swine burn model for the analysis of tissue regeneration in multiple depth wounds

Yucatan Minipig Burn Wound Model for Analysis of Multi-Depth Burns

Burns are a major public health problem and affect more than 480,000 patients in the US each year, according to the National Burn Repository1,2. This leads to more than 50,000 yearly hospitalizations for non-fatal complex cases requiring in-depth care2. Moreover, burns are a fundamental cause of military mortality and morbidity and are responsible for 10% to 30% of military casualties3,4. The management of burns has remained nearly unchanged for a long time, despite its immense and diverse impacts on patients, ranging from physical to psychological and emotional5.
Initial diagnosis and evaluation of burn injuries lead to a baseline classification according to the type of burns (first, second, and third) or the depth of the affected tissue (superficial, partial thickness, and deep burns)6,7,8. Partial-thickness burns (first and second-degree) involve the epidermis and different depths of the dermis (superficial or deep dermis, i.e., superficial and deep second-degree burns)9. In particular, damage to the appendages in the deep dermis excludes the possibility of re-epithelialization from the adnexal epithelium10. By definition, full-thickness burns reach the subcutaneous fat, fascia and/or the underlying muscle (third-degree burns), and sometimes the bone (also referred to as fourth-degree burns)11,12.
Following hospitalization, burn patients receive special care involving a strategy consisting of a delicate balance between tissue debridement and preservation. The damaged and/or secondarily infected soft tissue needs to be progressively removed until healthy tissue is exposed, allowing for the use of specific dressings and skin grafts to improve the healing process13,14,15,16. Yet, caution is required during surgery to avoid unintentional removal of healing tissue and reduce complications for optimal recovery. Biologically, burns exhibit a central necrotic area encircled by a &#39;shadow&#39; or &#39;stasis&#39; zone, indicating potentially reversible ischemia. This area can either deteriorate, resulting in an extended necrosis zone, or heal by reversing the apoptotic process17,18. This varying severity of burns presents challenges for surgeons to assess accurately, complicating the balance between conservative treatments and surgical excision19. To date, no efficient tool is available to help characterize this &#34;shadow zone&#34; preceding burn conversion. Developing such tools is crucial for optimizing this delicate balance.
Several treatments have been tested to help decrease secondary burn conversion. Yet, no specific therapy is currently available in the clinic18. Other examples of advances in burn treatments include the development of modern wound dressings and nanomaterials20,21, tissue-engineered skin22,23, and novel epidermal culture approaches24,25. Also, modern reconstructive surgery and fasciocutaneous flaps have improved the management of long-term after-effects, particularly burn contractures following pathologic healing of fold areas26,27. These advancements give promising prospects for burn patients, improving their treatment strategies and quality of life, but recent results show that the functional impact still remains substantial, both in the physical and psychological spheres28. Taken together, the demand for innovative advancements in both burn diagnosis and burn treatment is substantial.
Overall, many approaches are aiming at improving the diagnosis, management, and treatment of complex burn cases, and researchers need a reproducible and relevant model to test these new approaches. Due to its biological complexity, involving several organs and systemic reactions, no in vitro model proved itself relevant to study the burn wound process29. Rodent models have shown major discrepancies with humans due to major differences in biology, skin architecture, elasticity, and lack of adherence to the underlying structures29. In contrast, the swine model has proven to be relevant due to the structural similarity of swine skin to human skin30,31,32. It presents with a similar vascularization, elastic fiber composition, and renewal timing. Moreover, the hair follicle and apocrine annexes allow for islanded re-epithelialization, as can be observed in clinical superficial burns33,34. More specifically, Yucatan minipig models provide interesting features, making them relevant to studying pigmented skin35 and long-term outcomes with minimal physical changes36.
The purpose of this article is to describe a reliable multi-degree burn model in Yucat&#225;n pigs, enabling the study of several second and third-degree burns on the same subject. This provides a relevant and reproducible model for studying diagnostic and therapeutic innovations for the management of burns. Further, this model features different burn types and severity, a long-term follow-up allowing the study of burn contracture and pathologic healing, and pigmented skin differential behavior, which is known to have specific characteristics.

Author Spotlight: A Multi-Depth Porcine Model for Comprehensive Study of Burn Injuries and Healing Processes

A Swine Burn Model for Investigating the Healing Process in Multiple Depth Burn Wounds

The objective of our research is to provide a reliable and robust model to study multiple burn injuries and its healing process. This is relevant for both diagnosis and treatment research. We successfully established a multi depth model of burns that accurately mimics the burns in humans.We standardized this protocol by providing specific details of one, making device, temperature and time of contact, which makes it easy to reproduce the model by other researchers in the field. By using this model, we allow studying the healing process with a long-term follow-up while minimizing intra-individual variability. In addition, the high melanin content of the skin allows advanced research relevant to high prototypes.Swine models of burn injury are important due to their similarities with human burns. Our model allows us to observe the changes in the early phase of healing when treatment decisions need to be made, as well as in the late phase when scar formations need to be minimized for aesthetic and functional recovery. Our lab at Massachusetts General Hospital is developing non-invasive biomedical devices to assess burn severity and healing potential at various stages, aiming to improve clinical burn management through insights from initial experiments.

Swine Burn Model for the Analysis of Tissue Regeneration in Multiple Depth Wounds

To begin, place an anesthetized pig in a prone position. Disinfect the skin with 7.5%povidone iodine, followed by 0.9%saline solution. Then dry the skin.Grasp a heated brass block with heat-resistant gloves and place it on the designated tattoo spot. Start the timer as soon as the brass block touches the skin. Remove the brass block after 30 seconds, then place it back in its dedicated heating container.Monitor the temperature until it reaches the target. Assess the aspect of wounds following burn creation. Next, place a petroleum-impregnated gauze on each burn location.Cover it with dry non-woven gauze. Spray a tincture of benzoin solution on the surrounding skin to help the dressings adhere better. Then place a large, transparent adhesive dressing over it.Wrap the animal in a sufficiently tight self-adherent adhesive wrap. Add a final layer of tubular stockinette to complete the multilayer dressing.

swine-burn-model-for-analysis-tissue-regeneration-multiple-depth

Research

JoVE Journal

Medicine

Burn wound healing is a complex and long process. Despite extensive experience, plastic surgeons and specialized teams in burn centers still face significant challenges. Among these challenges, the extent of the burned soft tissue can evolve in the early phase, creating a delicate balance between conservative treatments and necrosing tissue removal. Thermal burns are the most common type, and burn depth varies depending on multiple parameters, such as temperature and exposure time. Burn depth also varies in time, and the secondary aggravation of the &#34;shadow zone&#34; remains a poorly understood phenomenon. In response to these challenges, several innovative treatments have been studied, and more are in the early development phase. Nanoparticles in modern wound dressings and artificial skin are examples of these modern therapies still under evaluation. Taken together, both burn diagnosis and burn treatments need substantial advancements, and research teams need a reliable and relevant model to test new tools and therapies. Among animal models, swine are the most relevant because of their strong similarities in skin structure with humans. More specifically, Yucatan minipigs show interesting features such as melanin pigmentation and slow growth, allowing for studying high phototypes and long-term healing. This article aims to describe a reliable and reproducible protocol to study multi-depth burn wounds in Yucatan minipigs, enabling long-term follow-up and providing a relevant model for diagnosis and therapeutic studies.

This protocol describes a reproducible multi-depth burn wound model in a Yucatan minipigs.