The 1999 clinical research award. Cultured skin substitutes combined with Integra Artificial Skin to replace native skin autograft and allograft for the closure of excised full-thickness burns

Prompt and permanent closure of excised full-thickness burns remains a critical factor in a patient's recovery from massive burn injuries. Hypothetically, Integra Artificial Skin (Integra) may replace the need for allografts for immediate wound coverage, and cultured skin substitutes (CSS) that contain stratified epithelium may replace the need for autografts for definitive wound closure. To test this hypothesis, 3 patients with full-thickness burns of greater than 60% of their total body surface areas had their eschar excised within 14 days of admission. Integra was applied, and a skin biopsy was collected from each patient for the preparation of CSS. At 3 weeks or more after the application of the Integra and the collection of skin biopsies, the outer silastic cover of the Integra was removed and CSS were grafted. The CSS were irrigated with nutrients and antimicrobials for 6 days and then dressed with antimicrobial ointment and cotton gauze. Treated wounds were traced on days 14 and 28 after the grafting of CSS for determination of engraftment and wound closure, respectively. Cost analysis was not performed. Engraftment on postoperative day (POD) 14 was 98%+/-1% (mean +/- standard error of the mean), the ratio of closed:donor areas on POD 28 was 52.3+/-5.2, and no treated sites required regrafting. The histology of the closed wounds showed stable epithelium that covered a layer of newly formed fibrovascular tissue above the reticulated structure of the degrading Integra. The clinical outcomes of the closed wounds after POD 28 demonstrated smooth, pliable, and hypopigmented skin. Two patients who had received CSS grafts over Integra on their backs were positioned supine on air beds from POD 8 or POD 9 with minimal graft loss because of mechanical loading. One patient with a full-thickness burn of 88% of the total body surface area was covered definitively at 55 days postburn. These results demonstrate that the combination of CSS and Integra can accomplish functionally stable and cosmetically acceptable wound closure in patients with extensive full-thickness burns. This combination of alternatives to the conventional grafting of split-thickness skin permits the substitution of cadaveric allograft with Integra and the substitution of donor autograft with CSS. This approach to the closure of excised full-thickness burns is expected to reduce greatly the time to definitive closure of burn wounds and to reduce the morbidity associated with the harvesting of donor sites for split-thickness skin autografts.     

Immunologic study of artificial skin used in the treatment of thermal injuries

Artificial skin (Integra) has been developed as an effective treatment of full-thickness burns. The material consists of a bovine collagen and chondroitin-6-sulfate dermal matrix with a silicone rubber "epidermal" layer. After burn wound excision, the artificial skin is implanted. Only the temporary silicone rubber epidermal membrane is removed. The dermal collagen matrix is incorporated by the host. Serial serum samples were obtained from patients who had grafts of Integra artificial skin for the determination of the humoral immune response to Integra. Integra artificial skin presents few if any humoral immunologic problems to patients. Increased antibody activity to bovine skin collagen, bovine skin collagen with chondroitin sulfate, and human skin collagen was not considered immunologically significant.     

Clinical trials of a living dermal tissue replacement placed beneath meshed, split-thickness skin grafts on excised burn wounds.

We evaluated the ability of Dermagraft (Advanced Tissue Sciences, La Jolla, Calif.), a living tissue analog that is composed of human neonatal fibroblasts, which are grown on a polyglactin acid Vicryl mesh (Ethicon Inc., Somerville, N.J.), to function as a dermal replacement when placed beneath meshed, expanded split-thickness skin grafts (MESTSGs). Full-thickness burn wounds in 17 patients with burns (mean age, 31 years; range, 6 to 69 years; mean burn size, 23.8% total body surface area) were excised to subcutaneous fat (nine patients), to fascia (three patients), or to a combination of deep dermis and fat (five patients). Dermagraft was placed over the experimental sites, which were then covered with MESTSGs. Paired control sites on each patient received MESTSGs only. The results showed that "take" of MESTSGs on control sites was slightly better than take on experimental sites that contained the Dermagraft; however, the differences were not statistically significant. Mesh interstices epithelialized over the surface of the full-thickness wound (control sites) or over the surface of Dermagraft (experimental sites). Wound biopsy specimens demonstrated no evidence of rejection of the cultured allogeneic fibroblasts and minimal inflammatory reaction to the Vicryl fibers. Evidence of continuous basement membrane formation at the epithelial-Dermagraft junction, which was identified by immunohistochemical staining for laminin and type IV collagen, was seen by day 14 beneath the healed epithelium in the skin graft interstices. The Vicryl fibers were hydrolyzed in the wound over a 2-to-4-week period, although some expulsion of fibers occurred as the healing epithelium advanced to close the MESTSG interstices. Elastic fibers were not seen in neodermal tissue in either control or experimental wounds at periods of up to 1 year after grafting. Further trials with this living tissue replacement are in progress.     

