Tissue Engineering Epithelium Flashcards
What is epithelial tissue?
consists of a flat sheet of closely adhering cells, one or more cells thick, with the upper surface usually exposed to the environment or to an internal space in the body
What is the structure of epithelium?
1) squamous epithelium
2) connective tissue
3) muscle tissue
4) inflammatory cells
What are the key characteristics of epithelium tissue structure?
- Tightly packed epithelial cells. • Strong intracellular junctions. • Can be single layer (simple), or multi layered (stratified).
- Does not contain blood supply • Relies on nutrients from underlying connective tissues
What are the cell types in the simple epithelium?
1) simple squamous
2) simple cuboidal
3) simple columnar
(All epithelial cells form tight cell-cell junctions (eg. Tight junctions, desmosomes)
What are the cell types found in the stratified epithelium?
!) stratifies squamous
2) stratified cuboidal
3) stratified columnar (very rare)
4) pseudostratified columnar
What is a basement membrane?
made of collagen, laminin and fibronectin
What are the functions of the epithelia?
protection, absorption, filtration, excretion, secretion
Why does the structure of the different epithelia vary as a result of their distinct functions?
as a result of their distinct functions and anatomical locations
What are the common characteristics of epithelia?
1) specialised contacts: adjacent cells bound together by cell-cell junctions • Very little extracellular material-comprised of tightly packed cells
2) Polarity – Basal and Apical
3) Basement membrane
4) Regenerative capacity
5) Epithelial/mesenchymal co-dependency
What is the need for tissue engineering epithelia?
- Congenital defects • Surgical resections • Stricture and fibrosis • Cancer excision • Trauma
- Toxicity testing • In vitro disease models • Epithelial biology • Diagnostic development
What are the stages of epithelisation?
• Cell migration • Cell adhesion • Cell proliferation • Cell differentiation
How are epithelial cells grown?
• Normal oral keratinocytes • Isolated from small biopsy • Grown with support cells • Limited proliferation capacity
How are stromal cells grown?
• Human oral fibroblasts • Variable • Different to skin • Needed for keratinocyte attachment
What is the epithelial-mesenchyme inter dependency?
• Keratinocyte limit fibroblast proliferation • Fibroblasts drive epithelial differentiation • Keratinocytes rely on fibroblasts for attachment
What are the different scaffold selection?
- Natural vs synthetic • Mechanical properties • Porosity • Wettability • Degradation
- Fabrication • Surface topography • Growth factors • Storage • Surgical handling
What are the different environments for the cells?
1) bioreactors
2) air-liquid interface
3) animal models
Why is hollow tube tissue engineering important?
Many epithelia line hollow tubes • Inner lumen posses epithelium Eg. Oesophagus, Trachea, Gastrointestinal tract, Bladder, etc
Why produce tissue engineering oral mucosa?
1) disease models
2) reduce use of animals
3) diagnostic technology development
4) biocompatibility testing
5) intra-oral recontruction
How do tissue engineered and in vivo models compare?
IN VIVO MODEL
- limited models of oral disease
- strict controls over in vivo experiments
- genetically different to human disease
TISSUE ENGINEERING MODEL
- tissue engineering models have been developed for a number of oral diseases
- strict control in obtaining primary cells, but once isolated can be expanded and used for many experiments
- grown using human cells or oral origin
What is the method for tissue engineering oral mucosa?
1) waste tissue form oral surgery
2) normal oral fibroblasts + normal oral keratinocytes
3) grown on de-cellularised skin scaffold
4) cultured at air-liquid interface
5) tissue engineered oral mucosa
What is the scaffold choice?
- Acellular dermis • Retains native ECM
- Retains basement membrane proteins
- Can be stored in glycerol
- Collagen gels lack basement membrane
- High level of contraction
- Collagen lacks organisation
What are the pros and cons of acellular dermis as a scaffold choice?
pros: biologically relevant
cons: disease transmission
limited quantities
variability
What are the pros and cons of collagen as a scaffold choice?
pros: good cell attachment
cons: batch to batch variability
animal origin
expensive
What are the pros and cons of fibrin as a scaffold choice?
pros: good cell attachment
cons: variability
animal origin
