Human Wound-Healing Research: Issues and Perspectives for Studies Using Wide-Scale Analytic Platforms

Image-based non-invasive assessment of suction blister wounds for clinical safety and efficacy

Recognising the need for objective imaging-based technologies to assess wound healing in clinical studies, the suction blister wound model offers an easily accessible wound model that creates reproducible epidermal wounds that heal without scarring. This study provides a comprehensive methodology for implementing and evaluating photography-based imaging techniques utilising the suction blister wound model. Our method encompasses a protocol for capturing consistent, high-quality photographs and procedures for quantifying these images via a visual wound healing score and a computer-assisted colour analysis of wound exudation and wound redness. We employed this methodology on 16 suction blister wounds used as controls in a clinical phase-1 trial. Our method enabled us to discern and quantify subtle differences between individual wounds concerning healing progress, erythema and wound exudation. The wound healing score exhibited a high inter-rater agreement. There was a robust correlation between the spectrophotometer-measured erythema index and photography-based wound redness, as well as between dressing protein content and photography-based dressing yellowness. In conclusion, this study equips researchers conducting clinical wound studies with reproducible methods that may support future wound research and aid in the development of new treatments.

Local Insulin Improves Wound Healing: A Systematic Review and Bayesian Network Meta-Analysis

BACKGROUND

Wounds are a significant health issue, and reliable and safe strategies to promote repair are needed. Clinical trials have demonstrated that local insulin promotes healing in acute and chronic wounds (ie, reductions of 7% to 40% versus placebo). However, the trials' sample sizes have prevented drawing solid conclusions. Furthermore, no analysis has focused on safety concerns (ie, hypoglycemia). Under the hypothesis that local insulin promotes healing through proangiogenic effects and cellular recruitment, the aim of this systematic review and network meta-analysis (NMA) was to assess its safety and relative effectiveness using a Bayesian approach.

METHODS

Medline, CENTRAL, Embase, Scopus, LILACS, and gray literature sources were searched for human studies assessing the local use of insulin versus any comparator since inception to October of 2020. Data on glucose changes and adverse events, wound and treatment characteristics, and healing outcomes were extracted, and an NMA was conducted.

RESULTS

A total of 949 reports were found, of which 23 ( n = 1240 patients) were included in the NMA. The studies evaluated six different therapies, and most comparisons were against placebo. NMA showed -1.8 mg/dL blood glucose level change with insulin and a lack of reported adverse events. Statistically significant clinical outcomes identified include reduction in wound size (-27%), increased healing rate (23 mm/day), reduction in Pressure Ulcer Scale for Healing scores (-2.7), -10 days to attain complete closure, and an odds ratio of 20 for complete wound closure with insulin use. Likewise, significantly increased neoangiogenesis (+30 vessels/mm 2 ) and granulation tissue (+25%) were also found.

CONCLUSION

Local insulin promotes wound healing without significant adverse events.

Preclinical evidence of polyherbal formulations on wound healing: A systematic review on research trends and perspectives

BACKGROUND

The disruptions in skin integrity contribute to its disorientation, and tissue annihilations result in acute or chronic wound formation. Polyherbal formulations are widely used in traditional systems of mecdicine like ayurveda for wound healing. The combination of these traditional therapies with clinical therapies has helped in the development of various wound-healing products.

METHOD

In this systematic review, the therapeutic potency of several polyherbal formulations from different medicinal floras is summed together in response to their impact on wound healing. The literature search was performed on Pubmed, Scopus, and ScienceDirect databases between 2010-2020. PRISMA methodology was applied to extract relevant information about polyherbal formulations.

RESULT

A total of 54 articles were selected under all themes for the data extraction as per the PRISMA guidelines. These 54 articles have high-quality scores ≥3. Forty-three records were used for the narrative analysis, while nine records were used for the critical analysis in the narrative review. Further, theme-wise key data sets were screened from the selected literature and summarized in a tabular form. Bibliometric analysis of the Scopus database has also drawn attention to limited academic literature showcasing randomized clinical trials in the current subject. Most of these polyherbal formulations are tested in laboratory-scale studies, thus portraying further research options.