Histologic study of artificial skin used in the treatment of full-thickness thermal injury

Integra artificial skin is an effective means of treatment for full-thickness burns. In extensive burn injury the use of such skin substitutes may become the treatment of choice. The artificial skin consists of a dermal substitute of bovine collagen and chondroitin-6-sulfate and an epidermal layer of synthetic polysiloxane polymer (Silastic). Serial biopsy specimens were obtained from 131 patients during a period of 7 days to 2 years after application. In this histologic study, six sequential phases of repair were discerned. In addition, there were occasional unusual histologic features, eosinophilic infiltration, and/or macrophage-derived giant cell formation in the wound area; however, such findings did not clinically correlate with a negative response to Integra artificial skin. Good repair was obtained, with rare exceptions. An intact dermis was achieved as well as definitive closure of a complete epidermal layer with a minimum of scarring.     

Application of split-thickness dermal grafts in deep partial- and full-thickness burns: a new source of auto-skin grafting

Early tangential excision of nonviable burn tissue, followed by immediate skin grafting with autograft or allograft, has resulted in the improvement of burn patient survival. The aim of this study was to add split-thickness dermal grafts (STDGs) as a new source of auto-skin grafting tool to our reconstructive armamentarium in deep partial- and full-thickness burns and soft tissue defects. The authors successfully applied STDGs along with split-thickness skin grafts as a new source of auto-skin grafting in 11 deep partial- and full-thickness burns over a period of 1 year without any significant donor site morbidity. Dermal graft take was complete in all but one patient. There was no donor site healing problem, and donor site epithelization was completed generally 1 week later than split-thickness skin graft by semi-open technique. Autologous split-thickness skin grafting still remains the standard therapy for burn wound closure but may be in limited availability in severe burns. The authors conclude that STDGs may be a new source of auto-skin grafting tool in extensive deep partial- and full-thickness burns.     

Healing characteristics of expanded autografts on wounds covered with homograft and Biobrane temporary wound dressing

This study compared the healing characteristics of expanded autografts on wounds with interstices that were closed with cryopreserved cadaver homograft split-thickness skin and wounds with interstices that were closed with the synthetic skin substitute, Biobrane temporary wound dressing. Nine paired wounds in four patients with large burns were used in this study. When Biobrane temporary wound dressing adhered to a wound, epithelial migration did not proceed until it was removed. Although wounds covered with homograft immediately had the appearance of healed wounds, biopsy specimens showed evidence of a delay in epithelial migration. Although these results indicate impaired epithelial migration with the use of both materials, we concluded that homograft offered an advantage because the wounds that were covered with it remained closed during the entire reepithelialization process.     

A prospective controlled trial of Biobrane versus scarlet red on skin graft donor areas

A prospective trial of Biobrane versus scarlet red as a skin graft donor site dressing was done in 21 burn patients with mean total body surface area burns of 31.9%. Corresponding body areas were randomly selected on each patient to receive one of the dressings. Daily evaluations were made of subjective expression of pain, exudate formation and infection, and time of separation of the dressing from the wound. Biobrane was found to be superior in reducing donor site pain. However, with Biobrane there was a higher incidence of infection (57% v 9.5%) and a significant delay in separation from the wound. Scarlet red was found to be more cost-effective. Occlusive dressings have previously been shown to have a high incidence of complications (30%). In extensive burns, isolating the donor site from the wound is difficult and may lead to increased complications. Scarlet red appears to be superior to Biobrane for skin graft donor sites in this patient population.     

Skin coverage with Biobrane biomaterial for the treatment of patients with toxic epidermal necrolysis.

