This presentation talks about various skin substitutes and their use in burn care.

1. Skin Substitutes
By-Dr Raghav Shrotriya
Department of Plastic Surgery
KEM Hospital, Mumbai

2. Definition
 Skin substitutes are heterogeneous group of wound
coverage materials that aid in wound closure and replace
the functions of the skin, either temporarily or
permanently, depending on the product characteristics.
 These substances are alternatives to the standard wound
coverage in circumstances when standard therapies are
not desirable

3. Introduction
 The need for supplements to autologous skin grafts has
prompted development and use of wide variety of skin
substitutes as biologic and synthetic wound dressings
 Functions:
 Permanent wound coverage
 Temporary coverage to promote healthy wound bed

4. Ideal Skin Substitutes
 little or no antigenicity
 tissue compatibility
 lack of toxicity, either local or systemic
 permeability to water vapor just like normal skin
 impenetrability to microorganisms
 rapid and persistent adherence to a wound surface
 porosity for ingrowth of fibrovascular tissue from the
wound bed
 Able to resist infection

5.  Able to prevent water loss
 Able to withstand the shear forces
 Cost effective
 Widely available
 Long shelf life and easy to store
 Flexible in thickness
 Durable with long-term wound stability
 Can be conformed to irregular wound surfaces and
 Easy to be secured and applied

6. Classification (Kumar P, 2008)
 Class I: Temporary impervious dressing materials
a) single layer materials
 naturally occurring or biological dressing substitute, e.g. amniotic
membrane, potato peel
 synthetic dressing substitute, e.g. synthetic polymer sheet
(Tegaderm®, Opsite®), polymer foam or spray
b) bi-layered tissue engineered materials, e.g. TransCyte®

7.  Class II: Single layer durable skin substitutes
 Epidermal substitutes, e.g. cultured epithelial autograft (CEA),
Apligraf®
 Dermal substuitutes
 bovine collagen sheet, e.g. Kollagen®
 porcine collagen sheet
 bovine dermal matrix, e.g. Matriderm®
 human dermal matrix, e.g. Alloderm®

8.  Class III: Composite skin substitutes (containing both
dermal and epidermal component)

a) Skin graft
 Allograft
 Xenograft
b) Tissue engineered skin
 Dermal regeneration template, e.g. Integra®
 Biobrane®

10. Use of Bioactive Skin Substitutes
 Wound cover
 Improve wound healing
 Control pain
 Improve functional and cosmetic outcome
 Increase survival

11. Temporary
1. Porcine xenograft
2. Human Allograft
3. Human amnion
4. Biobrane
5. Transcyte

12. Xenografts
 Earliest In 1500 BC
 Homogenised cryopreserved porcine xenograft
 recent modifications to the porcine skin include aldehyde
cross-linking and silver ion impregnation to increase the
antimicrobial properties

13.  Advantages:
 Low cost
 Reduces pain
 Decreased fluid loss
 Good wound adherence
 Disadvantages:
 Lack of revascularisation
 Lack of transparency

14. Cadaver Allograft
 Most common
 2 types:
 Cryopreserved
 Glycerol preserved

15.  Uses:
 Wound bed preparation
 provide growth factors and essential cytokines
 creating chemotaxis and proliferation at wound beds.
 increase vascularity in the wound bed
 promoting angiogenesis with enhanced capillary ingrowth on the wound bed
 Pain free dressings
 Sandwich grafting technique
 prevents desiccation of the wound bed in the interstices of widely expanded
autografts
 reduces bacterial colonisation
 autograft is protected from shear

16.  Advantages :
 Provide biologically active temporary wound cover
 Decrease metabolic demands
 Provide a ‘test’ to assess whether wound is ready for
autograft
 Disadvantages:
 Expensive
 Risk of disease transmission
 Need for further procedure for wound closure

17. Amnion
 thin semi-transparent tissue forming the innermost layer
of the foetal membrane
 Advantages:
 maintains low bacteria count
 reduces loss of protein, electrolytes and fluids, decreasing the
risk infection
 minimises pain
 acceleration of wound healing
 good handling properties.

