Multiple actions ofLucilia sericatalarvae in hard-to-heal wounds

Pain Assessment in Patients Undergoing Maggot Debridement Therapy in the Process of Local Treatment of Chronic Wounds

(1) Background: Developing and implementing strategies for local wound care focused on improving the quality of life related to health status and reducing treatment costs for this patient group poses a challenge to contemporary healthcare systems. The utilization of Maggot Debridement Therapy (MDT) is one potential form of local therapy for preparing wounds for the healing process. The debridement of the wound bed with medical maggots is highly precise, and the defensins produced by the larvae eliminate bacteria and stimulate tissue regeneration. However, the presence of larvae in the wound may lead to the occurrence of pain symptoms. The aim of the study was to assess the intensity of pain during larval therapy in patients with chronic wounds treated in outpatient settings. (2) Patients and Methods: The study employed a diagnostic survey and estimation; the tool consisted of a research protocol comprising three parts (questionnaires). Inclusion criteria for the study were voluntary consent to participate (completion of the MDT acceptance questionnaire), chronic wounds of vascular etiology or pressure injuries, full-thickness skin or deep tissue damage, and pain intensity not exceeding four on the NRS (Numerical Rating Scale: 0-no pain, 10-the most severe pain) at the time of the study. Patient observation during the 3-day treatment was conducted by a wound care clinic nurse, assessing pain intensity once every 24 h during the larval dressing changes. (3) Results: Out of 348 individuals who qualified for MDT during the study period, 215 individuals participated in the study: 94 women (43.7%) and 121 men (56.3%). The age of the participants ranged from 28 to 97 years (mean 69.87 ± 12.95). Each participant experienced mild pain (2.26 ± 1.60 on the NRS) on the day of qualification for the study. An increase in pain intensity, according to subjective assessments, was reported by 29.3% of participants (n = 63). On the third day of MDT therapy, an increase in pain intensity was observed, reaching a mean value of 4.79 ± 2.12 (p < 0.0001). Participants with pressure injuries showed the lowest pain intensity, which increased in consecutive days for all types of wounds. Additionally, the increase in pain intensity in patients with vascular etiology wounds was greater compared to patients with pressure injuries (p < 0.001). (4) Conclusions: Local wound therapy with Lucilia sericata larvae increases pain intensity in the consecutive days of treatment. The wound area and the time since its occurrence may determine pain symptoms.

Cloning, expression and molecular analysis of recombinant Netrin-A protein of Lucilia sericata Meigen (Diptera: Calliphoridae) larvae

Objectives

Lucilia sericata (Diptera: Calliphoridae) is used in larval therapy for wound healing. Netrin-A is an enzyme secreted from the salivary glands of these larvae, and has a central role in neural regeneration and angiogenesis. This study aimed to produce the recombinant Netrin-A protein from Lucilia sericata larvae by the baculovirus expression vector system in the Sf9 insect cell line.

Methods

The coding sequence of Netrin-A was cloned, amplified in the pTG19 vector, and then cloned in the pFastBac HTA vector. It was then transformed into DH10Bac, and the recombinant Bacmid was subsequently transfected into Sf9 cells. The recombinant Netrin-A was purified by Ni-NTA agarose. The evaluation was done using SDS-PAGE and western blot, respectively. Finally, its concentration was calculated with the Bradford assay.

Results

The molecular weight of this protein was 52 kDa with 404 amino acids. The signal peptide was located between amino acids 24 and 25. The concentration of Netrin-A was calculated to be 48.8 μg/ml. It reaffirmed the characterized gene codes of Lucilia sericata Netrin-A in a previous study.

Conclusions

The generation of recombinant Netrin-A could be used in larval therapy, and as a biomarker in certain diseases. The netrin-A of Lucilia sericata was unprecedentedly cloned and expressed in a eukaryotic cell line. Given that this larva is FDA-approved, and non-pathogenic, it conduces to research on the development of maggot therapy in future.

Development of dual-functional core-shell electrospun mats with controlled release of anti-inflammatory and anti-bacterial agents for the treatment of corneal alkali burn injuries

In this study, a novel dual-drug carrier for the co-administration of an anti-inflammatory and antibiotic agent consisting of core-shell nanofibers for the treatment of cornea alkali burns was designed. The core-shell nanofibers were prepared via coaxial electrospinning of curcumin-loaded silk fibroin as the core and vancomycin-loaded chitosan/polyvinyl alcohol (PVA) as the shell. Electron microscopy (SEM and TEM) images confirmed the preparation of smooth, bead-free, and continuous fibers that formed clear core-shell structures. For further studies, nanofiber mats were cross-linked by heat treatment to avoid rapid disintegration in water and improve both mechanical properties and drug release. The release profile of curcumin and vancomycin indicated an initial burst release, continued by the extended release of both drugs within 72 hours. Rabbit corneal cells demonstrated high rates of proliferation when evaluated using a cell metabolism assay. Finally, the therapeutic efficiency of core/shell nanofibers in healing cornea alkali burn was studied by microscopic and macroscopic observation, fluorescence staining, and hematoxylin-eosin assay on rabbit eyes. The anti-inflammatory activity of fabricated fibers was evaluated by enzyme-linked immunosorbent assay and Immunofluorescence analysis. In conclusion, using a robust array of in vitro and in vivo experiments this study demonstrated the ability of the dual-drug carriers to promote corneal re-epithelialization, minimize inflammation, and inhibit corneal neovascularization. Since these parameters are critical to the healing of corneal wounds from alkali burns, we suggest that this discovery represents a promising future therapeutic agent that warrants further study in humans.

Larval Wound Therapy: Possibilities and Potential Limitations-A Literature Review

Patient-centered care (PCC) is recognized as a standard in healthcare for determining high quality. Honoring patients' values, experiences, needs, and preferences in devising, coordinating, and delivering care underscores the enhancement of the therapeutic rapport between patients and healthcare providers. Wound treatment involves a multi-stage process encompassing diagnostics and local wound dressing, which reduces the risk of infection through a coordinated interdisciplinary team. Within this team, nurses undertake specific professional functions and roles. The implementation of local therapy using innovative and scientifically substantiated methods may be hindered by a deficit of knowledge or inappropriate knowledge among staff and patients themselves. This study presents the challenges concerning the care of patients with chronic wounds treated using Lucilia sericata larvae, based on a review of the current scientific literature. A critical analysis of the literature spanning from 2002 to 2022 was conducted using the Medline, PubMed, Cochrane, and Termedia databases, employing keywords such as "maggot debridement therapy" in relation to acceptance and perception. As a result of the preliminary selection, 472 papers were identified, of which 12 publications were included in the development of this concept. The acquired data were organized and presented in the concluding section in the form of tables, accompanied by descriptions and references to individual studies. Negative psychological and somatic sensations were among the most prominent challenges among patients treated with Maggot Debridement Therapy (MDT). Pain related to peripheral ischemia or infection in this group of patients requires pain prophylaxis, including hyperalgesia and allodynia, in order to improve method tolerance. On the other hand, augmenting patients' understanding of MDT diminishes negative emotions, reinforces positive behaviors, and mitigates anxiety levels. MDT constitutes an effective and safe method. Its widespread use for chronic wounds requires substantial knowledge among healthcare professionals and patient education, along with that of their caregivers, to develop a positive attitude.

