Bioresorbable Scaffolds: Contemporary Status and Future Directions

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

Introduction

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).

Aim

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.

Material and methods

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).

Results

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).

Conclusions

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.

Resveratrol Inhibits Restenosis through Suppressing Proliferation, Migration and Trans-differentiation of Vascular Adventitia Fibroblasts via Activating SIRT1

AIM

After the balloon angioplasty, vascular adventitia fibroblasts (VAFs), which proliferate, trans-differentiate to myofibroblasts and migrate to neointima, are crucial in restenosis. Resveratrol (RSV) has been reported to protect the cardiovascular by reducing restenosis and the mechanism remains unclear.

METHODS

This study was dedicated to investigate the effect of RSV on VAFs in injured arteries and explore the potential mechanism. In this work, carotid artery balloon angioplasty was performed on male SD rats to ensure the injury of intima and VAFs were isolated to explore the effects in vitro. The functional and morphological results showed the peripheral delivery of RSV decreased restenosis of the injured arteries and suppressed the expression of proliferation, migration and transformation related genes. Moreover, after being treated with RSV, the proliferation, migration and trans-differentiation of VAFs were significantly suppressed and exogenous TGF-β1 can reverse this effect.

RESULT

Mechanistically, RSV administration activated SIRT1 and decreased the translation and expression of TGF-β1, SMAD3 and NOX4, and reactive oxygen species (ROS) decreased significantly after VAFs treated with RSV.

CONCLUSION

Above results indicated RSV inhibited restenosis after balloon angioplasty through suppressing proliferation, migration and trans-differentiation of VAFs via regulating SIRT1- TGF-β1-SMAD3-NOX4 to decrease ROS.

3D-Printed Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)-Cellulose-Based Scaffolds for Biomedical Applications

While biomaterials have become indispensable for a wide range of tissue repair strategies, second removal procedures oftentimes needed in the case of non-bio-based and non-bioresorbable scaffolds are associated with significant drawbacks not only for the patient, including the risk of infection, impaired healing, or tissue damage, but also for the healthcare system in terms of cost and resources. New biopolymers are increasingly being investigated in the field of tissue regeneration, but their widespread use is still hampered by limitations regarding mechanical, biological, and functional performance when compared to traditional materials. Therefore, a common strategy to tune and broaden the final properties of biopolymers is through the effect of different reinforcing agents. This research work focused on the fabrication and characterization of a bio-based and bioresorbable composite material obtained by compounding a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) matrix with acetylated cellulose nanocrystals (CNCs). The developed biocomposite was further processed to obtain three-dimensional scaffolds by additive manufacturing (AM). The 3D printability of the PHBH-CNC biocomposites was demonstrated by realizing different scaffold geometries, and the results of in vitro cell viability studies provided a clear indication of the cytocompatibility of the biocomposites. Moreover, the CNC content proved to be an important parameter in tuning the different functional properties of the scaffolds. It was demonstrated that the water affinity, surface roughness, and in vitro degradability rate of biocomposites increase with increasing CNC content. Therefore, this tailoring effect of CNC can expand the potential field of use of the PHBH biopolymer, making it an attractive candidate for a variety of tissue engineering applications.

First-in-human evaluation of a novel ultrathin sirolimus-eluting iron bioresorbable scaffold: 3-year outcomes of the IBS-FIM trial

BACKGROUND

The first-generation polymeric bioresorbable scaffolds resulted in higher than acceptable 3-year rates of device-related adverse outcomes.

AIMS

We aimed to assess the intermediate-term safety and performance of a novel ultrathin-strut sirolimus-eluting iron bioresorbable scaffold (IBS) in non-complex coronary lesions.

METHODS

The prospective, single-arm, open-label IBS first-in-human study enrolled 45 patients, each with a single de novo lesion. Enrolled patients were randomly assigned to 2 follow-up cohorts. Angiographic and imaging follow-up with intravascular ultrasound and optical coherence tomography (OCT) were conducted at 6 and 24 months in cohort 1 (n=30) and at 12 and 36 months in cohort 2 (n=15). Clinical follow-up was conducted at 1, 6 and 12 months, and annually thereafter up to 5 years. The coprimary outcomes were target lesion failure (TLF) and angiographic late lumen loss (LLL) at 6 months.

RESULTS

A total of 45 patients were enrolled between April 2018 and January 2019. The mean age was 53.2 years, 77.8% were male, and 26.7% had diabetes. The TLF rates were 2.2% at 6 months and 6.7% at 3 years, which in all cases were due to clinically indicated target lesion revascularisation. No deaths, myocardial infarctions or stent thromboses occurred during 3-year follow-up. In-scaffold LLL was 0.33±0.27 mm at 6 months and 0.37±0.57 mm at 3 years. By OCT, the proportion of covered struts was 99.8% at 6 months and 100% after 1 year. The 3-year strut absorption rate was 95.4%.

