Artificial skin, split-thickness autograft and cultured autologous keratinocytes combined to treat a severe burn injury of 93% of TBSA

Tissue engineering of skin

The engineering of skin substitutes and their application on human patients has become a reality. However, cell biologists, biochemists, technical engineers, and surgeons are still struggling with the generation of complex skin substitutes that can readily be transplanted in large quantities, possibly in only one surgical intervention and without significant scarring. Constructing a dermo-epidermal substitute that rapidly vascularizes, optimally supports a stratifying epidermal graft on a biodegradable matrix, and that can be conveniently handled by the surgeon, is now the ambitious goal. After all, this goal has to be reached coping with strict safety requirements and the harsh rules of the economic market.

[Cultured keratinocyte cells from foreskin and future application for burns in children]

PURPOSE OF THE STUDY

We tested in vitro the keratinocytes capacity for division and differentiation. The donor site was the human foreskin.

PATIENTS AND METHODS

For 12 months, we harvested 18 foreskins after circumcision. The middle age of the operated children was four years. The keratinocytes were isolated after double enzymatic digestion (thermolysin and trypsin, respectively). After filtration and centrifugation we put the keratinocytes in culture. In parallel, the keratinocytes were cultivated on the surface of collagen lattices. The keratinocytes were cultured in submerged condition for two days and then in an air-liquid interface condition for further differentiation. After nine days of culture, a histological examination and immunostain were used. An immunohistologic analysis made it possible to highlight the markers characteristic of epidermal skin differentiation.

RESULTS

We obtained an average of 8.8 10(6) cells per foreskin. After seven days of culture, we obtained on average 23.7 10(6) cells by culture. In contact with the collagen lattices, we obtained an epidermal skin and we highlighted the markers of keratinocytes differentiation as well as the markers of the dermoepidermic junction.

CONCLUSION

The keratinocytes resulting from foreskin have a high capacity of division. These cells can divide a long time before differentiation. The observations enable us to propose with our patients the keratinocytes from foreskin for wound healing especially for burns in children.

[The use of Integra "artificial skin, dermal regeneration template" and the reverse radial forearm fasciocutaneous flap in the primary reconstruction of a septic hand injury]

Reconstruction was performed on the back of a hand following a poorly managed septic hand injury leading to skin and extensor apparatus necrosis using a reverse radial forearm fasciocutaneous flap and a bilayer artificial skin substitute.

CASE DEMONSTRATION

Authors report on the first Hungarian case using Integra dermal regeneration template. Integra was placed on the back of the hand on an area left uncovered by the reverse radial forearm fasciocutaneous flap as well as on the flap harvest area. After biointegration of the regeneration template, the outer silicon layer was removed and a split thickness skin graft was applied.

CONCLUSION

The take-rate on the donor area was 100% for Integra and 99% for the skin graft, and 90% for both Integra and the skin graft on the back of the hand, providing a good functional and aesthetic result.

[Skin replacement with biological and biosynthetic materials following burn injury]

Autotransplantation is currently regarded as the optimal skin replacement method, sufficient donor site, however, is often not available in extensively burned patients. Intensive research and development of skin replacement products is conducted worldwide in order to decrease the size of the required donor site. Short- and long-term wound coverage is made possible by temporary synthetic and non-synthetic skin substitutes. Autografts and cultured epithelial autografts are used for permanent skin substitution. Until this is possible, the barrier function of the skin is provided by bio-engineered temporary skin substitutes. Some products and methods are currently available in Hungary, while others are still in the introductory phase. In order to provide an overview, authors summarize the skin replacement methods and compare the different skin replacement products used worldwide from the perspective of the burn surgeon. The use of new methods to be introduced in the near future needs to be rationalized due to financial considerations.

