Split-Thickness Skin and Dermal Pixel Grafts Can Be Expanded up to 500 Times to Re-Epithelialize a Full-Thickness Burn Wound.

Objective: Autologous skin transplantation is limited by donor site availability for patients with extensive burns. The objective of this study was to demonstrate the feasibility and efficacy of split-thickness skin (STS) and dermal pixel grafts (PG) in the treatment of burns. Approach: The study was divided into three arms of validation, expansion, and combination that all followed the same study design. Sixteen deep partial-thickness burns were created on the dorsum of anesthetized pigs. Three days postinjury the burns were debrided and grafted with STS and dermal PGs. The PGs were prepared by harvesting two skin grafts (split-thickness skin graft [STSG] and dermal graft) from the same donor site going down in depth. The grafts were minced to 0.3 × 0.3 × 0.3 mm PGs and suspended in a small volume of hydrogel. Healing was monitored for 6, 10, 14, or 28 days. In the validation study the PGs at 1:2 expansion ratio were transplanted and compared with STSG and untreated controls. The expansion study investigated the maximum expansion potential of the PGs and the combination of the benefits of transplanting STS and dermal PGs together. Results: The validation study showed that when STS and dermal PGs were transplanted in a 1:2 ratio they fully re-epithelialized the wounds in 14 days. The expansion study demonstrated that using expansion ratios up to 1:500 the wounds were re-epithelialized by day 28. The combination study showed that there was no additional benefit to use STS and dermal PGs together. Innovation: Pixel grafting provides expansion ratios greater than conventional STSG. The possibility to harvest both STS and dermal PGs from the same donor area further reduces the need for healthy skin. Conclusion: STSG and dermal grafts can be minced to PGs with preserved viability and expanded up to 500 times to re-epithelialize a wound.

Study Comparing Platform Wound Dressing, a Negative-Pressure Device without a Filler, with Three Conventional Negative-Pressure Wound Therapy Systems in the Treatment of Excisional and Incisional Wounds.

BACKGROUND: All common negative-pressure wound therapy systems include a material, usually foam or gauze, at the wound/device interface. In this preclinical study, the authors have compared the effects on different wound healing parameters in the three most common negative-pressure wound therapy systems (i.e., V.A.C.VIA, PREVENA, and PICO) with a new device without foam or gauze (i.e., Platform Wound Dressing). A strong effort was made to avoid bias. The study was conducted under good laboratory practice conditions, with the presence of an independent observer. METHODS: In pigs, three types of wounds were studied: full-thickness excisions, open incisions, and sutured closed incisions. Several macroscopic and microscopic parameters were studied. The pigs were euthanized on day 9 and all wounds were processed for histology and excisions for immunohistochemistry. RESULTS: In general, the devices produced similar results, with only a few significant differences. In the excisions, the Platform Wound Dressing reduced wound area more than the V.A.C.VIA and the PICO. In the excisional wounds, reepithelialization was the same. In open incisions, PREVENA was better than the Platform Wound Dressing. Histologic examination showed that, in open incisions, there was less inflammation in the PREVENA-treated in comparison with the Platform Wound Dressing- and the PICO-treated wounds. Immunohistochemical analyses showed that the Platform Wound Dressing-treated excisions had significantly more blood vessels (von Willebrand factor) than the V.A.C.VIA-treated ones and that the PICO caused less T-cell activation (CD3) than the other two. CONCLUSION: The devices-with foam, with gauze, or without either and just an embossed membrane-performed equally in general.

Immediate Treatment of Burn Wounds with High Concentrations of Topical Antibiotics in an Alginate Hydrogel Using a Platform Wound Device.

Objective: There is an unmet need to improve immediate burn care, particularly when definitive treatment is delayed. Therefore, the purpose of this project was to formulate a hydrogel that contains very high concentrations of antibiotics and validate its use together with a platform wound device (PWD) for the immediate care of burns. Approach: The hydrogel properties were optimized by using a rheometer, differential scanning calorimetry, and liquid chromatography-mass spectrometry and were tested in an infected porcine burn model. Immediately, after burn creation, the burns were infected with different bacteria. Subsequently, the burns infected with Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii were covered with the PWD and treated with a single dose of hydrogel containing 1000 × minimum inhibitory concentration of vancomycin, gentamicin, and minocycline, respectively. On day 7 or 45, the animals were euthanized, and the burns were harvested for histology and quantitative bacteriology. Results: 0.625% was the best alginate concentration for the hydrogel in terms of viscosity, stability, and drug release. The porcine studies demonstrated that vancomycin-, gentamicin-, and minocycline-treated tissues contained significantly less bacteria and reduced depth of tissue necrosis in comparison to controls. Innovation: The PWD represents a platform technology that begins at the point of the first treatment by protecting the wound and allowing administration of topical therapeutics. The device can be adapted to enclose any size burn over any contour of the body. Conclusion: Antibiotics can be delivered safely in very high concentrations in a hydrogel using the PWD, and burn infections can be treated successfully with this method.