Effectiveness of Secretome from Human Umbilical Cord Mesenchymal Stem Cells in Gel (10% SM-hUCMSC Gel) for Chronic Wounds (Diabetic and Trophic Ulcer) - Phase 2 Clinical Trial

Background

Chronic wounds carry financial burdens and increase morbidity and mortality, especially in diabetic ulcers and Hansen's Morbus. More than 50% of chronic ulcers are difficult to heal with regular treatment and require new types of therapy such as the use of secretome of human umbilical cord mesenchymal stem cells (SM-hUCMSC).

Methods

This experimental study was carried out to see the effectiveness of using SM-hUCMSC in diabetic ulcers and Hansen's Morbus in four medical facilities (multicentre). The level of active secretion has been measured by default in 10% SM-hUCMSC gel, used as a treatment intervention. The primary outcome is wound healing in terms of the length, width, and extent of the wound. The secondary is the side effects of treatment 2 weeks after administration. Follow-up visits will be scheduled at 1 and 2 weeks post-treatment.

Results

Forty-one chronic ulcers successfully followed the study until the end. In patients with chronic ulcers, the mean ulcer length, width, and area were 1.60 (0,50-13,0), 1.3 (0,5-6,0), and 2.21 (0,25-78) cm square, respectively, before interventions and 1 (0-12), 0,8 (0-6,0), and 1 (0-72) square cm after interventions at the second follow-up. The change between the beginning and end of the intervention was significant (p-value <0.05).

Conclusion

The use of 10% SM-hUCMSC gel topically has been proven effective in accelerating the process of wound healing, especially chronic ulcers with side effects that are not present in this study.

Transdermal drug delivery via microneedles to mediate wound microenvironment

Cutaneous wound healing is a complex process, while modulating the wound microenvironment has become an essential therapeutic goal. In clinics, advanced dressings or dermal templates can promote wound healing but their ability in mediating wound microenvironment is limited. In the last decade, microneedle (MN) array patches have emerged as a new class of wound dressings. These dressings enable non-invasive transdermal and precise medication delivery. Combined with smart materials, MN additionally allows real-time monitoring of wound site markers such as inflammatory factors, oxygen levels, vascularization, pH and temperature, etc., while releasing therapeutic molecules responsively to the wound site. In this review, the MN-based strategies were reviewed for modulating wound microenvironment via introducing the main characteristics of the wound microenvironment and various types of MN-based delivery systems. Additionally, the progress and future trends in the application of MNs in mediating wound microenvironments are also discussed.

Diabetic foot ulcer: Challenges and future

Diabetic foot ulcers (DFUs) have become one of the important causes of mortality and morbidity in patients with diabetes, and they are also a common cause of hospitalization, which places a heavy burden on patients and society. The prevention and treatment of DFUs requires multidisciplinary management. By controlling various risk factors, such as blood glucose levels, blood pressure, lipid levels and smoking cessation, local management of DFUs should be strengthened, such as debridement, dressing, revascularization, stem cell decompression and oxygen therapy. If necessary, systemic anti-infection treatment should be administered. We reviewed the progress in the clinical practice of treating DFUs in recent years, such as revascularization, wound repair, offloading, stem cell transplantation, and anti-infection treatment. We also summarized and prospectively analyzed some new technologies and measurements used in the treatment of DFUs and noted the future challenges and directions for the development of DFU treatments.

Identification, molecular characterization, and in silico structural analysis of larval salivary glands Netrin-A as a potent biomarker from Lucilia sericata (Diptera: Calliphoridae)

The greenbottle blowfly Lucilia sericata (L. sericata) is increasingly used in larval therapy of chronic wounds. Netrins as bifunctional proteins are in the superfamily of Laminins secreted from larval salivary glands. The Netrin protein has a significant instructive role in axon guidance, causing neuronal outgrowth, angiogenesis, and cell migration. It seems to be crucial in wound healing and acts as a potential biomarker in diagnosing some clinical diseases. This survey aimed to identify molecular features and analyze in silico structural configuration of Netrin-A in L. sericata larvae. The larvae were reared under standard maggotarium conditions. The nucleic acid sequence of L. sericata Netrin-A (LSN-A) was then identified using rapid amplification of circular DNA ends (RACE) and rapid amplification of genomic ends (RAGE). Parts of the Netrin-A gene, including the middle, 3'-, and 5'-ends, were identified, TA cloned in pTG19 plasmid, and transferred into DH5ɑ Escherichia coli. Each part was sequenced and assembled using SeqMan software. This gene structure was further subjected to in silico analysis. The DNA of LSN-A was identified to be 2407 bp, while its mRNA sequence was recognized as 2115 bp by Oligo0.7 software. It translated the Netrin-A protein with 704 amino acid residues. Its estimated molecular weight was 78.6 kDa. Sequencing of this fragment and its BLAST analysis revealed laminin-based high (95%) similarity with the mRNA sequence of Lucilia cuprina Netrin-A. The 3-D structure of Netrin-A drawn by SWISS-MODEL exhibited its partial resemblance to the reference molecule Netrin-1 of Homo sapiens. This study supports the molecular and structural analyses of LSN-A protein, which could lead to wound treatment. Ultimately, it can be an effective candidate to ameliorate injury. Our next attempt is to produce LSN-A recombinant protein for use in biomedical sciences.

Larval Therapy for Treatment of Chronic Wounds Colonized by Multi-resistant Pathogens in a Pediatric Patient: A Case Study

BACKGROUND

Chronic wounds are susceptible to colonization with gram-positive and gram-negative bacteria that may be resistant to antimicrobial dressings and systemic antibiotics. In January 2004, the US Food and Drugs Administration approved use of medicinal larvae for use in humans and animals for resistant organisms. Despite use in adults, there is a paucity of evidence evaluating its efficacy and safety in the pediatric population.

CASE

T was a 5-year-old boy with several chronic wounds infected with multidrug-resistant Pseudomonas aeruginosa. The wounds were originally treated with chemical debridement, dressings containing ionic silver, negative-pressure wound therapy (NPWT), and antibiotics without success. Consequently, a multidisciplinary team implemented maggot debridement therapy (MDT).

CONCLUSIONS

After MDT, one wound completely epithelialized and the other wounds achieved a reduction in size with 70% epithelization. Therapy also led to a reduction in wound odor, exudate, and pain. The other wounds were closed after additional management with dressing containing nanocrystalline silver and NPWT.

Burn Wound Healing: Clinical Complications, Medical Care, Treatment, and Dressing Types: The Current State of Knowledge for Clinical Practice

According to the World Health Organization (WHO), it is estimated that each year approximately 11 million people suffer from burn wounds, 180,000 of whom die because of such injuries. Regardless of the factors causing burns, these are complicated wounds that are difficult to heal and are associated with high mortality rates. Medical care of a burn patient requires a lot of commitment, experience, and multidirectional management, including surgical activities and widely understood pharmacological approaches. This paper aims to comprehensively review the current literature concerning burn wounds, including classification of burns, complications, medical care, and pharmacological treatment. We also overviewed the dressings (with an emphasis on the newest innovations in this field) that are currently used in medical practice to heal wounds.

Maggot Debridement Therapy for Chronic Leg and Foot Ulcers: A Review of Randomized Controlled Trials

OBJECTIVE

To critically analyze the existing randomized controlled trials (RCTs) on the clinical, economic, and psychological implications of maggot debridement therapy (MDT).

DATA SOURCES

An exhaustive literature search for English-language publications was conducted using MEDLINE, EMBASE, and PubMed.