Decellularized dermis in combination with cultivated keratinocytes in a short- and long-term animal experimental investigation

Decellularized human dermis as a potentially ideal scaffold for dermal substitution in severe burns was examined in a two-staged animal experiment. In an initial step, an in vitro generated composite graft consisting of human keratinocytes and decellularized dermis (AlloDerm) was transplanted onto nude mice in a short-term trial (n = 20, 14 days). Subsequently, a combined one-step grafting of full thickness wounds with both decellularized dermis (in part preincubated with fibroblasts) and cultivated autologous keratinocytes as a cell suspension in fibrin glue was done in a long-term porcine animal model (n = 10, 6 months). In both series, macroscopic wound healing was evaluated by planimetry. Histological investigations included morphological as well as immunohistochemical parameters. The short-term study showed both successful integration of the composite grafts and reduction of wound contraction compared with the control group (epithelial grafts). The long-term porcine study displayed reduced myofibroblast formation and contraction in the wounds that had been treated with fibroblast-preincubated dermis. After 4 weeks, a decline of the structural integrity of the dermal matrix could be noticed. The utility of decellularized dermis as template for both dermal reconstitution and keratinocyte delivery vehicle was shown. The closure of full thickness wounds by a single-step combination of an autologous keratinocyte fibrin sealant suspension and acellular dermis in a pig animal model could be shown. Incorporation of fibroblasts led to reduced wound contraction but could not prevent the loss of dermal integrity. The engineered 'skin' remained viable and stable over a period of 6 months.

Artificial skin

Replacement of skin has been one of the most challenging aims for surgeons ever since the introduction of skin grafts in 1871. It took more than one century until the breakthrough of Rheinwald and Green in 1975 that opened new possibilities of skin replacement. The combination of cell culture and polymer chemistry finally led to the field of tissue engineering. Many researchers all over the world have been fascinated by the chance of creating a skin-like substitute ex vivo without any further harm to the patients, especially those with massive burns. Many different approaches to create new substitutes and further improvements in genetical and stem cell research led to today's skin equivalents. But still, the "gold standard" for wound coverage is the autologous split-thickness skin graft. Future research will aim at originating biologically and physiologically equal skin substitutes for the treatment of severe burns and chronic ulcers.

Suprathel®—An innovative, resorbable skin substitute for the treatment of burn victims

Autologous split skin grafts are the most reliable method for closing third degree burns. Under this scheme, donor sites as well as second degree burns under conservative treatment, however, would benefit from rapid wound closure. For this treatment, biological as well as synthetic materials are available. For the improvement of these materials, primary goals are pain reduction and easy handling in the absence of biological risk. From a synthetic copolymer mainly based on DL-lactic acid a new skin substitute was developed, marketed as Suprathel. Within the scope of a bicentric study Suprathel was compared versus paraffin gauze intraindividually applied on split skin donor sites. Wound pain was measured on the Visual Pain Analog Scale over a period of 10 days as the critical criterion. Accordingly Suprathel versus Omiderm were compared on second degree burns (degree 2a, partial thickness burns). In both study parts, Suprathel significantly reduced pain. Its easy handling was superior compared to other materials. The Suprathel membrane adhered rapidly to the wound thus protecting against infections and promoting wound healing. No allergic reactions were observed. The ability of the material to resorb ensured pain-free removal after complete healing of the wound.

