Fe3O4 coated stent prevent artery neointimal hyperplasia by inhibiting vascular smooth muscle cell proliferation

In-stent restenosis (ISR), caused by aggressive vascular smooth muscle cell (VSMC) proliferation, is a serious complication of stenting. Therefore, developing therapeutic approaches that target VSMC inhibition is imperative. Our previous study showed that VSMC hyperplasia was attenuated after iron stent degradation, and VSMC proliferation around the stented section was arrested. The corrosion products of the iron stents were primarily Fe3O4 particles. Therefore, we hypothesized that Fe3O4 particles generated by iron stents would prevent neointimal hyperplasia by inhibiting VSMC proliferation. To test this hypothesis, culture assays and flow cytometry were performed to investigate the proliferation of VSMC. Global gene sequencing and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed to investigate the underlying mechanisms. Fe3O4-coated stents were implanted into rabbit carotid arteries to evaluate the inhibitory effects of Fe3O4 on neointimal hyperplasia. The major findings of the study were as follows: 1) Fe3O4 attenuated neointimal hyperplasia by preventing VSMC proliferation after stenting; 2) Fe3O4 exerted inhibitory effects on VSMCs by downregulating proliferative genes such as SOX9, EGR4, and TGFB1, but upregulated inhibitory genes such as DNMT1, TIMP3, and PCNA; 3) Fe3O4 inhibited VSMCs by preventing phenotypic transformation from the contractile to the synthetic phase; and 4) Fe3O4-coated stents achieved satisfactory hemocompatibility in a rabbit model. Our study highlights the additional benefits of Fe3O4 particles in inhibiting VSMC proliferation, indicating that Fe3O4 coated stent potentially served as an attractive therapeutic approach for ISR prevention.

Remodelers of the vascular microenvironment: The effect of biopolymeric hydrogels on vascular diseases

Vascular disease is the leading health problem worldwide. Vascular microenvironment encompasses diverse cell types, including those within the vascular wall, blood cells, stromal cells, and immune cells. Initiation of the inflammatory state of the vascular microenvironment and changes in its mechanics can profoundly affect vascular homeostasis. Biomedical materials play a crucial role in modern medicine, hydrogels, characterized by their high-water content, have been increasingly utilized as a three-dimensional interaction network. In recent times, the remarkable progress in utilizing hydrogels and understanding vascular microenvironment have enabled the treatment of vascular diseases. In this review, we give an emphasis on the utilization of hydrogels and their advantages in the various vascular diseases including atherosclerosis, aneurysm, vascular ulcers of the lower limbs and myocardial infarction. Further, we highlight the importance and advantages of hydrogels as artificial microenvironments.

A Systematic Analysis of Additive Manufacturing Techniques in the Bioengineering of In Vitro Cardiovascular Models

Additive Manufacturing is noted for ease of product customization and short production run cost-effectiveness. As our global population approaches 8 billion, additive manufacturing has a future in maintaining and improving average human life expectancy for the same reasons that it has advantaged general manufacturing. In recent years, additive manufacturing has been applied to tissue engineering, regenerative medicine, and drug delivery. Additive Manufacturing combined with tissue engineering and biocompatibility studies offers future opportunities for various complex cardiovascular implants and surgeries. This paper is a comprehensive overview of current technological advancements in additive manufacturing with potential for cardiovascular application. The current limitations and prospects of the technology for cardiovascular applications are explored and evaluated.

Drug-coated balloon for the treatment of small vessel disease: 9 months of angiographic results and 12 months of clinical outcomes of the PEPCAD China SVD study

BACKGROUND

Whether the drug-coated balloons (DCBs)-alone strategy was superior to plain old balloon angioplasty (POBA) in treating SVD remains unknown.

AIMS

We aimed to evaluate the efficacy and safety of DCBs for the treatment of coronary de novo small vessel disease (SVD) and provide further evidence for extending the clinical indications of DCBs. (ChiCTR1800014966).

METHODS

Eligible patients were randomized at a 2:1 ratio to receive DCB treatment or POBA in this prospective, multicenter clinical trial. The reference vessel diameter of lesions was visually assessed to be 2.0 to 2.75 mm. The primary endpoint of the study was angiographic in-segment late luminal loss (LLL) at the 9-month follow-up to demonstrate the superiority of DCB treatment to POBA in SVD. The composite clinical endpoints included clinically driven target lesion revascularization (CD-TLR), target lesion failure (TLF), major adverse cardiac events (MACEs), and thrombosis at the 12-month follow-up.