STUDY SELECTION

Keywords used for the search were based on the PICO (Population, Intervention, Comparison, Outcome) framework. The titles, abstracts, and relevant full-text articles were screened. Seven RCTs were selected after applying the inclusion and exclusion criteria.

DATA EXTRACTION

Data pertaining to the primary and secondary outcomes of each study were extracted.

DATA SYNTHESIS

The data extracted were evaluated and categorized into clinical, economic, and psychological outcomes pertaining to MDT. A judicious evaluation of these outcomes was made, and the following conclusions were drawn.

CONCLUSIONS

There exists heterogeneity in the extant RCTs, but MDT appears to be effective for a quick early debridement. For diabetic foot ulcers, MDT improves debridement, controls infection, and enhances wound healing. In chronic peripheral vascular disease ulcers, it aids in early debridement, but the final outcome is equivocal. Further robust integrated health economic and parallel qualitative assessment studies are recommended to understand the cost-effectiveness and patient acceptability and experience.

A narrative review of the epidemiology and economics of chronic wounds

Chronic wounds have a debilitating effect on the quality of life of many individuals, and the large economic impact on health system budgets warrants greater attention in policy making and condition management than is currently evident. The aim of this narrative review is to summarize the nature and extent of the chronic wound problem that confronts health systems across the world. The first section is used to highlight the underlying epidemiology relating to chronic wounds, while the second explores the economic costs associated with them and the relative efficiency of measures designed to manage them.

The effect of Lucilia sericata larval excretion/secretion (ES) products on cellular responses in wound healing

Chronic wounds are still regarded as a serious public health concern, which are on the increase mainly due to the changes in life styles and aging of the human population. There are different types of chronic wounds, each of which requires slightly different treatment strategies. Nevertheless, wound bed preparation is included in treatment of all types of chronic wounds and involves tissue debridement, inflammation, and infection control, as well as moisture balance and epithelial edge advancement. Maggot therapy (MT) is a form of biological debridement which involves the application of live medical grade Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae) larvae. Whereas it was initially thought to act mainly through debridement, today MT is known to influence all four overlapping physiological phases of wound repair: homeostasis, inflammation, proliferation, and remodelling/maturing. During MT, medical-grade larvae are applied either freely or enclosed in tea-bag like devices (biobag) inside the wounds, which suggests that larva excretion/secretion (ES) products can facilitate the healing processes directly without the need of direct contact with the larvae. This review summarizes the relevant literature on ES-mediated effects on the cellular responses involved in wound healing.

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.

Maggot debridement therapy in critical limb ischaemia: a case study

OBJECTIVE

In critical limb ischaemia (CLI), first-line therapy is revascularisation, but alternative treatment options are needed in certain cases. Maggot debridement therapy (MDT) is historically considered to be contraindicated in ischaemic ulcers. Wound care in patients with CLI is becoming increasingly diverse with the development of novel revascularisation strategies; therefore, CLI now needs to be reconsidered as an indication for MDT.

METHOD

We retrospectively reviewed five legs with CLI (five male, one female) treated with MDT between January 2013 and December 2017. Changes in skin perfusion pressure (SPP) around the ulcer before and after MDT were evaluated. One or two cycles of MDT were performed (eight in total). We also evaluated the proportion of necrotic tissue in the ulcer and the presence of exposed necrotic bone. The proportion of necrotic tissue in the ulcer was classified as NT 1+ (<25%), NT 2+ (25-50%), NT 3+ (50-75%) or NT 4+ (>75%).

RESULTS

When the proportion of necrotic tissue was >50%, with no exposed necrotic bone in the wound, an increase in SPP was observed after five (62.5%) of eight cycles of MDT. And with a proportion of necrotic tissue of <25% and/or exposed necrotic bone in the wound, a decrease in SPP was observed after three (37.5%) of eight cycles. Wound healing was accelerated in the presence of increased SPP.

CONCLUSION

Effective MDT with increased SPP requires an ulcerative state of necrotic tissue grade > NT 3+, with no exposed necrotic bone.

What is the effect of larval therapy on the debridement of venous leg ulcers? A systematic review

AIM

To determine the impact of larval therapy on the debridement of venous leg ulcers, in comparison to other debridement methods or no debridement.

METHOD

Using systematic review methodology, published quantitative studies focusing on the effect of larval therapy on the debridement of venous leg ulcers were included. The search was conducted in January 2020 and updated in May 2021 using CINAHL, PubMed, Embase, and the Cochrane library, and returned 357 records, of which six studies met the inclusion criteria. Data were extracted using a predesigned extraction tool and all studies were quality appraised using the RevMan risk of bias assessment tool.

RESULTS

Larval therapy was found to debride at a faster rate than hydrogel (p = 0.011, p < 0.001, p = 0.0039), have a similar effect to sharp debridement (p = 0.12, p = 0.62), and was a resource-effective method of debridement (p < 0.05, p < 0.001, p < 0.001). When larval therapy in combination with compression therapy was compared to compression alone, larvae had a greater effect on debridement (p < 0.05), however, it did not improve overall wound healing rates (p = 0.54, p = 0.664, p = 0.02). Pain levels increased during larval therapy and reduced after treatment, when compared to other standard debridement techniques.

CONCLUSION

Larval therapy promotes rapid debridement of venous leg ulcers. However, further high quality randomised controlled trials, comparing larval therapy to other debridement methods for venous leg ulcers, incorporating the use of compression is required to determine the long term effects of larval therapy.

Advantages of Maggot Debridement Therapy for Chronic Wounds: A Bibliographic Review

GENERAL PURPOSE

To present an overview of the advantages of maggot debridement therapy as a treatment for chronic wounds through the review of several larval properties.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant will be able to:1. Summarize the use, process, and precautions for maggot debridement to treat chronic wounds.2. Synthesize the results of the bibliographic review of the use of maggot debridement to treat chronic wounds.

ABSTRACT

Maggot debridement therapy (MDT) is effective for ulcer debridement, achieving it in less time than other therapies. It offers a benefit to healing. However, it is unclear whether maggots reduce treatment time and there is considerable controversy around the treatment's potential antimicrobial action and cost-effectiveness. Nevertheless, it can be effective in preventing amputations and reducing the need for systemic antibiotics. This bibliographic review assesses the advantages of MDT as a treatment for chronic wounds through the review of several larval properties. The review was carried out by consulting biomedical databases including CINAHL, MEDLINE (PubMed), and Scopus, and concludes that MDT is an effective debridement and potential technique to facilitate healing. However, more data is needed on the wound type application frequency and the efficacy of treatment.

Functional Mining of the Crotalus Spp. Venom Protease Repertoire Reveals Potential for Chronic Wound Therapeutics

Chronic wounds are a major health problem that cause millions of dollars in expenses every year. Among all the treatments used, active wound treatments such as enzymatic treatments represent a cheaper and specific option with a fast growth category in the market. In particular, bacterial and plant proteases have been employed due to their homology to human proteases, which drive the normal wound healing process. However, the use of these proteases has demonstrated results with low reproducibility. Therefore, alternative sources of proteases such as snake venom have been proposed. Here, we performed a functional mining of proteases from rattlesnakes (Crotalus ornatus, C. molossus nigrescens, C. scutulatus, and C. atrox) due to their high protease predominance and similarity to native proteases. To characterize Crotalus spp. Proteases, we performed different protease assays to measure and confirm the presence of metalloproteases and serine proteases, such as the universal protease assay and zymography, using several substrates such as gelatin, casein, hemoglobin, L-TAME, fibrinogen, and fibrin. We found that all our venom extracts degraded casein, gelatin, L-TAME, fibrinogen, and fibrin, but not hemoglobin. Crotalus ornatus and C. m. nigrescens extracts were the most proteolytic venoms among the samples. Particularly, C. ornatus predominantly possessed low molecular weight proteases (P-I metalloproteases). Our results demonstrated the presence of metalloproteases capable of degrading gelatin (a collagen derivative) and fibrin clots, whereas serine proteases were capable of degrading fibrinogen-generating fibrin clots, mimicking thrombin activity. Moreover, we demonstrated that Crotalus spp. are a valuable source of proteases that can aid chronic wound-healing treatments.