Seven years' experience with Integra as a reconstructive tool

The bilayered dermal substitute Integra (Integra Life Sciences Corp., Plainsboro, NJ) was developed and has been widely used as primary coverage for excised acute burns. Our take has been slightly different, finding it most useful in the management of complex soft-tissue loss and threatened extremities as the result of tendon, joint, or bone exposure. Often tasked to fill significant volume loss, we have become adept at stacked multiple-layer applications. Creative use of this material has resulted in unexpected successes with distal limb salvage; the technique takes its place beside adjacent tissue transfer, composite flaps, and vascular pedicle flaps in our burn reconstructive practice. A prospective registry (44 patients) has been kept during the past 7 years that catalogs wounds with complex soft-tissue loss treated with Integra grafts. Many of these patients were at risk of extremity loss because of exposed tendons, joints, or bone. Integra was applied after 1:1 meshing. With profound soft-tissue defects, multiple layers of Integra were serially applied 1 to 2 weeks apart for reconstitution of soft-tissue contours. Local Integra graft infections were managed by silicone unroofing followed by topical sulfamylon liquid dressings. Wounds addressed included fourth-degree burns, necrotizing fasciitis, pit-viper envenomations, and total abdominal wall avulsion in one patient after being run over by a bus. Patients generally were free of pain from their wounds during the maturation phase of the Integra neodermis. Restoration of tissue contour was significantly better when using multiple layers for deep defects. Second and third layers of Integra were successfully applied after an abbreviated first graft maturation period of 7 days. Epithelial autografts on multilayer Integra applications frequently "ghosted"; they would auto-digest to dispersed cells followed subsequently by the reappearance of a confluent epithelial layer. Final grafted skin morphology over palmar and plantar surfaces assumed the type and fingerprint pattern of the original tissues. Infections were readily visible. Early recognition kept them to easily treated circumscribed areas, which did not jeopardize the entire wound. Lengths of stay were long (range, 2-246 days) but not significantly greater than with traditional techniques. The specific reconstructive use of Integra permitted unexpected salvage of several threatened extremities by protecting exposed tendons, bones and joints. Long-term histologic examination revealed unexpected persistence of Integra collagen. Large volume loss wounds benefited from the ability to fill voids with multilayered applications.

The effect of gelatin–chondroitin sulfate–hyaluronic acid skin substitute on wound healing in SCID mice

Tissue-engineered skin substitutes provided a feasibility to overcome the shortage of skin autograft by culturing keratinocytes and dermal fibroblasts in vitro. In this study, we applied bi-layer gelatin-chondrointin-6-sulfate-hyaluronic acid (gelatin-C6S-HA) biomatrices onto the severe combined immunodeficiency (SCID) mice to evaluate its effect on promoting wound healing. Human foreskin keratinocytes and dermal fibroblasts were cultured with reconstructed skin equivalent (rSE) for 7 days. The rSE was then grafted to the dorsum of SCID mice to evaluate its biocompatibility by histologic and immunohistochemistry analysis. The results showed that human epidermis were well-developed with the expression of differentiated markers and basement membrane-specific proteins at 4 weeks. After implantation, the percentages of skin graft take were satisfactory, while cell-seeded group was better than non-cell-seeded one. The basement membrane proteins including laminin, type IV collagen, type VII collagen, integrin alpha6, and integrin beta4 were all detected at the dermal-epidermal junction, which showed a continuous structure in the 4 weeks after grafting. This bi-layer gelatin-C6S-HA skin substitute not only has positive effect on promoting wound healing, but also has high rate of graft take. This rSE would have the potential to be applied on the extensively and deeply burned patients who suffer from severe skin defect in the near future.

High yields of autologous living dermal equivalents using porcine gelatin microbeads as microcarriers for autologous fibroblasts

Permanent skin replacement requires a dermal component to ensure adequate long-term graft stability and to prevent wound contraction. This study was to construct a bioreactor microcarrier cell culture system (Bio-MCCS) to produce autologous living dermal equivalents on a large scale. Autologous fibroblasts were isolated from split-thickness skin biopsy from a leg ulcer patient, inoculated onto macroporous porcine gelatin microbeads, and incubated in a bioreactor (Cellspin) in serum-free fibroblast growth medium or in DMEM medium containing 10% fetal calf serum (FCS). Fibroblasts rapidly adhered to and actively proliferated on the microbeads in the bioreactor in both serum-free and serum-containing medium. MTT assay showed the number of fibroblasts on the microbeads reached up to 5.3- or 4.0-fold the cells seeded in DMEM medium containing 10% FCS or serum-free medium, respectively. When removed from Bio-MCCS and cultured under static conditions, fibroblasts were able to leave the microbeads and proliferate to confluence on the bottom of tissue culture flasks. When stored at room temperature in DMEM containing 10% FBS, fibroblast cultured on the microbeads retained highest viabilities for at least 3 weeks, up to 82% of originals. This Bio-MCCS using porcine gelatin microbeads as carriers for fibroblasts offers a new option of mass production of autologous living dermal equivalents.

