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

Identification of a gene promoter active in Lucilia sericata larval salivary glands using a rapid transient expression assay

Tissue-specific gene promoters are desired as they provide the specificity needed for control of gene expression in transgenic animals. Here we describe a relatively rapid two-component transient expression assay that was used to identify a gene promoter active in the larval salivary glands of the green blow fly, Lucilia sericata. Sterile L.sericata maggots are widely used for wound debridement. A larval salivary gland gene promoter could be used to make maggots that secrete factors for enhanced wound therapy. Embryos from a line that carry a tetracycline transactivator (tTA)-activated red fluorescent protein gene were injected with plasmid DNA with the tTA gene driven by a constitutive or tissue-specific gene promoter. The hatched larvae were reared on diet and then examined for red fluorescence. A promoter from the LsCG30371 gene was active in the larval salivary glands. The tissue-specificity of the promoter was subsequently confirmed with stable transgenic lines that carried the LsCG30371-tTA gene. The relatively rapid transient expression assay could potentially be used to determine the tissue-specificity of other gene promoters. Further, the stable LsCG30371-tTA lines could be used to make sterile maggots that secrete factors from the salivary glands for enhanced wound healing.

An Overview of Recent Developments in the Management of Burn Injuries

According to the World Health Organization (WHO), around 11 million people suffer from burns every year, and 180,000 die from them. A burn is a condition in which heat, chemical substances, an electrical current or other factors cause tissue damage. Burns mainly affect the skin, but can also affect deeper tissues such as bones or muscles. When burned, the skin loses its main functions, such as protection from the external environment, pathogens, evaporation and heat loss. Depending on the stage of the burn, the patient's condition and the cause of the burn, we need to choose the most appropriate treatment. Personalization and multidisciplinary collaboration are key to the successful management of burn patients. In this comprehensive review, we have collected and discussed the available treatment options, focusing on recent advances in topical treatments, wound cleansing, dressings, skin grafting, nutrition, pain and scar tissue management.

Research hotspot and trend of chronic wounds: A bibliometric analysis from 2013 to 2022

Chronic wounds have been confirmed as a vital health problem facing people in the global population aging process. While significant progress has been achieved in the study of chronic wounds, the treatment effect should be further improved. The number of publications regarding chronic wounds has been rising rapidly. In this study, bibliometric analysis was conducted to explore the hotspots and trends in the research on chronic wounds. All relevant studies on chronic wounds between 2013 and 2022 were collected from the PubMed database of the Web of Science (WOS) and the National Center for Biotechnology Information (NCBI). The data were processed and visualised using a series of software. On that basis, more insights can be gained into hotspots and trends of this research field. Wound Repair and Regeneration has the highest academic achievement in the field of chronic wound research. The United States has been confirmed as the most productive country, and the University of California System ranks high among other institutions. Augustin, M. is the author of the most published study, and Frykberg, RG et al. published the most cited study. Furthermore, the hotspots of wound research over the last decade were identified (e.g., bandages, infection and biofilms, pathophysiology and therapy). This study will help researchers gain insights into chronic wound research's hotspots and trends accurately and quickly. Moreover, the exploration of bacterial biofilm and the pathophysiological mechanism of the chronic wound will lay a solid foundation and clear direction for treating chronic wounds.

Function and mechanism of mesenchymal stem cells in the healing of diabetic foot wounds

Diabetes has become a global public health problem. Diabetic foot is one of the most severe complications of diabetes, which often places a heavy economic burden on patients and seriously affects their quality of life. The current conventional treatment for the diabetic foot can only relieve the symptoms or delay the progression of the disease but cannot repair damaged blood vessels and nerves. An increasing number of studies have shown that mesenchymal stem cells (MSCs) can promote angiogenesis and re-epithelialization, participate in immune regulation, reduce inflammation, and finally repair diabetic foot ulcer (DFU), rendering it an effective means of treating diabetic foot disease. Currently, stem cells used in the treatment of diabetic foot are divided into two categories: autologous and allogeneic. They are mainly derived from the bone marrow, umbilical cord, adipose tissue, and placenta. MSCs from different sources have similar characteristics and subtle differences. Mastering their features to better select and use MSCs is the premise of improving the therapeutic effect of DFU. This article reviews the types and characteristics of MSCs and their molecular mechanisms and functions in treating DFU to provide innovative ideas for using MSCs to treat diabetic foot and promote wound healing.

