13. Skin Reconstruction and Dermal Equivalents

Question 1

How often does the body replace skin?

Answer 1

1 month entirely new layer of skin

Question 2

What are the layers of skin?

Answer 2

Epidermis - Keratinocytes (90%) melanocytes

Dermis - Fibroblasts (matrix), endothelial cells, hair follicle cells

Question 3

What are the 4 grades of burns?

Answer 3

Epidermal burn
Partial thickness burn
Deep dermal burn
 - Mesh graft to treat
Full thickness burn

Question 4

What is the ultimate goal of burn repair?

Answer 4

Reduce scar formation

Question 5

What are some complications associated with burns?

Answer 5

Delayed healing increases scar risk
Infection leads to delay in healing
Oedema increases infection risk
Inflammation increases oedema

Question 6

What are the aims of cell based therapies?

Answer 6

Reduce inflammation

Decrease time to cover wound

Question 7

What are some cell types being used in cell based therapies of burns?

Answer 7

Keratinocytes - epithelial cover
Fibroblasts - dermal matrix
Melanocytes - pigmentation
Endothelial cells - revascularisation

Question 8

What are combined therapies and what do they treat?

Answer 8

Dermal matrices and scaffolds

- Greater depth

Question 9

What is the process for a skin graft?

Answer 9

Skin taken
Meshed to cover larger surface area
Mesh pattern of healed skin

Question 10

What are some complications on skin grafts?

Answer 10

Donor site morbidity, ugly

Question 11

What are the three types of grafts?

Answer 11

Xenografts
Allografts
Autografts

Question 12

What are the drawbacks of xenografts?

Answer 12

rejected very often

Temporary dressing

Question 13

What are the drawbacks of allografts?

Answer 13

Eventual rejection
Immunosupressive therapy must be given
Cross contamination

Question 14

Are autografts and allografts cultured?

Answer 14

They can be. Depends on how you feel

Question 15

What are cultured epithelial autograft sheets?

Answer 15

Cultured using large full thickness biopsy
3 - 10 cell layers thick
Clipped to petrolatum gauze
Available up to 3-5 weeks after initial biopsy

Question 16

What is the optimal surgical timing in regards to scar formation?

Answer 16

10 days = 4%

21 days = 78% risk

Question 17

Why is the need for cell culture a limitation for burn treatment?

Answer 17

Increase risk of scar formation due to time required to culture cells

Question 18

What did Fiona Wood do so well?

Answer 18

Developed Autologous non-cultured Skin Cell Based Therapy

Question 19

What shift is happening in the treatment of burns?

Answer 19

Moving from skin derived cells to multipotent/pluripotent cells

Question 20

What are the origin of stem cells used in treatment of burns?

Answer 20

Hematopoietic
Mesenchymal
Adipose derived
reprogrammed

Question 21

What are some of the functions of these stem cells?

Answer 21

Immune modulation (anti-inflammatory)
Growth factor stores
Cell engraftment

Question 22

What is the importance of ECM?

Answer 22

Previously though ECM was passive scaffold
However.....
Physical characteristics important
 - Strength 
  - Stress
Biological characteristics also important
   - Secreted factors
   - Glycosylation/sugars

Question 23

What are matrices good for in treatment of burns?

Answer 23

Enhance recovery in deep burns
Rapid replacement of dermal template
Limited by angiogenesis however

Question 24

What is an example of a matrice used clinically?

Answer 24

INTEGRA
3 weeks until epidermal cells plated
Collagen based

Question 25

What is still currently the most common treatment for burns?

Answer 25

Split thickness skin grafts (STKG)