Biosafety and efficacy evaluation of a biodegradable magnesium-based drug-eluting stent in porcine coronary artery.

Although the drug-eluting stent (DES) has become the standard for percutaneous coronary intervention (PCI)-based revascularization, concerns remain regarding the use of DES, mainly due to its permanent rigid constraint to vessels. A drug-eluting bioresorbable stent (BRS) was thus developed as an alternative to DES, which can be absorbed entirely after its therapeutic period. Magnesium (Mg)-based BRSs have attracted a great deal of attention due to their suitable mechanical properties, innovative chemical features, and well-proven biocompatibility.

In vivo and in vitro evaluation of a biodegradable magnesium vascular stent designed by shape optimization strategy.

The performance of biodegradable magnesium alloy stents (BMgS) requires special attention to non-uniform residual stress distribution and stress concentration, which can accelerate localized degradation after implantation. We now report on a novel concept in stent shape optimization using a finite element method (FEM) toolkit. A Mg-Nd-Zn-Zr alloy with uniform degradation behavior served as the basis of our BMgS.

Modeling and Experimental Studies of Coating Delamination of Biodegradable Magnesium Alloy Cardiovascular Stents.

Biodegradable magnesium alloy stents exhibit deficient corrosion period for clinic applications, making the protective polymer coating more crucial than drug-eluting stents with the permanent metal scaffold. We implemented a cohesive method based on a finite element analysis method to predict the integrity of adhesive between coating and stent during the crimping and deployment. For the first time, the three-dimensional quantitative modeling reveals the process of polymer coating delamination and stress concentration.

MicroRNA-26a inhibits proliferation and tumorigenesis via targeting CKS2 in laryngeal squamous cell carcinoma.

Laryngeal squamous cell carcinoma (LSCC) is one of the most common head and neck cancers, with high mortality and incidence. MicroRNA-26a (miR-26a) is involved in the development and progression of several tumours. However, the roles of miR-26a and its target CKS2 in LSCC progression are not yet clear.

MTA1 promotes viability and motility in nasopharyngeal carcinoma by modulating IQGAP1 expression.

Nasopharyngeal carcinoma (NPC) is frequently seen in Chinese, especially the population that resides in southeast China. Metastasis-associated protein 1 (MTA1) is a chromatin modifier and plays a role in tumor cell metastasis. IQGAP1 is a ubiquitously expressed protein that contributes to cytoskeleton remodeling.

In vitro and in vivo degradation of rapamycin-eluting Mg-Nd-Zn-Zr alloy stents in porcine coronary arteries.

In this work, rapamycin-eluting poly (d, l-lactic acid) coating (PDLLA/RAPA) was prepared on biodegradable Mg-Nd-Zn-Zr alloy (JDBM) for both in vitro and in vivo investigation of the degradation behaviors of the magnesium alloy stent platform. Electrochemical tests and hydrogen evolution test demonstrated significant in vitro protection of the polymeric coating against magnesium degradation both in short and long term. The 3-month in vivo study on the RAPA-eluting JDBM stent implanted into porcine coronary arteries confirmed its favorable safety, and in the meanwhile revealed similar neointima proliferation compared to the second generation DES Firebird 2 with no occurrence of adverse complications.

Facile Preparation of Poly(lactic acid)/Brushite Bilayer Coating on Biodegradable Magnesium Alloys with Multiple Functionalities for Orthopedic Application.

Recently magnesium and its alloys have been proposed as a promising next generation orthopedic implant material, whereas the poor corrosion behavior, potential cytotoxicity, and the lack of efficient drug delivery system have limited its further clinical application, especially for the local treatment of infections or musculoskeletal disorders and diseases. In this study, we designed and developed a multifunctional bilayer composite coating of poly(lactic acid)/brushite with high interfacial bonding strength on a Mg-Nd-Zn-Zr alloy, aiming to improve the biocorrosion resistance and biocompatibility of the magnesium-based substrate, as well as to further incorporate the biofunctionality of localized drug delivery. The composite coating consisted of an inner layer of poly(lactic acid) serving as a drug carrier and an outer layer composed of brushite generated through chemical solution deposition, where a facile pretreatment of UV irradiation was applied to the poly(lactic acid) coating to facilitate the heterogeneous nucleation of brushite.

Enhanced corrosion resistance and cytocompatibility of biodegradable Mg alloys by introduction of Mg(OH) particles into poly (L-lactic acid) coating.

A strategy of suppressing the fast degradation behaviour of Mg-based biomaterials by the introduction of one of Mg degradation products Mg(OH) was proposed according to the following degradation mechanism, Mg + 2HO ⇋ Mg(OH) + H↑. Specifically, Mg(OH) submicron particles were mixed into poly (L-lactic acid) (PLLA) to synthesize a composite coating onto hydrofluoric acid-pretreated Mg-Nd-Zn-Zr alloy. The in vitro degradation investigations showed that the addition of Mg(OH) particles not only slowed down the corrosion of Mg matrix, but also retarded the formation of gas pockets underneath the polymer coating.

Influence of fluoride treatment on surface properties, biodegradation and cytocompatibility of Mg-Nd-Zn-Zr alloy.

Fluoride treatment is a commonly used technique or pre-treatment to optimize the degradation kinetic and improve the biocompatibility of magnesium-based implant. The influence of changed surface properties and degradation kinetics on subsequent protein adsorption and cytocompatibility is critical to understand the biocompatibility of the implant. In this study, a patent magnesium alloy Mg-Nd-Zn-Zr alloy (JDBM) designed for cardiovascular stent application was treated by immersion in hydrofluoric acid.