Tag Archives: Bioengineered alternative tissues

Collagen in Wound Healing: Are We Onto Something New or Just Repeating the Past?

by Ryan H. Fitzgerald, DPM1 , John S. Steinberg, DPM2

The Foot and Ankle Online Journal 2 (9): 3

Lower extremity amputations in patients living with diabetes have significant morbidity and mortality. Given the obvious link between lower extremity amputations and the ulcerations that precede them, it is incumbent upon the wound care provider to become familiar with advanced wound care products. The importance of re-establishing a functional extracellular matrix (ECM) in chronic wounds has led to a renewed interest in collagen-based wound healing products. These products can be applied either in the surgical or clinical setting. An intact functional ECM will seek to promote normal progression through the stages of wound healing. This article presents several representative collagen-based advanced wound care products utilized in wound healing, discusses their mechanism of action, and the appropriate indication for each product’s usage.

Key Words: Collagen, wound, diabetes, matrix metalloproteases, bioengineering, alternative tissue.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.  It permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ©The Foot and Ankle Online Journal (www.faoj.org)

Accepted: July, 2009
Published: September, 2009

ISSN 1941-6806
doi: 10.3827/faoj.2009.0209.0003

Chronic lower extremity wounds demonstrate a considerable health care dilemma and substantial health care cost in the United States. [1,2] Chronic wounds and diabetic ulcerations represent a large component of this cost, with nearly one million new lesions diagnosed each year. [3,4,5] Furthermore, greater than 60% of non-traumatic amputations in the western world are performed on persons with diabetes [6] and the majority of these amputations are preceded by some form of infected ulceration. Therefore we can surmise that aggressive efforts at ulcer healing will have a direct influence on amputation rates. The risk is obvious; the relationship between diabetic foot ulcerations and subsequent amputation has been well documented and is well understood. [7]

There is significant morbidity and mortality at five years following amputation in this patient population. [8] This staggering data has prompted further research into the science of wound healing in an attempt to reduce diabetic foot ulcerations and their life changing sequelae.

Many of today’s wound care concepts have developed from research associated with burn therapies. [9] More recent research has focused on the wound environment, and on both the cellular and extracellular components necessary to promote wound healing. A better understanding of vasculopathy, infection, and poor nutritional status have enabled industry to target the failing biology of wounds with new products including many new collagen derivatives.

The Science

Throughout the four phases of wound healing, the extracellular matrix (ECM) provides a significant role in regulating and providing a framework for the many processes of healing. The ECM is the largest component of the dermal skin layer and is composed of a variety of polysaccharides, water and collagen proteins. [10] Collagens make up the largest fibrous components of the ECM; in the dermal matrix, the majority of collagen is type I and type III. These collagens demonstrate a fibrillar or rod shape and are composed of three triple-helix protein chains arranged in a linear fashion. This linear orientation provides much of the tensile strength of skin. In addition to longitudinal strength, bundles of collagen molecules in the ECM cross link with adjacent collagen molecules to provide additional strength and stability against shearing forces. [11]

Acute wounds create a provisional wound matrix which contains fibrin and fibronectin, which act as chemical mediators to direct cells to the site of injury and to motivate cells to proliferate and to differentiate into new, provisional matrix structures. [4,6] However, in chronic wounds, increased levels of inflammatory cells and proteases degrade the ECM components which are essential for healing. [8,12] Among these proteases, matrix metalloproteases (MMPs) play an important role in damaging the ECM and the extracellular growth factors present in a chronic wound. These MMPs are synthesized by multiple cell types, including neutrophils, fibroblasts and macrophages at the direction of chemical mediators such as inflammatory cytokines. [6] In normal healing, the MMPs function to debride away denatured elements of the ECM, thus exposing areas of intact functional matrix that are needed for wound healing. This process is highly regulated and controlled via tissue inhibitors of metalloproteases (TIMPs). [12] In chronic wounds, however, in addition to an excess number of MMPs, there is a failure in the regulation of protease activity between the MMPs and TIMPs which can result in further degradation of the ECM. This is followed by the destruction of growth factors, inhibition of angiogenesis, and breakdown of granulation tissue. [13]

For wound healing to occur, a balance is needed between the protein degrading activities of MMPs and other cellular activity that synthesizes and deposits protein components of granulation tissue. Many new collagen based wound care products aim to reduce excessive protease levels and reestablish balance in the wound environment. In addition, these products serve to contribute functional ECM proteins to stimulate the healing process. [1] Research has demonstrated that topically placed collagen can initiate wound healing by activating inflammatory cells and promoting increased vascularization of the healing tissue. [14] Other research has demonstrated that the physical three-dimensional structure of collagen has the ability to induce fibroblastic growth, which is essential in the formation of granulation tissue. [1]

The Products

There are an abundance of collagen-based products on the market today. These products can be loosely divided into groups based upon the setting in which they are applied (either in the clinic setting or in the operating room). In addition to differences in the application process, these collagen-based products can be combined with other treatment modalities, such as the addition of an alginate to manage exudate or the addition of silver to provide antimicrobial effects (See attached table).

Attached Table:  Collagen based products and their properties.

Below is a detailed discussion of several representative topical collagen products that are intended for use in the outpatient dressing setting:

FIBRACOL PLUS® (Systagenix Wound Management) combines the structural support of collagen with the exudate management of an alginate. In this way, the alginate component maintains a moist wound environment while the collagen component allows for cellular and vascular in-growth, which promotes formation of granulation tissue and neo-epithelialization at the wound site.

Promogran® (Systagenix Wound Management) combines oxidized regenerated cellulose (ORC) and collagen. This bioactive collagen product binds to and neutralizes destructive proteases in chronic wound fluid. [14]

Once bound, MMPs are rendered inactive due to alteration of their protein structure. Reduction of MMP burden in the chronic wound allows endogenous ECM protein cells to proceed to the formation of granulation tissue and normal wound healing.

PRISMA® (Systagenix Wound Management) is the next generation in the Promogran® line. This product provides the MMP binding function of Promogran® in the form of ORC and collagen with the addition of silver to provide antibiosis, thus lowering the bioburden in chronically colonized wounds. [14] PRISMA® provides a biodegradable cellular matrix that promotes cellular migration and neo-vascularization while helping to maintain bacterial balance at the wound site and to create an optimal wound healing environment.

PURACOL PLUS® (Medline Industries, Inc) is a bovine derived collagen matrix, which utilizes a native, triple-helical structure to stimulates fibroblastic activity in the wound bed to promote ECM formation and thus stimulate local wound healing. Additionally, this product controls moisture in the wound environment by converting to soft, gel-like sheet that maintains intimate contact with wound bed as it absorbs exudate. PURACOL PLUS® is most commonly utilized in chronic, partial thickness wounds which demonstrate light to heavy exudate and are non-infected and non-ischemic.

Biostep® and Biostep Ag® (Smith & Nephew) are two new collagen products which are demonstrating a great deal of success in the treatment of chronic wounds. The semi-denatured porcine collagen in Biostep® attracts and bind excess MMPs present in the chronic wound environment, and the EDTA component in the product irreversibly deactivates MMPs by binding to their zinc ions. In this way the collagen in Biostep®, coupled with EDTA, functions as a competitive substrate for the MMPs and thus allows endogenous collagen matrix formation to progress undeterred as granulation tissue forms. In addition, the product contains carboxy methyl cellulose and alginate which helps to provide moisture management in an actively draining wound environment.

Biostep Ag® provides similar anti-MMP activity, while the addition of silver ions helps to maintain bacterial balance in the wound site.