Skin graft fixation by slow clotting fibrin sealant applied as a thin layer

Human fibrin sealant (FS) has been proven effective for skin grafting after severe burn, however no systematic evaluation of application conditions has been performed so far. In order to find the optimal FS amount for fixation of skin grafts to deep defects, we created four full thickness wounds (8 cmx4 cm) on the dorsum of six male pigs. Wounds were covered with unmeshed split thickness skin grafts and fixed either with a thin layer (0.05 ml/cm2) or a thick layer (0.15 ml/cm2) of fibrin sealant (FS) without additional sutures. Sutures served as controls. FS was used as a slow clotting spray (4-5 IUthrombin/ml). Outcome measurements revealed that hematoma formation (day of surgery) was more extensive and occurred more frequently in the suture group as compared to FS 0.05 ml/cm2 (p<0.05). Areas of graft dislocation tended to be larger in the suture group versus the FS 0.05 ml/cm2. The FS 0.05 ml/cm2 graft take on day 5 appeared to be enhanced in comparison to the suture group. Excellent outcome was notable on the final observation day (day 21) in the FS 0.05 ml/cm2 group with a take of 99.7% (IQR 96.1-100%). Corresponding values in the FS 0.15 ml/cm2 group were 96.9% (IQR 92.2-99%) and 95.9% (IQR 93.2-98%) in the suture group. The results indicate, that the usage of a sprayed thin FS layer (0.05 ml/cm2) in a slow clotting rate (4-5 IUthrombin/ml) is an appropriate fixation method in split thickness skin transplantation.

The role of skin substitutes in the treatment of burn injuries

Extensive burn wounds are difficult to manage and repair. Several engineered skin substitutes have been developed to aid in this process. These substitutes are designed with particular objectives in mind which dictate the circumstances under which they can, and should, be employed to promote healing or prepare the burn wound for final closure with autograft. This article discusses some of the rationale behind the use of skin substitutes and reviews some of the substitutes in use at the present time. Current perspectives suggest that skin substitute use is still in its infancy and that there is some way to go before their role in clinical practice becomes clear. Nevertheless the prospect of being able to supply new wound repair components and to influence the healing process to modify outcome and improve the quality of the healed burn wound will ensure a continuing high degree of interest in these potentially useful and beneficial medical devices.

Artificial Dermis as an Alternative for Coverage of Complex Scalp Defects following Excision of Malignant Tumors

BACKGROUND

Artificial dermis has been used successfully for coverage of full-thickness wounds with a well-vascularized surgical bed. However, the use of artificial dermis in the reconstruction of partial- and full-thickness scalp defects has not been well documented.

METHODS

Seven patients (six men and one woman; mean age, 70 +/- 14 years) with partial-thickness (three patients) and full-thickness (four patients) soft-tissue defects of the scalp (mean defect area, 97 +/- 58 cm) following resection of recurrent malignant tumors and/or previous failed reconstructions underwent staged scalp reconstruction with a bilaminate skin substitute (Integra). After adequate debridement of scalp wounds, including burring the outer table of the calvaria down to bleeding bone for full-thickness defects, Integra was scored and applied unexpanded. A split-thickness skin graft (0.011 +/- 0.0 inch in thickness) was placed on the operative site at postoperative day 36 +/- 15 after removal of the silicone layer of the artificial dermis. Two patients required repeated applications of artificial dermis to compensate for contour deficits before skin grafting.

RESULTS

Clinically, all reconstructed areas showed well-vascularized neodermis before skin grafting. There was a 100 percent take of the skin grafts, with no infections or other complications noted. All reconstructive procedures were performed in less than 3 hours of combined operative time, with the last stage performed on an outpatient basis.