Practical context of enzymatic treatment for wound healing: A secreted protease approach (Review)

Skin wounds have been extensively studied as their healing represents a critical step towards achieving homeostasis following a traumatic event. Dependent on the severity of the damage, wounds are categorized as either acute or chronic. To date, chronic wounds have the highest economic impact as long term increases wound care costs. Chronic wounds affect 6.5 million patients in the United States with an annual estimated expense of $25 billion for the health care system. Among wound treatment categories, active wound care represents the fastest-growing category due to its specific actions and lower costs. Within this category, proteases from various sources have been used as successful agents in debridement wound care. The wound healing process is predominantly mediated by matrix metalloproteinases (MMPs) that, when dysregulated, result in defective wound healing. Therapeutic activity has been described for animal secretions including fish epithelial mucus, maggot secretory products and snake venom, which contain secreted proteases (SPs). No further alternatives for use, sources or types of proteases used for wound healing have been found in the literature to date. Through the present review, the context of enzymatic wound care alternatives will be discussed. In addition, substrate homology of SPs and human MMPs will be compared and contrasted. The purpose of these discussions is to identify and propose the stages of wound healing in which SPs may be used as therapeutic agents to improve the wound healing process.

Bacteriophages for Chronic Wound Treatment: from Traditional to Novel Delivery Systems

The treatment and management of chronic wounds presents a massive financial burden for global health care systems, with significant and disturbing consequences for the patients affected. These wounds remain challenging to treat, reduce the patients' life quality, and are responsible for a high percentage of limb amputations and many premature deaths. The presence of bacterial biofilms hampers chronic wound therapy due to the high tolerance of biofilm cells to many first- and second-line antibiotics. Due to the appearance of antibiotic-resistant and multidrug-resistant pathogens in these types of wounds, the research for alternative and complementary therapeutic approaches has increased. Bacteriophage (phage) therapy, discovered in the early 1900s, has been revived in the last few decades due to its antibacterial efficacy against antibiotic-resistant clinical isolates. Its use in the treatment of non-healing wounds has shown promising outcomes. In this review, we focus on the societal problems of chronic wounds, describe both the history and ongoing clinical trials of chronic wound-related treatments, and also outline experiments carried out for efficacy evaluation with different phage-host systems using in vitro, ex vivo, and in vivo animal models. We also describe the modern and most recent delivery systems developed for the incorporation of phages for species-targeted antibacterial control while protecting them upon exposure to harsh conditions, increasing the shelf life and facilitating storage of phage-based products. In this review, we also highlight the advances in phage therapy regulation.

Terapia Larval con Musca Domestica en el Tratamiento de la úlcera Leishmánicaen un Modelo Murino

La leishmaniosis es una enfermedad con gran impacto en salud pública dado a las características de las lesiones tegumentarias. El tratamiento experimental con terapia larval (TL) ha mostrado su uso potencial para la cura de la leishmaniosis, sin embargo, se han utilizado especies de moscas para TL en heridas causadas por Leishmania que no son de fácil colecta y cultivo bajo condiciones de laboratorio como Lucilia sericata o Calliphora vicina. El objetivo del presente trabajo fue usar una especie de mosca de fácil colecta, y de alta fecundidad como la Musca domestica para aplicarlas en TL de úlceras leishmánicas. Se realizó un estudio cuali-cuantitativo, de tipo descriptivo, mediante un diseño experimental empleado un modelo animal (Mesocricetus auratus), infectado con Leishmania amazonensis para evaluar el efecto terapéutico de la TL y comparar los resultados con el tratamiento químico antimonial de la droga experimental “Ulamina”. Se evidencia cicatrización y cura de la úlcera leishmánica en el 66,66 % de los animales tratados con TL en aplicación simple y del 100 % en TL combinada con Ulamina. El uso combinado de TL+Ulamina, muestra un efecto potenciador de la cura clínica de las úlceras, pero con persistente inflamación. Se observó una efectividad óptima de la TL con M. domestica, sobre las úlceras, aunque no se evidenció un efecto sobre L. amazonensis dado a la presencia de amastigotes en los frotis y a los amplicones obtenidos de 480 bp desde las improntas de los animales.

Effectiveness of Chronic Wound Debridement with the Use of Larvae of Lucilia Sericata

The process of successful wound healing depends on effective debridement and infection control. One method of wound debridement, known since antiquity, is based on the use of fly larvae. Solid scientific evidence proves that maggot debridement therapy (MDT), like surgical intervention, can be effectively and safely used to remove necrotic tissue. Based on a review of the related literature, this study was designed to assess the effectiveness of chronic wound cleansing with the use of larvae of Lucilia sericata (Phaenicia sericata). Maggot therapy, applied in wound debridement and treatment, is a safe and effective method. Its benefits are associated with debridement, disinfection and faster tissue growth. MDT may reduce the duration of antibiotic therapy and the need for hospitalization, or it may decrease the number of outpatient visits required. It is a relatively cost-effective method, and, in addition to financial gains, it may reduce the frequency of inpatient treatment. In the literature, an increasing amount of scientific evidence confirms that such treatment can effectively reduce the biofilm and bacterial load in a wound.

Regeneration and Repair of Skin Wounds: Various Strategies for Treatment

Skin as a mechanical barrier between the inner and outer environment of our body protects us against infection and electrolyte loss. This organ consists of 3 layers: the epidermis, dermis, and hypodermis. Any disruption in the integrity of skin leads to the formation of wounds, which are divided into 2 main categories: acute wounds and chronic wounds. Generally, acute wounds heal relatively faster. In contrast to acute wounds, closure of chronic wounds is delayed by 3 months after the initial insult. Treatment of chronic wounds has been one of the most challenging issues in the field of regenerative medicine, promoting scientists to develop various therapeutic strategies for a fast, qualified, and most cost-effective treatment modality. Here, we reviewed more recent approaches, including the development of stem cell therapy, tissue-engineered skin substitutes, and skin equivalents, for the healing of complex wounds.

