Bioresorbable Scaffold Research Articles

Optimal lesion preparation before implantation of a Magmaris bioresorbable scaffold in patients with coronary artery stenosis: Rationale, design and methodology of the OPTIMIS study

IntroductionPercutaneous coronary intervention with implantation of a bioresorbable scaffold (BRS) provide the vessel support for a limited period allowing the vessel to restore normal vasomotion after degradation of the BRS, opposed to treatment with drug-eluting stents where the metal persist in the vessel wall. Late lumen loss and reduction in lumen area after implantation have been reported. The purpose of this study was to investigate whether intense pre-dilatation before BRS implantation resulted in less reduction of minimal lumen area at 6- and 12-month follow-up after implantation of a Magmaris BRS (MgBRS). Coronary imaging with optical coherence tomography (OCT) and intravascular ultrasound (IVUS) was assessed to track changes in lumen and vessel dimensions. MethodsThe prospective Optimal lesion PreparaTion before Implantation of the Magmaris bioresorbable scaffold In patients with coronary artery Stenosis (OPTIMIS) study randomly assigned eighty-two patients with chronic coronary syndrome to two pre-dilatation treatment strategies. Patients were randomized in a 1:1 ratio to pre-dilatation with either a non-compliant scoring balloon or a standard non-compliant balloon prior to implantation of a MgBRS. The treated segment was evaluated with OCT and IVUS at baseline, after 6 and 12 months to assess changes in lumen and vessel dimensions. The hypothesis was that more intense pre-dilatation with a non-compliant scoring balloon before MgBRS implantation can reduce the risk of late lumen reduction compared to standard pre-dilatation. The power calculation used expected MLA after 6 months (6.22 mm2 for the scoring balloon and 5.01 mm2 for the standard non-compliant balloon), power of 80 %, significance level of 0.05 and expected drop-out rate of 15 %, requiring 82 patients to be enrolled. ResultsEighty-two patients were included in the study. Enrollment was from December 2020 to September 2023. ConclusionThe hypothesis was that more intense pre-dilatation with a non-compliant scoring balloon before MgBRS implantation can reduce the risk of late lumen reduction compared to standard pre-dilatation.

Size effects and the deformation behaviour of a dilute Mg-Zn-Ca alloy subjected to cyclic four-point bending

In biodegradable stents made from dilute Mg-Zn-Ca alloys a small number of grains constitute the thickness of a sample limiting the mechanical constrain typically seen in polycrystalline alloys. At the same time such stents are exposed to complex loading conditions, which could potentially lead to premature failure particularly in the presence of limited slip mode activation. In order to improve our understanding of the prevailing micromechanics for such conditions hot-rolled, thin strip samples were produced with thickness to grain size ratios (t/D) of 100 and 17. Samples were extracted from such thin strips and subjected to interrupted cyclic four-point bending in order to study the in-grain misorientation axis (IGMA) evolution of selected grains during cyclic loading using quasi-in-situ electron back-scattered diffraction (EBSD). Grains were selected at the tensile and compressive faces of samples, and in the vicinity of the neutral band. Analysis of the evolution of IGMA and misorientation profiles during the bending showed that extension twinning was the dominant deformation mode in the compressive region for both t/D ratios. In addition, non-basal <a>-type slip systems were active as a result of work hardening. In the tensile region, the activity of <a>-type non-basal slip systems was observed for the t/D of 100, but basal/double basal slip was the dominant deformation mode for the t/D of 17. No signs of failure were observed for the sample with a t/D of 17 at the tensile region, implying that these basal slip modes can accommodate deformation largely without the assistance of other deformation modes. The neutral band evolution was mapped using grain orientation spread (GOS) analysis. In contrast to the continuum mechanics solution, a neutral band was observed instead of an axis. The position of the neutral band was dependant on the local orientation organization of the grains and the extent of work-hardening.

Prostatic stents: a narrative review of current evidence.