CONCLUSION

Polyherbal formulations are effective in promoting the wound-healing process. They can stimulate a variety of physiological functions that accelerates the process of healing. These formulations merit further investigation in clinical trials, and production up scaling will aid in the creation of a new horizon of polyherbal wound healing products.

Biomaterials-Based Regenerative Strategies for Skin Tissue Wound Healing

Skin tissue wound healing proceeds through four major stages, including hematoma formation, inflammation, and neo-tissue formation, and culminates with tissue remodeling. These four steps significantly overlap with each other and are aided by various factors such as cells, cytokines (both anti- and pro-inflammatory), and growth factors that aid in the neo-tissue formation. In all these stages, advanced biomaterials provide several functional advantages, such as removing wound exudates, providing cover, transporting oxygen to the wound site, and preventing infection from microbes. In addition, advanced biomaterials serve as vehicles to carry proteins/drug molecules/growth factors and/or antimicrobial agents to the target wound site. In this review, we report recent advancements in biomaterials-based regenerative strategies that augment the skin tissue wound healing process. In conjunction with other medical sciences, designing nanoengineered biomaterials is gaining significant attention for providing numerous functionalities to trigger wound repair. In this regard, we highlight the advent of nanomaterial-based constructs for wound healing, especially those that are being evaluated in clinical settings. Herein, we also emphasize the competence and versatility of the three-dimensional (3D) bioprinting technique for advanced wound management. Finally, we discuss the challenges and clinical perspective of various biomaterial-based wound dressings, along with prospective future directions. With regenerative strategies that utilize a cocktail of cell sources, antimicrobial agents, drugs, and/or growth factors, it is expected that significant patient-specific strategies will be developed in the near future, resulting in complete wound healing with no scar tissue formation.

Healing Mechanisms in Cutaneous Wounds: Tipping the Balance

Acute and chronic cutaneous wounds pose a significant health and economic burden. Cutaneous wound healing is a complex process that occurs in four distinct, yet overlapping, highly coordinated stages: hemostasis, inflammation, proliferation, and remodeling. Postnatal wound healing is reparative, which can lead to the formation of scar tissue. Regenerative wound healing occurs during fetal development and in restricted postnatal tissues. This process can restore the wound to an uninjured state by producing new skin cells from stem cell reservoirs, resulting in healing with minimal or no scarring. Focusing on the pathophysiology of acute burn wounds, this review highlights reparative and regenerative healing mechanisms (including the role of cells, signaling molecules, and the extracellular matrix) and discusses how components of regenerative healing are being used to drive the development of novel approaches and therapeutics aimed at improving clinical outcomes. Important components of regenerative healing, such as stem cells, growth factors, and decellularized dermal matrices, are all being evaluated to recapitulate more closely the natural regenerative healing process.

Cutaneous Regeneration Mechanism of β-Sheet Silk Fibroin in a Rat Burn Wound Healing Model

Therapeutic dressings to enhance burn wound repair and regeneration are required. Silk fibroin (SF), a natural protein, induces cell migration and serves as a biomaterial in various dressings. SF dressings usually contain α-helices and β-sheets. The former has been confirmed to improve cell proliferation and migration, but the wound healing effect and related mechanisms of β-sheet SF remain unclear. We investigated the effects of β-sheet SF in vivo and in vitro. Alcohol-treated α-helix SF transformed into the β-sheet form, which promoted granulation formation and re-epithelialization when applied as lyophilized SF dressing (LSFD) in a rat burn model. Our in vitro results showed that β-sheet SF increased human dermal fibroblast (HDF) migration and promoted the expression of extracellular matrix (ECM) proteins (fibronectin and type III collagen), matrix metalloproteinase-12, and the cell adhesion molecule, integrin β1, in rat granulation tissue and HDFs. This confirms the role of crosstalk between integrin β1 and ECM proteins in cell migration. In summary, we demonstrated that β-sheet SF facilitates tissue regeneration by modulating cell adhesion molecules in dermal fibroblasts. LSFD could find clinical application for burn wound regeneration. Moreover, β-sheet SF could be combined with anti-inflammatory materials, growth factors, or antibiotics to develop novel dressings.

