Technology and product reviews
of the same species, but with a different genotype (eg, human to human) and contains both epidermis and dermis. Cadaver skin allografts have been used for many years, but provide only temporary coverage because of host rejection. In 1981, Integra® (LifeSciences), a collagen-
based dermal substitute with a silicone top layer, was engineered to serve as a dermal template. Although promising results have been obtained, Integra requires a two-step approach where the top layer, which serves as a temporary epidermal replacement, is removed when the artificial dermis appears macroscopically revascularised[7]
. This is generally performed 2–3
weeks post-application. Subsequently in 1994, AlloDerm® (LifeCell), a chemically treated ‘decellularised’ allograft, was developed to be used alone or in combination with cultured autologous keratinocytes for the closure of burns and chronic wounds. Another acellular product TransCyte®
(Advanced BioHealing), consists of an inner nylon mesh, in which human foreskin fibroblasts are embedded, and an outer silicone layer designed to limit evaporation. It has been successfully used as temporary wound coverage after the excision of burn wounds and other complex ulcers. A cellular composite, Dermagraft®
(Advanced BioHealing), has also been designed to treat diabetic foot ulcers and again uses human foreskin fibroblasts cultured in a biodegradable polyglactin mesh and then cryopreserved so that they remain viable. However, such meshes die a few weeks after implantation, therefore, the product probably acts as a delivery vehicle for growth factors and ECM produced by fibroblasts. A porcine small intestinal submucosa
acellular collagen matrix (Oasis® [Cook Biotech]) and an acellular xenogeneic collagen matrix (EZ-DermTM
[AM Scientifics]) are also References
7. Dantzer E, Brave FM. Reconstructive surgery using an artificial dermis (Integra): results with 39 grafts. JPRAS 2001; 54(8): 659–64.
8. de Vries HJ, Middelkoop E, Dutrieux DP, Wildevuur CH, Westerhof H. Dermal regeneration in native
non-cross-linked collagen sponges with different extracellular matrix molecules. Wound Repair Regen 1994; 2(1): 37–47.
available and have relatively long shelf lives. However, evidence of their efficacy is limited. The Unite® Biomatrix collagen wound
dressing (Synovis) is another crosslinked native collagen structure that is designed to provide a biologic solution for chronic wounds, such as diabetic foot ulcers, venous ulcers, pressure ulcers and vasculitic ulcers.
THE ROLE OF COLLAGEN IN DERMAL CONSTRUCTS Collagen is the most effective biocompatible
38 Wounds International Vol 3 | Issue 2 | ©Wounds International 2012
Technology and product reviews
material for dermal substitution in full- thickness wounds. It is normally present in large quantities in the skin and is vital for normal wound healing. Reconstituted collagen is made of soluble collagen fragments, whereas native collagen is built up from insoluble collagen fibres. It is important that any dermal matrix does not degrade too quickly in the wound. Reconstituted collagen matrices disintegrate within a week and do not contribute to dermal regeneration. However, native collagen matrices composed of intact collagen fibres survive for longer and contribute to dermal regeneration. The addition of extracellular matrix proteins further delay disintegration for up to four weeks[8]
.
Elastin is a protein made of simple amino acids such as glycine and praline. It is elastic and allows tissues, including skin, to return to their original shape after stretching or contracting. Dermal substitution of full-thickness
skin defects with a native collagen matrix incorporating elastin contributes to skin regeneration. The native collagen fibres form a scaffold that guides fibroblasts and possibly other cells toward dermal regeneration, while the presence of elastin particles in the collagen matrix diminishes the formation of granulation tissue in the early phase of wound healing. As a result, a high-quality neodermis with randomly organised collagen bundles is regenerated. Also, by diminishing the expression of myofibroblasts, the presence of elastin reduces wound contraction.
MATRIDERM MatriDerm is a dermal substitute suitable for one-step repair of full-thickness skin defects in combination with STSG. MatriDerm is a scaffold consisting of a native bovine type I, III and V collagen fibre template incorporating elastin hydrolysate that is converted into native host collagen within weeks following application. The matrix can be stored at room temperature and comes in 1mm and 2mm thick sheets.
Application MatriDerm can be applied straight from the pack onto the wound bed following the debridement of any slough, exudate or unhealthy tissue, and after careful haemostasis. The matrix can easily be rehydrated in the wound bed by 0.9% physiological saline solution.
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