Anti-inflammatory and wound healing potential of medicinal maggot excretions/secretions at the ocular surface

PURPOSE

In the skin, Lucilia sericata maggot excretions/secretions (ES) accelerate wound healing and limit inflammation. This study aimed to determine whether ES have similar beneficial effects at the ocular surface.

METHODS

Human corneal epithelial cells (HCEC) were cultured with ES and cell viability was determined by the MTT assay. Additionally, mRNA expression of growth factors, antimicrobial peptides (AMPs) and cytokines was assessed by qPCR. ES ability to modulate TLR-induced IL-6 and IL-8 expression was determined by qPCR and ELISA. ES potential to promote corneal healing was evaluated in vitro by a migration assay in HCEC, and in vivo using a mouse model.

RESULTS

ES did not impair HCEC viability up to 25 μg/ml. Among the factors evaluated, only hBD-2 was upregulated (2.5-fold) by 1.5 μg/ml ES after 6 hrs (P = 0.04). In HCEC, ES reduced Poly I:C-induced IL-6 and IL-8 mRNA (P ≤ 0.001) and protein (P ≤ 0.0001) expression. A similar effect was observed with Flagellin (TLR5 agonist) but it was less robust for FSL-1 (TLR2/6 agonist) and Pam3CSK4 (TLR1/2 agonist). The greatest in vitro migration effect was observed with 6.2 μg/ml ES after 44 hrs where gap area compared to vehicle was 53.3 ± 3.7% vs. 72.6 ± 5.4% (P = 0.001). In the mouse model, the maximum healing effect was present with 1.5 μg/ml ES after 12 hrs with a wound area of 19.0 ± 2.7% vs. 60.1 ± 21.6% (P = 0.003) or 77% reduction of the wound area compared to the negative control.

CONCLUSIONS

ES significantly reduce in vitro TLR-induced production of inflammatory cytokines and promote corneal wound healing.

A human tissue-based assay identifies a novel carrion blowfly strain for maggot debridement therapy

Maggot debridement therapy (MDT) is a form of therapeutic wound treatment in which live fly larvae are used intentionally to debride necrotic tissues. MDT has been widely used to treat chronic wounds in humans or animals, such as diabetic foot ulcers. Larvae of a carrion blowfly, Lucilia sericata (green bottle fly), debride wounds by consuming necrotic tissue and removing pathogenic bacteria, promoting effective wound healing. Most medical L. sericata strains were initially collected from natural environments using animal meat as bait and reared on artificial protein-rich media or ground meat. It remains to be examined which strain would be more appropriate for MDT, whereas any method for evaluating the fly’s therapeutic potential in humans has not been available. A feeding assay was developed using minced human tissues obtained from surgical waste. To establish L. sericata strains highly eligible for MDT, carrion fly larvae were collected from 45 corpses subjected to forensic autopsy (such as decomposed bodies). Four corpse-derived L. sericata strains were obtained and evaluated using the feeding assay. One strain showed that its feeding activity was 1.4 times higher than the control strain used in conventional MDT. The body length of the adult fly of the corpse-derived strain was longer than the control, which was consistent with the observation that its cell size was enlarged. The human tissue-based assay developed in this study accurately evaluated the ability of fly larvae to debride necrotic wounds. The L. sericata strain newly established from human corpses harboring high feeding activity may offer a clinically significant improvement in MDT.

Gene expression in Lucilia sericata (Diptera: Calliphoridae) larvae exposed to Pseudomonas aeruginosa and Acinetobacter baumannii identifies shared and microbe-specific induction of immune genes

Antibiotic resistance is a continuing challenge in medicine. There are various strategies for expanding antibiotic therapeutic repertoires, including the use of blow flies. Their larvae exhibit strong antibiotic and antibiofilm properties that alter microbiome communities. One species, Lucilia sericata, is used to treat problematic wounds due to its debridement capabilities and its excretions and secretions that kill some pathogenic bacteria. There is much to be learned about how L. sericata interacts with microbiomes at the molecular level. To address this deficiency, gene expression was assessed after feeding exposure (1 h or 4 h) to two clinically problematic pathogens: Pseudomonas aeruginosa and Acinetobacter baumannii. The results identified immunity-related genes that were differentially expressed when exposed to these pathogens, as well as non-immune genes possibly involved in gut responses to bacterial infection. There was a greater response to P. aeruginosa that increased over time, while few genes responded to A. baumannii exposure, and expression was not time-dependent. The response to feeding on pathogens indicates a few common responses and features distinct to each pathogen, which is useful in improving the wound debridement therapy and helps to develop biomimetic alternatives.