Role of Nrf2 in MALAT1/ HIF-1α loop on the regulation of angiogenesis in diabetic foot ulcer

Diabetic non healing wounds often result in significant morbidity and mortality. The number of effective targets to detect these wounds are meagre. Slow lymphangiogenesis is one of the complex processes involved in impaired healing of wounds. Long non coding RNAs (lncRNAs) have been importantly recognized for their role in pathological conditions. Multiple studies highlighting the role of lncRNAs in the regulation of several biological processes and complex diseases. Herein, we investigated the role of lncRNA Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in the progression of diabetic foot ulcer (DFU). We report a significant reduction in the expression of lncRNA MALAT1 in the infected DFU subjects which was positively correlated with the expression of angiogenic factors such as Nrf2, HIF-1α and VEGF. Further, expression of pro-inflammatory markers TNF-α and IL-6 were found to be increased while, the expression of anti-inflammatory marker IL-10 was decreased in infected DFU tissues. Involvement of lncRNA MALAT1 in angiogenesis in EA.hy926 cells was demonstrated by silencing the expression of Nrf2, HIF-1α, and VEGF through interference mediated by MALAT1. In addition, its inflammatory role was demonstrated by decreased expression of TNF-α, IL-6 and not affecting the expression of IL-10. Further, CRISPR-Cas9 knock out of Nrf2 decreased the expression of lncRNA MALAT1, HIF-1α and VEGF which revealed the association of Nrf2 in regulating MALAT1/HIF-1α loop through positive feedback mechanism. Collectively, our results suggested the role of Nrf2 on MALAT1/HIF-1α loop in the regulation of angiogenesis, which could act as a novel target in the treatment of diabetic wounds.

Nanomedicine in Healing Chronic Wounds: Opportunities and Challenges

The poor healing associated with chronic wounds affects millions of people worldwide through high mortality rates and associated costs. Chronic wounds present three main problems: First, the absence of a suitable environment to facilitate cell migration, proliferation, and angiogenesis; second, bacterial infection; and third, unbalanced and prolonged inflammation. Unfortunately, current therapeutic approaches have not been able to overcome these main issues and, therefore, have limited clinical success. Over the past decade, incorporating the unique advantages of nanomedicine into wound healing approaches has yielded promising outcomes. Nanomedicine is capable of stimulating various cellular and molecular mechanisms involved in the wound microenvironment via antibacterial, anti-inflammatory, and angiogenetic effects, potentially reversing the wound microenvironment from nonhealing to healing. This review briefly discusses wound healing mechanisms and pathophysiology and then highlights recent findings regarding the opportunities and challenges of using nanomedicine in chronic wound management.

Natural composite dressings based on collagen, gelatin and plant bioactive compounds for wound healing: A review

Skin wound dressings are commonly used to stimulate and enhance skin tissue repair. Even if wounds seem easy to repair for clinicians and to replicate in an in vitro set-up for scientists, chronic wounds remain currently an open challenge in skin tissue engineering for patients with complementary diseases. The seemingly simple process of skin healing hides a heterogenous sequence of events, specific timing, and high level of organization and coordination among the involved cell types. Taken together, all these aspects make wound healing a unique process, but we are not yet able to completely repair the chronic wounds or to reproduce them in vitro with high fidelity. This review highlights the main characteristics and properties of a natural polymer, which is widely used as biomaterial, namely collagen and of its denatured form, gelatin. Available wound dressings based on collagen/gelatin and proposed variants loaded with bioactive compounds derived from plants are presented. Applications of these composite biomaterials are discussed with emphasis on skin wound healing. A perspective on current issues is given in the light of future research. The emerging technologies support the development of innovative dressings based exclusively on natural constituents, either polymeric or bioactive compounds.