Benign prostatic hyperplasia (BPH) is a common chronic urologic condition affecting approximately 50% of men above the age of 60. As per European Association of Urology Guidelines, BPH can be treated according to a stepwise approach starting from a conservative management, a pharmacologic approach, and finally surgery. Both medical and surgical therapies have side effects, impacting on ejaculation and sexual function and patients with multiple comorbidities might not be considered surgically suitable candidates. Prostatic stents offer a minimally invasive procedures in an out-patient setting, possibly under local anaesthesia. Utilized since the 1980s, the past stents encompassed permanent (epithelializing) or temporary (non-epithelializing) devices, like the Uro-Lume (American Medical Systems, Minnetonka, MN, USA) and the Memokath, or Memotherm (Engineers & Doctors A/S, Denmark), and the biodegradable stents made of self-reinforced poly-L-lactide or braided poly lactic-co-glycolic acid. Previous stents however showed a quite high rate of complications among which pain, incontinence, infections, stent migration or blockage, and incomplete degradation that might lead to premature removal of stent. The stents currently available on the market instead are the temporary device Allium Triangular Prostatic Urethral Stent (Allium Urological Solutions, Caesarea, Israel) and the temporary stent SPANNER (AbbeyMoor Medical, Inc., Parkers Prairie, MN, USA), which might be used in case of bladder outflow obstruction, post-operatively, or for acute urinary retention. Studies showed encouraging results, in terms of effectiveness and safety improving patients' quality of life and International Prostate Symptom Score, but longer-term studies are needed to identify the most suitable patients who might benefit from their use. Newer stents and nitinol devices are currently investigated, and we are waiting for the results of the ongoing clinical trials.

An integrated mechanical degradation model to explore the mechanical response of a bioresorbable polymeric scaffold

Simulation of bioresorbable medical devices is hindered by the limitations of current material models. Useful simulations require that both the short- and long-term response must be considered; existing models are not physically-based and provide limited insight to guide performance improvements. This study presents an integrated degradation framework which couples a physically-based degradation model, which predicts changes in both crystallinity (Xc) and molecular weight (Mn), with the results of a micromechanical model, which predicts the effective properties of the semicrystalline polymer. This degradation framework is used to simulate the deployment of a bioresorbable PLLA (Poly (L-lactide) stent into a mock vessel and the subsequent mechanical response during degradation under different diffusion boundary conditions representing neointimal growth. A workflow is established in a commercial finite element code that couples both the immediate and long-term responses. Clinically relevant lumen loss is reported and used to compare different responses and the effect of neo-intimal tissue regrowth post-implantation on degradation and on the mechanical response is assessed. In addition, the effects of possible changes in Xc, which could occur during processing and stent deployment, are explored.

Aneurysm healing following treatment with biodegradable embolization materials: assessment in a rat sidewall aneurysm model

BackgroundBiodegradable materials that dissolve after aneurysm healing are promising techniques in the field of neurointerventional surgery. We investigated the effects of various bioabsorable materials in combination with degradable magnesium alloy...

Effect of trimethylene carbonate segments on the structure and properties of poly(L‐lactide‐glycolide‐trimethylene carbonate) terpolymers for biodegradable vascular stents

AbstractThe total biodegradable vascular stent made of poly(L‐lactide‐glycolide‐trimethylene carbonate) terpolymers with excellent performances has the potential to be used in a new generation of medical implant devices. In this work, the properties and structure of terpolymers were investigated, which were found to be controlled by the composition of the copolymer chain. The amorphous trimethylene carbonate segments not only disturbed the sequence regularity of the L‐lactide segment, but also reduced the crystallization ability of the material. Furthermore, it is the flexible segments in the terpolymer chains that improve the plastic flow capacity, increase the flexibility of chains as well as reduce the apparent activation energy of thermal degradation of materials. Such a chain structured terpolymer exhibited good extrudability and buildability in 3D printing and formed a vascular stent with a cohesion entanglement characteristic microstructure during the process. The crush resistance with radially applied load and crush resistance with parallel plates of stent were 2561.4 mm Hg and 0.24 N/mm, respectively.