OASIS® Wound Matrix (HealthPoint) is a biologically derived extracellular matrix-based wound product which is derived from porcine small intestine submucosa. Indicated in the management of partial and full thickness wounds, this product provides intact acellular collagen scaffold that allows promotes a favorable host tissue response and stimulates cellular migration, leading to restoration of tissue structure and promotion of wound healing.

Integra® Matrix (Integra Life Sciences) consists of a cross-linked bovine tendon collagen and glycosaminoglycan matrix which is available with and without a semi-permeable polysiloxane layer. [2] Glycosaminoglycans are large saccharide polymers that are important elements of the ECM; these proteins aid in cellular adhesion to the matrix, as well as playing a role in cell and tissue differentiation necessary for wound healing. [9] The semi-permeable polysiloxane membrane of the bilayer matrix functions as a temporary epidermis by protecting the deeper collagen graft tissue and wound while also controlling water vapor loss. Below the silicone layer, the collagen-glycosaminoglycan biodegradable matrix provides a scaffold for cellular invasion and capillary growth. As the graft is incorporated, the silicone layer peels away to expose new granulation tissue formation and neo-epithelialization. Additionally, this product is available in a “flowable” or injectable form that can be utilized to provide collagen and glycosaminoglycan matrix to difficult to manage wounds with tunneling or tracking components. Often this modality can be used in conjunction with the conventional graft to provide three dimensional reconstruction at complex wound sites.

GraftJacket® Regenerative Tissue Matrix (Wright Medical), which is a collagen based graft processed from donated cadaveric skin. As an allograft, this product contains components of normal skin including collagen, elastin, hyaluronan, fibronectin, and blood vessel channels. [8]

In this way, GRAFTJACKET® provides soft tissue coverage over deep structures, functions as a scaffold for new cellular in-growth. It preserves the vascular channels in the donor graft and allows for rapid revascularization necessary for wound healing.

In the operating room setting, collagen-containing products are often applied to provide coverage over a soft tissue deficit following surgical debridement or serve as a scaffold initiate the filling of a void. As with the clinically applied products described above, these collagen grafts were originally designed to be used in the treatment of partial and full thickness burns. These surgically applied collagen products, such as Integra® Matrix and GraftJacket® Regenerative Tissue Matrix, are not specifically designed to neutralize proteases as several of the previously described products. Instead, they provide a functional cellular scaffold that promotes cellular in-growth and formation of granular tissue while also providing soft tissue coverage over bone, tendons, and other deep structures. As a result, it reduces the risk of contamination and subsequent infection.

To reduce MMP burden in a wound site prior to application of these surgically applied collagen grafts, it is recommended that the wounds be debrided sharply to promote local bleeding and to remove any nonviable and necrotic soft tissue and bone that will further stagnate a wound site. Localized bleeding following debridement stimulates influx of alpha-2-macroglobin (A2M), which is a chemical agent that acts as a protease inhibitor, thus reducing proteolytic destruction of the graft. [1,11]


In discussion of collagen products in wound healing, it is important to understand the underlying etiologies of wound chronicity. Vascular and nutritional status, the presence of an infection or colonization, and the microenvironment present in the wound bed all combine to affect healing. Each barrier must be addressed to ensure that the wound progresses through the normal stages of healing. [1]

Research has demonstrated the importance of re-establishing a functional ECM in chronic wounds and this has led to a renewed interest in collagen based wound healing products. [8] These products seek to provide a functional ECM as well as to reduce MMP levels present in the wound bed and seek to promote normal progression through the stages of wound healing. In addition, these products can be combined with other modalities, such as alginates or heavy metals to provide additional effects to the wound environment such as management of exudate or bacterial load.

The collagen-based surgical grafting materials, such as Integra Matrix® and GraftJacket® have filled a niche that have allowed for significant increases in salvage options due to the ability to provide collagen ECM to the wound site, following sharp debridement. These surgically applied collagen wound fillers can provide soft tissue coverage over deeper structures to reduce the risk of infection. Pioneered in the burn community, much of these techniques are now being utilized to preserve limb length in partial foot amputations, which is important as the costs of health care spiral and the annual incidence of foot ulcerations continue to climb. [2]

Considering the significant morbidity and mortality associated with lower extremity amputations, and the obvious link between lower extremity amputations and the ulcerations that precede them, it is incumbent upon the clinician involved in wound care to become familiar with these advanced wound care products in order to provide patients with the greatest possibility for successful outcomes in the treatment of chronic wounds.


1. Schultz GS, Sibbald RG, Falanga V, Ayello EA, Dowsett C, Harding K et al: Wound bed preparation: a systematic approach to wound management. Wound Repair Regen, 2003. 11 (suppl 1): S1 – 28, 2003.
2. Voigt DPC, Edwards P: Economic study of collagen-
glycosaminoglycan biodegradable matrix for chronic wounds. Wounds 18 (1): p. 1 – 7, 2006.
3. Physicians AAoF: Clinical guidelines on diabetic foot disorders. J Foot Ankle Surgery 63 (5): 290 – 295, 2001.
4. Greiling DCR: Fibronectin provides a conduit for fibroblast transmigration from collagenous stroma into fibrin clot provisional matrix. J cell science 110 (7): 861 – 870, 1997.
5. Gordois A, Scuffham P, Shearer A, Oglesby A: The health care costs of diabetic nephropathy in the United States and the United Kingdom. J Diabetes Complications 18 (1): 18 – 26, 2004.
6. Ovington L: Overview of matrix metalloprotease modulation and growth factor protection in wound healing. Wounds 14(5): 3 – 7, 2002.
7. Moulik PK, Mtonga R, Gill GV: Amputation and mortality in new-onset diabetic foot ulcers stratified by etiology. Diabetes Care 26 (2): 491 – 494, 2003.
8. Loots MA, Lamme EN, Zeegelaar J, Mekkes JR, Bos JD, Middelkoop E: Differences in cellular infiltrate and extracellular matrix of chronic diabetic and venous ulcers versus acute wounds. J Invest Dermatol 111 (5): 850 – 857, 1998.
9. Ehrenreich RZ, Ruszczak Z: Update on tissue-engineered biological dressings. Tissue Engineering 12 (9): 2407 – 2424, 2006.
10. Dalla Paola L, Faglia E: Treatment of diabetic foot ulcer: an
overview strategies for clinical approach. Curr Diabetes Rev 2 (4): 431 – 447, 2006.
11. Kainulainen V, Wang H, Schick C, Bernfield M: Syndecans, heparan sulfate proteoglycans, maintain the proteolytic balance of acute wound fluids. J Biol Chem 273 (19): 11563 -11569, 1998.
12. Trengove NJ, Stacey MC, MacAuley S, Bennett N, Gibson J, Burslem F, Murphy G, Schultz G: Analysis of the acute and chronic wound environments: the role of proteases and their inhibitors. Wound Repair Regen 7 (6): p. 442 – 452, 1999.
13. Ladwig GP, Robson MC, Liu R, Kuhn MA, Muir DF, Schultz GS: Ratios of activated matrix metalloproteinase-9 to tissue inhibitor of matrix metalloproteinase-1 in wound fluids are inversely correlated with healing of pressure ulcers. Wound Repair Regen 10 (1): 26 – 37, 2002.
14. Cullen B, Watt PW, Lundqvist C, Silcock D, Schmidt RJ, Bogan D, Light ND: The role of oxidised regenerated cellulose/collagen in chronic wound repair and its potential mechanism of action. Int J Biochem Cell Biol 34 (12): 1544 – 1556, 2002.