Biochemical, Histopathologic, and Genotoxic Effects of Ethanol Extract of Salvia hypargeia (Fisch. & Mey.) on Incisional and Excisional Wounded Diabetic Rats

Purpose: Nonhealing wounds are a serious problem of diabetic patients. Salvia species are traditionally used for the treatment of wounds. The aim of the study was to investigate the effects of ointment prepared with ethanol extract obtained from the aerial parts of Salvia hypargeia, an endemic plant from Turkey, on diabetic rat incisional and excisional skin wounds. Materials and Methods: Male Wistar albino rats (n: 60) were divided into five groups. Diabetes was induced and two concentrations (0.5% and 1%) of the extract were used for ointments and applied on wounds for 7 and 14 days. Fito cream was chosen as a reference drug. Results: In excisional wounds, healing ratios of 0.5% (63.4% and 99.3%) and 1% (65.5% and 99.9%) S. hypargeia groups were higher compared to control (35.9% and 75.1%), and in incisional wounds, healing ratios of 0.5% (78.1% and 98.5%) and 1% (84.4% and 99.4%) S. hypargeia groups were higher compared to control (30.5% and 72.9%) (p < .01). Hydroxyproline (0.31 ± 0.3 and 0.34 ± 0.2) levels were lower and GSH (10.7 ± 3.1 and 7.6 ± 0.9) levels were higher in 0.5% and 1% S. hypargeia groups on the 14th day (p < .01). Histopathological results revealed re-epithelialization and formation of granulation tissue in all S. hypargeia groups. Genotoxicologic results indicated, GDI, DCP values, and MN frequency of 0.5% and 1% S. hypargeia groups did not reach to significant levels both on the 7 and 14 days. Conclusions: S. hypargeia may have a potential for therapeutic use in treatment and management of diabetic wounds with a successful topical application.

Animal Models for Studies of Keloid Scarring

Significance: Keloid scarring is a disfiguring fibroproliferative disorder that can significantly impair the quality of life in affected individuals. The mechanisms that initiate keloid scarring are incompletely understood, and keloids remain one of the most challenging skin conditions to treat. Keloids are unique to humans; thus, the lack of adequate animal models has hindered research efforts aimed at prevention and effective therapeutic intervention. Recent Advances: In the absence of a suitable animal model, keloid researchers often rely on studying excised keloid scar tissue and keloid-derived cultured cells. Recently, in vivo models have been described that involve transplantation to mice of reconstructed skin containing keloid-derived fibroblasts and/or keratinocytes. These mouse-human hybrid animal models display some similarities with keloids and may enable investigation of novel therapies, although no model yet recapitulates all the features of human keloid scarring. Critical Issues: Differences in skin physiology and modes of healing contribute to challenges in modeling keloids in laboratory animals. Furthermore, recent studies suggest that cells of the immune system contribute to keloid pathology. The need to use immunodeficient hosts for transplanted human keloid cells in recently described animal models precludes studying the role of the immune system in keloid scarring. Future Directions: Future animal models may take advantage of humanized mice with immune systems reconstituted using human immune cells. Such models, when combined with grafted tissues prepared using keloid-derived cells, might enable investigation of complex interactions between systemic and local factors that combine to promote keloid scar formation and may aid in the development of novel therapies.

Macrophage functions in wound healing

Macrophages play a crucial role in regeneration and consecutive phases of wound healing. In this review, we summarise current knowledge on the ontogeny, origin, phenotypical heterogeneity, and functional exchangeability of macrophages participating in these processes. We also describe the genetic, pharmacologic, and bioengineering methods for manipulation of macrophage phenotype and functions and their potential for development of the novel, clinically applicable therapies.

Healing Chronic Wounds: Current Challenges and Potential Solutions

PURPOSE OF REVIEW

The purpose of this review is to raise awareness, examine the challenges faced by wound care researchers and explore opportunities for potential improvements.

RECENT FINDINGS

Chronic wounds are associated with significant morbidity and mortality, and they represent a major medical and financial burden. Despite this, no new therapy has received FDA efficacy approval for the treatment of chronic wounds since 1997. Previous preclinical studies using animal models did not translate to human wounds due to inherent limitations of experimental models, variability in assessment methods and overall experimental design. Clinical trials continued to be challenged by the balance of the inclusion and exclusion criteria, the high cost and time expenditure of the trials, and the constraint of a single FDA-acceptable outcome of complete wound closure.

SUMMARY

Wound research faces multiple challenges in both pre-clinical and clinical research that slowed progress and development of efficacious therapies. Solutions to such challenges will provide new opportunities for improved study design in the future.

