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Magnetic Delivery of Cell-Based Therapies
Published in Jon Dobson, Carlos Rinaldi, Nanomagnetic Actuation in Biomedicine, 2018
Boris Polyak, Richard Sensenig
In this section, we discuss a magnetic cell delivery application in the context of treatment of coronary and peripheral artery disease. Angioplasty has become the most common revascularization procedure for coronary and peripheral artery disease. However, recurrent arterial narrowing (restenosis) is the major complication limiting the success of this revascularization procedure. A combination of processes causes restenosis. In the short term, it may be caused by elastic recoil of the vessel wall, thrombus formation at the site of injury, and variations in operative technique that lead to a smaller anastomosis or kinking of the vessel. Longer term patency over the preceding months to years may be limited by intimal hyperplasia, involving the proliferation and migration of intimal smooth muscle cells (SMCs).71,72 The overall incidence or restenosis is approximately 30% a year after coronary angioplasty and bare metal stenting,73 and there is a similar incidence following angioplasty for peripheral arterial disease.74 Drug-eluting stents have been developed as a means of preventing intimal hyperplasia and appear to have reduced the early risk of coronary restenosis, although this still occurs in over 10% of stented vessels at 12 months.73 There are also concerns of an increased incidence of stent thrombosis and myocardial infarction in patients who have had a drug-eluting stent inserted.73
Mg-Based Biodegradable Metals for Scaffolds
Published in Gilson Khang, Handbook of Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine, 2017
Previous progress on AMSs showed no adverse effects and good potential as temporary scaffolds to treat cardiovascular disease, but the corrosion resistance, which strongly affects the service in vivo, needed to be enhanced. A drug-eluting stent is a kind of stent with specific functional coatings to protect the substrate and/or release drugs treating vascular diseases. Compared to a bare metal stent, a drug-eluting stent can effectively treat thrombosis and the restenosis rate is lower. Mostly loaded drugs include the limus family and paclitaxel. As for the coating on a magnesium stent to improve biocompatibility, the following purposes are desired. Firstly, promote endothelial adhesion and proliferation, which will help vascular remodeling. Secondly, reduce restenosis and thrombosis. Thirdly, reduce platelet adhesion.87
Recent Advances in Biocompatibility
Published in Yaser Dahman, Biomaterials Science and Technology, 2019
Drug-eluting stents cannot achieve full potential when the patient suffers from diseases such as diabetes, renal dysfunction, or patients with small vessel diameters (Slee et al. 2016). Stents coated with drugs also have a higher occurrence of late stent thrombosis by preventing endothelium re-growth (Slee et al., 2016). However, an alternative stent that improves biocompatibility is still required (Slee et al., 2016). Slee et al. (2016) used CD47 as an alternative coating for stents. CD47 is a transmembrane protein that, when it binds to Signal Regulatory Protein Alpha (SIRP α), provides an anti-inflammatory response. In 2011, Stachelek et al. was able to demonstrate that CD47 modified polymer surfaces reduce inflammation in-vivo and in-vitro (Stachelek et al., 2011; Slee et al., 2016). Another study completed by Finley et al. (2012) demonstrated that CD47 surfaces reduced cell adhesion and platelets and neutrophils activation. Slee et al. (2016), suggest the use of CD47 on the stent’s surface to enhance biocompatibility and prevent early inflammatory events that result in restenosis (Slee et al., 2016). The purpose of this study was to demonstrate an in-vitro CD47 anti-inflammatory capacity and in-vivo CD47 inhibition of ISR in rats (Slee et al., 2016). Figure 2.10 illustrates the design of CD47 stent. The in-vitro anti-inflammatory capacity of CD47 was determined using different steel foil samples by investigating their ability to inhibit macrophage attachment. The results demonstrated that CD47-steel foil samples had a lower macrophage attachment compared to other samples. This suggests that CD47 has the potential to prevent acute inflammation (Slee et al., 2016). The in-vivo efficacies of stents with and without CD47 were investigated using rats. pepCD47 was chosen due to results from Figure 2.11. The stents were placed in the rats’ carotid arteries for 30 minutes, 3 days, and 14 days. After each time period, inflammatory responses (the number of white, red, and platelet cells) and thrombosis were quantified. The SEM results demonstrated that CD47 reduced platelet attachment within 30 minutes (Figure 2.12a) and macrophage recruitment after 3 days (Figure 2.12 b), indicating that CD47 can prevent early acute inflammatory responses, thus having the ability to prevent ISR (Slee et al., 2016).