Address correspondence to: Ryan H. Fitzgerald, DPM, AACFAS. Hess Orthopaedics & Sports Medicine, PLC
4165 Quarles Court, Harrisonburg, Virginia 22801.

Attending physician, Hess Orthopaedics & Sports Medicine, Harrisonburg Virginia.
Assistant Professor, Department of Plastic Surgery, Georgetown University School of Medicine.

© The Foot and Ankle Online Journal, 2009

Creating the Ideal Microcosm for Rapid Incorporation of Bioengineered Alternative Tissues Using An Advanced Hydrogel Impregnated Gauze Dressing: A Case Series

by Jonathan Moore, DPM, MS1

The Foot & Ankle Journal 1 (9): 2

The purpose of this article is to demonstrate the effectiveness of a novel hydrogel impregnated gauze dressing in creating the ideal microcosm around a bioengineered alternative tissue to prevent tissue dehydration and cell death, accelerate angiogenesis, prevent infection and facilitate the interaction of growth factors with the target cells. Using the BRAIN principles along with this hydrogel impregnated gauze dressing in 50 diabetic patients with neuropathic foot ulcerations (including the six cases presented herein) resulted in substantially improved incorporation rates, increased frequency of wound closure, decreased time to achieve wound closure and a reduction in overall costs. Based on a log transformation the typical healing time is 17.8 days with a 95% confidence interval of 15.6 days to 20.2 days.

Key Words: Bioengineered alternative tissue, diabetic wounds, neuropathic wounds, Amerigel®, BRAIN principle

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.  It permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ©The Foot & Ankle Journal (www.faoj.org)

Accepted: August, 2008
Published: September, 2008

ISSN 1941-6806
doi: 10.3827/faoj.2008.0109.0002

The efficacy of bioengineered alternative tissue (BAT) for lower extremity ulcers (diabetic and non-diabetic) is well described in the literature. [1-6] As the use of BATs continue to grow world wide, it is important that the wound care specialist consider the principles and tools that will maximize the effectiveness of these tissues to enable wounds to heal faster. Using the BRAIN principles (Table 1) will be fundamental in improving incorporation rates and maximizing the effectiveness of BATs. [7]

Table 1  The BRAIN principles to maximize BAT incorporation and wound healing.

Treating wounds in patients with diabetes is more complex than simply choosing what dressing to use. Emerging technologies over the past decade have not only helped improve our understanding of how wounds heal, but more importantly why wounds do not heal. Understanding and addressing the physiological alterations of the wound healing cycle in the diabetic patient is fundamental. As diabetic wounds become stalled in the inflammatory phase of wound repair, chronic wound fluid with elevated levels of matrix metalloproteinases (MMPs) increases proteolytic activity in the wound, which in turn inactivates growth factors.

In addition, with decreased collagen synthesis and impaired cellular activity due to hyperglycemia, there is less nitric oxide available and less endothelial cell proliferation. [8]

With this impaired wound healing physiology, it is vital for the wound care specialist to provide the wound what it lacks (i.e. growth factors, BATs, etc.) and decrease excess chronic wound fluid. Consequently, providing the wound with what it needs at the right time is imperative.

So how can we create the perfect environment for wounds to heal? What is the perfect environment to incorporate BATs into to the wound? Although there is no one right answer, we do know that creating the perfect “microcosm” around the wound will not only actively modify the physiology of the wound environment, but it will also stimulate cellular activity and growth factor release. While no perfect dressing exists for every type of wound, understanding the properties necessary to create the ideal microcosm for the BAT and the periwound area is crucial. [9] (Table 2)

Table 2  The properties of the ideal wound dressing to help incorporate BATs into the wound.

With these characteristics in mind, the AmeriGel® Hydrogel Saturated Gauze Dressing (Amerx Health Care Corp., Clearwater, FL) has, in my experience, been the product of choice in creating the ideal microcosm for both the BAT (cellular or acellular) and the periwound area.

This product utilizes a polyethylene glycol base (polyethylene glycol 400 and polyethylene glycol 3350) that has the ability to remain moist without causing maceration. Because the product is still technically a gauze dressing, it will also absorb excess wound fluid into its fibers while keeping the wound moist for up to 5-7 days.

Although there are other hydrogel impregnated gauze products on the market, such as Aquagauze TM (DeRoyal, Powell, TN), Curafil® Hydrogel Impregnated Gauze (Kendall, Mansfield, MA) and Derma Cool® (Afassco, Carson City, NV), none of these products possess the antimicrobial or antifungal properties that are in the AmeriGel® Hydrogel Saturated Gauze Dressing. [10] While most hydrogel impregnated gauze products are capable of absorbing excess fluid, the AmeriGel® Hydrogel Saturated Gauze Dressing (AmeriGel®) can effectively reduce the bioburden through not only its intrinsic antimicrobial and antifungal properties, but also through its absorptive capabilities that trap debris and bacteria in its fibers. AmeriGel® is an easy to apply, non-woven 4-ply, 2×2 inch dressing that is non-cytotoxic, nonadherent, and antimicrobial.

The antimicrobial agent is Oakin®, an oak extract containing tannins. Its mode of antimicrobial action is through its ability to inactivate microbial adhesins, enzymes, and cell envelope transport proteins. [11,12] Tannins are astringent compounds that act locally by precipitating proteins to the wound, decreasing cell membrane permeability, and exerting anti-inflammatory and bactericidal properties.

The use of AmeriGel® over the BAT application site will facilitate not only a closer adherence of the living or acellular tissue to the wound bed, it will also have an “anchoring” effect by its adherence to the surrounding tissues thus reducing the incidence of hematoma or seroma formation under the BAT.

Although some controversy exists regarding the use of certain products with or on a living skin equivalent, there is no definitive evidence that demonstrates that hydrogels (especially the one being proposed in this paper) are cytotoxic. The objective of using any adjunctive wound care product (i.e. AmeriGel® Hydrogel Saturated Gauze Dressing) with a BAT (cellular or acellular) is to enhance its incorporation into the wound while maintaining the ideal environment in and around the wound site. Using the right product is key, but putting the right product on the wound in and of itself won’t get wounds healed.

The following is a series of case reports utilizing the BRAIN principles along with the AmeriGel® Hydrogel Saturated Gauze Dressing as the product of choice for local BAT incorporation into the wound.

We utilized a variety of products for a variety of particular wound beds. Strict protocol to maintain the consistency of wound preparation and BAT application was followed. The following protocol was used for every BAT application:

1. Conservative topical wound care was performed in every case (collagen wound care products, enzymatic agents etc. ) prior to every BAT application.
2. Sharp debridements were performed regularly to prepare the wound base for the application of the chosen BAT.
3. Care was taken to assure that no active bleeding was occurring prior any BAT application
4. Wound margins were thoroughly debrided to remove any hyperkeratosis and or any undermined tissue.
5. All patients in this series were diabetic, although some wounds treated using this protocol were of venous origin.
6. The BAT was placed on the wound bed such that the entire wound was covered.
7. BATs were not applied to wounds in which tendon or bone was exposed.
8. BATs were not applied in cases of infection or active drainage.
9. BATs were not applied to arterial leg ulcers.
10. AmeriGel® was applied directly over the BAT, followed by a secondary dressing (or some cases a compressive wrap in cases of edema)
11. More than one AmeriGel® Gauze Dressings were used in cases were one did not cover the wound site entirely.
12. All wounds were appropriately offloaded according to the BRAIN principles.
13. In cases where there was lower extremity edema, compression was applied over the BAT site using either an Unna’s boot, or a ProFore® Bandage System (Smith & Nephew, Largo, FL)
14. The patient was instructed to leave the dressing intact and dry for one week after application.
15. The patients returned for follow-up no more than 10 days after application, most returned at 7 days.
16. GammaGraft® (Promethean LifeSciences, Inc., Pittsburgh, PA) was chosen in most cases for two reasons; The product has a greater than 2 year shelf life and it is easy to apply and manage.
17. AmeriGel® Gauze Dressing was used daily until wound closure in every case after BAT application.

