The use of larvae therapy to debride full thickness burns in the anaesthetically unfit patient: The Nottingham experience

Evolution of a concept with enzymatic debridement and autologous in situ cell and platelet-rich fibrin therapy (BroKerF)

BACKGROUND

Deep partial-thickness burns are traditionally treated by tangential excision and split thickness skin graft (STSG) coverage. STSGs create donor site morbidity and increase the wound surface in burn patients. Herein, we present a novel concept consisting of enzymatic debridement of deep partial-thickness burns followed by co-delivery of autologous keratinocyte suspension and plated-rich fibrin (PRF) or fibrin glue.

MATERIAL AND METHODS

In a retrospective case study, patients with deep partial-thickness burns treated with enzymatic debridement and autologous cell therapy combined with PRF or fibrin glue (BroKerF) between 2017 and 2018 were analysed. BroKerF was applied to up to 15% total body surface area (TBSA); larger injuries were combined with surgical excision and skin grafting. Exclusion criteria were age <18 or >70 years, I°, IIa°-only, III° burns and loss of follow-up.

RESULTS

A total of 20 patients with burn injuries of 16.8% ± 10.3% TBSA and mean Abbreviated Burn Severity Score 5.45 ± 1.8 were identified. Of the patients, 65% (n = 13) were treated with PRF, while 35% (n = 7) were treated with fibrin glue. The mean area treated with BroKerF was 7.5% ± 0.05% TBSA, mean time to full epithelialization was 21.06 ± 9.2 days and mean hospitalization time was 24.7 ± 14.4 days. Of the patients, 35% (n = 7) needed additional STSG, 43% (n = 3) of whom had biopsy-proven wound infections.

CONCLUSION

BroKerF is an innovative treatment strategy, which, in our opinion, will show its efficacy when higher standardization is achieved. The combination of selective debridement and autologous skin cells in a fibrin matrix combines regenerative measures for burn treatment.

LAY SUMMARY

Patients suffering from large burn wounds often require the use of large skin grafts to bring burned areas to heal. Before the application of skin grafts, the burned skin must be removed either by surgery or using enzymatic agents. In this article, we describe a method where small areas of skin are taken and skin cells are extracted and sprayed on wound areas that were treated with an enzymatic agent. The cells are held in place by a substance extracted from patients' blood (PRF) that is sprayed on the wound together with the skin cells. We believe this technique can be helpful to reduce the need of skin grafts in burned patients and improve the healing process.

A molecular approach to maggot debridement therapy with Lucilia sericata and its excretions/secretions in wound healing

Chronic wounds caused by underlying physiological causes such as diabetic wounds, pressure ulcers, venous leg ulcers and infected wounds affect a significant portion of the population. In order to treat chronic wounds, a strong debridement, removal of necrotic tissue, elimination of infection and stimulation of granulation tissue are required. Maggot debridement therapy (MDT), which is an alternative treatment method based on history, has been used quite widely. MDT is an efficient, simple, cost-effective and reliable biosurgery method using mostly larvae of Lucilia sericata fly species. Larvae can both physically remove necrotic tissue from the wound site and stimulate wound healing by activating molecular processes in the wound area through the enzymes they secrete. The larvae can stimulate wound healing by activating molecular processes in the wound area through enzymes in their excretions/secretions (ES). Studies have shown that ES has antibacterial, antifungal, anti-inflammatory, angiogenic, proliferative, hemostatic and tissue-regenerating effects both in vivo and in vitro. It is suggested that these effects stimulate wound healing and accelerate wound healing by initiating a direct signal cascade with cells in the wound area. However, the enzymes and peptides in ES are mostly still undefined. Examining the molecular content of ES and the biological effects of these ingredients is quite important to illuminate the molecular mechanism underlying MDT. More importantly, ES has the potential to have positive effects on wound healing and to be used more as a therapeutic agent in the future, so it can be applied as an alternative to MDT in wound healing.

Evidence and Trends in Burn Wound Debridement: An Evidence Map

Treatment of the burn wound is crucial in care of severely burned patients. Surgical strategies differ in technique and timing of wound excision and are considered to have an impact on morbidity and mortality of burn patients. Most techniques and strategies have been established during the last century and are still standard of care. Nonetheless, several newer techniques have been presented and evaluated recently. To summarize the evidence and trends for eschar removal by burn wound debridement currently available, an evidence map as variant of the systematic review, was prepared. For this purpose, a systematic literature search was performed in the PubMed databases until December 2016. While overall evidence in this domain is low, recent publications focus on optimal timing of wound excision, enzymatic debridement, and hydrosurgery. Several studies report the benefit of an early wound excision in terms of shorter hospital stay, lower wound infection rate, and reduction of postburn metabolic changes. Enzymatic debridement has been shown to be an effective tool for early eschar removal and in addition reduces the need for autografting of the debrided burn wound with a relatively high level of evidence (LoE 2-). Wound debridement by means of hydrosurgery is more precise compared to conventional wound excision and preserves viable dermis, but a positive effect on wound healing or scar formation could not been shown (LoE 2). Furthermore, rarely reported techniques comprise larvae therapy, debridement by laser, and other technical adjuncts, but the level of evidence is limited (LoE 4-/5).