Collagenolytic Enzymes and their Applications in Biomedicine

Nowadays, enzymatic therapy is a very promising line of treatment for many different diseases. There is a group of disorders and conditions, caused by fibrotic and scar processes and associated with the excessive accumulation of collagen that needs to be catabolized to normalize the connective tissue content. The human body normally synthesizes special extracellular enzymes, matrix metalloproteases (MMPs) by itself. These enzymes can cleave components of extracellular matrix (ECM) and different types of collagen and thus maintain the balance of the connective tissue components. MMPs are multifunctional enzymes and are involved in a variety of organism processes. However, under pathological conditions, the function of MMPs is not sufficient, and these enzymes fail to deal with disease. Thus, medical intervention is required. Enzymatic therapy is a very effective way of treating such collagen-associated conditions. It involves the application of exogenous collagenolytic enzymes that catabolize excessive collagen at the affected site and lead to the successful elimination of disease. Such collagenolytic enzymes are synthesized by many organisms: bacteria, animals (especially marine organisms), plants and fungi. The most studied and commercially available are collagenases from Clostridium histolyticum and from the pancreas of the crab Paralithodes camtschatica, due to their ability to effectively hydrolyse human collagen without affecting other tissues, and their wide pH ranges of collagenolytic activity. In the present review, we summarize not only the data concerning existing collagenase-based medications and their applications in different collagen-related diseases and conditions, but we also propose collagenases from different sources for their potential application in enzymatic therapy.

What is the optimal treatment time for larval therapy? A study on incubation time and tissue debridement by bagged maggots of the greenbottle fly, Lucilia sericata

The effective use of larvae of the greenbottle fly, Lucilia sericata, in wound debridement requires a working knowledge of how feeding changes over time. Using a laboratory assay and bagged larval dressings, the effect of incubation time on larval feeding rates and body mass was investigated for up to 120 hours at 32°C. The mass of tissue digested increased significantly in incremental 24-hour periods up to 72 hours, with no significant consumption occurring afterwards. Larval mass increased only up to 48 hours. A further test comparing the efficacy of a single 96-hour application of larvae against two consecutive 48-hour applications found that the mass of tissue digested in the latter was 14.3% higher than the former, a difference that was statistically significant. Current clinical guidance suggests a 4-day application period for bagged larvae. Based on these results, an incubation time of 72 hours (3 days) for bagged larvae would be the most effective at the study temperature. However, it is acknowledged that wound temperature can vary, whereby feeding rates would likely differ. In view of this, we conclude that a period of 3 to 4 days is optimum for the application of larvae, and current guidelines should be adhered to.

The transcriptional responses of cultured wound cells to the excretions and secretions of medicinal Lucilia sericata larvae

Maggots, through their excretions and secretions (ES), promote wound healing by removing necrotic tissue, counter bacterial infection, and activate wound associated cells. We investigated the effects of a physiological dose of maggot ES on four wound-associated cell types in vitro with Affymetrix gene expression arrays; keratinocytes, endothelial cells, fibroblasts, and monocytes. Keratinocytes showed the fewest (n = 5; p < 0.05, fold-change ±2) and smallest fold-changes (up to 2.32×) in gene expression and conversely THP1 monocytes had the most (n = 233) and greatest magnitude (up to 44.3×). There were no genes that were altered in all four cell-lines. Gene pathway analysis identified an enrichment of immune response pathways in three of the treated cell-lines. Analyses by quantitative RT-PCR found many genes dynamically expressed in ES dose dependent manner during the three day treatments. Phenotype analyses, however, found no effects of ES on cell viability, proliferation, migration and angiogenesis. ES was 100× less potent at triggering IL-8 secretion than fibroblasts treated with purified bacterial lipopolysaccharide (LPS; in equivalent amounts to that found in ES; ∼40 EU/ml). Furthermore, co-treatment with LPS and ES decreased the LPS-alone triggered IL-8 secretion by 13%. Although ES had no direct effect on wound cell phenotypes it did partially reduce the immune response to bacterial LPS exposure. These observations were consistent with the profile of transcriptional responses that were dominated by modulation of immune response genes. Maggot therapy may therefore improve wound healing through the secondary effects of these gene changes in the wound cells.

Benefits of maggot debridement therapy on leg ulcers: a literature review

Maggot debridement therapy (MDT) is an effective method for debriding wounds such as leg ulcers, supporting the concept of wound bed preparation ( Dumville et al, 2009 ; Soares et al, 2009 ; Mudge et al, 2014 ). New evidence is emerging to suggest that maggots might contribute to wound healing in other ways. For example, the reduction of biofilms and disinfection of wounds ( Van Der Plas et al, 2008 ; Brown et al, 2012 ; Pritchard and Brown, 2015 ) plus regulation of protease levels ( Chambers et al, 2003 ; Van Der Plas et al, 2009a ; Van Der Plas et al, 2009b ). This review will discuss research exploring new benefits of maggots in the management of individuals with chronic leg ulcers.

Flying maggots: a smart logistic solution to an enduring medical challenge

Purpose

Whilst there is a growing body of research which discusses the use of remotely piloted aircraft systems (RPAS) (otherwise known as “drones”) to transport medical supplies, almost all reported cases employ short range aircraft. The purpose of this paper is to consider the advantages and challenges inherent in the use of long endurance remotely piloted aircraft systems (LE-RPAS) aircraft to support the provision of medical supplies to remote locations – specifically “medical maggots” used in maggot debridement therapy (MDT) wound care.

Design/methodology/approach

After introducing both MDT and the LE-RPAS technology, the paper first reports on the outcomes of a case study involving 11 semi-structured interviews with individuals who either have experience and expertise in the use of LE-RPAS or in the provision of healthcare to remote communities in Western Australia. The insights gained from this case study are then synthesised to assess the feasibility of LE-RPAS assisted delivery of medical maggots to those living in such geographically challenging locations.

Findings

No insuperable challenges to the concept of using LE-RPAS to transport medical maggots were uncovered during this research – rather, those who contributed to the investigations from across the spectrum from operators to users, were highly supportive of the overall concept.

Practical implications

The paper offers an assessment of the feasibility of the use of LE-RPAS to transport medical maggots. In doing so, it highlights a number of infrastructure and organisational challenges that would need to be overcome to operationalise this concept. Whilst the particular context of the paper relates to the provision of medical support to a remote location of a developed country, the core benefits and challenges that are exposed relate equally to the use of LE-RPAS in a post-disaster response. To this end, the paper offers a high-level route map to support the implementation of the concept.

Social implications

The paper proposes a novel approach to the efficient and effective provision of medical care to remote Australian communities which, in particular, reduces the need to travel significant distances to obtain treatment. In doing so, it emphasises the importance in gaining acceptance of both the use of MDT and also the operation of RPAS noting that these have previously been employed in a military, as distinct from humanitarian, context.

Originality/value

The paper demonstrates how the use of LE-RPAS to support remote communities offers the potential to deliver healthcare at reduced cost compared to conventional approaches. The paper also underlines the potential benefits of the use of MDT to address the growing wound burdens in remote communities. Finally, the paper expands on the existing discussion of the use of RPAS to include its capability to act as the delivery mechanism for medical maggots.

Maggot debridement therapy for a patient with critical limb ischaemia and severe cardiac dysfunction: possibility of limb salvage

Ischaemic skin ulcer occurred on the foot of a 73-year-old man who had a history of fulminant myocarditis with severe cardiac dysfunction. We attempted wound bed preparation by maggot debridement therapy and salvaged his limb. It can be one of the adjuvant treatment strategies for critical limb ischaemia.

Genome Sequence of a Providencia stuartii Strain Isolated from Luciliasericata Salivary Glands

We present here the draft genome sequence of a Providencia stuartii strain, derived from the salivary glands of larval Lucilia sericata, a common blow fly important to forensic, medical, and veterinary science. The genome sequence will help dissect coinfections involving P. stuartii and Proteus mirabilis, as well as blow fly–bacteria interactions.

