This document discusses skin substitutes, which are materials that can aid in wound closure and replace skin functions temporarily or permanently. It defines various types of skin substitutes and outlines their classification. It describes both temporary skin substitutes like porcine xenografts, human allografts, and synthetic options. It also discusses permanent skin substitutes that contain dermal and epidermal components, such as Integra, Apligraf, and cultured epithelial autografts. The document concludes that skin substitutes are important in plastic surgery and wound management but are limited by high costs and availability.

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