A mechanistic model for drug release from PLGA-based drug eluting stent: A computational study

Mechano-chemo-biological Computational Models for Arteries in Health, Disease and Healing: From Tissue Remodelling to Drug-eluting Devices

This review aims to highlight urgent priorities for the computational biomechanics community in the framework of mechano-chemo-biological models. Recent approaches, promising directions and open challenges on the computational modelling of arterial tissues in health and disease are introduced and investigated, together with in silico approaches for the analysis of drug-eluting stents that promote pharmacological-induced healing. The paper addresses a number of chemo-biological phenomena that are generally neglected in biomechanical engineering models but are most likely instrumental for the onset and the progression of arterial diseases. An interdisciplinary effort is thus encouraged for providing the tools for an effective in silico insight into medical problems. An integrated mechano-chemo-biological perspective is believed to be a fundamental missing piece for crossing the bridge between computational engineering and life sciences, and for bringing computational biomechanics into medical research and clinical practice.

Application of Implantable Polylactic-Co-Glycolic Acid Microcapsule in Repairing Alveolar Bone Defects

Alveolar bone defects (ABDs) were a perennial problem, especially in the aged. Bisphosphonates, especially etidronate sodium (ET), were frequently used in clinical treatment of ABD. However, the oral administration of ET had poor absorption (<1%). Therefore, optimization of a suitable dosage form substituted with ET to locally repair the ABD was a straightforward approach. Polylactide-co-glycolide (PLGA) is a biodegradable material and had been used in locally implanted medical devices. Therefore, an ET-PLGA microcapsule may help local delivery and prolong the activity of healing ABD. In this paper, a preparation method of ET-PLGA microcapsule was optimized by the single-factor investigation and response surface method. Subsequently, the rat ABD model was used to evaluate the enhancement effect of these microcapsules. Finally, the optimum parameters were determined as follows: 40% dichloromethane, 160 mg/mL PLGA, 10% internal aqua/oil phase, 4% PVA, and emulsifying for 10 min. These microcapsules were spherical in shape and fairly monodisperse in a particle size of 27,51 μm (PDI = 0.3), encapsulation rate 96.6%, and drug loading 4.58%. Compared with the ET groups, the total healing volume of ABD in ET-PLGA groups was significantly increased (P < 0.05). ET-PLGA microcapsules significantly enhanced the effect of ET on ABD. This study provided important technical support for the treatment of ABD with bisphosphonates by local administration. This paper has an exploratory significance for the development of water-soluble bioactive components with low bioavailability for ABD.

Characterization of Hybrid Materials Prepared by Sol-Gel Method for Biomedical Implementations. A Critical Review

The interaction between tissues and biomaterials (BM) has the purpose of improving and replacing anatomical parts of the human body, avoiding the occurrence of adverse reactions in the host organism. Unfortunately, the early failure of implants cannot be currently avoided, since neither a good mixture of mechanical and chemical characteristics of materials nor their biocompatibility has been yet achieved. Bioactive glasses are recognized to be a fine class of bioactive substances for good repair and replacement. BM interact with living bones through the formation of a hydroxyapatite surface layer that is analogous to bones. Bioglasses' composition noticeably affects their biological properties, as does the synthesis method, with the best one being the versatile sol-gel technique, which includes the change of scheme from a 'sol' fluid into a 'gel'. This process is widely used to prepare many materials for biomedical implants (e.g., hip and knee prostheses, heart valves, and ceramic, glassy and hybrid materials to serve as carriers for drug release). Nanoparticles prepared by the sol-gel method are interesting systems for biomedical implementations, and particularly useful for cancer therapy. This review provides many examples concerning the synthesis and characterization of the above-mentioned materials either taken from literature and from recently prepared zirconia/polyethylene glycol (PEG) hybrids, and the corresponding results are extensively discussed.

Influence of vessel curvature and plaque composition on drug transport in the arterial wall following drug-eluting stent implantation

In the last decade, many computational models have been developed to describe the transport of drug eluted from stents and the subsequent uptake into arterial tissue. Each of these models has its own set of limitations: for example, models typically employ simplified stent and arterial geometries, some models assume a homogeneous arterial wall, and others neglect the influence of blood flow and plasma filtration on the drug transport process. In this study, we focus on two common limitations. Specifically, we provide a comprehensive investigation of the influence of arterial curvature and plaque composition on drug transport in the arterial wall following drug-eluting stent implantation. The arterial wall is considered as a three-layered structure including the subendothelial space, the media and the adventitia, with porous membranes separating them (endothelium, internal and external elastic lamina). Blood flow is modelled by the Navier-Stokes equations, while Darcy's law is used to calculate plasma filtration through the porous layers. Our findings demonstrate that arterial curvature and plaque composition have important influences on the spatiotemporal distribution of drug, with potential implications in terms of effectiveness of the treatment. Since the majority of computational models tend to neglect these features, these models are likely to be under- or over-estimating drug uptake and redistribution in arterial tissue.

Implantable zoledronate-PLGA microcapsules ameliorate alveolar bone loss, gingival inflammation and oxidative stress in an experimental periodontitis rat model

The effect of implantable Zoledronate-PLGA microcapsules (PLGA-ZOL) in periodontitis remains unclear. In this study, we aimed to explore the potential role of PLGA-ZOL in protecting periodontitis and elucidate the underlying mechanism. A rat model of periodontitis was established by ligation the mandibular first molars, then PLGA-ZOL was implanted. The healing volume was scanned by cone-beam computed tomography. Cytokine levels in the gingival tissues were determined by ELISA and RT-PCR. Oxidative stress was indicated by detecting superoxide dismutase concentration and catalase activity. After periodontitis model was successfully established in rats, PLGA-ZOL treatment significantly attenuated alveolar bone loss, as indicated by the increased total healing volume, bone volume/tissue volume and osteoprotegerin level, as well as decreased sRANKL level. PLGA-ZOL treatment also suppressed the inflammatory activities by inhibiting pro-inflammatory cytokine production (TNF-α, IL-1β) but increasing anti-inflammatory cytokine secretion (IL-10). Furthermore, PLGA-ZOL was found to ameliorate oxidative stress in gingival tissues. In conclusion, PLGA-ZOL microcapsules ameliorate alveolar bone loss, gingival inflammation and oxidative stress in an experimental rat model of periodontitis.

Tunable Release of Curcumin with an In Silico-Supported Approach from Mixtures of Highly Porous PLGA Microparticles

In recent years, drug delivery systems have become some of the main topics within the biomedical field. In this scenario, polymeric microparticles (MPs) are often used as carriers to improve drug stability and drug pharmacokinetics in agreement with this kind of treatment. To avoid a mere and time-consuming empirical approach for the optimization of the pharmacokinetics of an MP-based formulation, here, we propose a simple predictive in silico-supported approach. As an example, in this study, we report the ability to predict and tune the release of curcumin (CUR), used as a model drug, from a designed combination of different poly(d,l-lactide-co-glycolide) (PLGA) MPs kinds. In detail, all CUR-PLGA MPs were synthesized by double emulsion technique and their chemical-physical properties were characterized by Mastersizer and scanning electron microscopy (SEM). Moreover, for all the MPs, CUR encapsulation efficiency and kinetic release were investigated through the UV-vis spectroscopy. This approach, based on the combination of in silico and experimental methods, could be a promising platform in several biomedical applications such as vaccinations, cancer-treatment, diabetes therapy and so on.