Case 1

A 63-year-old female with diabetes and rheumatoid arthritis presented with a chronic venous ulceration (2 cm X 2.6 cm) to the dorsal aspect of the right leg. (Fig. 1A) The wound had been present for over two months despite application of compression therapy and topical agents. The GraftJacket® (Wright Medical Technology, Inc., Arlington, TX) was sutured to the wound site followed by AmeriGel® placed directly over the BAT site. (Fig. 1B)


Figures 1AB  Application of GraftJacket® and AmeriGel® Dressing over this non-healing venous ulceration. Sutures were applied to assure fixation of the BAT under a compressive wrap.

A 4” X 4” fluff and an elastic bandage were applied over the AmeriGel® for moderate compression. After one week, the initial dressing was removed (Fig. 1C) and was changed daily thereafter with AmeriGel® at home by the patient. The secondary dressing was dry sterile gauze. Four weeks after application of the GraftJacket®, the wound site along with all of the surrounding erythema was completely resolved. (Fig. 1D) It was surmised that AmeriGel® facilitated significant reduction of the erythema that had been persistent around the wound.


Figures 1CD  The wound site 1 week and 4 weeks after application of BAT. Compression and continued use of AmeriGel® played a pivotal role.

Learning points: Treating wounds on the leg in the presence of venous insufficiency will require compression in conjunction with proper local wound care. Although care must be taken not to apply too much compression such that the BAT is disrupted, no compression or too little can be equally harmful.

Tip: Size and trim the BAT prior to application to ensure the BAT is capable of covering the deepest portion of the wound without tenting.

Case 2

A 42-year-old poorly controlled diabetic male presented with a chronic interdigital ulceration (1.6 cm X .9 cm) to the right foot. (Fig. 2A) The ulcer started as a result of a severe Tinea pedis infection. After the fungal infection was cleared, the ulceration was recalcitrant to traditional topical wound care agents and regular debridements. Thus, a GammaGraft® was chosen to close the wound. The GammaGraft® was anchored securely to the surrounding tissue followed by the AmeriGel® carefully placed to serve as a spacer interdigitally as well as to cover the BAT to promote more rapid healing. (Fig. 2B) After one week, the initial dressing was removed and the patient was instructed to change the dressing daily by applying AmeriGel® over the wound site followed by dry sterile gauze as a secondary dressing. After 3 weeks and 4 days, the wound site completely closed. (Fig. 2C)


Figures 2ABC  In case 2, GammaGraft® was used with AmeriGel® to advance closure of this chronic interdigital ulcer that occurred from a long standing and ignored fungal infection.

Learning points: Desiccation of the BAT is a major concern when treating distal extremity wounds where there is often autonomic impairment common in patients with diabetes. A dressing like AmeriGel® will supplement moisture to the wound site.

Tip: Because of the previous fungal infection, the antifungal properties of AmeriGel® served well to provide the ideal environment for healing.

Case 3

A 54-year-old diabetic male with a long history of Charcot deformity presented with a plantar ulcer (2.1 cm X 2.5 cm) of greater than 6 months duration. After the patient was offloaded in a Bledsoe® Walker (Bledsoe Brace Systems, Grand Prairie, TX), a granular bed was achieved after two weeks of aggressive debridement and topical wound care agents. (Fig. 3A) A GammaGraft® was then chosen to bring total closure to the wound site. The GammaGraft® was anchored to the wound site followed by AmeriGel®. (Fig. 3B) After one week, the initial dressing was changed and the patient was instructed to apply AmeriGel® every day thereafter, using dry sterile gauze as a secondary dressing. 3 weeks and 1 day later, the patient achieved complete healing. (Fig. 3C) Patient compliance with offloading and proper use of the prescribed dressings played a major role in this patient’s quick healing time.


Figures 3ABC  In case 3, GammaGraft® was used with AmeriGel® to facilitate healing of this plantar ulcer that occurred due to Charcot deformity.

Learning points: Offloading wounds like the one above is the cornerstone to success in wound healing. Encourage patients to agree and be compliant with your treatment regimen.

Tip: Avoid using questionable cytotoxic agents over or on the BAT site.

Case 4

A 68-year-old diabetic female on dialysis presented with a chronic right heel ulcer (3.4 cm X 3.1 cm) of greater than 3 months duration. After thorough wound bed preparation over the course of 2 weeks (Fig. 4A), GammaGraft® and AmeriGel® was chosen to bring closure to the wound site. (Fig. 4B) The patient’s dressing was changed at one week followed by daily applications of AmeriGel®, using dry sterile gauze as a secondary dressing. After 5 weeks and 3 days, the patient achieved total healing. (Fig. 4C)


Figures 4ABC  GammaGraft® and  AmeriGel® were used to together to facilitate closure of this chronic heel ulceration that occurred as a result of dyshidrosis and neuropathy. 

Learning points: Initial dressing changes after application of a BAT should occur between 5-7 days. This may vary depending on the presence of drainage or infection.

Tip: The heel can be a very difficult place to heal a chronic wound for many reasons. Hydration was really the key to healing this wound as this patient developed the wound initially from excess dryness, cracking and fissuring.

Case 5

A 71-year-old diabetic male smoker with severe peripheral arterial disease presented with a dorsal foot ulceration (2.5 cm X 2.4cm) that had been chronically open for nearly 2 years. After months of treatment at 2 different wound care centers and several interventions by local vascular specialists, the patient was referred for consultation. After 2 weeks of aggressive wound debridements and the use of a collagen topical dressing, the wound bed improved to the point of accepting a BAT. (Fig. 5A) The GammaGraft® was anchored to the surrounding tissues with Steri-Strips™ (3M, St Paul, MN) (Fig. 5B) and covered with AmeriGel®. (Fig. 5C) After one week, the initial dressing was changed and daily applications of the AmeriGel® was performed using dry sterile gauze as a secondary dressing. The patient achieved complete healing in 6 weeks. (Fig. 5D)


Figures 5AB  Application of GraftJacket® and AmeriGel® in the presence of vascular disease.


Figures 5CD  Despite poor vascular status, early intervention and rigorous wound care helped heal this longstanding foot ulceration.

Learning points: This patient’s ABI demonstrated dismal PVR’s, yet despite this, a rigorous wound care regimen was instituted that eventually led to complete healing.

Tip: Thoroughly assessing vascular status with each and every wound care patient is not only good practice; it can prevent limb loss with timely intervention.

Case 6

A 47-year-old diabetic patient with profound peripheral neuropathy developed a blister on the plantar aspect of her right heel that became recalcitrant to conservative treatment. The patient’s wound was debrided weekly and had Promogran™ (Johnson & Johnson Wound Management, Somerville, NJ) applied to the site until the wound developed a healthy granular base.  Apligraf® (Organogenesis, Inc., Canton, MA) was chosen to close the wound. It was secured in place with Steri-Strips™ and covered with AmeriGel®, along with the use of a Bledsoe® boot and wheel chair.