Stem cells, niches and scaffolds: Applications to burns and wound care

The importance of skin to survival, and the devastating physical and psychological consequences of scarring following reparative healing of extensive or difficult to heal human wounds, cannot be disputed. We discuss the significant challenges faced by patients and healthcare providers alike in treating these wounds. New state of the art technologies have provided remarkable insights into the role of skin stem and progenitor cells and their niches in maintaining skin homeostasis and in reparative wound healing. Based on this knowledge, we examine different approaches to repair extensive burn injury and chronic wounds, including full and split thickness skin grafts, temporising matrices and scaffolds, and composite cultured skin products. Notable developments include next generation skin substitutes to replace split thickness skin autografts and next generation gene editing coupled with cell therapies to treat genodermatoses. Further refinements are predicted with the advent of bioprinting technologies, and newly defined biomaterials and autologous cell sources that can be engineered to more accurately replicate human skin architecture, function and cosmesis. These advances will undoubtedly improve quality of life for patients with extensive burns and difficult to heal wounds.

Next Generation Sequencing Identifies Five Major Classes of Potentially Therapeutic Enzymes Secreted by Lucilia sericata Medical Maggots

Lucilia sericata larvae are used as an alternative treatment for recalcitrant and chronic wounds. Their excretions/secretions contain molecules that facilitate tissue debridement, disinfect, or accelerate wound healing and have therefore been recognized as a potential source of novel therapeutic compounds. Among the substances present in excretions/secretions various peptidase activities promoting the wound healing processes have been detected but the peptidases responsible for these activities remain mostly unidentified. To explore these enzymes we applied next generation sequencing to analyze the transcriptomes of different maggot tissues (salivary glands, gut, and crop) associated with the production of excretions/secretions and/or with digestion as well as the rest of the larval body. As a result we obtained more than 123.8 million paired-end reads, which were assembled de novo using Trinity and Oases assemblers, yielding 41,421 contigs with an N50 contig length of 2.22 kb and a total length of 67.79 Mb. BLASTp analysis against the MEROPS database identified 1729 contigs in 577 clusters encoding five peptidase classes (serine, cysteine, aspartic, threonine, and metallopeptidases), which were assigned to 26 clans, 48 families, and 185 peptidase species. The individual enzymes were differentially expressed among maggot tissues and included peptidase activities related to the therapeutic effects of maggot excretions/secretions.

Maggot Debridement Therapy in Disaster Medicine

BACKGROUND

When disaster strikes, the number of patients requiring treatment can be overwhelming. In low-income countries, resources to assist the injured in a timely fashion may be limited. As a consequence, necrosis and wound infection in disaster patients is common and frequently leads to adverse health outcomes such as amputations, chronic wounds, and loss of life. In such compromised health care environments, low-tech and cheap wound care options are required that are in ready supply, easy to use, and have multiple therapeutic benefits. Maggot debridement therapy (MDT) is one such wound care option and may prove to be an invaluable tool in the treatment of wounds post-disaster.

DISCUSSION

This report provides an overview of the wound burden experienced in various types of disaster, followed by a discussion of current treatment approaches, and the role MDT may play in the treatment of complex wounds in challenging health care conditions. Maggot debridement therapy removes necrotic and devitalized tissue, controls wound infection, and stimulates wound healing. These properties suggest that medicinal maggots could assist health care professionals in the debridement of disaster wounds, to control or prevent infection, and to prepare the wound bed for reconstructive surgery. Maggot debridement therapy-assisted wound care would be led by health care workers rather than physicians, which would allow the latter to focus on reconstructive and other surgical interventions. Moreover, MDT could provide a larger window for time-critical interventions, such as fasciotomies to treat compartment syndrome and amputations in case of life-threatening wound infection.

RECOMMENDATIONS

There are social, medical, and logistic hurdles to overcome before MDT can become widely available in disaster medical aid. Thus, research is needed to further demonstrate the utility of MDT in Disaster Medicine. There is also a need for reliable MDT logistics and supply chain networks. Integration with other disaster management activities will also be essential.

CONCLUSIONS

In the aftermath of disasters, MDT could play an important role facilitating timely and efficient medical treatment and improving patient outcomes. Existing social, medical, and logistic barriers will need to be overcome for MDT to be mainstreamed in Disaster Medicine.

The immunobiology of myiasis infections--whatever happened to vaccination?

The current state of myiasis vaccine technologies are reviewed mainly in the primary research genera of Lucilia and Hypoderma. The importance of myiasis flies as primary causes of morbidity and mortality in agricultural species and man has not diminished despite the existence of good control strategies. However, the development of vaccines against myiasis infections has been relatively quiescent for more than 10 years despite the rapid development of genomic and proteomic analysis and of skills in data interpretation. The value of vaccine research in an era of chemical primacy is analysed. In fact, recent findings of drug resistance and the impact of animal welfare concerns should mean a renewed interest in alternative controls. The reasons that this has not been true to date are explored and new possibilities discussed.