Toxic epidermal necrolysis (TEN) is an exfoliative skin disorder that may involve a large body surface area and mucosal surfaces. The microscopic changes that occur with this condition are similar to those that occur with superficial dermal burns, such as dermal detachment from the underlying dermis. Complications of TEN are related to the loss of the epithelial skin barrier and include pain, fluid and electrolyte loss, and an increased risk of sepsis. The treatment of a patient with TEN is best accomplished in a burn unit, where expert treatment of these complications can be provided. Medical treatment includes the administration of immunosuppressive therapy and the discontinuation of any previous corticosteroid treatment. Surgical management includes the debridement of necrotic areas. In this article, the surgical management of 8 consecutive patients with TEN who were admitted to the intensive care burn unit at the Hospital Universitario de Getafe in Madrid, Spain, from 1996 to 1998 is described. These patients were treated with extensive early debridement of necrotic skin areas followed by wound coverage with Biobrane (Dow B. Hickam, Inc, Sugarland, Tex), a temporary semisynthetic skin substitute. Skin coverage with this material decreases pain and fluid loss, and it possibly facilitates epithelization and decreases the risk of sepsis, without adverse side effects. This semisynthetic material meets some standards of an ideal skin substitute: it is easy to use, provides several beneficial physiologic effects, and improves patients' comfort. In the 8 cases of patients with TEN that were studied, the use of Biobrane skin substitute for the coverage of massive areas of detached skin was found to be an important aspect of treatment.     

异种(猪)无细胞真皮基质与自体微粒皮复合移植修复深度烧伤创面的实验研究

目的　观察异种 (猪 )无细胞真皮支架与自体微粒皮加同种异体皮复合移植修复全层皮肤缺损的效果。方法　 4 8只 SD大鼠背部全层皮肤缺损创面 ,分别行异种 (猪 )无细胞真皮支架与自体微粒皮移植(复合皮组 )和单纯微粒皮移植 (对照组 ) ,术后定期观察创面愈合情况并行创面愈合率和收缩率的计算 ,同时取创面组织进行组织学观察。结果　复合皮组的创面愈合情况良好 ,未见明显挛缩 ,皮肤弹性较好 ,两组异体皮成活情况及创面愈合情况相近 ,但是复合皮组创面收缩率显著低于对照组。组织学观察复合皮组上皮化良好 ,胶原纤维排列有序 ,基底膜结构完整。结论　异种 (猪 )无细胞真皮支架与自体微粒皮复合移植能修复全层皮肤缺损 ,改善创面愈合质量。     

Sensibility after burn injury

Summary. Thresholds for touch, temperature, pain and two-point discrimination were examined in 27 healthy subjects and in 36 burn patients. Three groups of injuries were examined; superficial dermal burns, which were allowed to heal spontaneously, deep dermal and subdermal burns treated by either early or late excision and skin grafting. Uninjured areas on the contralateral side served as control. In spontaneously healed superficial burns, the sensibility recovered to normal, except for touch. In deep dermal or subdermal burns all thresholds were significantly higher than in the corresponding control areas. There was no recovery beyond one month after the injury. The sensibility was better on the upper than on the lower extremities and also in deep dermal than in subdermal burns. There was no significant difference in sensibility between burns excised and grafted early or late, respectively. The results indicate that current treatment of deep dermal and subdermal burns is not followed by complete recovery of cutaneous sensation. Furthermore, even superficial burns results in incomplete recovery of touch sensibility.     

Effect of graft bed on long-term functional results of extremity skin grafts

The purpose of the current study was to determine whether the long-term functional results of extremity burns grafted on fat were different from those grafted on fascia. Twelve patients (mean burn size, 38% TBSA) who had fascial excision of the majority of one or more extremities were examined a minimum of one year postinjury. Range of motion, motor strength, and sensation of the fascially excised extremities were measured. Twelve comparable patients with extremity burns (mean burn size, 35% TBSA) who had grafts placed on fat were used as positive controls. Patients whose burns were excised to fat had better joint mobility (P = 0.001) and sensory function (P = 0.001) than did patients whose burns were excised to fascia. Both groups had comparable muscle strength. These results indicate that patients with full-thickness burns of the extremities who have grafts placed on fat have significantly better long-term extremity function than do patients who have their skin grafts placed on fascia.     

A preliminary report on transplantation of microskin autografts overlaid with sheet allograft in the treatment of large burns

The technique of transplantation of autologous microskin grafts (MG) with overlays of split-thickness skin allografts was used in the treatment of nine extensively burned patients. Preparation of MG includes: 1) mincing small pieces of split-thickness skin autografts into skin particles (SPs); 2) dispersing the SPs evenly on a piece of silk cloth; 3) transferring SPs to the dermal surface of an allograft sheet (20/1000 in.); 4) transplanting the allograft with SPs to the excised wound. The mean burn area (total/3 degrees, mean +/- SEM) of this group was 74.9 +/- 16.6/62.1 +/- 18.1% TBSA (range 40 to 94/28 to 90%). The mean age was 27 years (range 19 to 38). Early staged excisions followed immediately by MG applications were performed on 35 large body sites, including extremities, chests plus abdomens and backs. The mean area excised and grafted with MG was 41.7 +/- 11.0% TBSA (range 26 to 62%). The average time for complete healing was about six to seven weeks postgrafting. Eight patients survived; one died of overwhelming pulmonary infection 22 days postburn. Advantages of this technique are: 1) the great potential of MG to provide a large expansion ratio of 8:1 to 15:1, average greater than 10:1 in this series; 2) good maintenance of the healed graft to withstand trauma except in areas of repeated flexion; 3) ease of preparation and application with less cost compared to cultured epidermal sheet grafts; 4) prevention of infection in extremely large burns by providing continuous epidermal coverage following sheet allograft application.     