Urate Oxidase produced by Lucilia sericata medical maggots is localized in Malpighian tubes and facilitates allantoin production

Lucilia sericata maggots are the only species currently approved for maggot debridement therapy (MDT), an alternative treatment for chronic and recalcitrant wounds. Maggots promote wound debridement, disinfection and healing by producing a complex mixture of proteins, peptides and low-molecular-weight compounds in their secretions and excretions, but the individual components are not well characterized at the molecular level. Here we investigated the purine catabolism pathway in L. sericata, focusing on the production of allantoin by Urate Oxidase (UO), which is thought to promote wound healing. We produced recombinant L. sericata UO in Escherichia coli, and characterized the properties of the pure enzyme in terms of the optimum pH (7-10) and temperature (20-25 °C), its stability, sensitivity to inhibition and ion dependency. We used quantitative RT-PCR and RNA in situ hybridization to monitor the expression of the UO gene, and we used a guinea pig anti-UO antibody to detect the native enzyme by western blot and by florescence immunohistochemistry in larval tissues. We found that L. sericata UO is exclusively present in the larval excretion organ (the Malpighian tubes) and is freely available in the cytoplasm rather than restricted to a specific subcellular compartment. Allantoin is a final product of L. sericata purine catabolism. It is produced by UO in the Malpighian tubes to remove uric acid from the hemolymph and is consequently excreted via the hindgut. Our findings confirm the hypothesis that both actively secreted molecules and excretion products contribute to the beneficial effects of MDT.

Excretions/secretions from medicinal larvae (Lucilia sericata) inhibit complement activation by two mechanisms

Larvae of the blowfly Lucilia sericata facilitate wound healing by removing dead tissue and biofilms from non-healing and necrotic wounds. Another beneficial action of larvae and their excretions/secretions (ES) is down-regulation of excessive inflammation. As prolonged complement activation is key to excessive inflammation, the aim of this study was to elucidate the mechanisms underlying the anti-complement activities of ES. Results revealed that heat sensitive serine proteases in ES degrade multiple complement proteins in all steps of the three complement activation pathways. Importantly, C3a and C5a-major activators of inflammation-were also degraded by ES and pretreatment of these factors with ES completely blocked their ability to induce activation of human neutrophils. Pre-exposure of the neutrophils to ES did not affect their responsiveness to C3a/C5a and fMLP, indicating that the receptors for these activators on neutrophils were not affected by ES. Surprisingly, heat and serine protease inhibitor pretreatment did not affect the ability of ES to inhibit C5b-9 complex formation despite degrading complement proteins, indicating a second complement-inhibiting molecule in ES. Heated ES was as effective as intact ES in inhibiting C3 deposition upon activation of the alternative pathway, but was significantly less effective in wells with a classical or lectin pathway-specific coating. Unfortunately, the molecules affecting the complement system could not be identified due to an insufficient database for L. sericata. Together, larval ES inhibit complement activation by two different mechanisms and down-regulate the C3a/C5a-mediated neutrophil activation. This attenuates the inflammatory process, which may facilitate wound healing.

The humanistic and economic burden of chronic wounds: a protocol for a systematic review

BACKGROUND

Chronic non-healing wounds present a substantial economic burden to healthcare system; significant reductions in quality of life for those affected, and precede often serious events such as limp amputations or even premature deaths. This burden is also likely to increase with a larger proportion of elderly and increasing prevalence of life-style diseases such as obesity and diabetes. Reviews of the evidence on the burden of illness associated with chronic wounds have not been comprehensive in scope and have not provided an assessment of the distribution of the health care costs across categories of resource use.

METHODS/DESIGN

This study is a systematic review of multiple databases for studies on adult patients with chronic wounds and with the primary objective to assess the impact on health-related quality of life by category of ulcers, and associated direct and indirect costs. Eligible studies will primary be empirical studies evaluating, describing or comparing measurement of quality of life and economic impact. Two reviewers will independently screen titles and abstracts and select studies involving adults with chronic wounds. These investigators will also independently extract data using a pre-designed data extraction form. Differences in applied methodologies and uncertainties will clearly be accounted for. Conservative valuations of costs and impact on health-related quality of life will be prioritised. Variations that may depend on age distribution, the categorisation of ulcer, healthcare system etc. will be described clearly.

DISCUSSION

The proposed systematic review will yield a comprehensive assessment of the humanistic and economic burden of chronic wounds in an adult population. A better understanding of the humanistic and economic burden of chronic wounds is essential for policy and planning purposes, to monitor trends in disease burden and not at least in order to estimate the real-world cost-effectiveness of new treatments and therapies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016037496.

Prevalence and incidence of chronic wounds and related complications: a protocol for a systematic review

BACKGROUND

Chronic wounds impose a significant and often underappreciated burden to the individual, the healthcare system and the society as a whole. Preliminary literature search suggests that there are at present no reliable estimates on the total prevalence of chronic wounds for different settings and categories of chronic wounds. Such information is essential for policy and planning purposes as the increasing number of elderly and the prevalence of lifestyle diseases point in the direction of an increased burden. Knowledge about the prevalence and incidence of chronic wounds in relation to population characteristics is important for informing healthcare planning and resource allocation. The objective is to present a transparent process for how to review the existing literature on the prevalence and incidence rates of chronic wounds and resulting implications.

METHODS/DESIGN

We will search electronic bibliographic databases (MEDLINE, EMBASE, the EBM Reviews and Cochrane, Cumulative Index to Nursing and allied Health Literature (CINAHL), PsycINFO, Global Health) and reference lists of included articles. Two investigators will independently screen titles and abstracts and select studies involving adults with chronic wounds. These investigators will also independently extract data using a pre-designed data extraction form that will cover information on demographics, diagnostics including disease prevalence, medical history, hospital and community-based management and outcomes. Subgroup analysis and sensitivity analysis will be performed to address the heterogeneity across studies. Meta-analysis will also be performed if homogeneous group of studies will be found. The collective evidence will be further stratified according to the important background variables if allowed.

DISCUSSION

This study will describe the available epidemiological evidence and summarise prevalence and incidence rates of chronic wounds and related complications. A better understanding of the relationship between population profile and the prevalence of chronic wounds and related complications will be helpful in the development of guidelines for patient management.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016037355.

Traditional Therapies for Skin Wound Healing

Significance: The regeneration of healthy and functional skin remains a huge challenge due to its multilayer structure and the presence of different cell types within the extracellular matrix in an organized way. Despite recent advances in wound care products, traditional therapies based on natural origin compounds, such as plant extracts, honey, and larvae, are interesting alternatives. These therapies offer new possibilities for the treatment of skin diseases, enhancing the access to the healthcare, and allowing overcoming some limitations associated to the modern products and therapies, such as the high costs, the long manufacturing times, and the increase in the bacterial resistance. This article gives a general overview about the recent advances in traditional therapies for skin wound healing, focusing on the therapeutic activity, action mechanisms, and clinical trials of the most commonly used natural compounds. New insights in the combination of traditional products with modern treatments and future challenges in the field are also highlighted. Recent Advances: Natural compounds have been used in skin wound care for many years due to their therapeutic activities, including anti-inflammatory, antimicrobial, and cell-stimulating properties. The clinical efficacy of these compounds has been investigated through in vitro and in vivo trials using both animal models and humans. Besides the important progress regarding the development of novel extraction methods, purification procedures, quality control assessment, and treatment protocols, the exact mechanisms of action, side effects, and safety of these compounds need further research. Critical Issues: The repair of skin lesions is one of the most complex biological processes in humans, occurring throughout an orchestrated cascade of overlapping biochemical and cellular events. To stimulate the regeneration process and prevent the wound to fail the healing, traditional therapies and natural products have been used with promising results. Although these products are in general less expensive than the modern treatments, they can be sensitive to the geographic location and season, and exhibit batch-to-batch variation, which can lead to unexpected allergic reactions, side effects, and contradictory clinical results. Future Directions: The scientific evidence for the use of traditional therapies in wound healing indicates beneficial effects in the treatment of different lesions. However, specific challenges remain unsolved. To extend the efficacy and the usage of natural substances in wound care, multidisciplinary efforts are necessary to prove the safety of these products, investigate their side effects, and develop standard controlled trials. The development of good manufacturing practices and regulatory legislation also assume a pivotal role in order to improve the use of traditional therapies by the clinicians and to promote their integration into the national health system. Current trends move to the development of innovative wound care treatments, combining the use of traditional healing agents and modern products/practices, such as nanofibers containing silver nanoparticles, Aloe vera loaded into alginate hydrogels, propolis into dressing films, and hydrogel sheets containing honey.