Design of novel poly(L-lactide)-based shape memory multiblock copolymers for biodegradable esophageal stent application

Esophageal cancer is a globally prevalent malignancy known for its extremely aggressive nature and high fatality rates. However, the conventional stents used in its treatment pose limitations including rigidity, non-degradability, and a lack of anti-inflammatory action. Shape memory multiblock copolymer stents (SMBS) have attracted considerable attention because of their distinctive characteristics. Nonetheless, achieving a variety of key functionalities, such as biocompatibility, biodegradability, thermoresponsiveness (body temperature, 37 °C), water responsiveness (biofluid), flexibility, and robustness, in a simple polymer system for practical applications still presents a significant problem. Herein, a versatile SMBS that is capable of delivering all the aforementioned key functionalities is proposed. This SMBS can efficiently be prepared via a rapid two-step strategy, leveraging the shape memory effect (SME) of a poly(L-lactide) (PLA)-based physical crosslinking network programmed into specific shapes. The proposed stent design incorporates bio-based PLA with flexible and hydrophilic polyethylene glycol (PEG), resulting in PEG-PLA multiblock copolymers with tunable transition temperatures (31.90–54.60 °C), effectively covering the body temperature (37 °C). Additionally, PEG-PLA exhibited a wide range of water uptake ratio of 41 % to 328 % and satisfactory elongation at break (142.8 % to 1920.6 %), and desired pH-dependent and simulated gastrointestinal biodegradability. Specifically, PEG4000PLA1500 displayed excellent body temperature-triggered (with a recovery rate of 99.5 %) and water-triggered dual SME, which allowed it to potentially be fabricated into on-demand synchronous shape memory and drug-release functional SMBS for esophageal stenosis therapy. The results of this study indicate that the proposed SMBS holds substantial potential for biomedical applications.

A phenomenological model of pulsatile blood pressure-affected degradation of polylactic acid (PLA) vascular stent.

The stent implantation may alter the post-operative patient's blood pressure, and bioresorbable vascular stents (BVS) as a candidate to treat vascular diseases, its degradation is affected by mechanical stress, thus, the altered pressure representing varying stress level will result in different degradation behaviors of the BVS. This paper first proposed a novel stress-regulated PLA degradation model that included swelling factor, and then the degradation evolutions of a PLA BVS within 180days under normal and high blood pressures were simulated by finite element method, and more four degradation indexes were defined to study the effects of the two blood pressures on the degradation of the PLA BVS. The results showed that the high pressure weakly accelerated the degradation of the PLA BVS with respect to the normal pressure by examining the four indexes, e.g., the residual stent volume decreased to 0.72 and 0.69, respectively for the normal and high pressures at day 180. The current finding provided a theoretical understanding of the PLA BVS degradation, and hinted that the PLA BVS may not need to be elaborately selected in clinical practices for treating hypertensive patients.

A Versatile Passivated Protein‐Adsorption Platform for Rapid Healing of Vascular Stents by Modulating the Microenvironment

AbstractBiodegradable stents have paved the way to treat coronary artery disease. However, rapid reendothelialization is required to solve the problems of mismatched degradation rates, localized inflammation, and insufficient biocompatibility. Herein, a novel passivated protein‐adsorption coating is synthesized by coordination chelation, oxidation, cross‐linking, polymerization, and deposition of dopamine, (‐)‐epigallocatechin gallate (EGCG), and copper ions (Cu2+) using two‐electron oxidation. This coating exhibits hierarchical functionality, that is, at the macroscale, its superhydrophilicity conveys antifouling ability; whereas at the microscale, the active groups (quinone‐, amino‐, hydroxyphenyl groups and aromatic ring) facilitate protein adsorption. Antifouling ability prevents acute thrombosis and inflammation and maintains initial microenvironment stability post‐implantation. The active groups facilitate gradual endothelial cells (ECs) adhesion. Meanwhile, the decomposition of nitric oxide (NO) donors to release NO is catalyzed by Cu2+, and EGCG alleviates or prevents oxidative stress damage, inflammatory responses, thrombosis formation, and excessive smooth muscle cells proliferation in the stent microenvironment. This provides favorable conditions for the rapid and healthy growth of ECs. This study proposes a novel strategy for rapid neointima formation comprising healthy ECs on the surfaces of biodegradable stents by depositing a passivated protein‐adsorption coating (polydopamine/EGCG/Cu), opening new possibilities for the efficient treatment of coronary artery disease.

Safety and efficacy of everolimus-eluting bioresorbable vascular scaffold for cardiac allograft vasculopathy (CART).