CONCLUSIONS

Artificial dermis can be used successfully for reconstruction of complex scalp defects following oncologic resection, offering minimal donor-site morbidity, expedient operative time, and when needed, temporary quality closure until final pathologic results are known. Integra skin may offer another option for definitive management of extensive full-thickness scalp defects.

An Improved Organ Culture for Regeneration of Pure Autologous Keratinocytes from Small Split-Thickness Skin Specimens

BACKGROUND

Failure of autologous keratinocyte culture from small split-thickness skin specimens or contamination of the keratinocyte culture by melanocytes represents practical problems in basic medical research and clinical studies.

PURPOSE

To establish a simple and reliable method of harvesting pure autologous keratinocytes from a small split-thickness skin specimen.

METHODS

Split-thickness (0.3 mm) skin explants (1 x 2 mm) were firstly cultured in DMEM containing 10% FCS till formation of keratinocyte strips, then cultured in serum-free keratinocyte growth medium or cocultured with lethally irradiated 3T3 fibroblasts (J2) in a mixture of DMEM and Ham's F12 (DF) medium.

RESULTS

Pure autologous keratinocyte culture is easily and reliably established by this organ culture technique.

CONCLUSION

Culturing of skin explants in serum-free keratinocyte growth medium or coculturing of the skin explants with lethally irradiated 3T3 cells in DF medium is proved to be a useful, simple and reliable method of harvesting pure autologous keratinocytes from a small split-thickness skin biopsy.

Combined use of a collagen-based dermal substitute and a fibrin-based cultured epithelium: a step toward a total skin replacement for acute wounds

Integra, a dermal replacement, is used as an immediate and temporary coverage for acute wounds, after which, autograft is used to reconstitute permanently the epidermal coverage. The fibrin sheet-cultured epithelium autograft (FS-CEA) could provide an effective alternative to the surgical procedure. To evaluate this hypothesis, we compared the association of Integra/FS-CE to Integra/control-cultured epithelium (control-CE). Their respective abilities: (1) to produce dermal-epidermal construct in vitro; (2) to generate skin replacement when grafted onto athymic mice were studied. We have shown that: (1) 83% of the FS-CE attached to the artificial dermis in vitro compared to only 33% for control-CE; (2) retraction of the grafted area was significantly lower 2 weeks after grafted with FS-CE than with the control-CE (P < 0.05); (3) 83% of the mice grafted with FS-CE showed the presence of a differentiated human epidermis 21 days after grafting, while such an epidermis was absent in all the animals of the control-CE group. We found that the use of FS-CE greatly improved adhesion, development of the epithelium and graft take onto the artificial dermis. We believe this technology should significantly improve the performance of dermal-epidermal skin replacement for acute wounds.

Update on the use of collagen/glycosaminoglycate skin substitute-six years of experiences with artificial skin in 15 German burn centers

The clinical use of an artificial skin substitute (Integra) has been celebrated enthusiastically as an improvement in burn therapy over a period of more than 10 years. Many case-reports have shown the positive effects of the treatment with Integra as a skin substitute. In this study we examine the alterations of Integra-usage in Germany. Fifteen German burn centres have been interviewed respectively over a time period of 6 years with interviews in the years 1999, 2001, and 2003. The goal of this study is to focus on the problems associated with the use of artificial skin and to create a manual for Integra-therapy including indication, pre-, intra-, and postoperative treatment. Since the first Integra Users seminar in Germany in 1999 repeated interviews have been conducted with fifteen German burn centres. The collected results of the last 6 years were evaluated. These results show a change in the indication for the therapy with artificial skin towards extensive full thickness burned patients and as extended indication especially for posttraumatic reconstruction. This article gives our guidelines for the usage and handling of Integra and shows that Integra is an important reconstructive dermal substitute for the severely burned or posttraumatic patient if handled by a skilled surgeon in a correct way.