Genome and transcriptome sequencing of the green bottle fly, Lucilia sericata, reveals underlying factors of sheep flystrike and maggot debridement therapy

The common green bottle blow fly Lucilia sericata (family, Calliphoridae) is widely used for maggot debridement therapy, which involves the application of sterile maggots to wounds. The larval excretions and secretions are important for consuming necrotic tissue and inhibiting bacterial growth in wounds of patients. Lucilia sericata is also of importance as a pest of sheep and in forensic studies to estimate a postmortem interval. Here we report the assembly of a 565.3 Mb genome from long read PacBio DNA sequencing of genomic DNA. The genome contains 14,704 predicted protein coding genes and 1709 non-coding genes. Targeted annotation and transcriptional analyses identified genes that are highly expressed in the larval salivary glands (secretions) and Malpighian tubules (excretions) under normal growth conditions and following heat stress. The genomic resources will underpin future genetic studies and in development of engineered strains for genetic control of L. sericata and for biotechnology-enhanced maggot therapy.

Health professionals' perceptions of maggot debridement therapy

BACKGROUND

Maggot debridement therapy (MDT), or the use of maggots in dead tissue removal, has been shown to be beneficial in wound healing. Yet MDT in the US is often only used once conventional debridement methods have failed.

METHOD

In this study, nine health professionals, experienced in MDT, were interviewed in order to identify and analyse the perceived societal barriers to MDT acceptance and usage in the US.

RESULTS

Through qualitative analysis, using the grounded theory framework, this study found that among those interviewed, insurance reimbursement restrictions and stigmatisation of medicinal maggots were the factors driving resistance to MDT use.

CONCLUSION

Specifically, the 'yuck' factor and the perception of MDT as an 'ancient' modality contributed towards MDT stigma; in addition, lack of outpatient insurance coverage deterred MDT use. These findings provide useful information regarding the perceptual and systemic barriers that prevent greater acceptance of MDT. Ultimately, these barriers must be understood if we are to facilitate MDT implementation and improve MDT usage in the future.

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.

3D scaffolds in the treatment of diabetic foot ulcers: New trends vs conventional approaches

Diabetic foot ulcer (DFU) is a serious complication of diabetes mellitus, affecting roughly 25% of diabetic patients and resulting in lower limb amputation in over 70% of known cases. In addition to the devastating physiological consequences of DFU and its impact on patient quality of life, DFU has significant clinical and economic implications. Various traditional therapies are implemented to effectively treat DFU. However, emerging technologies such as bioprinting and electrospinning, present an exciting opportunity to improve current treatment strategies through the development of 3D scaffolds, by overcoming the limitations of current wound healing strategies. This review provides a summary on (i) current prevention and treatment strategies available for DFU; (ii) methods of fabrication of 3D scaffolds relevant for this condition; (iii) suitable materials and commonly used molecules for the treatment of DFU; and (iv) future directions offered by emerging technologies.

Managing Diabetic Foot Ulcers: Pharmacotherapy for Wound Healing

Historically, there has been a scarcity of evidence-based topical therapy to hasten the healing of diabetic foot ulcers. But recently new evidence-based treatments have emerged from multicentre, randomised, controlled trials. This article highlights those trials, and describes the current pharmacological management of the diabetic foot ulcer and the advances that have been made in wound therapy to date. It provides an overview of topical and systemic pharmacotherapies in current use and those in development for future use in managing the diabetic foot. For each treatment, proposed mechanisms of action and evidence available to support their clinical use are presented. There is supporting randomised, controlled evidence for sucrose octasulfate in the treatment of neuro-ischaemic ulcers, and multi-layered patch of autologous leucocytes, platelets and fibrin in ulcers with or without ischaemia. There is also evidence for placentally derived products and for topical and systemic oxygen therapy in the healing of diabetic foot ulcers. Growth factors, bio-engineered tissues, stem cell therapy, gene therapy and peptide therapy also have some supporting evidence in the healing of diabetic foot ulcers. Nonsurgical debriding agents may be useful when the optimum approach of sharp debridement is not possible, and immunomodulators may be helpful for their antimicrobial effects, but robust data is still required to strengthen the case for general use. The review does not cover antimicrobials as their primary role are as anti-infectives and not in wound healing. The development of nanotechnology has created a means of prolonging the bioavailability of target molecules at the wound site, with the use of glass/hydrogel nanoparticles, polyethylene glycol and hyaluronic acid. Looking forward, novel therapies, including traction force-activated payloads, local delivery of short-interfering RNA and finally hydrogels incorporating bioactive agents or cells may provide possibilities for pharmacotherapy in the future.