Due to the patient’s severe neuropathy, among other balance concerns, the patient could not use crutches. (Fig. 6A) One week post application, the absorptive capability of the AmeriGel® was evident (Fig. 6B) as well as its ability to maintain a moist, healthy wound base. (Fig. 6C) At 4 weeks and 4 days, after daily applications of AmeriGel® and dry sterile gauze as the secondary dressing, the wound was healed. (Fig. 6DE)


Figures 6ABC  After regular debridements,  aggressive offloading and conservative treatments including the use of collagen dressings, Apligraf® was chosen for closure along with AmeriGel® per the BRAIN principals.  Excellent incorporation was noted as early as one week (Fig. C). 


Figures 6DE At two weeks, the wound size had been reduced by half and following daily applications of AmeriGel®.  The wound was closed 4 weeks and 4 days after the BAT was applied. 

Learning points: The above case illustrates well the concept of meeting the needs of the wound through the use of more than one product. Aside from regular wound debridements, collagen dressings were initially used to promote a healthy wound base followed by the Apligraf® and AmeriGel®.

Tip: Do NOT mechanically debride the wound bed for at least 4-6 weeks after applying a BAT [this may vary depending on the type of BAT being utilized (i.e. GammaGraft®)] unless the presence of significant exudate and colonization is present.


Since using the BRAIN principles in my own clinics, successful incorporation rates have substantially improved when compared to conventional protocols used previously (i.e. petrolatum impregnated gauze, 4X4’s and roll gauze). Over the past two years, 50 diabetic patients with similar ulcerations were treated using the BRAIN principles along with AmeriGel®. Approximately 90% of those patients had allograft tissue (GammaGraft® and GraftJacket®) applied while the other 10% had Apligraf® applied. To date, only two of the 50 patients have demonstrated BAT failure (non-healing of the wound). Failure in these two patients was attributed to peripheral vascular disease in one and non-compliance in the other.

BATs applied to the legs healed quicker clinically than those applied to the foot. The legs being better vascularized in most cases constitute a viable reason for the comparably faster healing times. For chronic venous insufficiency ulcer patients, compression and a BAT covered by AmeriGel® allowed for healing in the majority of cases within two to three weeks. In some cases wounds were healed at one week. (Graph 1)

Graph 1 This histogram shows that, with the exception of the extreme value (55 days to healing), healing times are reasonably normally distributed, represented by the dashed curve. Based on a log transformation the typical healing time is 17.8 days with a 95% confidence interval of 15.6 days to 20.2 days.

In all cases, only one BAT was used during the entire course of treatment, which certainly reduced costs. After application of the BAT, AmeriGel® continued to be employed as the primary dressing over the wound until closure.


Successfully combining BAT application along with other adjunctive therapies is not a new concept. Armstrong combined Dermagraft® (Advanced BioHealing, Inc., La Jolla, CA) with a vacuum-assisted closure system demonstrating quicker healing rates. [13]

One may also combine BAT’s with hyperbaric oxygen treatment in wounds with local ischemia in turn improving the likelihood of BAT incorporation. [14] Furthermore, venous ulcerations in patients with edema may benefit from compression bandages in turn reducing healing times.

Clinical protocols incorporating the BRAIN principles will not only improve outcomes, but will also improve efficacy and patient satisfaction. No matter what your BAT of choice is, using the BRAIN principles to maximize the incorporation or transfer of the contents in the tissue to the wound will improve outcomes. [7] It has been evident in my patient population that the AmeriGel® gauze significantly helped to provide the ideal microcosm for the BAT after application. Reducing healing times will decrease wound infection rates and lowers the risk of amputation. When patients have faster healing wounds, the necessity for adjunctive diagnostic studies diminishes and patients may return more quickly to normal function thus reducing the costs associated with the increased number of supplies and physician office visits. [15]


This study was retrospective and conducted out of a single multi-office practice. Furthermore, this study did not ascertain the impact of age, length of time the ulcer was present, nor previous treatment modalities. Although this case series is small, the results suggest that this protocol may be beneficial in ulcers from multiple causes, including those of diabetic and venous origin. Future studies may determine efficacy of this protocol as compared to a placebo group with traditional application of the BAT alone. The rapid healing noted in this study can be attributed not only to the use of the BRAIN principles, but also to the meticulous wound bed preparation and proper offloading that took place in every case prior to and after the BAT application.


1. Kim PJ, Dybowski KS, Steinberg JS. A Closer Look at Bioengineered Alternative Tissues. Podiatry Today – ISSN: 1045-7860 – Volume 19 – Issue 7: Pages: 38 – 55, July 2006.
2. Pham HT, Rich J, Veves A, Using Living Skin Equivalents for Diabetic Foot Ulceration: Lower Extremity Wound 1(1); 27-32, 2002.
3. Falanga V, Sabolinski M. A bilayered living skin equivalent construct (Apligraf) accelerates complete closure of hard to heal venous ulcers. Wound Repair Regen 7:201-7, 1999.
4. Bello YM, Falabella AF, Eaglstein WH. Tissue-engineered skin, current status in wound healing. Am J. Clin Dermatol 2(5):303-313, 2001.
5. Claxton MJ, Armstrong DG, Boulton AJM. Healing the diabetic wound and keeping it healed: modalities for the early 21st century. Cur Diab Rep. 2(6):510-8, December 2002.
6. Lee KH. Tissue-engineered human skin substitutes; development and clinical application. Yonsei Medical Journal 41(6):774-779, 2000.
7. Moore, J. The BRAIN Principle: Managing Wounds After Application of Bioengineered Alternative Tissues to Maximize Incorporation and Wound Healing, doi: 10.3827/faoj.2008.0105.0003, The Foot & Ankle Journal, 1(5):3, 2008
8. Loots MA, Lamme EN, Zeegelaar J, et al. Differences in cellular infiltrate and extracellular matrix of chronic diabetic and venous ulcers versus acute wounds. J Invest Dermatol 111:850–7, 1998.
9. Dinh T, Pham H, Veves A. Emerging Treatments in Diabetic Wound Care. Wounds 14(1) 2-10, 2002.
10. Eisenbud D, Hunter H, Kessler L, et al. Hydrogel Wound Dressings: Where Do We Stand in 2003. Ostomy/Wound Management 49(10) 52-57, 2003
11. Akiyama, H., Kazuyasu, F., Yamasaki, O., Oono, T., Iwatsuki, K., Antibacterial action of several tannins against staphylococcus aureus, Journal of Antimicrobial Chemotherapy 48: 487-491, 2001.
12. Cowan, MM: Plant Products as Antimicrobial Agents; Clinical Microbiology Reviews, 12(4) 564-582, 1999.
13. Espensen EH, Nixon BP, Lavery LA, Armstrong, DG.  Use of subatmospheric (VAC) therapy to improve bioengineered tissue grafting in diabetic foot wounds. Journal of the American Podiatric Medical Association. 92(7): 395-401, 2002.
14. Hopf HW, Humphrey LM, Puzziferri N, et al. Adjuncts to preparing wounds for closure hyperbaric oxygen, growth factors, skin substitutes, negative pressure wound therapy (vacuum-assisted closure). Foot and Ankle Clinics. 6: 661-682, 2001.
15. Harold Brem, MD; Jeroen Balledux, MD et al. Healing of Diabetic Foot Ulcers and Pressure Ulcers With Human Skin Equivalent, A New Paradigm in Wound Healing, Arch Surg. 135:627-634, 2000.

Address correspondence to: Jonathan Moore, DPM, MS. Cumberland Foot & Ankle Center.
117 Tradepark Drive, Somerset, KY 42503

1Cumberland Foot & Ankle Center. 117 Tradepark Drive, Somerset, KY 42503.

