OE L35 Tissue Engineering 1

Question 1

What tissue types must be considered in the context of craniofacial repair?

Answer 1

• Skin
• Soft tissue
• Cartilage
• Bone

Question 2

What material can be used in bone grafting?

Answer 2

Bone mineral (granules)

Question 3

What are the 3 main approaches of tissue engineering and what do they each involve?

Answer 3

• Conduction: uses 3D scaffold on which cells can attach, migrate, proliferate and differentiate. Scaffold can also act as barrier to promote repopulation of defective site with selected cell population.
• Induction: using bioactive signals to induce cell migration and control cell behaviour/differentiation
• Cell transplantation: biopsy taken from patient or donor, cells isolated and expanded in vitro, placed onto scaffold and implanted back into defective site in patient

Question 4

How can mucosal tissues be enginnered?

Answer 4

• Small piece of mucosal tissue extracted and seperated into individual components and individual cells (epithelial cells and fibroblasts)
• Collagen matrix containing fibroblasts produced
• Epithelial cells plated onto matrix

Tissue can be regenerated.

Question 5

What are the cellular requirements for stem-cell based tissue regeneration?

Answer 5

• Directed cell migration: cells must be able to migrate from surrounding tissue to defective area, movement in correct direction
• Organised cell division: rate determines effectiveness, orientation determines daughter cell fate
• Targeted cell differentiation: cell lineage must be correct

Question 6

Describe totipotent stem cells.

Answer 6

Stem cells produced from the fusion of an egg and sperm cell. The cells produced by the first few divisions of the embryo.
Can differentiate into embryonic and extraembryonic cell types.

Question 7

Describe pluripotent stem cells.

Answer 7

Can differentiate into cells derived from any of the 3 germ layers (ectoderm, mesoderm, endoderm).

Question 8

Describe multipotent stem cells.

Answer 8

Can produce cells of closely related cells e.g. hematopoietic stem cells into erythrocytes, leukocytes, platelets etc.

Question 9

Describe unipotent stem cells.

Answer 9

Can only produce one cell type but have self renewal properties which distinguishes them from non-stem cells. E.g. muscle stem cells.

Question 10

What are the advantages and disadvantages of mesenchymal stem cells?

Answer 10

• Easy to isolate
• High proliferative potential
• Cell therapies can be autologous
• Don’t elicit alloreactive lymphocyte response
• Decreased numbers with age
• Several surgical interventions required
• Potential donor site problems

Question 11

What are the advantages and disadvantages of embryonic stem cells?

Answer 11

• High proliferative potential
• Pluripotent
• Ethical considerations
• Must be allogenic, therefore potential for immune response/rejection
• Plasticity of cells may question the purity of any isolated population

Question 12

What does self-renewal mean?

Answer 12

The ability to go through numerous cycles of cell division while maintaining the undifferentiated state.

Question 13

How can embryonic stem cells be obtained?

Answer 13

• From blastocysts (fertilised embryos)
• Somatic cell nuclear transfer using unfertilised embryos
• Induced pluripotent stem cells (reprogamming somatic cells into stem cells)

Question 14

Where can adult stem cells be found?

Answer 14

• Epidermal stem cells reside in the basal layer of the epidermis
• Gut epithelium stem cells
• Cornea epithelial stem cells in the limbus
• Hematopoitic stem cells in bone marrow/umbilical cord blood
• Neural stem cells found in hippocampus
• Dental pulp stem cells

Question 15

What tissues can dental pulp stem cells differtiate into?

Answer 15

• Teeth
• Nerve and spinal cord
• Brain
• Heart
• Liver
• Muscle
• Skin
• Cartilage
• Bone

Question 16

What are the benefits of dental pulp stem cells?

Answer 16

• Access to the collection site of these sites is easy and produces very low morbidity e.g. wisdom tooth extraction
• Extraction of stem cells from pulp tissue is highly efficient
• They have an extensive differentiation ability
• Demonstrated interactivity with biomaterials makes them ideal for tissue reconstruction

Question 17

What has current research taught us about dental pulp stem cells?

Answer 17

• They can differentiate down all 3 mesenchymal lineages (ectoderm, mesoderm, endoderm)
• They have been used to differentiate into neuronal specific progenitor cells in the treatment of spinal cord injuries

Question 18

What factors influence stem cell fate?

Answer 18

• Intrinsic factors
• Cell division (symmetric or asymmetric)
• Cell density
• Exposure to different factors or substrates e.g. GFs, CSF influences neutrophil and marcophage production
• Interactions with other cells
• Mechanical forces
• Hepatotactic cues