In-vivo efficacy of biodegradable ultrahigh ductility Mg-Li-Zn alloy tracheal stents for pediatric airway obstruction

Degrees of Inflammation in the Treatment of Subglottic Stenosis in a Rabbit Model: Histopathological Assessment of a Novel Bioabsorbable Ultra-high Ductility Magnesium Alloy Stent

OBJECTIVE

Utilizing a novel histopathological scoring system and subglottic stenosis (SGS) rabbit model, we aimed to compare degrees of inflammation and severity of narrowing in the subglottis between two minimally invasive therapeutic modalities: endoscopic balloon dilation (EBD) alone versus EBD with placement of a bioabsorbable ultra-high ductility magnesium (UHD-Mg) alloy stent.

METHODS

SGS was induced endoscopically via microsuspension laryngoscopy in 23 New Zealand white rabbits. The control group (n = 11) underwent EBD alone, the study arm (n = 12) underwent EBD with implantation of bioabsorbable UHD-Mg alloy stents. Rabbits were euthanized at 2-, 3-, and 6-weeks after SGS induction, coinciding with wound healing stages. Using Optical Coherence Tomography (OCT), cross-sectional areas of airways were compared to calculate the mean percentage of intraluminal area at sequential time points. A novel histopathological scoring system was used to analyze frozen sections of laryngotracheal complexes. The degree of inflammation was quantified by scoring changes in inflammatory cell infiltration, epithelial ulceration/metaplasia, subepithelial edema/fibrosis, and capillary number/dilation. Univariate analysis was utilized to analyze these markers.

RESULTS

We found rabbits implanted with the bioabsorbable UHD-Mg alloy stent had statistically significantly higher scores in categories of hyperplastic change (stents vs controls: 1.48 vs 0.46 p < 0.001), squamous metaplasia (22 vs 5 p < 0.001), and neutrophils/fibrin in lumen (31 vs 8, p < 0.001). Rabbits who received EBD alone had higher scores of subepithelial edema and fibrosis (2.70 vs 3.49, p < 0.0256). The stented rabbits demonstrated significantly increased mean percent stenosis by intraluminal mean area compared to controls at 2 weeks (88.56 vs 58.98, p = 0.032), however at all other time points there was no significant difference between intraluminal subglottic stenosis by mean percent stenosis area.

DISCUSSION

Rabbits with SGS treated with UHD-Mg alloy stents demonstrated histopathologic findings suggestive of lower levels of tracheal fibrosis. This could indicate a reduced tendency towards the development of stenosis when compared to EBD alone. There was not a difference in luminal size between stent and non-stented rabbits at the six-week end point. Histologically, however, overall the use of bioabsorbable UHD-Mg alloy stenting elicited a greater tissue response at the level of the superficial mucosa rather than fibrosis of the lamina propria seen in the stented rabbits. This suggests more favorable healing and less of a tendency towards fibrosis and stenosis even though there may not be a benefit from a luminal size standpoint during this early healing period. Compared to known complications of currently available non-bioabsorbable metal or silicone-based stents, this proof-of-concept investigation highlights the potential use of a novel biodegradable UHD-Mg stent as a therapeutic modality for pediatric SGS.

Synergistic Effects of SDS and H2O2 Combinations on Tracheal Scaffold Development: An In Vitro Study Using Goat Trachea

Currently, a tissue-engineered trachea has been popularly used as a biological graft for tracheal replacement in severe respiratory diseases. In the development of tissue-engineered tracheal scaffolds, in vitro studies play a crucial role in allowing researchers to evaluate the efficacy and safety of scaffold designs and fabrication techniques before progressing to in vivo or clinical trials. This research involved the decellularization of goat trachea using SDS, H2O2, and their combinations. Various quantitative and qualitative assessments were performed, including histological analysis, immunohistochemistry, and biomechanical testing. Hematoxylin and eosin staining evaluated the cellular content, while safranin O-fast green and Masson's trichrome staining assessed glycosaminoglycan content and collagen distribution, respectively. The immunohistochemical analysis focused on detecting MHC-1 antigen presence. Tensile strength measurements were conducted to evaluate the biomechanical properties of the decellularized scaffolds. The results demonstrated that the combination of SDS and H2O2 for goat tracheal decellularization yielded scaffolds with minimal cellular remnants, low toxicity, preserved ECM, and high tensile strength and elasticity. This method holds promise for developing functional tracheal scaffolds to address severe respiratory diseases effectively.

Exploring the Potential of Nanotechnology in Pediatric Healthcare: Advances, Challenges, and Future Directions

The utilization of nanotechnology has brought about notable advancements in the field of pediatric medicine, providing novel approaches for drug delivery, disease diagnosis, and tissue engineering. Nanotechnology involves the manipulation of materials at the nanoscale, resulting in improved drug effectiveness and decreased toxicity. Numerous nanosystems, including nanoparticles, nanocapsules, and nanotubes, have been explored for their therapeutic potential in addressing pediatric diseases such as HIV, leukemia, and neuroblastoma. Nanotechnology has also shown promise in enhancing disease diagnosis accuracy, drug availability, and overcoming the blood-brain barrier obstacle in treating medulloblastoma. It is important to acknowledge that while nanotechnology offers significant opportunities, there are inherent risks and limitations associated with the use of nanoparticles. This review provides a comprehensive summary of the existing literature on nanotechnology in pediatric medicine, highlighting its potential to revolutionize pediatric healthcare while also recognizing the challenges and limitations that need to be addressed.