Steam press hand burns: A serious burn injury

Steam presses cause full-thickness burns when the operator's extremity is caught between the buck and the head of the steam press. Patients with serious steam press burns should be referred to a regional burn center for excision of the full-thickness burn and coverage by either a split-thickness skin graft or a flap. The safety features in steam presses that could prevent this serious injury include: (1) emergency safety releases, (2) peripheral safety bars, and (3) two-hand operator control.     

Correction of hypercromic palmar graft with split-thickness instep plantar graft: case report.

The plantar skin is the best donor site for grafting third-degree burn wounds onto volar aspect of hands and digits. In children, however, it is difficult to harvest the instep for a split-thickness graft. Most of these cases are treated with full-thickness or split-thickness skin grafts and dyspigmentation of the grafted area becomes a reality. We present a case of full-thickness graft hyperpigmentation that was treated with instep plantar graft.     

Conservative treatment of scald burns is superior to early excision.

Early excision of deep burns has been advocated; however, it is difficult to clinically determine the depth of scald burns during the early postburn period. This prospective, randomized study was designed to determine whether early excision was superior to conservative treatment of scald injuries. Patients with scald injuries (which were not caused by grease) of clinically indeterminant depth were randomized to early (n = 12) or late (n = 12) excision; all patients with obvious superficial and full-thickness injuries were excluded. In the early excision group, all deep wounds were tangentially excised and grafted within 72 hours of admission, whereas in the late treatment group wounds were excised and grafted after 2 weeks had passed since injury. Area excised, postburn day of excision, percent graft take, operating-room time, blood replacement, incidence of infection, and length of hospital stay were compared. No patient experienced a significant wound infection or systemic sepsis. A significantly smaller area of excision was necessary for those patients who were treated with delayed surgery, and concomitant decreases in operating-room time and blood loss were observed. Notably, only one half of the patients who were randomized to the delayed excision group ultimately required surgical intervention to achieve wound closure. Graft take was comparable for both groups, as was length of hospital stay. Early clinical evaluation of scald injuries appears to be equivocal, and later evaluations reveal a less severe injury. Financial gains can be made when surgical excision of scald injuries is delayed until 2 weeks after injury because of a related reduction in hospital expenditures.     

Lack of long-term durability of cultured keratinocyte burn-wound coverage: a case report.

Cultured epithelial autografts have been advocated for permanent closure of skin surfaces after massive thermal injuries. A 10-year-old boy sustained a nearly 100% total body surface area burn (98% full-thickness) in an explosion accident. Cultured epithelial autograft was used to cover 70% of the total body surface area on postburn day 26. In spite of early success of coverage, 60% of cultured epithelial autograft areas blistered and sloughed over the ensuing weeks. Electron microscopic examination of a biopsy specimen of the healed cultured epithelial autograft (80 days after placement) revealed a lack of dermal attachments of the anchoring fibrils. Additionally, blister fluid that was taken from the bullae of the cultured epithelial autograft revealed levels of 18 ng/ml thromboxane and 24 ng/ml prostaglandin E2. These levels are significantly higher than those seen in acute burn blister fluid and indicate an ongoing inflammatory process. Cultured keratinocytes, although they provide early wound closure, may not provide adequate long-term coverage for patients with massive burns.     

皮能快愈敷料在深度烧伤创面治疗中的改良应用

目的 探讨皮能快愈敷料对深度烧伤患者的治疗效果.方法 2008年8月至2010年8月我们收治深度烧伤患者22例.患者入院后立即进行创面深度及烧伤严重程度评估,待生命体征稳定,创面水肿高峰期结束后行创面治疗,1期清创手术,行皮能快愈敷料移植术,皮能快愈敷料外加湿性敷料(德湿威);2周后Ⅱ期手术,去除皮能快愈敷料硅胶膜行自身刃厚皮移植.结果 22例深度烧伤创面均愈合,皮能快愈敷料无感染及溶解.皮片移植存活,创面外观满意,供皮区瘢痕增生轻.结论 改良皮能快愈敷料与自体刃厚皮复合修复深度烧伤创面具有较好的临床应用价值.     