© The Foot & Ankle Journal, 2008

The BRAIN Principle: Managing Wounds After Application of Bioengineered Alternative Tissues to Maximize Incorporation and Wound Healing

by Jonathan Moore, DPM, MS1

The Foot & Ankle Journal 1 (5): 3

The efficacy of bioengineered alternative tissue (BAT) for lower extremity ulcers (diabetic and non-diabetic) is well described in the literature. What is not present in the literature is a concise description of how to manage these fragile biological tissues after application. This paper introduces the BRAIN principle for adjuvant management of wounds after application of bioengineered alternative tissues. Based on the experience of the author, utilizing the principles found in the BRAIN protocol have not only demonstrated improved BAT incorporation rates, it also increased the rate of wound closure.

Key words: Diabetic wounds, bioengineered alternative tissues, wound healing

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.  It permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ©The Foot & Ankle Journal (www.faoj.org

Accepted: April 1, 2008
Published: May 1, 2008

ISSN 1941-6806
doi: 10.3827/faoj.2008.0105.0003

Bioengineered Alternative Tissues (BAT’s) have revolutionized the science of wound healing. These new technologies offer the wound care specialist an important tool in the battle to prevent nearly 90,000 amputations that occur annually among diabetic patients. [7] However, this technology is of little value when not used as a part of a comprehensive approach to wound healing. This includes assessing nutrition, metabolic status, vascular status, off loading options, and choosing the right wound healing product.

As new bioengeenered alternative tissue products enter the market it is important to consider patient expectations and treat the patient with the best product available for their specific wound. While there are procedures described for many of the better-known BAT’s on the market, they differ in many respects. The table in the study demonstrates the differing protocols for “after-care” following applications of these products. (Table 1)

Table 1 Application and Aftercare Instructions to Providers from the Manufacturer.

Choosing the right BAT along with the appropriate topical wound care agent is critical not only to improve healing times, but to also lower costs.

It has been estimated that 15 to 20 percent of individuals with diabetes will suffer from lower extremity ulceration during their lifetime. [8] Furthermore, half of the diabetic patients who have had a leg amputated will loose the other leg in three to five years. In 1997 it was estimated that total costs for both direct and indirect health care for the persons with diabetes was $98 billion. Of this total, direct medical costs including hospitalization, medical care, and dressing supplies, accounts for $44.1 billion. [9] What is more startling is the annual $5 billion dollar price tag estimated for the cost of dressings for these conditions. With the increased cost of wound care, the wound care specialist should consider using protocols that not only maximize wound healing, but also minimize the risk of BAT failure by providing the best tools to maintain the optimum environment for the wound.

While it is not the purpose of this paper to review every type of BAT on the market, it is vital to understand the characteristics of these products in order to understand how they work and how they should be adjunctively managed after application.

For purposes of defining terms, BAT’s are products that have been produced artificially or modified in some way that alters the biology and its interaction with the wound bed with the goal of creating an optimal environment to stimulate healing.

These tissues include both allograft, xenografts and manufactured/engineered biologic products like Apligraf® (Organogenesis, Inc., Canton, MA). The purpose of these tissues has been well established in the medical literature. However, the primary goal in using a BAT is to stimulate granulation of a chronic wound and augment the wound’s intrinsic healing pathway, thus creating a bridge to epithelialization of the wound.

The literature has well described the process of preparing the wound bed for application of a BAT. The TIME acronym as proposed by the International Wound Bed Preparation Advisory Board provides an exceptional framework for the physician to improve the opportunity for wounds to heal. The TIME principle in essence describes an approach to remove the barriers to the wound-healing process in order to optimize wound repair and healing. Removal of these barriers will not only help to establish a well-vascularized wound bed, but they will also be vital for the incorporation and success of a BAT. (Table 2). [10]

Table 2   International Wound Bed Preparation Advisory Board – TIME principles.

While the principles of TIME described above remains important a new set of principles are needed to assure the BAT has the best chance of incorporation and healing the wound in a timely manner.

Thus, the following acronym called BRAIN is proposed. (Table 3)

Table 3   The BRAIN principles to maximize BAT incorporation and wound healing.

The BRAIN Principle

B (Bioburden)

Despite having properly prepared the wound bed before application of the bioengineered tissue through debridement, among other modalities, maintenance of the bioburden after BAT application remains important. Non-cytotoxic antimicrobials should be considered to prevent colonization after application of bioengineered tissues.

Proper assessment to the needs of the wound is vital after application of the BAT in order to reduce the chances of infection. In the event of a clinical infection of a chronic wound, aggressive treatment is recommended to prevent limb loss. The following are recommendations that should be considered after application of a BAT for the prevention of infection:

1. Sharp debridement is the fundamental component in preparing the chronic wound for the BAT, whether it is an allograft or a bioengineered skin equivalent, like Apligraf®. Sharp debridement too early after application of the BAT may result in destruction of the bioengineered tissue or disruption of the materials the BAT was able to establish in the wound bed. Debridement post BAT application should only be considered if there is necrotic or infected tissue present.

2. Application of a topical antimicrobial agent for use on the wound bed prior to application of the BAT (at least 2 weeks prior), in order to decrease bacterial colonization, should be considered for both cellular engineered tissues and allografts. Use of a silver containing antimicrobial agent, as a part of wound bed preparation should not be a problem, as the silver will be inactivated by wound fluid among other wound components. Application of a topical antimicrobial agent post application of a BAT remains controversial

Living skin equivalents like Apligraf® should not be used in conjunction with any silver-based topical antimicrobial agent as these can be, at certain levels, cytotoxic to keratinocytes and fibroblasts.11 While there is debate about other types of topical agents used on or with a living skin equivalent like Apligraf®, I have used Bacitracin ointment as well as AmeriGel®

Hydrogel Saturated Gauze Dressing (Amerx Health Care Corporation, Clearwater, FL) pre and post application of Apligraf® pose no adverse clinical effects. Agents that are known to be cytotoxic to living skin equivalents include: Dakin’s solution, Mafenide Acetate, Scarlet Red Dressing, Tincoban, Zinc Sulfate, Povidone-iodine solution, Polymyxin/Nystatin and Chlorhexidine.

3. Care must be taken to control swelling and edema with careful compression over the BAT site taking care not to compromise circulation. Edema can significantly compromise wound healing and incorporation of the BAT.

4. Systemic antibiotics should be considered in the presence of malodorous drainage, friable necrotic tissue, increased levels of wound exudate, increasing pain, surrounding cellulitis, crepitus, necrosis and lymphadenopathy. Fever, chills, malaise, leukocytosis, and an elevated erythrocyte sedimentation rate are also common systemic manifestations of wound infection. Superficial contaminants are not always representative of the wound status, as healing wounds will have some contamination. Macerated tissue culture or curettage is a reliable way to determine the etiology of a serious wound infection. Infected wounds will typically respond to aggressive debridement with appropriate systemic antibiotic therapy. Indiscriminate use of oral antibiotics will not decrease infection rates, but can result in resistance. Gram-negative bacterial infections can be severe and need to be treated aggressively. [12]

R (Reduction of pressure and shear force)

In order for incorporation of the BAT to take place in the chronic wound, excess pressure, motion and shearing must be eliminated. Unless the bioengineered tissue maintains adherence to the wound bed with proper pressure redistribution, BAT incorporation will fail. The medical literature is replete with articles that stress the importance of offloading during wound healing. [13]

Although there are many devices on the market that can be employed to remove plantar pressure {Bledsoe® Walker (Bledsoe Brace Systems, Grand Prairie, TX), DH Walker® (Royce Medical, Inc., Camarillo, CA) or total contact casting}, care must further be taken when applying the BAT to the wound site.