Building a transgenic sexing strain for genetic control of the Australian sheep blow fly Lucilia cuprina using two lethal effectors

Background

The sterile insect technique (SIT) has been successfully used in many pest management programs worldwide. Some SIT programs release both sexes due to the lack of genetic sexing strains or efficient sex separation methods but sterile females are ineffective control agents. Transgenic sexing strains (TSS) using the tetracycline-off control system have been developed in a variety of insect pests, from which females die by either of two commonly used lethal effectors: overexpression of the transcription factor tetracycline transactivator (tTA) or ectopic expression of a proapoptotic gene, such as head involution defective (hid). The lethality from tTA overexpression is thought to be due to “transcriptional squelching”, while hid causes lethality by induction of apoptosis. This study aims to create and characterize a TSS of Lucilia cuprina, which is a major pest of sheep, by combining both lethal effectors in a single transgenic strain.

Results

Here a stable TSS of L. cuprina (DH6) that carries two lethal effectors was successfully generated, by crossing FL3#2 which carries a female-specific tTA overexpression cassette, with EF1#12 which carries a tTA-regulated Lshid^Ala2 cassette. Females with one copy of the FL3#2 transgene are viable but up to 99.8% of homozygous females die at the pupal stage when raised on diet that lacks tetracycline. Additionally, the female lethality of FL3#2 was partially repressed by supplying tetracycline to the parental generation. With an additional Lshid^Ala2 effector, the female lethality of DH6 is 100% dominant and cannot be repressed by maternal tetracycline. DH6 females die at the late-larval stage. Several fitness parameters important for mass rearing such as hatching rate, adult emergence and sex ratio were comparable to those of the wild type strain.

Conclusions

Compared to the parental FL3#2 strain, the DH6 strain shows stronger female lethality and lethality occurs at an earlier stage of development. The combination of two tTA-dependent lethal effectors could improve strain stability under mass rearing and could reduce the risk of resistance in the field if fertile males are released. Our approach could be easily adapted for other pest species for an efficient, safe and sustainable genetic control program.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-020-00947-y.

Nonpharmacological Management of Diabetic Foot Ulcers: An Update

Diabetic foot ulcers (DFUs) are a common and serious complication of diabetes mellitus that is associated with increased morbidity and mortality, as well as substantial economic burden for the health care system. The standard of care for DFUs includes pressure off-loading, sharp debridement, and wound moisture balance, along with infection control and management of peripheral arterial disease. A variety of advanced modalities that target distinct pathophysiological aspects of impaired wound healing in diabetes are being studied as possible adjunct therapies for difficult to heal ulcers. These modalities include growth factors, stem cells, cultured fibroblasts and keratinocytes, bioengineered skin substitutes, acellular bioproducts, human amniotic membranes, oxygen therapy, negative pressure wound therapy, and energy therapies. Additionally, the use of advanced biomaterials and gene delivery systems is being investigated as a method of effective delivery of substances to the wound bed. In the present narrative review, we outline the latest advances in the nonpharmacological management of DFUs and summarize the efficacy of various standard and advanced treatment modalities.

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.

The maggot therapy supply chain: a review of the literature and practice

Maggot therapy (MT) is the clinical application of living fly larvae for the treatment of non-healing wounds and wounds that require debridement. This systematized and expanded literature review is the first study to investigate MT through the conceptual and disciplinary framework of supply chain management. The review of 491 selected academic papers was expanded to include the grey literature and online information resources to construct a first-pass theory of the medicinal maggot supply chain. It shows that the literature to date has focused on isolated discussions of echelon-specific issues such as diet improvement and sterilization protocols in the production echelon, and the relative effectiveness of medicinal maggot application methods in the treatment echelon. There is little knowledge in the public domain regarding the transport and distribution of medicinal maggots, but existing supply chains for vaccines, blood and pathology specimens may provide learning and supply chain integration opportunities. Maggot therapy knowledge across the treatment echelon is generally substantive but there is still insufficient knowledge regarding patients' and health care providers' attitudes toward the therapy, and their experiences of receiving and administering MT. Moreover, there is no research concerned with the humane disposal of medicinal flies during production and after treatment.