RESULTS

A total of 270 patients were enrolled (181 for DCB, 89 for POBA) at 18 centers in China. The primary endpoint of 9-month in-segment LLL in the intention-to-treat population was 0.10 ± 0.33 mm with DCB and 0.25 ± 0.38 mm with POBA (p = 0.0027). This difference indicated significant superiority of DCB treatment (95% CI: -0.22, -0.04, p_superiority  = 0.0068). The rates of the clinical endpoints-CD-TLR, TLF, and MACEs-were comparable between groups. No thrombosis events were reported.

CONCLUSIONS

DCB treatment of de novo SVD was superior to POBA with lower 9-month in-segment LLL. The rates of clinical events were comparable between the two devices.

Polylactide Perspectives in Biomedicine: From Novel Synthesis to the Application Performance

The incessant developments in the pharmaceutical and biomedical fields, particularly, customised solutions for specific diseases with targeted therapeutic treatments, require the design of multicomponent materials with multifunctional capabilities. Biodegradable polymers offer a variety of tailored physicochemical properties minimising health adverse side effects at a low price and weight, which are ideal to design matrices for hybrid materials. PLAs emerge as an ideal candidate to develop novel materials as are endowed withcombined ambivalent performance parameters. The state-of-the-art of use of PLA-based materials aimed at pharmaceutical and biomedical applications is reviewed, with an emphasis on the correlation between the synthesis and the processing conditions that define the nanostructure generated, with the final performance studies typically conducted with either therapeutic agents by in vitro and/or in vivo experiments or biomedical devices.

A First-in-Human Study of the Bioheart Sirolimus-Eluting Bioresorbable Vascular Scaffold in Patients with Coronary Artery Disease: Two-Year Clinical and Imaging Outcomes

INTRODUCTION

Newer generation bioresorbable scaffolds (BRSs) with thinner struts and improved deliverability are expected to enhance safety and efficacy profiles. Bioheart (Bio-Heart, Shanghai, China) BRS is constructed from a PLLA (poly-l-lactic acid) backbone coated with a PDLLA (poly D-l-lactic acid) layer eluting sirolimus. We report 2-year serial intracoronary imaging findings.

METHODS

In this first-in-human study, 46 patients with single de novo lesions in native coronary vessels (vessel size 3.0-3.75 mm, lesion length ≤ 25 mm) were enrolled at a single institution. Baseline intravascular ultrasound (IVUS) and post-implantation IVUS and optical coherence tomography (OCT) examinations were mandatory. After successful implantations of BRS, the 46 patients were randomized to two different follow-up cohorts in a 2:1 ratio. Thirty patients in cohort 1 had to undergo angiography, IVUS, and OCT follow-ups at 6 and 24 months, respectively. The 16 patients in cohort 2 underwent the same types of imaging follow-ups at 12 and 36 months, respectively. Clinical follow-ups were scheduled uniformly in both cohorts at 1, 6, and 12 months and annually up to 5 years for all patients.

RESULTS

Between August and November 2016, a total of 54 patients were assessed. However, 8 patients could not meet all the inclusion criteria; thus, the remaining 46 patients (age 57.5 ± 8.7 years, 34.8% female, 50.0% with unstable angina, 26.1% diabetics) with 46 target lesions were enrolled in this study. All patients in both cohorts were required to complete clinical follow-up uniformly and regularly. In cohort 1, one patient had definite scaffold thrombosis within 6 months of follow-up; thus, after 6 months, cohort 1 had 96.7% patients . Imaging follow-up was available in 24 patients, and in-scaffold late loss was 0.44 ± 0.47 mm; intracoronary imaging confirmed the late loss was mainly due to to neointimal hyperplasia, but not scaffold recoil.

CONCLUSIONS

Serial 2-year clinical and imaging follow-up results confirmed the preliminary safety and efficacy of Bioheart BRS for treatment of simple coronary lesions.

Design and Analysis of a Biodegradable Polycaprolactone Flow Diverting Stent for Brain Aneurysms

The flow diverting stent (FDS) has become a promising endovascular device for the treatment of aneurysms. This research presents a novel biodegradable and non-braided Polycaprolactone (PCL) FDS. The PCL FDS was designed and developed using an in-house fabrication unit and coated on two ends with BaSO₄ for angiographic visibility. The mechanical flexibility and quality of FDS surfaces were examined with the UniVert testing machine, scanning electron microscope (SEM), and 3D profilometer. Human umbilical vein endothelial cell (HUVEC) adhesion, proliferation, and cell morphology studies on PCL FDS were performed. The cytotoxicity and NO production by HUVECs with PCL FDS were also conducted. The longitudinal tensile, radial, and bending flexibility were found to be 1.20 ± 0.19 N/mm, 0.56 ± 0.11 N/mm, and 0.34 ± 0.03 N/mm, respectively. The FDS was returned to the original shape and diameter after repeated compression and bending without compromising mechanical integrity. Results also showed that the proliferation and adhesion of HUVECs on the FDS surface increased over time compared to control without FDS. Lactate dehydrogenase (LDH) release and NO production showed that PCL FDS were non-toxic and satisfactory. Cell morphology studies showed that HUVECs were elongated to cover the FD surface and developed an endothelial monolayer. This study is a step forward toward the development and clinical use of biodegradable flow diverting stents for endovascular treatment of the aneurysm.

