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Autologous fat grafting, or lipotransfer, is an important surgical approach to relocate adipose tissue within an individual to create volume. While used extensively in plastic and reconstructive surgery, significant drawbacks exist, including unpredictable volume retention. Thus, considerable research has been undertaken to identify surgical or therapeutic approaches that improve outcomes, primarily utilizing a xenograft immunocompromised mouse model. Large animal models are an important step in translating preclinical laboratory studies to the clinic, and previous studies utilizing pigs have been applied successfully for fat grafting research, but protocol variability exists across studies, and no previous publication has adequately described the impact of the swine breed on the experimental outcomes. In this report, we provide information on the critical attributes of the swine fat grafting model, including the following: (1) model selection; (2) donor site and surgical harvest approach; (3) tissue processing; (4) recipient site location and preparation; (5) post-operative care; and (6) longitudinal fat grafting assessments. Our experience comparing the use of Yorkshire and Yucatan breeds in our model showed that Yorkshire adipose tissue was fibrotic, extremely difficult to obtain through liposuction, and labor intensive to process into injectable formats. Alternatively, Yucatan adipose was more similar to human tissue, could be readily obtained through the surgical excision of inguinal fat pads, was amenable to mincing with surgical scissors, and yielded injectable tissue with a 95% efficiency. We determined that generation of a surgical pocket reduced the graft migration and spread, consequently facilitating the graft retrieval without significantly impacting retention. Using 5 cc grafts, the ultimate 3-month volume retention in 16 grafts was 19% ± 17% (or 1.14 cc ± 1.08 cc). While the use of ultrasound did not readily enable graft volume approximation during the study, it was a useful method to visualize the graft placement and ensure injection into the subcutaneous adipose layers. [ABSTRACT FROM AUTHOR]

Introduction: Complex burns are a challenge, often requiring prolonged reconstruction. Management requires consideration not only to the skin but to underlying structures and often requires staged-reconstruction and revision for increasingly unsatisfactory results. This standard is expensive, limited by donor-site availability, and often impacts quality of life. Here we demonstrate the efficacy of single-staged minced skin grafting in an incubator-like microenvironment with a negative-pressure moist wound chamber device to achieve rapid epithelialization after burns. Methods: Full-thickness burns were induced to female Yorkshire swine. Escharectomies were performed to the level of fascia after seventy-two hours. One group received standard of care skin grafting with a bolster dressing. In another group, split-thickness skin was cut into pixel size (0.3x0.3 mm) grafts, followed by application of either bolster or negative-pressure moist wound chamber dressing. Wounds were followed for 4-weeks with serial photography, ultrasound, and biopsies for histology. Results: As early as one week, epithelialization started in the group with pixel grafts with negative-pressure moist wound chamber dressings with visible epithelioid islands on the wound bed granulation tissue. This progressed with a similar trend throughout the 4-week period eventually leading to near-complete epithelization and keratinization. There was reconstruction of trilaminar cutaneous architecture demonstrated by the presence of distinct, viable epidermal, dermal and hypodermal elements as well as viability of adipose on histology. Distinct differences in contour were noted between the bolster and negative-pressure moist wound chamber groups. Conclusions: Minced grafting minimized donor burden and alleviated the need for graft orientation. In both the bolstered and negative-pressure moist wound chambers, pixel-grafts viably survived to form a viable basal layer. Use of positive-pressure (bolster) vs. negative-pressure moist wound chamber dressings demonstrated distinct differences in the convexity/concavity and topography of the singe-stage skin graft with critical implications for aesthetic reconstruction. Applicability of Research to Practice: This study introduces the efficacy of a single-staged trilaminar reconstruction with the use of a negative-pressure moist wound chamber for complex burns. These findings support the potential for a new paradigm in the treatment of complex burns which allows for single-stage reconstruction with minimal donor site morbidity. [ABSTRACT FROM AUTHOR]

Introduction: Complex burns are highly morbid injuries that can cause severe disfigurement and can be devastating to one's quality of life and psychosocial well-being. Currently, there are no simple, single-stage procedures available for extensive or multifocal burns to address full-thickness trilaminar defects. Our team has previously demonstrated the viability of an adipose-first reconstruction to address hypodermal defects. In this study, we demonstrate the efficacy of a combined adipose plus finely minced skin to achieve a single-stage trilaminar skin reconstruction. Methods: Full-thickness burns were created on female Yorkshire swine. After 48-hours, escharectomies were performed to the level of fascia. The wounds were layered with adipose harvested from female Yorkshire swine. In one group, autologous split-thickness skin grafts were cut into pixel size (0.3x0.3 mm) grafts and layered on top of the adipose. Pigs were maintained for 4-weeks with weekly photography, ultrasound, followed by endpoint histology and tension measurements. Results: At the end of the 4-week period, adipose combined with pixel graft demonstrated improved epithelialization and less contracture (p< 0.01). Thickness and mobility measurements were consistent in both groups. This findings were similar to our previous approaches using adipose following surgical debridement. Tissue pliability in the pixel grafting group was maintained to a high degree. Cross sections were performed which showed the persistence of fat graft at the base of the wounds. Conclusions: Immediate, single-stage trilaminar reconstruction of full-thickness complex burns reduces contracture, mitigates adhesion, and restores normal soft-tissue thickness, therefore, presenting a paradigm changing approach in the current practice of burn injuries to the mobile surfaces. Applicability of Research to Practice: Our results support the therapeutic potential of adipose-based soft-tissue reconstruction of burns to both enhance hypodermal augmentation and mitigate fibrotic complications including contracture and adhesions. Our data suggest that this approach is compatible with the standard of care skin grafting, and in fact provides improved epidermal thickness and pliability. [ABSTRACT FROM AUTHOR]