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.

Further Data on Wound Healing Rates After Application of Lucilia sericata

Maggot therapy has recently received a special medical and public attention, and according to the specialists’ opinion, it takes us to the future of a wound care. Simultaneously, as new biomechanisms were discovered, statistical analyses of wound healing rates were conducted usually adopting simple parametric and nonparametric tests. In this study, based on a set of statistical methods, we performed an advanced analysis of wound surface reduction using Lucilia sericata larvae in different clinical aspects: status of diabetes mellitus, maggots’ density, and pain intensity. Particularly, we employed these factors because, in our statistical analysis, they are easy to obtain and they proved to be the possible risk factors of wound regeneration. Furthermore, these factors represent different clinical, biological, and neurological spectra of knowledge. In our study, we have found further and statistically significant correlations between the analyzed variables and skin regeneration together with different time periods of the healing rate using maggot therapy in patients with lower limb ulceration.

Advanced drug delivery systems and artificial skin grafts for skin wound healing

Cutaneous injuries, especially chronic wounds, burns, and skin wound infection, require painstakingly long-term treatment with an immense financial burden to healthcare systems worldwide. However, clinical management of chronic wounds remains unsatisfactory in many cases. Various strategies including growth factor and gene delivery as well as cell therapy have been used to enhance the healing of non-healing wounds. Drug delivery systems across the nano, micro, and macroscales can extend half-life, improve bioavailability, optimize pharmacokinetics, and decrease dosing frequency of drugs and genes. Replacement of the damaged skin tissue with substitutes comprising cell-laden scaffold can also restore the barrier and regulatory functions of skin at the wound site. This review covers comprehensively the advanced treatment strategies to improve the quality of wound healing.

Diabetic wound management

Diabetes is a global disease, and its prevalence has increased rapidly in the last century. Many complications are associated with diabetes, and diabetic foot ulcers (DFU) are common. There is a variety of different treatments for DFU, and the aim of this article is to discuss the factors responsible for delayed wound healing in patients with diabetes, and the treatment strategies that are available.

Pharmacological Properties of the Medical Maggot: A Novel Therapy Overview

In the last decade, maggot has been hailed as the miraculous “medicinal maggot” for its diverse properties, including antimicrobial, antibiofilm, anti-inflammatory, and wound healing activities. The fact that maggots show so many beneficial properties has increased the interest in these tiny larvae dramatically. Whilst there is relatively abundant clinical evidence to demonstrate the success of maggots as debridement agents, not so much emphasis has been placed on the basic science evidence, which was a combination of physical and biochemical actions. This review differs from those earlier works in that it is undertaken to provide an update of the latest scientific basis published on maggot, particularly active ingredients within maggot excretions/secretions (ES). Further investigations should focus on the isolation, identification, recombination, transgenosis, and mass production of the beneficial molecules within maggots.

Update on management of diabetic foot ulcers

Diabetic foot ulcers (DFUs) are a serious complication of diabetes that results in significant morbidity and mortality. Mortality rates associated with the development of a DFU are estimated to be 5% in the first 12 months, and 5-year morality rates have been estimated at 42%. The standard practices in DFU management include surgical debridement, dressings to facilitate a moist wound environment and exudate control, wound off-loading, vascular assessment, and infection and glycemic control. These practices are best coordinated by a multidisciplinary diabetic foot wound clinic. Even with this comprehensive approach, there is still room for improvement in DFU outcomes. Several adjuvant therapies have been studied to reduce DFU healing times and amputation rates. We reviewed the rationale and guidelines for current standard of care practices and reviewed the evidence for the efficacy of adjuvant agents. The adjuvant therapies reviewed include the following categories: nonsurgical debridement agents, dressings and topical agents, oxygen therapies, negative pressure wound therapy, acellular bioproducts, human growth factors, energy-based therapies, and systemic therapies. Many of these agents have been found to be beneficial in improving wound healing rates, although a large proportion of the data are small, randomized controlled trials with high risks of bias.

