Bone morphogenetic protein (BMPs)
- Fibroblast growth factor (FGFs)
- Insulin-like growth factor (IGFs)
- Platelet-derived growth factor (PDGFs)
- Vascular endothelial growth factor (VEGFs)
What can these growth factors do to these cells
Cell proliferation
Cell migration
Cell differentiation
Stimulate increased growth factors or signalling molecules
How are these growth factors added
In vitro -
Externally via medium
Stimulating cell synthesis of GFs
Using another cell type to release GF and the cell medium to respond
In vitro -
Via tethering to scaffold
What did Bane 2009 use GFs for bones
Recombinant human bone morphogenetic protein 2 (rhBMP-2) as a bulking agent for vertebral fractures with a plate
66% fusion in control
95% fusion in GF exposed
What is one risk of GF use
Cancer
What is the future of tissue engineering
3D bioprinting of tissues and organs, specific to each patient - to form suitable scaffolds.
What is one debated point regarding bio-scaffolds
Cells are initially influenced by the scaffold but they then modify them by secreting their own scaffold and degrading the ECM.
How was 3D ECM scaffold used for cystoplasty
WIDER READING - Atala 2006
Took 7 patients with end-stage bladder disease and took a bladder biopsy from them which after 7 weeks an engineered bladder was formed with autologous cells seeded on collagen-polyglycolic acid scaffolds and wrapped in omentum.
How was tissue-engineering used to make a trachea
WIDER READING -Macchiarini 2008
Cultured mesenchymal stem cell derived chondrocytes from host which was inmplanted into the patient allowing her to have a functional airway by 4 months
Patient had end-stage bronchomalacia.
Was on no immunosuppresion
How was tissue engineering used for vascular grafts
WIDER READING - Tiwari 2001
Carried out in vitro-growth of blood vessels from saphenous or carotid artery which have been grown in a lab and been used on damage vessels without causing an immune response.
What are some of the issues with using growth factors in tissue engineering
WIDER READING - Ren et al 2020
Short half-life
Rapid diffusion from delivery site
Low cost-effectiveness
What is one way to keep GFs present for longer
WIDER READING - Ren et al 2020
Covalently bond them to immobilize them. They are then activated when the biomaterial is degraded or cleaved
How was 3D printing used for tissue engineering
WIDER READING - Kim 1998
Hepatic cells and nonparenchymal cells attached and survived on the 3D polymer scaffolds once implanted where previously inadequate oxygen diffusion as the culture grows is usually its demise once transplanted