Although most BAT manufacturers recommend some type of anchoring of the bioengineered tissue to the wound (i.e. sutures, staples, etc.), specific protocols are lacking. The following are recommendations to consider for the development of your protocols:

1. Determine the best and the most secure application method based upon the quality of the tissues and the location of the BAT. Plantar pressures will deteriorate the BAT unless properly offloaded and secured. With dorsal wounds, anything creating pressure or shear over the site will also result in the failure of the BAT.

2. Although suturing the BAT to the wound bed is ideal, in cases of severe tissue atrophy or poor skin perfusion, Steri-Strips™ (3M, St Paul, MN) should be considered to prevent worsening of the wound site.

3. If sutures or staples are employed, be careful to make sure the bioengineered tissue has been adequately fenestrated in order to prevent hematoma or seroma formation under the BAT.

4. Plantar ulcers MUST be offloaded in order for the BAT to incorporate. Ideally, no pressure should be applied to the wound site, if possible. Surgical shoes with a Velcro®(Velcro Industries B.V., Manchester, NH) latch should be considered for dorsal foot wounds in order to prevent rubbing or shearing forces.

5. Regular shoes, flip-flops or any like footwear are contraindicated after application of any BAT and should NOT be employed.

A (Adapting to the moisture needs of the wound and the bioengineered tissue.)

Any BAT must stay hydrated in order to achieve wound incorporation. Early desiccation of the wound bed and the surrounding tissues will ultimately lead to BAT failure and subsequent slower healing times. The concept of keeping wounds moist in order to accelerate wound healing has been known now for over 50 years. [14,15] Contrary to conventional wisdom, keeping the wound site and the BAT moist does not increase the risk of infection. In fact, a moist wound environment has been shown to improve wound healing by up to 50% compared with exposure to air. [16]

Many factors will determine the amount of wound fluid present in the wound bed. Venous ulcers, for instance, are more likely to produce more moisture than an ulcer on the top of the foot. Close assessment of the moisture balance in the wound is critical for the success of the BAT. Fluid from chronic wounds will block cellular proliferation and angiogenesis, and will ultimately impair wound healing through the build up of excessive amounts of matrix metalloproteinases (MMPs) that break down critical matrix proteins. [17]

The dressing choice after the application of the BAT to the wound site is vital in order to properly adapt to the moisture needs of the wound. Here are some considerations:

1. Upon review of many bioengineered tissue dressing protocols, as provided by the manufacturers of the top BAT’s on the market, regular gauze is recommended as a secondary dressing in nearly all. (Table 1) Although the purpose of the gauze is understood to provide some level of absorption of drainage from the wound, this concept is not ideal for several reasons. No matter how much hydrogel or mineral oil you use under a regular piece of dry gauze, most of this will be absorbed by the gauze and thus provide minimal moisture to the wound bed over time.

Regular gauze alone, even with a nonadherent dressing of some sort, cannot provide consistent and long lasting moisture to the wound site. Hydrogels and hydrogel impregnated gauzes formulated with substrates allowing for longer and controlled moisture balance reduces the incidence of adhesion to the BAT and wound site. Saline or glycerin-based hydrogels or hydrogel impregnated gauzes frequently result in premature desiccation and should be avoided.

2. In those cases where excessive wound fluid is evident, more frequent dressing changes is recommended.

3. In cases of severe exudate and draining from the wound site, the presence of infection needs to be addressed and antibiotics should be prescribed.

4. The ideal wound dressing will remove the excess amounts of wound exudates while retaining a moist environment that accelerates wound healing.

Keep in mind that healing wounds are always characterized by high mitogenic activity, low inflammatory cytokines (less chronic wound fluid), low proteases, mitotically competent cells and a moist environment.

I ( Incorporation and Identification)

Successful incorporation of a BAT hinges upon the molecular environment of the wound. Incorporation of the acellular BAT into the wound bed through a collagen matrix allows for the recruitment of cells into the wound and facilitates the induction and expression of growth factors and cytokines necessary for wound healing. The balance between collagen degradation and synthesis can be disrupted by disease states like diabetes. This can result in defective collagen metabolism and disrupted wound healing.

In contrast, cellular BAT’s are designed to accelerate tissue regeneration by stimulating the recipient’s own wound bed derived skin cells. [18,19] Some authors have called the BAT an interactive “drug” delivery system by the transfer of MMPs and cytokines from the BAT into the wound. [20] Acellular BAT’s work by effectively providing a cover for the wound that prohibits desiccation and fluid loss within the wound, thus decreasing the bacterial burden and promoting angiogenesis and allowing vascular ingrowth into the dermal layer of the allograft.

Identification and correction of factors that can cause tissue damage is essential after application of a BAT. Keep in mind that cellular bioengineered alternative tissues work by biochemically balancing the wound environment to promote tissue regeneration. This provides the “primordial soup” of mediators and growth factors. [21]

Among the many things that can impair wound healing (systemic steroids, non-steroidal anti-inflammatories, immunosuppressive drugs), several other factors must be recognized:

1. Localized edema from venous insufficiency or lymphedema must be addressed before and after application of a BAT. Compression therapy or a referral to a certified lymphedema specialist should be considered.

2. Low albumin can have a significant impact on wound healing. A deficiency in serum albumin, which accounts for more than 50% of total serum proteins, impairs the inflammatory and proliferative stages of wound healing while also decreasing wound perfusion.22 A dietary or nutritional consult should be ordered to maximize the body’s own potential to heal.

3. Autonomic Neuropathy resulting in over drying of the wound and surrounding tissues will impair wound healing in many ways. Desiccation within the wound site will slow epithelial cell migration and thus prevent the incorporation of the BAT.

4. Infection within the wound site can present many challenges to the incorporation of the BAT. Infection must be treated without delay through either debridement, antibiotics, wound cleansing, or wound disinfection.

5. Hyperglycemia must be addressed in order to have successful incorporation of the BAT. Although the wound care specialist may not be able to directly influence this factor, all efforts need to be made to communicate with the primary care provider and patient to gain better control the patient’s blood sugar. Behavior modification regarding diet and exercise is always an immense challenge in the diabetic population. [23]

N ( Nonadherent Dressing)

It has been said that the choice of the wound dressing at one stage of the wound may well influence subsequent events in the later phases of healing. [24] In reviewing the protocols set forth by most BAT manufacturers, the one common denominator among all of them is the recommendation of a “nonadherent dressing” as the primary dressing to be used over the bioengineered tissue. (Table 1)

While the goal of the nonadherent dressing is to prevent trauma or adhesion of the secondary dressing to the BAT (or underlying tissues), few of these products possess the characteristics ideal for covering a bioengineered tissue. While it is possible for several different types of dressings to be employed over the BAT at once (i.e. petrolatum impregnated gauze, antibiotic cream, hydrogel, mineral oil followed by an absorptive 4” X 4” pad or a foam), this is impractical and expensive.

Ideal Characteristics of the Primary Dressing for Coverage over a BAT:

1. Nonadhesive
2. Antimicrobial
3. Ability to absorb exudate
4. Maintains moisture on the BAT and within the wound site
5. Non-cytotoxic
6. Cost-effective

Of the myriad of different dressing options available that meet some of the criteria mentioned above, the AmeriGel® Hydrogel Saturated Gauze Dressing is an excellent option that meets most if not all of the characteristics above.