CONCLUSIONS

In this first-in-human experience, an ultrathin IBS was safe and effective for the treatment of de novo non-complex coronary lesions up to 3-year follow-up.

Clinical research of drug-coated balloon after rotational atherectomy for severe coronary artery calcification

BACKGROUND

Current research results show that drug-coated balloons (DCB) have unique advantages in the treatment of in-stent restenosis, small vessel disease, bifurcation lesions, and de novo lesions, but the data regarding rotational atherectomy (RA) followed by DCB treatment in calcified lesions, especially severe coronary artery calcification (CAC), are limited.

METHODS

A retrospective study was conducted on 318 individuals with severe CAC who underwent RA-assisted PCI at the First Affiliated Hospital of Zhengzhou University from May 2018 to July 2021. Among them, 57 patients (RA/DCB group) were treated with DCB, and 261 patients (RA/DES group) were treated with drug-eluting stents (DES). The two groups' clinical baseline data, lesion characteristics, intraoperative complications, in-hospital adverse events, and major adverse cardiovascular and cerebrovascular events (MACCE) were compared throughout the follow-up period.

RESULTS

The baseline clinical data, intraoperative complications, and in-hospital adverse events were not significantly different between the two groups. The anatomical categories in the RA/DES group were more complex and included left main coronary disease, bifurcation disease, and multivessel disease. Although target lesion revascularization (13.79% vs. 7.02%) and MACCE (18.77% vs. 12.28%) occurred more frequently in the RA/DES group than in the RA/DCB group, there was no statistically significant difference (p > 0.05). Multivariate Cox regression analysis showed that bifurcation lesions (HR 2.284, 95% CI 1.063-4.908, p = 0.034), total length of DCB/DES (HR 1.023, 95% CI 1.005-1.047, p = 0.014) and SYNTAX score (HR 1.047, 95% CI 1.013-1.082, p = 0.006) were independent risk factors for MACCE during the follow-up period.

CONCLUSION

Drug-coated balloon treatment after rotational atherectomy appears safe and effective in selected severe coronary artery calcification.

Iron corroded granules inhibiting vascular smooth muscle cell proliferation

In-stent restenosis after interventional therapy remains a severe clinical complication. Current evidence indicates that neointimal hyperplasia induced by vascular smooth muscle cell (VSMC) proliferation is a major cause of restenosis. Thus, inhibiting VSMC proliferation is critical for preventing in-stent restenosis. The incidence of restenosis was reduced in nitrided iron-based stents (hereafter referred to as iron stents). We hypothesized that the corroded granules produced by the iron stent would prevent in-stent restenosis by inhibiting VSMC proliferation. To verify this hypothesis, we introduced a dynamic circulation device to analyze the components of corroded granules. To investigate the effects of corroded granules on VSMC proliferation, we implanted the corroded iron stent into the artery of the atherosclerotic artery stenosis model. Moreover, we explored the mechanism underlying the inhibition of VSMC proliferation by iron corroded granules. The results indicated that iron stent produced the corroded granules after implantation, and the main component of the corrosion granules was iron oxide. Remarkably, the corroded granules reduced the neointimal hyperplasia in an atherosclerotic artery stenosis model, and iron corroded granules decreased the neointimal hyperplasia by inhibiting VSMC proliferation. In addition, we revealed that corroded granules reduced VSMC proliferation by activating autophagy through the AMPK/mTOR signaling pathway. Importantly, safety of iron corroded granules was evaluated and proved to be satisfactory hemocompatibility in rabbit model. Overall, the role of corroded granules in restenosis prevention was described for the first time. This finding highlighted the implication of corroded granules produced by iron stent in inhibiting VSMC proliferation, pointing to a new direction to prevent in-stent restenosis.

Drug-Eluting, Bioresorbable Cardiovascular Stents─Challenges and Perspectives

Globally, the leading causes of natural death are attributed to coronary heart disease and type 1 and type 2 diabetes. High blood pressure levels, high cholesterol levels, smoking, and poor eating habits lead to the agglomeration of plaque in the arteries, reducing the blood flow. The implantation of devices used to unclog vessels, known as stents, sometimes results in a lack of irrigation due to the excessive proliferation of endothelial tissue within the blood vessels and is known as restenosis. The use of drug-eluting stents (DESs) to deliver antiproliferative drugs has led to the development of different encapsulation techniques. However, due to the potency of the drugs used in the initial stent designs, a chronic inflammatory reaction of the arterial wall known as thrombosis can cause a myocardial infarction (MI). One of the most promising drugs to reduce this risk is everolimus, which can be encapsulated in lipid systems for controlled release directly into the artery. This review aims to discuss the current status of stent design, fabrication, and functionalization. Variables such as the mechanical properties, metals and their alloys, drug encapsulation and controlled elution, and stent degradation are also addressed. Additionally, this review covers the use of polymeric surface coatings on stents and the recent advances in layer-by-layer coating and drug delivery. The advances in nanoencapsulation techniques such as liposomes and micro- and nanoemulsions and their functionalization in bioresorbable, drug-eluting stents are also highlighted.