A comparative analysis of solvent cast 3D printed carbonyl iron powder reinforced polycaprolactone polymeric stents for intravascular applications

In the present research, the effectiveness of developed methodology based on solvent cast 3D printing technique was investigated by printing the different geometries of the stents. The carbonyl iron powder (CIP) reinforced polycaprolactone (CIPC) was used to print three pre-existing stent designs such as ABBOTT BVS1.1, PALMAZ-SCHATZ, and ART18Z. The physicochemical behavior was analyzed by X-ray diffraction and scanning electron microscopy. The radial compression test, three-point bending test and stent deployment test were carried out to analyze the mechanical behavior. The degradation behavior of the stents was investigated in static as well as dynamic environment. To investigate the hemocompatible and cytocompatible behaviors of the stents, platelet adhesion test, hemolysis test, protein adsorption, in vitro cell viability test, and live/dead cell viability assay were performed. The results revealed that stents had the adequate mechanical properties to perform the necessary functions in the human coronary. The degradation studies showed slower degradation rate in the dynamic environment in comparison to static environment. in vitro biological analysis indicated that the stents represented excellent resistance to thrombosis, hemocompatible functions as well as cytocompatible nature. The results concluded that PALMAZ-SCHATZ stent represented better mechanical properties, cell viability, blood compatibility, and degradation behavior.

Evaluation of a simple off-the-shelf bi-layered vascular scaffold based on poly(L-lactide-co-ε-caprolactone)/silk fibroin in vitro and in vivo

Purpose: In the field of small-caliber vascular scaffold research, excellent vascular remodeling is the key to ensuring anticoagulant function. We prepared an off-the-shelf bi-layered vascular scaffold with a dense inner layer and a loose outer layer and evaluated its remodeling capabilities by in vivo transplantation.

Materials and Methods: Based on poly(L-lactide-co-ε-caprolactone) (PLCL), silk fibroin(SF), and heparin (Hep), PLCL/SF/Hep bi-layered scaffolds and PLCL/Hep bi-layered scaffolds were prepared by electrospinning. The inner layer was a PLCL/SF/Hep or PLCL/Hep nanofiber membrane, and the outer layer was PLCL/SF nano yarn. The in vitro tests included a hydrophilicity test, mechanical properties test, and blood and cell compatibility evaluation. The in vivo evaluation was conducted via single rabbit carotid artery replacement and subsequent examinations, including ultrasound imaging, immunoglobulin assays, and tissue section staining.

Results: Compared to the PLCL/Hep nanofiber membrane, the hydrophilicity of the PLCL/SF/Hep nanofiber membrane was significantly improved. The mechanical strength met application requirements. Both the blood and cell compatibility were optimal. Most importantly, the PLCL/SF/Hep scaffolds maintained lumen patency for 3 months after carotid artery transplantation in live rabbits. At the same time, CD31 and α-SMA immunofluorescence staining confirmed bionic endothelial and smooth muscle layers remodeling.

Conclusion: Using this hybrid strategy, PLCL and SF were combined to manufacture bi-layered small-caliber vascular scaffolds; these PLCL/SF/Hep scaffolds showed satisfactory vascular remodeling.

Development of a 3D-Printed Drug-Eluting Stent for Treating Obstructive Salivary Gland Disease

Most studies of obstructive salivary gland disease have reported only statistical aspects, surgical operations, and prescriptions and have simulated the phenomena occurring in the salivary glands and ductal tissues. However, no direct lesion treatments involving drug-eluting stents have been used to reduce salivary pooling induced by inflammation. In this study, a biodegradable polymer polycaprolactone (PCL)-based antibiotic-eluting stent was developed to treat recurrent obstructive salivary gland disease. The structure's diameter was designed after consideration of the human anatomical structure, and the data were processed in a form suitable for three-dimensional (3D) printing via computer-aided design and manufacturing. After the proper mixing conditions of the antibiotics and PCL were ensured, the optimized printing conditions were secured and the stent was successfully printed with the original lumen size diameter maintained. Amoxicillin and cefotaxime, the antibiotics loaded in this study, did not lose their original antimicrobial activity under the 3D printing process and were effectively released from the constructs for verification of the antimicrobial activity against the causative bacteria according to their concentrations. In addition, antibiotic-eluting stents fabricated in a mesh-like network form were proven stable and capable of sustained release, thereby demonstrating the possibility of treating recurrent obstruction salivary gland disease.

