Paclitaxel-Loaded PLGA Coating Stents in the Treatment of Benign Cicatrical Airway Stenosis

Graphene oxide-loaded rapamycin coating on airway stents inhibits stent-related granulation tissue hyperplasia

OBJECTIVES

Our objective was to explore the safety and efficacy of a graphene oxide-loaded rapamycin-coated self-expandable metallic airway stent (GO@RAPA-SEMS) in a rabbit model.

METHODS

The dip coating method was used to develop a GO@RAPA-SEMS and a poly(lactic-co-glycolic)-acid loaded rapamycin-coated self-expandable metallic airway stent (PLGA@RAPA-SEMS). The surface structure was evaluated using a scanning electronic microscope. The in vitro drug-release profiles of the 2 stents were explored and compared. In the animal study, a total of 45 rabbits were randomly divided into 3 groups and underwent 3 kinds of stent placements. Computed tomography was performed to evaluate the degree of stenosis at 1, 2 and 3 months after the stent operation. Five rabbits in each group were sacrificed after the computed tomography scan. The stented trachea and blood were collected for further pathological analysis and laboratory testing.

RESULTS

The in vitro drug-release study revealed that GO@RAPA-SEMS exhibited a sudden release on the first day and maintained a certain release rate on the 14th day. The PLGA@RAPA-SEMS exhibited a longer sustained release time. All 45 rabbits underwent successful stent placement. Pathological results indicated that the granulation tissue thickness in the GO@RAPA-SEMS group was less than that in the PLGA@RAPA-SEMS group. The TUNEL and hypoxia-inducible factor-1α staining results support the fact that the granulation inhibition effect in the GO@RAPA-SEMS group was greater than that in the PLGA@RAPA-SEMS group.

CONCLUSIONS

GO@RAPA-SEMS effectively inhibited stent-related granulation tissue hyperplasia.

Recent developments in ureteral stent: Substrate material, coating polymer and technology, therapeutic function

The ureteral stent is an effective treatment for clinical ureteral stricture following urological surgery, and the functional coating of the stent could effectively inhibit bacterial colonization and other complications. The present review provides an analysis and description of the materials used in ureteral stents and their coatings. Emphasis is placed on the technological advancements of functional coatings, taking into consideration the characteristics of these materials and the properties of their active substances. Furthermore, recent advances in enhancing the therapeutic efficacy of functional coatings are also reviewed. It is anticipated that this article will serve as a valuable reference providing insights for future research development on new drug-loaded ureteral stents.

Analysis of clinical characteristics of 617 patients with benign airway stenosis

Introduction

Benign airway stenosis (BAS), namely airway narrowing caused by a variety of benign lesions, can lead to varying degrees of breathing difficulties and even death due to asphyxia. This study aimed to elucidate the clinical characteristics of BAS, including etiology, treatment and pathology, by analyzing the clinical data of BAS patients.

Methods

A retrospective analysis was conducted using the clinical data of 617 BAS cases from January 2017 to December 2022. The pathological characteristics of the tissues were assessed by hematoxylin-eosin (H&E) and Masson's staining. Besides, protein expression levels were determined by immunohistochemistry (IHC).