A review of keratinocyte delivery to the wound bed

Over the last 20 years, confluent sheets of cultured epithelial autograft have been used for patients with major burns. Problems with the lack of "take" and long-term durability, as well as the time delay to produce such grafts, have led to the development of delivery systems to transfer keratinocytes to the wound bed. This review article describes the problems of using cultured epithelial autograft and the advantages of using preconfluent keratinocytes. Despite the numerous delivery systems that have been reported, most studies are limited to animal wound bed models. There are a few small clinical studies that have demonstrated enhanced healing using mainly subjective methods. There is a need for controlled, randomized clinical trials to prove the efficacy of keratinocyte delivery systems. Proposals for the use of this technology are made.

Development of new reconstructive techniques: use of Integra in combination with fibrin glue and negative-pressure therapy for reconstruction of acute and chronic wounds

Large wounds resulting from severe injuries are generally treated with extended reconstructive operations (e.g., free flaps), which are accompanied by long hospitalizations and risks of infection, thrombosis, and flap loss. Integra is a collagen template that can be used for reconstruction of defects. The take rate and the rate of infection are essential for the successful use of Integra (Johnson and Johnson, Hamburg, Germany). Whether the take rate and integration of Integra could be improved with the use of fibrin glue and negative-pressure therapy was assessed. Between January of 2002 and December of 2002, patients with large defects who underwent Integra grafting for reconstruction were randomly divided into groups receiving either a new treatment with fibrin glue-anchored Integra and postoperative negative-pressure therapy or conventional treatment. Demographic features, cause of the wound, location of the wound, take rate, complications of Integra coverage, time from Integra coverage to skin transplantation, and functional and aesthetic results were assessed. Twelve patients (with similar group distributions with respect to sex, age, and location and cause of the injury) were included in the study. The take rate was 78 +/- 8 percent in the conventional treatment group and 98 +/- 2 percent in the fibrin/negative-pressure therapy group (p < 0.003). The mean period from Integra coverage to skin transplantation was 24 +/- 3 days in the conventional treatment group but only 10 +/- 1 days in the fibrin/negative-pressure therapy group (p < 0.002). The decrease in the interval between coverage with Integra and skin transplantation resulted in shorter hospital stays. The use of fibrin glue and negative-pressure therapy in combination with Integra could shorten the period from coverage to integration, which would be beneficial in terms of decreased risks of infection, thrombosis, and catabolism. Therefore, it is suggested that Integra be used in combination with fibrin glue and negative-pressure therapy to improve clinical outcomes and shorten hospital stays, with decreased risks of accompanying complications.

[Skin tissue engineering]

Cultivated epithelial autografts as multilayered, thin sheets represent a common standard in clinically applied tissue engineering substitutes, outnumbering all experimental alternatives. However, the unsatisfying short- and long-term results concerning mechanical stability and scarring require alternatives. The cultivation and transplantation of cultured autologous keratinocytes as a single cell suspension in a fibrin matrix, combined with allogenic skin grafting, has been investigated extensively in athymic nude mice. Wounds can be reliably reepithelialized after a cultivation period of only 14 days. Moreover, the successful combination of keratinocyte fibrin suspension and acellular dermis in an attempt to regenerate full thickness skin defects in a pig model has been demonstrated. The usefulness of subconfluently cultured keratinocytes-which can be harvested very early and are easy to handle-is enhanced by cotransplantation with decellularized dermis.

Skin tissue engineering

The coverage of extensive wounds with viable autologous keratinocytes remains the only option of treatment if autologous donor skin is not obtainable. There is evidence that proliferating keratinocytes, as suspended cells or as a single layer, are adequate for wound closure. Understanding keratinocyte-matrix interactions not only allows us to influence keratinocyte outgrowth, adhesion, and migration, but may also guide us to modify matrix molecules for enhancing keratinocyte take. Further approaches may include the generation of genetically manipulated keratinocytes, which allow the use of an off-the-shelf epidermal replacement. As surgeons, our goal is to help burn patients with the best quality of skin in the shortest time possible. As tissue engineers, we have not achieved the goal of a universal skin product. By continually reviewing the options and using them, we can at least use the proper material in the adequate situation. Because of the limited resources, the need for comparisons of clinical effectiveness and cost are ever more important. As anatomy and physiology of engineered skin substitutes improve, they will become more similar to native skin autografts. Improvement of skin substitutes will result from inclusion of additional cell types (eg, melanocytes) and from modifications of culture media and scaffolds. Skin-substitute materials may be able to stimulate regeneration rather than repair, and tissue-engineered skin may match the quality of split-skin autografts, our present gold standard.

