(A) Alloderm
(B) Apligraf
(C) Biobrane
(D) Integra
(E) Transcyte

The correct response is Option A.

Each of the biologic dressings listed above is either a synthetic or tissue-engineered biologic skin substitute that will provide a clean, moist environment and protect the open wound until definite wound coverage is obtained.

Alloderm is lyophilized acellular human cadaveric dermis. This dressing contains only human-derived materials. Because it is devoid of immunogenic cells, it does not undergo the rejection that occurs with cadaveric skin. Alloderm can also be used as soft-tissue filler in patients undergoing cosmetic procedures. In some instances, thin layers of this dressing can be placed on a wound bed to vascularize and support a skin graft.

Apligraf is comprised of a bilayer of neonatal epidermal keratinocytes and dermal fibroblasts within a matrix of bovine collagen. This dressing is used for coverage of venous stasis ulcers and foot ulcers. Its mechanism of action involves graft adherence and subsequent remodeling on the wound bed.
Biobrane is a synthetic wound dressing composed of nylon and silicone fabric coated with porcine collagen. It provides temporary coverage of partial-thickness wounds and can be removed when epithelialization of the wound occurs.

Integra is a bioengineered dermal substitute that consists of a dermal matrix of bovine collagen and shark-derived chondroitin-6-sulfate covered by a bilayer of Silastic epidermis. When the dermal replacement layer becomes infiltrated with capillaries, fibroblasts, and inflammatory cells, the Silastic cover can be removed and autografting can be performed.

Transcyte is a dermal substitute comprised of neonatal dermal fibroblasts cultured onto a thin, semipermeable membrane of silicone that is bonded to a nylon mesh and bovine collagen. The fibroblasts secrete structural proteins and growth factors, creating a dermal matrix for future grafting or temporary coverage of partial-thickness burns.

References
1. Hansbrough JF, Franco ES. Skin replacements. Clin Plast Surg. 1998;25:407-423.
2. Stanton RA, Billmire DA. Skin resurfacing for the burn patient. Clin Plast Surg. 2002;29:29-51.

Which of the following is the primary advantage of using Integra (artificial skin) for coverage of full-thickness burns?

(A) Allowing for immediate use of cultured epithelial autografts
(B) Allowing for use of thinner autografts
(C) Avoidance of autografting
(D) Complete revascularization within seven days
(E) Prevention of fibroblast ingrowth into the dermal replacement layer

The correct response is Option B.

Integra, or artificial skin, is the most widely used skin substitute. It is a synthetic bilaminar membrane composed of a dermal matrix of porous bovine collagen cross-linked with shark-derived chondroitin-6-sulfate and covered by temporary Silastic epidermis. It does not contain neonatal fibroblasts or autologous keratinocytes. A two-stage application process is required; the initial stage is application of the dressing.

Following its application, the dermal matrix of the Integra dressing acts as a template, becoming infiltrated with host fibroblasts, endothelial cells, and inflammatory cells. The host collagen gradually replaces the bovine collagen during the healing process, and the silicone cover controls moisture loss and protects the wound. Adequate revascularization occurs within two to three weeks, at which time the superficial silicone layer will have sloughed off as a result of ingrowth through the collagen and glycosaminoglycan matrix. At this time, the Integra graft can be removed, and a thinner autograft, such as a very thin sheet of split-thickness skin graft, can be applied for durable coverage.

In addition to allowing for use of thinner autografts, advantages of Integra include immediate temporary coverage, more rapid healing of donor sites, and improved cosmesis.

Because the revascularization process is delayed, cultured epithelial autografts would fail to take if applied immediately because of the lack of vascularization in the wound bed.

Although Integra can be used to cover partial-thickness burns, it does not relieve the need for autografting over full-thickness burns.

As mentioned above, Integra is revascularized in two to three weeks, not within seven days, and allows for fibroblast ingrowth into the dermal replacement layer.

References
1. Dantzer E, Braye FM. Reconstructive surgery using an artificial dermis (Integra): results with 39 grafts. Br J Plast Surg. 2001;54:659-664.
2. Hansbrough JF, Franco ES. Skin replacements. Clin Plast Surg. 1998;25:407-423.
3. Jones I, Currie L, Martin R. A guide to biological skin substitutes. Br J Plast Surg. 2002;55:185-193.
4. Kao CC, Garner WL. Acute burns. Plast Reconstr Surg. 2000;105:2482-2492.
5. Stanton RA, Billmire DA. Skin resurfacing for the burned patient. Clin Plast Surg. 2002;29:29-51.