Cardiac allograft vasculopathy (CAV) is still the main drawback of heart transplantation (HTx) and percutaneous coronary intervention (PCI) is a palliative measure because of the high incidence of failure. This study aimed to investigate the safety and efficacy of bioresorbable scaffolds (BRSs) as potential novel therapeutic tool for the treatment of coronary stenoses in CAV. This is a multicenter, single-arm, prospective, open-label study (CART, NCT02377648), that included patients affected by advanced CAV treated with PCI and second-generation ABSORB BRS (Abbott Vascular). The primary endpoint was the incidence of 12-month angiographic in-segment scaffold restenosis (ISSR). Secondary endpoints were the incidence of major adverse cardiac events (MACEs) at 12- and 36-month follow-up and the incidence of ISSR at 36months. A paired intracoronary imaging analysis at baseline and follow-up was also performed. Between 2015 and 2017 35 HTx patients were enrolled and treated for 44 coronary lesions with 51 BRSs. The primary endpoint occurred in 13.5% of the lesions (5/37), with a cumulative ISSR rate up to 3years of 16.2% (6/37). Angiographic lumen loss was 0.40 ± 0.62mm at 12months and 0.53 ± 0.57mm at 36months. Overall survival rate was 91.4% and 74.3%, and MACEs incidence 14.2% and 31.4% at 12 and 36months, respectively. At the paired intracoronary imaging analysis, a significant increase of the vessel external elastic membrane area in the treated segment and some progression of CAV proximally to the BRS were detected. BRS-based PCI for the treatment of CAV is feasible and safe, with an ISSR incidence similar to what reported in retrospective studies with drug-eluting stents.

Magnesium bioresorbable scaffold (Magmaris) versus polymer biodegradable ultrathin drug-eluting stent (Ultimaster) in acute coronary syndrome. Mid-term outcomes (2 years).

Acute coronary syndrome (ACS) is a well-known risk factor for adverse clinical outcomes in percutaneous coronary intervention (PCI). Therefore, evaluation of coronary stents in this challenging clinical scenario can provide unique information on device safety and efficacy. Bioresorbable scaffolds (BRS) were designed to overcome long-term complications related to permanent vessel caging with a permanent metallic drug-eluting stent (DES). We designed this study to evaluate the mid-term safety and efficiency of the Magmaris BRS in comparison to the leading new-generation ultrathin DES Ultimaster in the ACS population. We present a retrospective analysis of 2-year follow-up data. The primary outcomes consisted of death from cardiac causes, myocardial infarction, and in-stent thrombosis. The second main study endpoint was defined as target-lesion failure (TLF). The study population consisted of two cohorts, the first of 193 patients treated with Magmaris implantation and the second of 169 patients treated with Ultimaster implantation. At the 2-year follow-up, there were no significant differences in both study cohorts in terms of primary outcome (5.1% vs. 11%; p = 0.051), and TLF (5.6% vs. 8%, p = 0.41). Treatment with a second-generation BRS (Magmaris) versus a novel second-generation DES (Ultimaster) in non-ST-elevation acute coronary syndrome (NSTE-ACS) was associated with similar rates of target lesion failure at 2-year follow-up.

Three-dimensional printed bioresorbable scaffold for maxillofacial bone reconstruction: A Scoping Review.

This scoping review aimed to provide an overview of current advancements in virtual planning and custom-made 3D-printed bioresorbable scaffolds, and to evaluate their clinical outcomes in maxillofacial reconstructive surgeries. Electronic searches of PubMed, EMBASE, Web of Science, Scopus, and Cochrane Library databases were conducted for publications up to June 2024. Included in the review were reports evaluating patients who underwent maxillofacial bone defect reconstruction using virtual planning and custom-made 3D-printed bioresorbable scaffolds. Data on postoperative complications, new bone formation, scaffold resorption, dental implant success/survival, and patient satisfaction were collected. The electronic search found 5799 results (3438 unique citations). A total of 54 studies were evaluated for full-text reading, of which 41 were excluded based on the inclusion criteria. Thirteen studies (6 case reports, 5 case series, one prospective clinical study and one randomized clinical trial) were included. These studies assessed the effectiveness of 3D-printed scaffolds in reconstructing maxillofacial defects, bone augmentation for dental implant placement, and regeneration of periosseous defects. Most of the 3D-printed scaffolds were biocompatible and did not cause local or systemic adverse events. However, some postoperative complications were reported, including graft exposure, wound dehiscence, and local infection. Overall, the 3D-printed scaffolds demonstrated favorable dimensional compatibility with deformities, provided durable support, promoted bone formation, achieved adequate bone union with host bone tissues, and supported dental implant placement without additional guided bone regeneration. In conclusion, custom-made 3D-printed bioresorbable scaffolds, guided by virtual planning, present a promising option for maxillofacial reconstruction due to their accuracy, osteoconductivity, and biocompatible properties.

