tissue engineering & stem cell therapy Flashcards
what problems may there be for craniofacial reconstruction?
Insufficient host tissue for adequate repair of defect
Donor site morbidity
If indogenous disease - may not be suitable
what does craniofacial reconstruction and repair require a combination of altering
Skin
Soft tissue
Cartilage
Bone
Neural
Vascular regeneration
what is the simplifed steps of the routine exercise in craniofacial reconstruction
- Clear pathological site to remove damage and pathological tissue
- Use natural bone mineral tissues to graft on wound site
- After surgery
- Can do dental implants
What are the three approaches in tissue engineering?
conduction
induction
cell transplantation
What is conduction
- Guided tissue regeneration (GTR).
- Guided bone regeneration (GBR).
- using a 3D scaffold - usually nanomaterials
- on which cells can attach, migrate, proliferate and differentiate
- promotes proliferation
- the scaffold can also function as a barrier to promote repopulation of the defect site with a selected cell population
what is induction
- using bioactive signals to induce cell migration and control cell differentiation and behaviour
- delivered in form of proteins
- cytokines
- growth factors
- can be delivered using gene therapy
- transfer of specific genetic information to host cells
what are the steps of cell transplantation
- biopy from donour source (allogenic) or from patient’s own tissue (autologous) is obtained
- isolate and expand donor cells in vitro
- usually seeding cells onto scaffold such as fibre mesh or hydrogel
- cells attach to scaffold and proliferate
- formation of new tissue which may be implanted into defect site of the patient
where it regulation crucial during cell transplantation?
it is important to precisely control the lineage specific differentiation of the transplanted stem cells
which of the three approaches in tissue engineering lead to the most successful reconstruction?
all three factors in combination
steps of making mucosa :
- Small piece of tissue taken
- Separated into its components
- Then into individual cells
- These are grown in plastic dishes
- In organotypic air-nutrient fluid system
- One cell can divide to make several thousand cells
- Collagen matrix containing fibroblasts is made
- Epithelial cells are plated onto it and the construct raised to the air-liquid interface
= organotypic culture forms tough compound mucosa
- is elastic and strong
how does skin reconstruction occur naturally?
- basal cells do symmetrical cell division forming identical daughter cells
- cells begin to slightly tilt
- triggers differentiation
- one cell will stay in basal layer
- one cell will initate differentiation outward
- eventually cells lose nuclei and flake off surface
- skin tissue is replaced
what cellular requirements are there for tissue regeneration?
- directed cell migration
- ideal migration from surrounding tissues rather than transplant into centre of the wound site
- pathological environment and toxic factors in wound site could kill the stem cells
- organised cell division
- to achieve sufficient cell numbers
- rate
- determines effectiveness
- orientation
- determines daughter cell fate
- targeted cell differentiation
* how we control the lineage specific differentiation of the stem cells once they are transplanted into the recipient
what are totipotent stem cells
Produced from fusion of egg and sperm cell
Also cells produced by the first few divisions of the fertilised egg
These cells can differentiate into embryonic and extraembryonic cell types
what are pluripotent stem cells
Stem cells are the descendants of totipotent cells
can differentiate into cells derived from any of the 3 germ layers
- Ectoderm (outer layer)
- Mesoderm (middle layer)
- Endoderm (inner layer)
what are multipotent stem cells?
Stem cells can produce only cells of closely related family of cells
E.g. haematopoietic stem cells differentiate into red blood cells, white blood cells, platelets, etc.)