18. Synthetic Skin substitutes
 Advantages:
 composition and properties of the product can be much more
precisely controlled
 avoid complications due to potential disease transmission
 Disadvantages:
 lack basement membrane
 their architecture do not resemble native skin

19. Biobrane®
 Composed of bilaminated membrane formed by nylon
mesh filled with Type I porcine collagen (dermal analogue)
and covered by a thin membrane of silicon (epidermal
analogue)

20.  Indications:
 Superficial partial thickness burn wounds
 Donor sites
 TENS patients
 Contraindications:
 Full thickness burns
 Patial thickness burn with eschar
 Chemical or electrical burns

21.  Advantages:
 Pliability and elasticisity
 Confirms to irregular wounds
 Good pain control
 Less frequent dressing change
 Extended shelf life
 Transparent dressing for wound monitoring

22. Transcyte®
 Temporary
 Dermal layer of neonatal fibroblasts on a nylon mesh and
outer layer of synthetic epidermis
 Contains :
 Collagen type III, V
 Fibronectin and tenascin
 GAGs
 GF : TGF-B1, VEGF, IGF-1

23.  Similar to biobrane but with addition of growth factors
from lysed fibroblasts grown in culture

24.  Semipermeable to allow fluid and gas exchange
 Transparent for monitoring
 Used as substitute for cadaveric allograft in full thickness
burns after excision

25.  Permanent Skin Substitutes
1. Integra
2. Apligraf
3. Alloderm
4. Dermagraft
5. Orcel
6. Epicel

26. Integra® (Yannas et al, 1980)
 Dermal analog made of cross linked bovine collagen-
GAG (chondroitin -6- sulphate) copolymer matrix
 Epidermal analog thin silicone elastomer
 After dermal analog incorporates (2-3 wks), silicon layer
is removed and replaced by thin SSG or Epicel

28.  Advantages:
 Regenerated skin is more pliable
 Resembles normal skin
 Favourable scarring
 Provides physiologic wound closure
 Disadvantages:
 Costly
 2 stage procedure with 3-4 week interval

29.  Uses:
 Scar contracture release
 Excision of Giant congenital naevus
 Irradiated scalp chronic wound closure
 Exposed bone and tendons

30. Apligraf®
 Permanent bilayered skin substitute
 Dermal layer: Type I bovine collagen and allogenic
keratinocyte seeded with human foetal fibroblasts

31.  Advantages:
 Readily available
 Applied in OPD setting
 Disadvantages
 Remote risk of disease transmission
 Multiple applications
 Short shelf life (5 days)
 Expensive
 Uses:
 Diabetic ulcers
 Venous stasis ulcers
 Epidermolysis Bullosa.

32. Alloderm®
 Scar Contracture is inversely related to the amount of
dermis
 Treated human allograft with epidermis removed
resulting in intact BM and Collagen and removal of
antigenic Langerhans cells, melanocytes and fibroblasts
 Used as dermal implant
 Thin epithelial autograft is required

33.  Advantages:
 Thick dermis limits recontracture
 Disadvantages:
 Costly
 Disease transmission

34. Dermagraft®
 A cryopreserved human fibroblast derived dermal
substitute made of bioabsorbable polyglactin mesh
(bioabsorbable scaffold) seeded with allogenic neonatal
fibroblasts
 Dermagraft human fibroblasts which secrete growth
factors, cytokine, ECM proteins and GAGs
 Formation of neodermis through stimulation of
fibrovascular growth from wound bed and not by direct
re epithelialization from wound perimeter

35.  Indications
 chronic wounds and diabetic foot ulcers
 to support the take of meshed split-thickness skin grafts on
excised burn wounds

36. OrCel®
 Bilayered cellular matrix in which normal human
allogeneic skin cells (epidermal keratinocytes and dermal
fibroblasts) are cultured in two separate layers into a
type I bovine collagen sponge.
 Indication:
 treatment of chronic wounds
 skin graft donor sites
 as an overlay dressing on split-thickness skin grafts to improve
function and cosmesis

37. Cultured Epithelial Autografts
Epicel®
 Rhinewald and Green (1975)
 The autologous keratinocytes are isolated, cultured and
expanded into sheets over periods of 3–5 weeks. The
technique of suspension in fibrin glue has reduced the
time for clinical use to 2 weeks.
 Uses:
 Coverage of large TBSA wounds
 Coverage of giant congenital naevus wound
 Pressure ulcers
 Vitiligo

38.  Advantages:
 avoids the mesh aspect of split skin autografts
 avoids discomfort of donor site after skin harvesting.
 Disadvantages:
 fragility and difficulty of handling
 Shearing and blistering
 unpredictable take rate
 high cost.

42. Conclusion
 Skin substitutes have a important role to play in plastic
surgery in complex wound management for cutaneous
continuity
 Only a bridge until wound is better suited to accept graft
 Prohibitive costs and availability limit the usage to
research settings
 Future prospects

43. Thank you