In vitro and ex vivo systems at the forefront of infection modeling and drug discovery

Bacterial infections and antibiotic resistant bacteria have become a growing problem over the past decade. As a result, the Centers for Disease Control predict more deaths resulting from microorganisms than all cancers combined by 2050. Currently, many traditional models used to study bacterial infections fail to precisely replicate the in vivo bacterial environment. These models often fail to incorporate fluid flow, bio-mechanical cues, intercellular interactions, host-bacteria interactions, and even the simple inclusion of relevant physiological proteins in culture media. As a result of these inadequate models, there is often a poor correlation between in vitro and in vivo assays, limiting therapeutic potential. Thus, the urgency to establish in vitro and ex vivo systems to investigate the mechanisms underlying bacterial infections and to discover new-age therapeutics against bacterial infections is dire. In this review, we present an update of current in vitro and ex vivo models that are comprehensively changing the landscape of traditional microbiology assays. Further, we provide a comparative analysis of previous research on various established organ-disease models. Lastly, we provide insight on future techniques that may more accurately test new formulations to meet the growing demand of antibiotic resistant bacterial infections.

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

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

Interactions between TGF-β1, canonical WNT/β-catenin pathway and PPAR γ in radiation-induced fibrosis

Radiation therapy induces DNA damage and inflammation leading to fibrosis. Fibrosis can occur 4 to 12 months after radiation therapy. This process worsens with time and years. Radiation-induced fibrosis is characterized by fibroblasts proliferation, myofibroblast differentiation, and synthesis of collagen, proteoglycans and extracellular matrix. Myofibroblasts are non-muscle cells that can contract and relax. Myofibroblasts evolve towards irreversible retraction during fibrosis process. In this review, we discussed the interplays between transforming growth factor-β1 (TGF-β1), canonical WNT/β-catenin pathway and peroxisome proliferator-activated receptor gamma (PPAR γ) in regulating the molecular mechanisms underlying the radiation-induced fibrosis, and the potential role of PPAR γ agonists. Overexpression of TGF-β and canonical WNT/β-catenin pathway stimulate fibroblasts accumulation and myofibroblast differentiation whereas PPAR γ expression decreases due to the opposite interplay of canonical WNT/β-catenin pathway. Both TGF-β1 and canonical WNT/β-catenin pathway stimulate each other through the Smad pathway and non-Smad pathways such as phosphatidylinositol 3-kinase/serine/threonine kinase (PI3K/Akt) signaling. WNT/β-catenin pathway and PPAR γ interact in an opposite manner. PPAR γ agonists decrease β-catenin levels through activation of inhibitors of the WNT pathway such as Smad7, glycogen synthase kinase-3 (GSK-3 β) and dickkopf-related protein 1 (DKK1). PPAR γ agonists also stimulate phosphatase and tensin homolog (PTEN) expression, which decreases both TGF-β1 and PI3K/Akt pathways. PPAR γ agonists by activating Smad7 decrease Smads pathway and then TGF-β signaling leading to decrease radiation-induced fibrosis. TGF-β1 and canonical WNT/β-catenin pathway promote radiation-induced fibrosis whereas PPAR γ agonists can prevent radiation-induced fibrosis.

Radiotherapy-Induced Skin Reactions Induce Fibrosis Mediated by TGF-β1 Cytokine

Purpose:

This study aimed to investigate radiation-induced lesions on the skin in an experimental animal model. Methods and Materials: Cutaneous wounds were induced in Wistar rats by 4 MeV energy electron beam irradiation, using a dose rate of 240 cGy/min, for 3 different doses (10 Gy, 40 Gy, and 60 Gy). The skin was observed 5, 10, and 25 days (D) after ionizing radiation exposition.

Results:

Infiltrate inflammatory process was observed in D5 and D10, for the 40 Gy and 60 Gy groups, and a progressive increase of transforming growth factor β1 is associated with this process. It could also be noted a mischaracterization of collagen fibers at the high-dose groups.

Conclusion:

It was observed that the lesions caused by ionizing radiation in rats were very similar to radiodermatitis in patients under radiotherapy treatment.

Advances in Knowledge:

This study is important to develop strategies to prevent radiation-induced skin reactions.