Evaluation of cytotoxicity and antimicrobial activity of Acticoat Burn Dressing for management of microbial contamination in cultured skin substitutes grafted to athymic mice

Cultured skin substitutes (CSS) have become a useful adjunctive treatment for closure of burn wounds, but CSS are avascular and remain susceptible to microbial destruction longer than split-thickness skin grafts. Irrigation of CSS grafted to burn wounds with a topical antimicrobial solution (TAS) has been shown to promote engraftment of CSS, but TAS usage has potential limitations. Acticoat Burn Dressing (Acticoat; Westaim Biomedical, Exeter, NH) is a silver-coated barrier dressing reported to exhibit antimicrobial activity and to reduce infection in partial-thickness and full-thickness wounds. This study evaluated the cytotoxicity of Acticoat with CSS and the efficacy of Acticoat for the management of microbial contamination in CSS grafted to full-thickness wounds in athymic mice. The cytotoxicity of Acticoat was assessed in preliminary studies after 1 week of exposure to CSS during in vitro maturation or healing on wounds in athymic mice. Histologies were analyzed and cellular viability in the CSS was determined by MTT conversion on days 0, 1, and 7 of Acticoat exposure. At 1, 2, 3, and 4 weeks after grafting, wounds were traced, and areas of healing CSS were calculated by image analysis. At 4 weeks, wound biopsies were evaluated and scored for engraftment of human cells. In a subsequent study, wounds were inoculated with strain SBI-N of Pseudomonas aeruginosa at 1 x 10(5) cfu/wound before the application of CSS or inoculated onto the surface of Acticoat. At 4 weeks, swab cultures were collected from the surface of CSS and scored for the presence of SBI-N. Statistical significance was accepted at the 95% confidence level (P <.05). The data show that exposure in vitro of CSS to Acticoat was cytotoxic within 1 day, but 1 week of exposure in vivo did not injure CSS or inhibit wound healing. Contaminated wounds treated with Acticoat healed similarly to control treatments, with comparable rates of engraftment, and detection of SBI-N on the surface of only one graft. No SBI-N was detected on CSS after inoculation onto the surface of Acticoat. These results suggest that Acticoat may be suitable as a protective dressing to reduce environmental contamination of CSS, if used in conjunction with additional antimicrobials to control organisms present in the wound.     

The burned hemophiliac

Reports of the care of burned hemophiliac patients requiring cutaneous autografting are rare. A 28-year-old white male with classic hemophilia A sustained a 30.5% total body surface area burn. The patient received standard topical antimicrobial therapy and the majority of his burn wound healed. While undergoing therapy, multiple tooth extractions were recommended. On postburn day 25 the patient underwent multiple tooth extractions plus excision and grafting of his unhealed burn after preoperative infusion of cryoprecipitate. Despite a maximum factor VIII concentration of only 23%, no remarkable bleeding occurred from the excision sites, the skin graft donor site, or the tooth extraction wounds. Preoperative infusion of cryoprecipitate does not appear to be required for split-thickness skin graft harvest or excision of burns within the dermis.     

Cultured epidermal autograft and the treatment of the massive burn injury.

As a rule, adult and pediatric patients with thermal injuries that involve more than 90% total body surface area (TBSA) burn have poor prognoses. Even for patients who are 5 to 34 years old with a 70% TBSA burn, the mortality rate is 80%. Lack of autologous donor skin, which is essential for permanent wound closure, is the major problem. Recent advances in growth of cultured epidermal autograft (CEA) have allowed closure of full- and partial-thickness burns; in approximately 3 weeks, a 2 cm2 biopsy specimen will produce enough CEA to cover a pediatric patient. Since 1989, we have used this product on nine patients; the average age was 39, and the average TBSA burn was 70% (range, 44% to 93%). We report our approach to use of CEA in six of these patients, including topical applications of 1% silver sulfadiazine and excision of full- and deep partial-thickness wounds within 2 weeks of injury. Temporary closure was achieved with cadaver allograft. "Take" of the allograft forecasted take of CEA. The total operative time of CEA placement was decreased by a two-step technique that obviates repeating debridement: the technique consists of debriding and grafting with allograft, then removing it at the time of CEA placement. CEA take is best on early granulation tissue or freshly excised wounds. Early excision of burn eschar, temporary wound closure with cadaveric allograft and Biobrane (Winthrop Pharmaceuticals, Wound Care Div., Fountain Valley, Calif.), and permanent closure with CEA may improve survival rates among patients with massive burn wounds. CEA is a tremendous asset to the management of massive burn injuries.