A narrative review of new research progress regarding the use of airway stents in benign airway stenosis

INTRODUCTION

Benign airway stenosis is a severe disease that can result in death with improper treatment. Clinicians must know about airway stents to choose the best one in their daily practice.

AREAS COVERED

PubMed, Embase, and other electronic databases and websites were searched to identify relevant randomized controlled trials and meta-analyses. This review summarizes different types of airway stents and analyzes their advantages and disadvantages.

EXPERT OPINION

Increasing attention has been given to the indications and prognosis of benign airway stenosis treated with different airway stents. With more investigations and data, better alternatives to silicone stents could be developed in the future.

A Novel Decellularized Trachea Preparation Method for Rapid Construction of a Functional Tissue Engineered Trachea to Repair Tracheal Defects

Long segment trachea defects are repaired by tracheal substitution, while the decellularized technology has been effectively employed to prepare tissue engineering trachea (TET). However, its clinical application is restrictied by...

Current status and outlook of biodegradable metals in neuroscience and their potential applications as cerebral vascular stent materials

Over the past two decades, biodegradable metals (BMs) have emerged as promising materials to fabricate temporary biomedical devices, with the purpose of avoiding potential side effects of permanent implants. In this review, we first surveyed the current status of BMs in neuroscience, and briefly summarized the representative stents for treating vascular stenosis. Then, inspired by the convincing clinical evidence on the in vivo safety of Mg alloys as cardiovascular stents, we analyzed the possibility of producing biodegradable cerebrovascular Mg alloy stents for treating ischemic stroke. For these novel applications, some key factors should also be considered in designing BM brain stents, including the anatomic features of the cerebral vasculature, hemodynamic influences, neuro-cytocompatibility and selection of alloying elements. This work may provide insights into the future design and fabrication of BM neurological devices, especially for brain stents.

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The current status of the application of biodegradable metals (BM) in neuroscience was presented.

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We analyzed the possibility of producing biodegradable cerebrovascular Mg alloy stents for ischemic stroke treatment.

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Key factors in designing BM brain stents were discussed.

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This work may provide insights into the future design and fabrication of BM neurological devices, especially for brain stents.

State of the Science in Tracheal Stents: A Scoping Review

OBJECTIVE

Recent material science advancements are driving tracheal stent innovation. We sought to assess the state of the science regarding materials and preclinical/clinical outcomes for tracheal stents in adults with benign tracheal disease.

METHODS

A comprehensive literature search in April 2021 identified 556 articles related to tracheal stents. One-hundred and twenty-eight full-text articles were reviewed and 58 were included in the final analysis. Datapoints examined were stent materials, clinical applications and outcomes, and preclinical findings, including emerging technologies.

RESULTS

In the 58 included studies, stent materials were metals (n = 28), polymers (n = 19), coated stents (n = 19), and drug-eluting (n = 5). Metals included nitinol, steel, magnesium alloys, and elgiloy. Studies utilized 10 different polymers, the most popular included polydioxanone, poly-l-lactic acid, poly(d,l-lactide-co-glycolide), and polycaprolactone. Coated stents employed a metal or polymer framework and were coated with polyurethane, silicone, polytetrafluoroethylene, or polyester, with some polymer coatings designed specifically for drug elution. Drug-eluting stents utilized mitomycin C, arsenic trioxide, paclitaxel, rapamycin, and doxycycline. Of the 58 studies, 18 were human and 40 were animal studies (leporine = 21, canine = 9, swine = 4, rat = 3, ovine/feline/murine = 1). Noted complications included granulation tissue and/or stenosis, stent migration, death, infection, and fragmentation.

CONCLUSION

An increasing diversity of materials and coatings are employed for tracheal stents, growing more pronounced over the past decade. Though most studies are still preclinical, awareness of tracheal stent developments is important in contextualizing novel stent concepts and clinical trials. Laryngoscope, 2021.

In-vivo efficacy of biodegradable ultrahigh ductility Mg-Li-Zn alloy tracheal stents for pediatric airway obstruction

Pediatric laryngotracheal stenosis is a complex congenital or acquired airway injury that may manifest into a potentially life-threatening airway emergency condition. Depending on the severity of obstruction, treatment often requires a combination of endoscopic techniques, open surgical repair, intraluminal stenting, or tracheostomy. A balloon expandable biodegradable airway stent maintaining patency while safely degrading over time may address the complications and morbidity issues of existing treatments providing a less invasive and more effective management technique. Previous studies have focused on implementation of degradable polymeric scaffolds associated with potentially life-threatening pitfalls. The feasibility of an ultra-high ductility magnesium-alloy based biodegradable airway stents was demonstrated for the first time. The stents were highly corrosion resistant under in vitro flow environments, while safely degrading in vivo without affecting growth of the rabbit airway. The metallic matrix and degradation products were well tolerated by the airway tissue without exhibiting any noticeable local or systemic toxicity.