Can A New Biologic Matrix Facilitate Improved Wound Healing?

By Ann Anderson, DPM, and John S. Steinberg, DPM

   The field of advanced wound care science continues to deliver new products and concepts for use in healing problem wounds of the lower extremity. The market now includes two living cell products and numerous biologically active products that are the result of bioengineering research and development. The real advantage of these new technologies is that we can now actively stimulate healing whereas most of the prior advances in wound care simply helped to optimize the wound environment.    This ability to interact with the wound base and stimulate the production of local healing is a major advance in science and has already helped countless patients heal their lower extremity wounds. These advanced wound healing techniques attempt to reduce scarring and therefore yield a full thickness and durable wound covering that can better withstand weightbearing and the pressure of shoe gear.    Artificial skin substitutes have become popular because they act as a model for the synthesis of true dermis or epidermis, thereby reducing the amount of scar tissue in the healing wound. Dermal regeneration templates combine a structural scaffold and biologic factors that induce wound regeneration in partial and full thickness wounds.

What You Should Know About The Wound Dressing

   Integra Bilayer Matrix Wound Dressing (Integra LifeSciences) is a tissue engineered bilayer matrix that mimics dermal and epidermal function. The dermal component is a porous biodegradable matrix of bovine tendon collagen and a glycosaminoglycan (chondroitin-6-sulfate) obtained from shark cartilage. This biodegradable matrix provides a scaffold for cellular invasion and capillary growth into the wound defect occupied by the graft material. The collagen-glycosaminoglycan layer is bound to a temporary epidermal substitute layer consisting of a semi-permeable polysiloxane (silicone) layer that controls water vapor loss and provides a covering for the wound. The collagen-glycosaminoglycan matrix becomes vascularized over two to four weeks and is incorporated into the body similar to a full-thickness skin graft.    Integra provides some of the advantages of an autograft without the need of a donor site. This can be a significant factor in this patient population given the concern for creating an additional wound site. Once the collagen matrix has been vascularized in the wound bed and colonized with fibroblasts, the silicone component of the graft will begin to separate. At this point, it can be easily and safely removed. One would then treat the viable wound bed with additional tissue engineered grafting or consider autogenous split thickness graft application.    Integra is indicated for the treatment of partial and full-thickness wounds, pressure ulcers, venous ulcers, diabetic ulcers, chronic vascular ulcers, surgical wounds (wound dehiscence, donor sites/grafts), traumatic wounds (lacerations, second degree burns) and draining wounds. It is contraindicated in patients who have allergies to bovine products or patients with third-degree burns.    Integra interacts with the wound surface by inducing migration of normal fibroblasts and vessels into the collagen matrix while acting as a template for the synthesis of a new dermal matrix. The glycosaminoglycans promote revascularization and engraftment followed by regeneration of autologous dermal tissue. The porous quality of the collagen-glycosaminoglycans network allows infiltration of macrophages, fibroblasts, lymphocytes and endothelial cells derived from the wound to form a neovascular network. An endogenous collagen matrix is deposited via the fibroblasts as the dermal layer of the template degrades (usually over 30 days). Researchers have observed that the structure of the new tissue in the wound base resembles normal dermis rather than random scar tissue.

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