Results

A total of 617 patients were included (333 females [53.97%] and 284 males [46.03%]), with an average age of 48.93 ± 18.30 (range 14-87). Tuberculosis (n = 306, 49.59%) and trauma (n = 179, 29.02%) were the two leading etiologies of BAS, followed by airway foreign bodies (FB, n = 74, 11.99%), external compression (n = 25, 4.05%) and other etiologies (n = 33, 5.35%). Among 306 tuberculous tracheobronchial stenosis (TBTS) cases, most were females (n = 215, 70.26%), and TBTS mainly occurred in the left main bronchus (n = 97, 31.70%), followed by the right middle bronchus (n = 70 cases, 22.88%). The majority of TBTS patients (n = 259, 84.64%) were treated by interventional therapy. The condition of 179 BAS patients was ascribed to trauma, such as tracheal intubation (n = 92, 51.40%), tracheotomy (n = 69, 38.56%), injury (n = 15, 8.38%) and surgery (n = 3, 1.68%), which mostly took place in the trachea (n = 173, 96.65%). TAS patients mainly received interventional therapy (n = 168, 93.85%) and stent implantation (n = 47, 26.26%). The granulation tissues of BAS primarily featured inflammation, proliferation and fibrosis. IHC indicated the up-regulated expressions of transforming growth factor-β1 (TGF-β1), α-smooth muscle actin (α-SMA), collagen type I protein (COL-I) and vimentin, and the down-regulated expression of E-cadherin, which indicated fibrosis and epithelial-mesenchymal transition (EMT).

Conclusion

Tuberculosis was the main etiology, and trauma was the secondary etiology. The granulation tissues of BAS were characterized by inflammation, fibrosis and probably EMT. Comprehensive interventional therapy is an effective method of treating BAS.

Synergistic effect of VEGF and SDF-1α in endothelial progenitor cells and vascular smooth muscle cells

Vascular endothelial growth factor (VEGF) is a potent agonist of angiogenesis that induces proliferation and differentiation of endothelial progenitor cells (EPCs) after vascular injury. Previous studies have suggested that stromal cell-derived factor 1-alpha (SDF-1α) and VEGF have a synergistic effect on vascular stenosis. The aim of the present study was to investigate whether VEGF and SDF-1α act synergistically in EPCs and vascular smooth muscle cells (VSMCs). In this study, EPCs were isolated from rat bone marrow and their morphology and function were studied. Subsequently, VEGF was delivered into EPCs using an adenoviral vector. Tube formation, migration, proliferation, and apoptosis of VEGF-overexpressing EPCs was analyzed. Then, EPCs were co-cultured with VSMCs in the presence or absence of SDF-1α, the migration, proliferation, apoptosis, and differentiation capacity of EPCs and VSMCs were analyzed respectively. The isolated EPCs showed typical morphological features, phagocytic capacity, and expressed surface proteins. While stable expression of VEGF remarkably enhanced tube formation, migration, and proliferation capacity of EPCs, apoptosis was decreased. Moreover, the proliferation, migration, and differentiation capacity of EPCs in the co-cultured model was enhanced in the presence of SDF-1α, and apoptosis was decreased. However, these effects were reversed in VSMCs. Therefore, our results showed that VEGF and SDF-1α synergistically increased the migration, differentiation, and proliferation capabilities of EPCs, but not VSMCs. This study suggests a promising strategy to prevent vascular stenosis.

pH-Responsive Nanoparticles for Delivery of Paclitaxel to the Injury Site for Inhibiting Vascular Restenosis

A high incidence of restenosis has been reported at the site of inflammation following angioplasty and stent implantation. The anti-proliferative drug paclitaxel (PTX) could help to reduce inflammation and restenosis; however, it has poor water solubility and serious adverse side effects at high doses. Given the presence of metabolic acidosis at the site of inflammation, we hypothesized that nanoparticles that are responsive to low pH could precisely release the loaded drug at the target site. We successfully constructed pH-responsive poly(D, L-lactic-co-glycolic acid) (PLGA) nanoparticles loaded with PTX and NaHCO3 as a pH-sensitive therapeutic agent (PTX-NaHCO3-PLGA NPs). The NPs exhibited remarkable pH sensitivity and a good safety profile both in vitro in rat vascular smooth muscle cells and in vivo in Sprague Dawley rats after tail vein injection. In the rat model, the PTX-NaHCO3-PLGA NPs treatment group showed suppressed intimal proliferation following balloon-induced carotid artery injury compared with that of the saline-treated control. Overall, these results demonstrate that our newly developed pH-responsive nanodrug delivery platform has the potential to effectively inhibit restenosis.