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.

Towards next generation maggot debridement therapy: transgenic Lucilia sericata larvae that produce and secrete a human growth factor

BACKGROUND

Diabetes and its concurrent complications impact a significant proportion of the population of the US and create a large financial burden on the American health care system. FDA-approved maggot debridement therapy (MDT), the application of sterile laboratory-reared Lucilia sericata (green bottle fly) larvae to wounds, is a cost-effective and successful treatment for diabetic foot ulcers and other medical conditions. Human platelet derived growth factor-BB (PDGF-BB) is a secreted dimeric peptide growth factor that binds the PDGF receptor. PDGF-BB stimulates cell proliferation and survival, promotes wound healing, and has been investigated as a possible topical treatment for non-healing wounds. Genetic engineering has allowed for expression and secretion of human growth factors and other proteins in transgenic insects. Here, we present a novel concept in MDT technology that combines the established benefits of MDT with the power of genetic engineering to promote healing. The focus of this study is to create and characterize strains of transgenic L. sericata that express and secrete PDGF-BB at detectable levels in adult hemolymph, whole larval lysate, and maggot excretions/ secretions (ES), with potential for clinical utility in wound healing.

RESULTS

We have engineered and confirmed transgene insertion in several strains of L. sericata that express human PDGF-BB. Using a heat-inducible promoter to control the pdgf-b gene, pdgf-b mRNA was detected via semi-quantitative PCR upon heat shock. PDGF-BB protein was also detectable in larval lysates and adult hemolymph but not larval ES. An alternative, tetracycline-repressible pdgf-b system mediated expression of pdgf-b mRNA when maggots were raised on diet that lacked tetracycline. Further, PDGF-BB protein was readily detected in whole larval lysate as well as larval ES.

CONCLUSIONS

Here we show robust, inducible expression and production of human PDGF-BB protein from two conditional expression systems in transgenic L. sericata larvae. The tetracycline-repressible system appears to be the most promising as PDGF-BB protein was detectable in larval ES following induction. Our system could potentially be used to deliver a variety of growth factors and anti-microbial peptides to the wound environment with the aim of enhancing wound healing, thereby improving patient outcome in a cost-effective manner.

Evaluation of conventional therapeutic methods versus maggot therapy in the evolution of healing of tegumental injuries in Wistar rats with and without diabetes mellitus

Larval therapy consists on the application of sterilized carrion flies larvae, reared in laboratory, on acute, chronic, and/or infected wounds in order to promote healing. Conventional methods for treating injuries include mechanical debridement or silver-based dressings; however, they are not always effective for wound healing. Larval therapy is a feasible and safe treatment for therapeutic application and, in many cases, the only and the most recommended alternative for difficult healing injuries. Thus, this study aimed to evaluate the competence of Cochliomyia macellaria F. (Diptera: Calliphoridae) as a suitable species for therapeutic application and evaluate time and effectiveness of the types of treatments most commonly used to treat integumental injuries. C. macellaria eggs were obtained from colonies established in laboratory and sterilized prior to application. Twenty-five larvae were applied for each centimeter squared of lesion. Lesions were induced in 24 Wistar rats; type 1 diabetes mellitus was induced in 12 of them. Animals were divided in four groups with three individuals each, being denominated: larval therapy, larval therapy associated with foam dressing with silver release, mechanical debridement with foam dressing silver and control group, without treatment. All treatments were applied once and held for 24 h. Medical application of larvae was found to be safe, as only dead tissue was removed, and efficient to accelerate healing process when compared to other treatments.

A Jonah-like chymotrypsin from the therapeutic maggot Lucilia sericata plays a role in wound debridement and coagulation

Lucilia sericata larvae are used in maggot debridement therapy, a traditional wound healing approach that has recently been approved for the treatment of chronic wounds. Maggot excretion products (MEP) contain many different proteases that promote disinfection, debridement and the acceleration of wound healing, e.g. by activating the host contact phase/intrinsic pathway of coagulation. In order to characterise relevant procoagulant proteases, we analysed MEP and identified a chymotrypsin-like serine protease with similarities to Jonah proteases from Drosophila melanogaster and a chymotrypsin from Lucilia cuprina. A recombinant form of the L. sericata Jonah chymotrypsin was produced in Escherichia coli. The activated enzyme (Jonahm) had a pH optimum of 8.0 and a temperature optimum of 37 °C, based on the cleavage of the chromogenic peptide s-7388 and casein. Jonahm reduced the clotting time of human plasma even in the absence of the endogenous protease kallikrein, factor XI or factor XII and digested the extracellular matrix proteins fibronectin, laminin and collagen IV, suggesting a potential mechanism of wound debridement. Based on these characteristics, the novel L. sericata chymotrypsin-like serine protease appears to be an ideal candidate for the development of topical drugs for wound healing applications.

Evaluating Sarconesiopsis magellanica blowfly-derived larval therapy and comparing it to Lucilia sericata-derived therapy in an animal model

Larval therapy is used as alternative treatment for hard-to-heal chronic and infected wounds. Lucilia sericata is the most used blowfly species. However, it has been shown recently that Sarconesiopsis magellanica larval excretions and secretions have potent antibacterial activity; this blowfly belongs to the Calliphoridae family. The present work has dealt with evaluating larval therapy using S. magellanica on wounds induced in diabetic rabbits and its action was compared to the effect induced by L. sericata. Twelve New Zealand White rabbits (Oryctolagus cuniculus) were used; they were divided into 4 groups, the first two being treated with larval therapy derived from both aforementioned necrophagous blowflies, an antibiotic was used in the third and the fourth was used as control. All the animals were wounded on the back and infected with Pseudomonas aeruginosa and Staphylococcus aureus. Samples of the secretion from each animal's infected wound were taken and sown on blood agar. The colony forming units were then counted. The PUSH scale was used for the macroscopic evaluation of the wounds. Bacterial control was encountered 48 h post-treatment in the treatments involving larval therapy and to a lesser extent with the antibiotic. Likewise, wound debridement was quicker and more efficient with larval therapy compared to the antibiotic group; however, wound closing time was 23 days in all treatments. The group treated with S. magellanica larvae had relatively quicker evolution until the proliferation phase and the start of maturation, even though there were no significant differences between both blowfly species evaluated here regarding treatments by the end of the treatment period. The present study has validated the diabetic rabbit model for inducing chronic wounds regarding larval therapy and has likewise confirmed the effectiveness of S. magellanica-derived larval therapy as an alternative for curing and healing wounds.