Specific and nonspecific binding of drug eluted from a half-embedded stent in presence of atherosclerotic plaque
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Akash Pradip Mandal, Prashanta Kumar Mandal
Treatment of arterial lesions using drug-eluting stent is now a gold standard method of intervention and it is much superior to bare metal stent (BMS) in terms of safety and efficacy. DES is a wire scaffold coated with a therapeutic drug from which an anti-proliferative drug is released in a programmed fashion. It usually contains three parts, namely, the metallic platform, a polymer coating and the drug itself (Sarifuddin et al. 2020). Modeling of drug delivery in an artery is a much-researched topic for the last few decades, however, some important aspects of stent-based delivery still remain unanswered due to its inherent complexity to tackle the model. Clinicians are now interested to study the efficacy of polymer-free DES as the presence of polymer sometimes exhibits delayed re-endothelialisation. The polymer-free DES bears its own importance due to minimizing polymer contact and a wider range of potential elution kinetics than traditional DES (Finkelstein et al. 2003; Ernst and Bulum 2014; Sarifuddin et al. 2021). A number of theoretical, computational and/or experimental studies have been carried out on using first- and second-generation DES (Cummings et al. 2004; Hausleiter et al. 2005; Borghi et al. 2008; Mandal et al. 2015; Hopkins et al. 2016; Garot et al. 2017; Gudiño et al. 2019; McKittrick et al. 2019; Seidlitz 2019; Escuer et al. 2021; McQueen et al. 2021). Now, modellers, experimentalists and clinicians are busy in studying the safety and efficacy level of bioresorbable DES (Shazly et al. 2012; Ferdous et al. 2013)
Review of safety reports of cardiac MR-imaging in patients with recently implanted coronary artery stents at various field strengths
Published in Expert Review of Medical Devices, 2021
Christian David Schenk, Rolf Gebker, Alexander Berger, Burkert Pieske, Christian Stehning, Sebastian Kelle
Because of the current data situation MRI-examinations within 8 weeks after stent implantation seem to be safe, according to the current data situation after stent implantation at 1.5 Tesla [6]. All mentioned studies strengthened this thesis [3,5,15–26], but it came also apparent, that the data situation, concerning the safety of 3.0 Tesla MRI-examinations, is not sufficiently proved. This question is still more relevant, because patients are getting older than some years ago and this raises the incidence of cardiac events as well as the probability to get an MRI-examination after stent implantation, which raises systematically during the lifetime. Even the anchoring of the stent in the endothelium of the vessel protects it against a migration, induced by the magnetic field [6]. The endothelialization of the stent is completed after 6–8 weeks and protects it furthermore against migration [6], however it may take a longer time regarding DES [28]. Besides it was reported of light heating (<1 degree Celsius) [6]. The effect of the heating on the drug-eluting characteristics of the stent is unclear [6]. Moreover it’s possible that the heating of the stent can be reduced by the blood flow [6]. None of the investigated studies [3,5,19–26] reported of increased rates of cardiac events in comparison to the rate of incidences of cardiac events in the control-groups (without MRI-examination). This was independent of the type of stent (bare metal stent/drug-eluting stent) and of the used field strength (1.5 Tesla/3.0 Tesla).
Mechanical properties and performances of contemporary drug-eluting stent: focus on the metallic backbone
Published in Expert Review of Medical Devices, 2019
Ply Chichareon, Yuki Katagiri, Taku Asano, Kuniaki Takahashi, Norihiro Kogame, Rodrigo Modolo, Erhan Tenekecioglu, Chun-Chin Chang, Mariusz Tomaniak, Neville Kukreja, Joanna J. Wykrzykowska, Jan J. Piek, Patrick W. Serruys, Yoshinobu Onuma
The advent of drug-eluting stent (DES) was a breakthrough solution of the ISR. In general, DES is composed of three main components; stent platform, polymer, and anti-restenosis drug. The polymer controls drug release, allowing the drug to gradually accumulate in the vessel wall. The drug subsequently inhibits smooth muscle cell proliferation and NIH thereby reducing the rate of ISR and subsequent repeat revascularization [6]. The efficacy of DES depends on the type, dose, and kinetics of the drug [7]. The advance in polymer development allows the polymer to biodegrade after drug release. This biodegradable polymer DES thus leaves an uncoated surface of the metallic platform making the device similar to a conventional BMS. Theoretically, the inert metallic platform avoids triggering chronic inflammation [8]. Current technology also permits the drug to be coated on the stent platform without a polymer [9]. Systematic review and meta-analyses have demonstrated comparable safety and efficacy of biodegradable polymer DES and polymer free DES to durable polymer DES [10,11]. A recent study has even shown a better efficacy of biodegradable polymer DES than durable polymer DES [12].