Use of skin substitutes in pediatric patients

There are various artificial skin substitutes available commercially. The authors have used Integra, cultured epithelium, and Apligraf in their clinic. In the present report, they present their experiences based on two case reports. The first patient was a 12-year-old boy with widespread skin defects and left axillary contracture due to epidermolysis bullosa (EB). Apligraf was used to cover the skin defects on the trunk and face and to manage ectropion and axillary contracture. The second patient was a 6-year-old boy who suffered neurocutaneous melanosis. Partial excision of a pigmented lesion on the back created a large defect. Integra application followed by repair with cultured autologous skin was accomplished, and the results were satisfactory. Skin substitute products 1) are commercially immediately available; 2) are effective for management of contractures, chronic wounds, and chronic skin illnesses; 3) decrease or avoid the risk of donor area morbidity, which is more difficult to treat in children; 4) provide long-term coverage of the wound; and 5) can be used in conjunction with autologous tissue (e.g., Integra followed by cultured epithelium applications).

Radical resection of giant congenital melanocytic nevus and reconstruction with meek-graft covered integra dermal template

BACKGROUND

Giant congenital melanocytic nevi represent a surgical challenge, particularly in cases in which the size of the nevus exceeds certain extend and malignant transformations have to be considered.

OBJECTIVE

To discuss through case report considerable surgical options when extensive giant congenital melanocytic nevi with malignant transformation are encountered.

METHODS

We present an unusual case of a giant congenital melanocytic nevi of the entire back of a 44-year-old patient. To achieve radical resection with direct appropriate wound closure and acceptable outcome, the integument of the entire back was excised and covered with Integra, followed by split-thickness skin grafting after stable integration of the matrix.

RESULTS

The approach resulted in a complete excision of the tumor and acceptable cosmetic and excellent biomechanical outcome.

CONCLUSION

The introduced practice demonstrates a useful alternative to established methods, particularly if tumor excision in large areas and subsequent wound closure might be achieved in one procedure.

Multicenter postapproval clinical trial of Integra dermal regeneration template for burn treatment

The safety and effectiveness of Integra Dermal Regeneration Template was evaluated in a postapproval study involving 216 burn injury patients who were treated at 13 burn care facilities in the United States. The mean total body surface area burned was 36.5% (range, 1-95%). Integra was applied to fresh, clean, surgically excised burn wounds. Within 2 to 3 weeks, the dermal layer regenerated, and a thin epidermal autograft was placed. The incidence of invasive infection at Integra-treated sites was 3.1% (95% confidence interval, 2.0-4.5%) and that of superficial infection 13.2% (95% confidence interval, 11.0-15.7%). Mean take rate of Integra was 76.2%; the median take rate was 95%. The mean take rate of epidermal autograft was 87.7%; the median take rate was 98%. This postapproval study further supports the conclusion that Integra is a safe and effective treatment modality in the hands of properly trained clinicians under conditions of routine clinical use at burn centers.

Use of Integra to resurface a latissimus dorsi free flap

The successful use of Integra to cover a muscle flap as a secondary reconstructive procedure is presented.

Evaluation of tissue-engineered skin (human skin substitute) and secondary intention healing in the treatment of full thickness wounds after Mohs micrographic or excisional surgery

BACKGROUND

Human Skin Substitute (Apligraf, Organogenesis, Inc., Canton, MA) is a bi-layered tissue-engineered living biological dressing developed from neonatal foreskin. It consists of a bovine collagen matrix containing human fibroblasts with an overlying sheet of stratified human epithelium containing living human keratinocytes. Human Skin Substitute (HSS) appears to be immunologically inert, and has shown usefulness in the treatment of chronic and acute wounds.