Comparison of In-Vitro and Ex-Vivo Wound Healing Assays for the Investigation of Diabetic Wound Healing and Demonstration of a Beneficial Effect of a Triterpene Extract

Diabetes mellitus is a frequent cause for chronic, difficult-to-treat wounds. New therapies for diabetic wounds are urgently needed and in-vitro or ex-vivo test systems are essential for the initial identification of new active molecules. The aim of this study is to compare in-vitro and ex-vivo test systems for their usability for early drug screening and to investigate the efficacy of a birch bark triterpene extract (TE) that has been proven ex-vivo and clinically to accelerate non-diabetic wound healing (WH), in a diabetic context. We investigated in-vitro models for diabetic WH, i.e. scratch assays with human keratinocytes from diabetic donors or cultured under hyperglycaemic conditions and a newly developed porcine ex-vivo hyperglycaemic WH model for their potential to mimic delayed diabetic WH and for the influence of TE in these test systems. We show that keratinocytes from diabetic donors often fail to exhibit significantly delayed WH. For cells under hyperglycaemic conditions significant decrease is observed but is influenced by choice of medium and presence of supplements. Also, donor age plays a role. Interestingly, hyperglycaemic effects are mainly hyperosmolaric effects in scratch assays. Ex-vivo models under hyperglycaemic conditions show a clear and substantial decrease of WH, and here both glucose and hyperosmolarity effects are involved. Finally, we provide evidence that TE is also beneficial for ex-vivo hyperglycaemic WH, resulting in significantly increased length of regenerated epidermis to 188±16% and 183±11% (SEM; p<0.05) compared to controls when using two different TE formulations. In conclusion, our results suggest that microenvironmental influences are important in WH test systems and that therefore the more complex hyperglycaemic ex-vivo model is more suitable for early drug screening. Limitations of the in-vitro and ex-vivo models are discussed. Furthermore our data recommend TE as a promising candidate for in-vivo testings in diabetic wounds.

Titanium wound chambers for wound healing research

Standardized and reproducible animal models are crucial in medical research. Rodents are commonly used in wound healing studies since, they are easily available, affordable and simple to handle and house. However, the most significant limitation of rodent models is that the wounds heal by contraction while in humans the primary mechanisms of healing are reepithelialization and granulation tissue formation. The robust contraction results in faster wound closure that complicates the reproducibility of rodent studies in clinical trials. We have developed a titanium wound chamber for rodent wound healing research. The chamber is engineered from two pieces of titanium and is placed transcutaneously on the dorsum of a rodent. The chamber inhibits wound contraction and provides a means for controlled monitoring and sampling of the wound environment in vivo with minimal foreign body reaction. This technical report introduces two modalities utilizing the titanium chambers in rats: (1) Wound in a skin island model and, (2) Wound without skin model. Here, we demonstrate in rats how the "wound in a skin island model" slows down wound contraction and how the "wound without skin" model completely prevents the closure. The titanium wound chamber provides a reproducible standardized models for wound healing research in rodents.

A new removable airway stent

Background

Malignant airway obstruction is a feared complication and will most probably occur more frequently in the future because of increasing cancer incidence and increased life expectancy in cancer patients. Minimal invasive treatment using airway stents represents a meaningful and life-saving palliation. We present a new removable airway stent for improved individualised treatment.

Methods

To our knowledge, the new airway stent is the world's first knitted and uncovered self-expanding metal stent, which can unravel and be completely removed. In an in vivo model using two anaesthetised and spontaneously breathing pigs, we deployed and subsequently removed the stents by unravelling the device. The procedures were executed by flexible bronchoscopy in an acute and a chronic setting – a ‘proof-of-principle’ study.

Results

The new stent was easily and accurately deployed in the central airways, and it remained fixed in its original position. It was easy to unravel and completely remove from the airways without clinically significant complications. During the presence of the stent in the chronic study, granulation tissue was induced. This tissue disappeared spontaneously with the removal.

Conclusions

The new removable stent functioned according to its purpose and unravelled easily, and it was completely removed without significant technical or medical complications. Induced granulation tissue disappeared spontaneously. Further studies on animals and humans are needed to define its optimal indications and future use.