Mitigating the complexities of bile duct injury repair: biodegradable stents as a game-changer

Mitigating the complexities of bile duct injury repair: biodegradable stents as a game-changer

Intracranial graft of bioresorbable polymer scaffolds loaded with human Dental Pulp Stem Cells in stab wound murine injury model.

The prevalence of central nervous system (CNS) dysfunction as a result of disease or trauma remains a clinically unsolved problem which is raising increased awareness in our aging society. Human Dental Pulp Stem Cells (hDPSCs) are excellent candidates to be used in tissue engineering and regenerative therapies of the CNS due to their neural differentiation ability and lack of tumorigenicity. Accordingly, they have been successfully used in animal models of spinal cord injury, stroke and peripheral neuropathies. The ideal therapy in brain injury should combine strategies aiming to protect the damaged lesion and, at the same time, accelerate brain tissue regeneration, thus promoting fast recovery while minimizing side or long-term effects. The use of bioresorbable nanopatterned poly(lactide-co-ɛ-caprolactone) (PLCL) polymeric scaffolds as hDPCSs carriers can represent an advantage for tissue regeneration. In this chapter, we describe the surgical procedures to implant functionalized bioresorbable scaffolds loaded with hDPSCs to improve the brain lesion microenvironment in an intracranial stab wound injury model severing the rostral migratory stream (RMS) that connects the brain subventricular zone (SVZ) and the olfactory bulb in nude mice. Additionally, we also describe the technical steps after animal sacrifice for histological tissue observation and characterization.

Electrospinning Approach for Preparing Nanostructured Scaffolds for Stem Cell Seeding and/or Implantation in Neurotrauma.

Preparation of highly porous biocompatible and bioresorbable nerve conduit or scaffold by electrospinning based on synthetic polycaprolactone with a molecular weight of 80kDa (PCL 80kDa) has significance in the context of regenerative medicine with special emphasis on their application in neurotrauma. PCL conduits/scaffolds serving as a support structure for seeded stem cells show promising regenerative potential to promote functional recovery and tissue regeneration in models of neurotrauma. Here we describe a standard protocol for the production of conduits by electrospinning at high field-forming voltages (24kB) using a 6% solution of PCL 80kDa in a chloroform/methanol mixture.

Wavelet-based U-shape network for bioabsorbable vascular stents segmentation in IVOCT images.

Coronary artery disease remains a leading cause of mortality among individuals with cardiovascular conditions. The therapeutic use of bioresorbable vascular scaffolds (BVSs) through stent implantation is common, yet the effectiveness of current BVS segmentation techniques from Intravascular Optical Coherence Tomography (IVOCT) images is inadequate. This paper introduces an enhanced segmentation approach using a novel Wavelet-based U-shape network to address these challenges. We developed a Wavelet-based U-shape network that incorporates an Attention Gate (AG) and an Atrous Multi-scale Field Module (AMFM), designed to enhance the segmentation accuracy by improving the differentiation between the stent struts and the surrounding tissue. A unique wavelet fusion module mitigates the semantic gaps between different feature map branches, facilitating more effective feature integration. Extensive experiments demonstrate that our model surpasses existing techniques in key metrics such as Dice coefficient, accuracy, sensitivity, and Intersection over Union (IoU), achieving scores of 85.10%, 99.77%, 86.93%, and 73.81%, respectively. The integration of AG, AMFM, and the fusion module played a crucial role in achieving these outcomes, indicating a significant enhancement in capturing detailed contextual information. The introduction of the Wavelet-based U-shape network marks a substantial improvement in the segmentation of BVSs in IVOCT images, suggesting potential benefits for clinical practices in coronary artery disease treatment. This approach may also be applicable to other intricate medical imaging segmentation tasks, indicating a broad scope for future research.