OBJECTIVE

Primary objectives were to evaluate the safety and efficacy of HSS in the treatment of full-thickness wounds in a prospective case series. Secondary objectives were to determine the rate of complete wound reepithelialization, incidence of complete wound healing, pain at wound site, overall cosmetic outcome, and patient satisfaction.

METHODS

Fourteen patients were enrolled in the study, of which 12 were evaluable. HSS was applied in a blinded fashion to 6 of the patients immediately following Mohs or excisional surgery for skin cancer. The remaining 6 patients were allowed to heal by secondary intention. Both groups were evaluated at weekly appointments until complete reepithelialization occurred. During each evaluation, wound quality was assessed through the Vancouver Burn Scar Assessment Scale by the investigator and an independent blinded dermatologist. The investigator, blinded observer, and patient further evaluated the cosmetic outcome of the wound through the use of a Visual Analog Scale over a 6-month period.

RESULTS

HSS patients and secondary intention patients were equivalent in comorbid factors such as pain, erythema, edema, exudate, infection, or hematoma between the groups. The incidence of complete wound healing at 6 months was 100% for both groups. Both groups also appeared to heal at similar rates, as defined by the complete reepithelialization of the wound. HSS patients ultimately resulted in more pliable and less vascular wounds as defined by the Vancouver Burn Scar Assessment Scale. Patient satisfaction with cosmetic outcome in both groups was positive at 6 months.

CONCLUSIONS

HSS appears to be a safe, well-tolerated biological dressing with equivalent comorbid factors to secondary intention healing. HSS, however, seems to produce a more pliable and less vascular scar than those developed through healing by secondary intention. HSS also appears to produce more satisfactory cosmetic results when compared to secondary intention healing.

The use of split-thickness dermal grafts to resurface full thickness skin defects

Coverage of large burns may be difficult when skin graft donor sites are limited. This study explored the use of the split-thickness dermal graft (STDG), as an alternative to the standard split-thickness skin graft (STSG). STSGs and STDGs were compared experimentally by their ability to resurface full thickness skin defects in a pig model. Both types of grafts were harvested from the backs of six pigs and placed on full thickness wounds. From the same donor site a 0.012in. thick STSG and another two 0.012in. thick STDGs were harvested. Thus the deep surface of grafts measured 0.012, 0.024 and 0.036in. from the skin surface, respectively. All grafts were placed on 6cmx6cm full thickness wounds. The donor areas healed at 1 week. Epithelialization of the STDGs, was assessed by computerized planimetry, and was 100% at 4 weeks. Graft biopsies revealed that STSGs were significant thinner than STDGs at 1 week (P=0.0422, 0.0135), 2 weeks (P=0.0240) and 4 weeks (P=0.0516, 0.0425). We conclude that STDGs my provide definitive coverage of full thickness skin deficits in a pig wound model.

Dermatome setting for autografts to cover INTEGRA

Using the INTEGRA Dermal Regeneration Template requires the outer silastic layer to be replaced with an autograft. We followed the manufacturer's directions for epidermal autografting and frequently obtained shredded, useless grafts, therefore, it seemed important to determine the proper dermatome setting. We evaluated dermatome settings from 0.002 to 0.012 inches. First, with feeler gauges, we verified the dermatome settings. Second, we harvested skin at various dermatome settings and measured the thickness histologically. We found that 1) the dermatome settings are reasonably accurate; 2) harvesting useful sheets at 0.002 and 0.004 inches is virtually impossible; 3) the variability of histologic graft thickness is enormous; and 4) a dermatome setting of 0.006 inches yields useful grafts. We no longer use the term epidermal autografting but rather ultrathin split-thickness grafting. To harvest these grafts, we now merely set the dermatome to 0.006 inches and make whatever midcourse corrections are necessary to obtain translucent grafts.