Elevating VEGF-A and PDGF-BB secretion by salidroside enhances neoangiogenesis in diabetic hind-limb ischemia

Hind-limb ischemia (HLI) is one of the major complication of diabetic patients. Angiogenesis potential in diabetic patients is severely disrupted, and the mechanism underlying it has not been fully elucidated, making it an obstacle for developing an efficient therapeutic angiogenesis strategy. Skeletal muscle cells, through their paracrine function, had been known to be critical for neoangiogenesis. Here we found that hyperglycemia upregulates the expression of skeletal muscle cells prolyl hydroxylase domain 3 (PHD3), which resulted in the decrease of the secretion of angiogenic factors, especially VEGF-A and PDGF-BB. We showed that treatment with salidroside, a small molecule drug, significantly suppresses PHD3 expression and increases VEGF-A and PDGF-BB secretion from skeletal muscle cells, which in turn enhances the proliferation and migration potentials of endothelial and smooth muscle cells. Finally, we demonstrated that intramuscular injection of salidroside into the ischemic hind limbs of diabetic HLI model mice could efficiently induce neoangiogenesis and blood perfusion recovery. Thus, our novel findings not only reveal the effects of hyperglycemia on the angiogenesis potential of skeletal muscle cells and the mechanism underlying it, but also provides a novel finding suggesting that salidroside might be a potential small molecule drug for diabetic HLI.

Building early-larval sexing systems for genetic control of the Australian sheep blow fly Lucilia cuprina using two constitutive promoters

Transgenic sexing strains (TSS) that carry conditional female lethal genes are advantageous for genetic control programs based on the sterile insect technique (SIT). It is desirable if females die early in development as larval diet is a major cost for mass production facilities. This can be achieved by using a gene promoter that is only active in embryos to drive expression of the tetracycline transactivator (tTA), the transcription factor commonly used in two-component TSS. While an embryo-specific promoter is ideal it may not be essential for assembling an effective TSS as tTA can be repressed by addition of tetracycline to the diet at larval and/or adult stages. Here we have investigated this idea by isolating and employing the promoters from the Lucilia spitting image and actin 5C genes to drive tTA expression in embryos and later stages. L. cuprina TSS with the tTA drivers and tTA-regulated tetO-Lshid effectors produced only females when raised on a limited tetracycline diet. The Lshid transgene contains a sex-specific intron and as a consequence only females produce LsHID protein. TSS females died at early larval stages, which makes the lines advantageous for an SIT program.

Mesenchymal Stem Cells Improve Healing of Diabetic Foot Ulcer

Mesenchymal stem cells (MSCs), an ideal cell source for regenerative therapy with no ethical issues, play an important role in diabetic foot ulcer (DFU). Growing evidence has demonstrated that MSCs transplantation can accelerate wound closure, ameliorate clinical parameters, and avoid amputation. In this review, we clarify the mechanism of preclinical studies, as well as safety and efficacy of clinical trials in the treatment of DFU. Bone marrow-derived mesenchymal stem cells (BM-MSCs), compared with MSCs derived from other tissues, may be a suitable cell type that can provide easy, effective, and cost-efficient transplantation to treat DFU and protect patients from amputation.

The effect of Lucilia sericata- and Sarconesiopsis magellanica-derived larval therapy on Leishmania panamensis

This study's main objective was to evaluate the action of larval therapy derived from Lucilia sericata and Sarconesiopsis magellanica (blowflies) regarding Leishmania panamensis using an in vivo model. Eighteen golden hamsters (Mesocricetus auratus) were used; they were divided into 6 groups. The first three groups consisted of 4 animals each; these, in turn, were internally distributed into subgroups consisting of 2 hamsters to be used separately in treatments derived from each blowfly species. Group 1 was used in treating leishmanial lesions with larval therapy (LT), whilst the other two groups were used for evaluating the used of larval excretions and secretions (ES) after the ulcers had formed (group 2) and before they appeared (group 3). The three remaining groups (4, 5 and 6), consisting of two animals, were used as controls in the experiments. Biopsies were taken for histopathological and molecular analysis before, during and after the treatments; biopsies and smears were taken for assessing parasite presence and bacterial co-infection. LT and larval ES proved effective in treating the ulcers caused by the parasite. There were no statistically significant differences between the blowfly species regarding the ulcer cicatrisation parameters. There were granulomas in samples taken from lesions at the end of the treatments. The antibacterial action of larval treatment regarding co-infection in lesions caused by the parasite was also verified. These results potentially validate effective LT treatment against cutaneous leishmaniasis aimed at using it with humans in the future.