Long-Term Performance of the Magmaris Drug-Eluting Bioresorbable Metallic Scaffold in All-Comers Patients’ Population

Background: The long-term efficacy and safety of bioresorbable vascular scaffolds (BVS) in real world clinical practice including Magmaris need to be elucidated to better understand performance of this new and evolutive technology. The aim of this study was to evaluate long-term performance of Magmaris, drug-eluting bioresorbable metallic scaffold, in all-comers patients’ population. Methods: We included in this prospective registry first 54 patients (54 ± 11 years; male 46) treated with Magmaris, with at least 30 months of follow-up. Diabetes mellitus and acute coronary syndrome were present in 33 (61%) and 30 (56%) of the patients, respectively. Patients were followed for device- and patient-oriented cardiac events during a median follow-up of 47 months (DOCE–cardiac death, target vessel myocardial infarction, and target lesion revascularization; POCE–all cause death, any myocardial infarction, any revascularization). Results: Event-free survivals for DOCE and POCE were 86.8% and 79.2%, respectively. The rate of DOCE was 7/54 (13%), including in total target vessel myocardial infarction in two patients (4%), target lesion revascularization in six patients (11%), and no cardiac deaths. The rate of POCE was 11/54 (21%), including in total any myocardial infarctions in 3 patients (6%), any revascularization in 11 patients (20%), and no deaths. Definite Magmaris thrombosis occurred in two patients (3.7%), and in-scaffold restenosis developed in five patients (9.3%). Variables associated with DOCE were implantation of ≥2 Magmaris BVS (HR: 5.4; 95%CI: 1.21–24.456; p = 0.027) and total length of Magmaris BVS ≥ 40 mm (HR: 6.4; 95%CI: 1.419–28.855; p = 0.016), whereas previous PCI was the only independent predictor of POCE (HR: 7.4; 95%CI: 2.216–24.613; p = 0.001). Conclusions: The results of the long-term clinical outcome following Magmaris implantation in patients with complex clinical and angiographic features were acceptable and promising. Patients with multi-BVS and longer multi-BVS in lesion implantation were associated with worse clinical outcome.

Curcumin attenuates inflammation of Macrophage-derived foam cells treated with Poly-L-lactic acid degradation via PPARγ signaling pathway

Poly-L-lactic acid (PLLA) is considered to be a promising candidate material for biodegradable vascular scaffolds (BVS) in percutaneous coronary intervention (PCI). But, PLLA-BVS also faces the challenge of thrombosis (ST) and in-stent restenosis (ISR) caused by in-stent neo-atherosclerosis (ISNA) associated with inflammatory reactions in macrophage-derived foam cells. Our previous studies have confirmed that curcumin alleviates PLLA-induced injury and inflammation in vascular endothelial cells, but it remains unclear whether curcumin can alleviate the effect of inflammatory reactions in macrophage-derived foam cells while treated with degraded product of PLLA. In this study, PLLA-BVS was implanted in the porcine coronary artery to examine increased macrophages and inflammatory cytokines such as NF-κb and TNF-α by histology and immunohistochemistry. In vitro, macrophage-derived foam cells were induced by Ox-LDL and observed by Oil Red Staining. Foam cells were treated with pre-degraded PLLA powder, curcumin and PPARγ inhibitor GW9662, and the expression of IL-6, IL-10, TNF-α, NF-κb, PLA2 and PPARγ were investigated by ELISA or RT-qPCR. This study demonstrated that the macrophages and inflammatory factors increased after PLLA-BVS implantation in vivo, and foam cells derived from macrophages promoted inflammation by products of PLLA degradation in vitro. This present study was found that the inflammation of foam cells at the microenvironment of PLLA degraded products were significantly increased, and curcumin can attenuate the inflammation caused by the PLLA degradation via PPARγ signal pathway. In addition, curcumin should be further studied experimentally in vivo experiments on animal models as a potential therapeutic to reduce ISNA of PLLA-BVS. Graphical abstract.

The crosstalk between arterial components and the bioresorbable, 3-D printed poly-l-lactic acid scaffolds

Bioresorbable scaffolds (BRS) are designed to provide a temporary support that subsequently leaves behind native vessels after their complete degradation. The accumulation of mechanical changes influences the vascular histological characteristics...