Comparison of the “Late Catch-Up” Phenomenon Between BuMA Supreme and XIENCE Stents Through Serial Optical Coherence Tomography at 1–2 Month and 2 Year Follow-Ups: A Multicenter Study

Objectives: This study was aimed at comparing the “late catch-up” phenomenon between the BuMA Supreme bioresorbable polymer sirolimus-eluting stent and the XIENCE stent through serial optical coherence tomography (OCT) at within 2 months and 2 year follow-ups. Methods: A total of 49 of 75 patients from the PIONEER-II study were enrolled in a 2 year OCT follow-up study; 44 patients with 50 lesions were included in the statistical analysis. The primary endpoints were neointimal thickness and late luminal loss (LLL) after stent implantation. Results: The stenosis diameter, and minimum in-stent or in-segment diameter, did not significantly differ between the BuMA Supreme and XIENCE arms at within 2 months and 2 year follow-ups. The strut neointimal coverage and thickness were greater in the BuMA group than the XIENCE group at the 1 and 2 month follow-ups (P = 0.044 and P = 0.010, respectively) but not at the 2 year OCT follow-up. Neither early luminal loss at the within 2 months follow-up (P = 0.849) nor LLL at the 2 year OCT follow-up (P = 0.613) showed differences between device arms. No significant differences in imaging and clinical endpoints were observed between device arms at follow-up. Conclusions: The BuMA Supreme stent’s faster re-endothelization with no “late catch-up” phenomenon has potential advantages over the XIECE stent for patients with coronary artery disease and high bleeding risk because it decreases the duration of dual antiplatelet therapy.

The use of biodegradable biliary stents in deceased-donor liver transplantation, initial experience from a high-volume transplant centre

The use of biodegradable biliary stents in deceased-donor liver transplantation, initial experience from a high-volume transplant centre

Evaluating a 3D-printed biodegradable paclitaxel-eluting stent for biliary stricture management after liver transplantation: an in vivo porcine study

Evaluating a 3D-printed biodegradable paclitaxel-eluting stent for biliary stricture management after liver transplantation: an in vivo porcine study

Evaluation of Ultrathin Strut Biodegradable Polymer-Coated Sirolimus-Eluting Stents in an All-Comers Patient Population: 1-Year Results of the S-FLEX Slovakia Registry.

Supraflex (Sahajanand Medical Technologies Limited, Surat, India) is a new-generation, biodegradable polymer-coated sirolimus-eluting stent (SES) designed on an ultrathin (60 µm) cobalt-chromium platform with a flexible 'S-link.' The S-FLEX Slovakia registry aimed to assess the safety and effectiveness of Supraflex SES in an all-comers population, with a subgroup of diabetic patients. This was a prospective, observational, multi-center, post-market registry conducted between February 2018 and May 2019. All consecutive patients with symptomatic coronary artery disease scheduled for percutaneous coronary intervention with Supraflex SES were enrolled. The primary endpoint was target lesion failure (TLF), defined as a composite of cardiac death, target vessel myocardial infarction (TV-MI), or clinically indicated target lesion revascularization (CI-TLR) by percutaneous or surgical methods at 1-year follow-up. Stent thrombosis was a safety endpoint. A total of 413 patients was assessed (145 diabetics and 268 nondiabetics). At 1-year follow-up, the primary endpoint of TLF occurred in 5.1% patients, comprised of 3.9% cardiac deaths, 0.5% TV-MI, and 0.7% CI-TLR. Overall stent thrombosis occurred in 0.5% patients at 1-year follow-up. In the subgroup analysis, TLF occurred in 6.2% diabetics and 4.5% nondiabetics (P =.433) and comprised 4.8% and 3.4% cardiac deaths (P =.447), 0.7% and 0.4% TV-MI (P =.653), and 0.7%, and 0.7% CI-TLR (P =.952) in diabetics and non-diabetics, respectively. Overall stent thrombosis occurred in 0.7% diabetic and 0.4% non-diabetic patient (P =.659). This registry demonstrates favourable clinical outcomes after the implantation of the ultrathin biodegradable polymer coated Supraflex SES in an all-comers population, with event rates that were similar in diabetic and nondiabetic patients.