Case Example using the BRAIN Principal

A 47 year-old diabetic patient with profound peripheral neuropathy developed a blister on the plantar aspect of her right heel that became recalcitrant to conservative treatment. The patient’s wound was debrided weekly and had Promogran™ (Johnson & Johnson Wound Management, Somerville, NJ) applied to the site until the wound developed a healthy granular base. Apligraf® was chosen to close the wound, secured in place by Steri-Strips™. AmeriGel® Hydrogel Saturated Gauze Dressing covered the BAT to provide an antimicrobial barrier. A dry sterile secondary dressing was then applied. The bioburden of the BRAIN principle had been accomplished. (Fig. 1)

Figure 1  The Bioburden of the wound has been addressed with debridement and diligent local wound care.

To achieve the reduction of pressure and shear force, a Bledsoe® boot was utilized along with a wheel chair. Due to the patient’s severe neuropathy, as well as other balance concerns, the patient could not use crutches. The primary and secondary dressings remained dry and intact for one week. (Fig. 2)

Figure 2  Reduction of pressure and shear force is essential for incorporation of the BAT.

Once the AmeriGel® Hydrogel Saturated Gauze Dressing was removed, the absorptive capability was evident as well as its ability to maintain a moist wound environment. (Fig. 3) This demonstrates adapting to the moisture needs of the BAT and of the wound.

Figure 3  Adapting to the moisture needs of the wound.  Here, a healthy moisture balance has been achieved using AmeriGel® Hydrogel Saturated Gauze Dressing after BAT application.

The patient returned at two weeks and Incorporation was achieved. The wound had already started to reduce in size and was considered to be a healthy granulating wound. There was no evidence of bleeding or absence of tissue caused by traumatic dressing changes. (Fig. 4)

Figure 4  Incorporation of the Apligraf®.  Reduction of wound size is already appreciated.

At 4 weeks and 4 days, after daily applications of the AmeriGel® Hydrogel Saturated Gauze Dressing and dry sterile gauze as the secondary dressing, the wound was healed.

The nonadherent secondary dressing played a significant role in healing this wound quickly and without the need for subsequent applications of the BAT. (Fig. 5)

Figure 5  Nonadherence of the surrounding secondary dressings will help ensure the viability of the BAT.  Using the AmeriGel® Hydrogel Saturated Gauze Dressing as a secondary dressing provides a non adherent and antimicrobial barrier to facilitate rapid wound healing.


Effective management of lower extremity ulcerations using bioengineered alternative tissues requires a multidisciplinary approach, patient involvement and the right use of the proper adjunctive tools available to the wound care specialist.

Diabetic foot ulceration is a limb and life threatening condition that requires the establishment of sound, evidence-based protocols. It is the hope of the author that protocols be established in every wound care clinic that are based upon patient outcomes, cost and ease of use for the wound care specialist and the patient.

A protocol as described above certainly may be modified depending on many factors that may or may not be present in the wound, however the core principles as presented in the acronym BRAIN should provide a road map to maximizing the effectiveness of bioengineered tissues before, during and after BAT application.


1. Kim PJ, Dybowski KS, Steinberg JS. A Closer Look at Bioengineered Alternative Tissues. Podiatry Today – ISSN: 1045-7860 – Volume 19 – Issue 7 – Pages: 38 – 55, July 2006.
2. Pham HT, Rich J, Veves A, Using Living Skin Equivalents for Diabetic Foot Ulceration: Lower Extremity Wound 1(1);27-32, 2002.
3. Falanga V, Sabolinski M. A bilayered living skin equivalent construct (Apligraf) accelerates complete closure of hard to heal venous ulcers. Wound Repair Regen 7:201-7, 1999.
4. Bello YM, Falabella AF, Eaglstein WH. Tissue-engineered skin, current status in wound healing. Am J. Clin Dermatol 2(5):303-313, 2001.
5. Claxton MJ, Armstrong DG, Boulton AJM. Healing the diabetic wound and keeping it healed: modalities for the early 21st century. Cur Diab Rep. 2(6):510-8, Dec 2002.
6. Lee KH. Tissue-engineered human skin substitutes; development and clinical application. Yonsei Medical Journal 41(6):774-779, 2000.
7. Reiber GE: Epidemiology and health care costs of diabetic foot problems. From: The Diabetic Foot: Medical and Surgical Management, edited by Veves A, Giurini JM, LoGerfo FW, Humana Press, Totowa NJ, 2002
8. Reiber GE, Boyko EJ, Smith DG. Lower extremity foot ulcers and amputations in diabetes. In: Diabetes in America, Second Edition. Washington, DC: National Diabetes Data Group, National Institutes of Health, 409-28, 1995.
9. American Diabetes Association. Economic consequences of diabetes mellitus in the U.S.in 1997. Diabetes Care 21:296–309, 1998.
10. Sibbald RG, Williamson D, Orsted HL, Campbell K, Keast D, Krasner D, Sibbald D, Preparing the Wound Bed-Debridement, Bacterial Balance and Moisture Balance. Ostomy Wound Mgt 46: 14-35, 2000.
11. Poon, VKM, Burd A. In vitro cytoxicity of silver: Implications for clinical Wound Care. Burns 30: 140-147, 2004.
12. Edmonds, ME, Foster AM, Sanders L A. Practical Manual of Diabetic Footcare. Oxford: Blackwell Publishing, 2004.
13. Armstrong, DG, Ngugen, HC, Lavery LA, et al. Offloading the diabetic foot wound: a randomized clinical trial. Diabetes Care 24:1019-1022, 2001.
14. Winter GD: Formation of scab and rate of epithelialization of superficial wounds in the skin of the young domestic pig. Nature 193:293-294, 1962.
15. Haimowitz JE, Margolis DJ: Moist wound healing, in Krasner D, Kane D (eds): Chronic Wound Care: A Clinical Source Book for Healthcare Professionals. Wayne, PA, Health Management Publications, 49-55, 1997.
16. Geronemus RG, Robin P. The effect of two new dressings on epidermal wound healing. J Derm Surg Oncol 8:850-2, 1982.
17. Bucalo B, Eaglstein WH, Falanga V. Inhibition of cell proliferation by chronic wound fluid. Wound Rep Reg 1:181-6, 1993.
18. Coulomb B, Dubertret L. Skin cell culture and wound healing. Wound Repair Regen 10:109-12, 2002.
19. Rosales MA, Bruntz M, Armstrong DG. Gamma-irradiated human skin allograft; a potential treatment modality for lower extremity ulcers. Int. Wound J 1:201-206, 2004.
20. Shen JT, Falanga V. Innovative therapies in wound healing. J Cutan Med Surg 7(3):217-24, May-Jun 2003.
21. Eisenbud D. Huang, NF, Luke S. Silberklang M. Skin Substitutes and Wound Healing: Current Status and Challenges. Wounds 16(1): 2-17, 2004.
22. Sussman C, Bates-Jensen B. Wound healing biology and chronic wound healing. In: Wound Care- A Collaborative Practice Manual for Physical Therapists and Nurses. Gaithersburg, Md.: Aspen Publication 49–82, 1998.
23. Shultz GS, Sibbald GR, Falanga V, et al. Wound bed preparation: a systemic approach to wound management: Wound Rep Reg 11:1-28, 2003.
24. Kerstein MD. The scientific basis of healing. Adv Wound Care 10:30-6, 1997.

Address correspondence to: Jonathan Moore, DPM, MS, Cumberland Foot & Ankle Center. 117 Tradepark Drive, Somerset, KY 42503

1Cumberland Foot & Ankle Center. 117 Tradepark Drive, Somerset, KY 42503.

© The Foot & Ankle Journal, 2008