Growth and survival of blowfly Lucilia sericata larvae under simulated wound conditions: implications for maggot debridement therapy

Maggot debridement therapy has become a well-established method of wound debridement. Despite its success, little information is available about the optimum duration of the treatment cycle and larval growth in wounds. This study examines the development of Lucilia sericata (Diptera: Calliphoridae) larvae under two containment conditions (bagged and free range) under simulated wound conditions and assesses the impact of transport and further storage of larvae on their survival and growth. There was no significant difference in size between bagged and free-range larvae over the 72-h experimental period. Larvae grew fastest 8-24 h after inoculation and completed their growth at 40-48 h. Mortality rates were similar (0.12-0.23% per hour) in both containment conditions and did not differ significantly (P = 0.3212). Survival of free-range larvae was on average 16% lower than survival of bagged larvae. Refrigeration of larvae upon simulated delivery for > 1 day reduced their survival to < 50% and caused a reduction in growth of up to 30% at 12 h, but not at 48 h, of incubation. Therefore, it is recommended that free-range larvae are left in the wound for a maximum of 40-48 h, and bagged larvae for 48-72 h. Larvae should be used within 24 h of delivery to avoid high mortality caused by prolonged refrigeration.

Selection and Evaluation of Tissue Specific Reference Genes in Lucilia sericata during an Immune Challenge

The larvae of the common green bottle fly Lucilia sericata (Diptera: Calliphoridae) have been used for centuries to promote wound healing, but the molecular basis of their antimicrobial, debridement and healing functions remains largely unknown. The analysis of differential gene expression in specific larval tissues before and after immune challenge could be used to identify key molecular factors, but the most sensitive and reproducible method qRT-PCR requires validated reference genes. We therefore selected 10 candidate reference genes encoding products from different functional classes (18S rRNA, 28S rRNA, actin, β-tubulin, RPS3, RPLP0, EF1α, PKA, GAPDH and GST1). Two widely applied algorithms (GeNorm and Normfinder) were used to analyze reference gene candidates in different larval tissues associated with secretion, digestion, and antimicrobial activity (midgut, hindgut, salivary glands, crop and fat body). The Gram-negative bacterium Pseudomonas aeruginosa was then used to boost the larval immune system and the stability of reference gene expression was tested in comparison to three immune genes (lucimycin, defensin-1 and attacin-2), which target different pathogen classes. We observed no differential expression of the antifungal peptide lucimycin, whereas the representative targeting Gram-positive bacteria (defensin-1) was upregulated in salivary glands, crop, nerve ganglion and reached its maximum in fat body (up to 300-fold). The strongest upregulation in all immune challenged tissues (over 50,000-fold induction in the fat body) was monitored for attacin-2, the representative targeting Gram-negative bacteria. Here we identified and validated a set of reference genes that allows the accurate normalization of gene expression in specific tissues of L. sericata after immune challenge.

TIME management by medicinal larvae

Wound bed preparation (WBP) is an integral part of the care programme for chronic wounds. The acronym TIME is used in the context of WBP and describes four barriers to healing in chronic wounds; namely, dead Tissue, Infection and inflammation, Moisture imbalance and a non-migrating Edge. Larval debridement therapy (LDT) stems from observations that larvae of the blowfly Lucilia sericata clean wounds of debris. Subsequent clinical studies have proven debriding efficacy, which is likely to occur as a result of enzymatically active alimentary products released by the insect. The antimicrobial, anti-inflammatory and wound healing activities of LDT have also been investigated, predominantly in a pre-clinical context. This review summarises the findings of investigations into the molecular mechanisms of LDT and places these in context with the clinical concept of WBP and TIME. It is clear from these findings that biotherapy with L. sericata conforms with TIME, through the enzymatic removal of dead tissue and its associated biofilm, coupled with the secretion of defined antimicrobial peptides. This biotherapeutic impact on the wound serves to reduce inflammation, with an associated capacity for an indirect effect on moisture imbalance. Furthermore, larval serine proteinases have the capacity to alter fibroblast behaviour in a manner conducive to the formation of granulation tissue.

Apocrine secretion: New insights into an old phenomenon

BACKGROUND

While apocrine secretion was among the earliest secretory mechanisms to be identified, its underlying basis remains poorly understood.

SCOPE OF REVIEW

This review reappraises our understanding of apocrine secretion using insights about apocrine secretion from the salivary glands of Drosophila, in which molecular genetic analyses have provided a glimmer of hope for elucidating the mechanistic aspects of this fundamental process.

MAJOR CONCLUSIONS

In contrast to the well-defined process of exocytosis, apocrine secretion is non-vesicular transport and secretory pathway that entails the loss of part of the cytoplasm. It often involves apical protrusions and generates cytoplasmic fragments inside a secretory lumen. In its most intense phase this process is accompanied by the release of large fragments of cellular structures and entire organelles that include mitochondria, Golgi, and portions of the endoplasmic reticulum, among others. Proteomic analyses revealed that the secretion is composed of hundreds to thousands of membranous, cytoskeletal, microsomal, mitochondrial, ribosomal, and even nuclear as well as nucleolar proteins. Strikingly, although many nuclear proteins are released, the nuclear deoxyribonucleic acid itself remains intact. In spite of this complexity, it appears that several protein components of apocrine secretion are identical, regardless of the location of the apocrine gland.

GENERAL SIGNIFICANCE

This type of secretion appears to be common to many, if not all, barrier epithelial tissues including skin derivatives and the epididymis, and is implicated also in lung/bronchi and intestinal epithelium. Apocrine secretion is a mechanism that provides the en masse delivery of a very complex proteinaceous mixture from polarized epithelial tissues to allow for communication at exterior interfaces.

Maggot excretion products from the blowfly Lucilia sericata contain contact phase/intrinsic pathway-like proteases with procoagulant functions

For centuries, maggots have been used for the treatment of wounds by a variety of ancient cultures, as part of their traditional medicine. With increasing appearance of antimicrobial resistance and in association with diabetic ulcers, maggot therapy was revisited in the 1980s. Three mechanisms by which sterile maggots of the green bottle fly Lucilia sericata may improve healing of chronic wounds have been proposed: Biosurgical debridement, disinfecting properties, and stimulation of the wound healing process. However, the influence of maggot excretion products (MEP) on blood coagulation as part of the wound healing process has not been studied in detail. Here, we demonstrate that specific MEP-derived serine proteases from Lucilia sericata induce clotting of human plasma and whole blood, particularly by activating contact phase proteins factor XII and kininogen as well as factor IX, thereby providing kallikrein-bypassing and factor XIa-like activities, both in plasma and in isolated systems. In plasma samples deficient in contact phase proteins, MEP restored full clotting activity, whereas in plasma deficient in either factor VII, IX, X or II no effect was seen. The observed procoagulant/intrinsic pathway-like activity was mediated by (chymo-) trypsin-like proteases in total MEP, which were significantly blocked by C1-esterase inhibitor or other contact phase-specific protease inhibitors. No significant influence of MEP on platelet activation or fibrinolysis was noted. Together, MEP provides contact phase bypassing procoagulant activity and thereby induces blood clotting in the context of wound healing. Further characterisation of the active serine protease(s) may offer new perspectives for biosurgical treatment of chronic wounds.