Endovascular Metal Devices for the Treatment of Cerebrovascular Diseases

Cerebrovascular disease involves various medical disorders that obstruct brain blood vessels or deteriorate cerebral circulation, resulting in ischemic or hemorrhagic stroke. Nowadays, platinum coils with or without biological modification have become routine embolization devices to reduce the risk of cerebral aneurysm bleeding. Additionally, many intracranial stents, flow diverters, and stent retrievers have been invented with uniquely designed structures. To accelerate the translation of these devices into clinical usage, an in-depth understanding of the mechanical and material performance of these metal-based devices is critical. However, considering the more distal location and tortuous anatomic characteristics of cerebral arteries, present devices still risk failing to arrive at target lesions. Consequently, more flexible endovascular devices and novel designs are under urgent demand to overcome the deficiencies of existing devices. Herein, the pros and cons of the current structural designs are discussed when these devices are applied to the treatment of diseases ranging broadly from hemorrhages to ischemic strokes, in order to encourage further development of such kind of devices and investigation of their use in the clinic. Moreover, novel biodegradable materials and drug elution techniques, and the design, safety, and efficacy of personalized devices for further clinical applications in cerebral vasculature are discussed.

Improvement of Mechanical Performance of Bioresorbable Magnesium Alloy Coronary Artery Stents through Stent Pattern Redesign

Optimized stent pattern design can effectively enhance the mechanical performance of magnesium alloy stents by adjusting strain distribution and evolution during stent deformation, thereby overcoming the limitations imposed by the intrinsic mechanical properties of magnesium alloys. In the present study, a new stent design pattern for magnesium alloys was proposed and compared to two existing stent design patterns. Measures of the mechanical performance of these three stents, including crimping and expanding deformability, radial scaffolding capacity, radial recoil and bending flexibility, were determined. Three-dimensional finite element (FE) models were built to predict the mechanical performance of the stents with the three design patterns and to assist in understanding the experimental results. The results showed that, overall, the stent with the new design pattern was superior to the stents based on the existing designs, though the expanding capacity of the newly designed stent still needed to be improved.

3D-Printed PCL/PLA Composite Stents: Towards a New Solution to Cardiovascular Problems

Biodegradable stents (BRS) offer enormous potential but first they must meet five specific requirements: (i) their manufacturing process must be precise; (ii) degradation should have minimal toxicity; (iii) the rate of degradation should match the recovery rate of vascular tissue; (iv) ideally, they should induce rapid endothelialization to restore the functions of vascular tissue, but at the same time reduce the risk of restenosis; and (v) their mechanical behavior should comply with medical requirements, namely, the flexibility required to facilitate placement but also sufficient radial rigidity to support the vessel. Although the first three requirements have been comprehensively studied, the last two have been overlooked. One possible way of addressing these issues would be to fabricate composite stents using materials that have different mechanical, biological, or medical properties, for instance, Polylactide Acid (PLA) or Polycaprolactone (PCL). However, fashioning such stents using the traditional stent manufacturing process known as laser cutting would be impossible. Our work, therefore, aims to produce PCL/PLA composite stents using a novel 3D tubular printer based on Fused Deposition Modelling (FDM). The cell geometry (shape and area) and the materials (PCL and PLA) of the stents were analyzed and correlated with 3T3 cell proliferation, degradation rates, dynamic mechanical and radial expansion tests to determine the best parameters for a stent that will satisfy the five strict BRS requirements. Results proved that the 3D-printing process was highly suitable for producing composite stents (approximately 85⁻95% accuracy). Both PCL and PLA demonstrated their biocompatibility with PCL stents presenting an average cell proliferation of 12.46% and PLA 8.28% after only 3 days. Furthermore, the PCL/PLA composite stents demonstrated their potential in degradation, dynamic mechanical and expansion tests. Moreover, and regardless of the order of the layers, the composite stents showed (virtually) medium levels of degradation rates and mechanical modulus. Radially, they exhibited the virtues of PCL in the expansion step (elasticity) and those of PLA in the recoil step (rigidity). Results have clearly demonstrated that composite PCL/PLA stents are a highly promising solution to fulfilling the rigorous BRS requirements.

Design Principles of Bioresorbable Polymeric Scaffolds

The concept for a bioresorbable vascular scaffold combines the best features of the first 3 generations of percutaneous coronary intervention (namely), balloon angioplasty, bare metallic stents, and drug-eluting stents, into a single device. The principles of operation of a BRS follow 3 phases of functionality that reflect the different physiologic requirements over time; revascularization, restoration, and resorption. Most BRS designs make use of the continuum of hydrolytic degradation in aliphatic polyesters, such as poly(l-lactide), in which molecular weight, strength, and mass decrease progressively in 3 distinct stages, consistent with the in vivo requirements of each performance phase.