PWD: Treatment Platform for Both Prolonged Field Care and Definitive Treatment of Burn-Injured Warfighters.

INTRODUCTION: Burns are a very frequent injury type in the battlefield, comprising 5-20% of combat casualties in the recent conflicts. Almost 80% of the burns occur to the face, in part because the face is often not protected. Immediate treatment is critical in the first hours after severe burn injury in order to prevent infection and wound progression. Immediate treatment in the battlefield can be a serious challenge especially if the injury occurs in a remote area with limited transport options. Therefore, novel treatment modalities for prolonged field care when transport to the definitive care is delayed are needed. The purpose of this study was to utilize the platform wound device (PWD) with negative pressure capabilities for the immediate and definitive treatment of porcine full-thickness head burns. MATERIALS AND METHODS: Full-thickness burn wounds were created on foreheads of seven Yorkshire pigs. Burns were created on day 0, immediately enclosed with the PWD and treated topically with minocycline and lidocaine. On day 3, the burns were surgically debrided. Subsequently, new PWDs were placed on the wounds and continuous negative pressure wound therapy was initiated with either -50 mmHg or -80 mmHg. On day 7, the animals were euthanized and wounds were harvested for analyses. Control wounds were treated with silver sulfadiazine cream. RESULTS: The PWD treatment with negative pressure significantly reduced erythema and edema in the injured tissue and promoted granulation tissue and neocollagen formation by day 7 in comparison to control wounds. In addition, the PWD with both topical minocycline and negative pressure (-80 mmHg or -50 mmHg) reduced bacterial counts in the wounds similar to the current standard of care. CONCLUSION: This study demonstrates that the PWD is an effective platform for delivery of antibiotics and negative pressure wound therapy for the treatment of full-thickness burns. Therefore, the PWD may be utilized for both prolonged field care and definitive treatment of burn- and blast-injured warfighters.

Novel negative pressure wound therapy device without foam or gauze is effective at -50 mmHg.

Negative pressure wound therapy (NPWT) promotes healing in acute or chronic wounds. Conventional NPWT devices consist of a filler (such as foam or gauze) that covers the wound and of a permeable membrane and tubing that connects the space under the membrane to a suction pump. The permeable membrane increases airflow and thus increases the required pump capacity that can cause patient discomfort or even ischemia in wounds with compromised vascularity. In addition, foam or gauze may fragment and become colonized with bacteria over time. To mitigate these, negative aspects, we have developed a new impermeable single layer component membrane dressing to deliver NPWT that does not need a foam or gauze to function. Therefore, the purpose of this study was to introduce this novel NPWT system (platform wound device, PWD) and evaluate its usability and effectiveness in the treatment of porcine full-thickness burns. A total of 48 burn wounds were created across four Yorkshire pigs on the dorsum. Wounds were created on day 0 and continuous NPWT with -50 mmHg and - 80 mmHg was initiated immediately. Subsequently, the burns were debrided on day 3 and animals were euthanized on day 7. The efficacy of the PWD on wound healing and reduction of bacterial burden was measured and compared to wounds that did not receive NPWT. The results showed that PWD promoted wound healing by outperforming the wounds that did not receive NPWT and that PWD was efficient at reducing bacteria from the burn eschar and from the wound bed. In conclusion, this study demonstrated that PWD promoted wound healing with a negative pressure as low as -50 mmHg, which likely benefits healing and avoids potential safety issues.

Topically Delivered Minocycline Penetrates a Full-Thickness Burn Eschar and Reduces Tissue Bacterial Counts.

Injuries to the skin are often complicated by invasive infections. Standard treatment with intravenous antibiotics has limited tissue penetration and sometimes, major systemic toxicity. Traditional topical delivery of antimicrobials also has limited effectiveness and duration of action. We demonstrate the use of a new Platform Wound Device (PWD) for delivery of topical, ultrahigh concentrations of minocycline as well as lidocaine onto the burn eschar and on the surface of excisional wounds in a total of 56 burn wounds and 24 excisional wounds in a porcine model. Wounds were created on day 0, debrided on day 3, and pigs were killed on day 7. After 3 days of PWD with minocycline treatment, bacterial count was 5.44 log CFU/g in dorsal wound tissue inoculated with methicillin-resistant Staphylococcus aureus, less than that after treatment with silver sulfadiazine cream (7.64 log CFU/g). Pain was also relieved or eliminated in burn wounds and full-thickness excisional wounds when lidocaine was delivered by the PWD. The results demonstrate that ultrahigh concentrations of antibiotics can be delivered effectively by the PWD, and will accelerate wound bed preparation.