Arterial paclitaxel distribution and deposition

Safety and efficacy of drug-eluting stents versus heparin-bonded stents in treatment of femoropopliteal peripheral artery disease: study protocol for a multicentre, prospective randomised controlled trial in China (ELITE trial)

INTRODUCTION

Endovascular therapy has emerged as a prominent strategy for managing femoropopliteal peripheral artery disease, offering acceptable safety and efficacy compared with open surgical bypass. Both paclitaxel-eluting stents and heparin-bonded covered stents have exhibited enhanced clinical outcomes compared with bare metal stents. However, there is currently a lack of level I evidence comparing the safety and efficacy of paclitaxel-eluting stents and heparin-bonded covered stents. Therefore, the primary objective of this study is to systematically evaluate the efficacy and safety outcomes of these two types of stents.

METHODS AND ANALYSIS

The ELITE trial is a prospective, multicentre, parallel, randomised controlled trial. A total of 450 patients will be recruited. The primary endpoints of the study include primary patency at 1 year post-index procedure.

ETHICS AND DISSEMINATION

Ethical approval for this study was obtained from the Ethics Committee of West China Hospital of Sichuan University (approval number: 2023-1186). The results will be submitted to a major clinical journal for peer review and publication.

TRIAL REGISTRATION

ELITE trial was registered on 27 September 2023 in the Chinese Clinical Trials Registry (ChiCTR2300076236).

Hydrophilic Coating Microstructure Mediates Acute Drug Transfer in Drug-Coated Balloon Therapy

Drug-coated balloon (DCB) therapy is a promising endovascular treatment for obstructive arterial disease. The goal of DCB therapy is restoration of lumen patency in a stenotic vessel, whereby balloon deployment both mechanically compresses the offending lesion and locally delivers an antiproliferative drug, most commonly paclitaxel (PTX) or derivative compounds, to the arterial wall. Favorable long-term outcomes of DCB therapy thus require predictable and adequate PTX delivery, a process facilitated by coating excipients that promotes rapid drug transfer during the inflation period. While a variety of excipients have been considered in DCB design, there is a lack of understanding about the coating-specific biophysical determinants of essential device function, namely, acute drug transfer. We consider two hydrophilic excipients for PTX delivery, urea (UR) and poly(ethylene glycol) (PEG), and examine how compositional and preparational variables in the balloon surface spray-coating process impact resultant coating microstructure and in turn acute PTX transfer to the arterial wall. Specifically, we use scanning electron image analyses to quantify how coating microstructure is altered by excipient solid content and balloon-to-nozzle spray distance during the coating procedure and correlate obtained microstructural descriptors of coating aggregation to the efficiency of acute PTX transfer in a one-dimensional ex vivo model of DCB deployment. Experimental results suggest that despite the qualitatively different coating surface microstructures and apparent PTX transfer mechanisms exhibited with these excipients, the drug delivery efficiency is generally enhanced by coating aggregation on the balloon surface. We illustrate this microstructure-function relation with a finite element-based computational model of DCB deployment, which along with our experimental findings suggests a general design principle to increase drug delivery efficiency across a broad range of DCB designs.

Endovascular Drug Delivery

Drug-eluting stents (DES) and balloons revolutionize atherosclerosis treatment by targeting hyperplastic tissue responses through effective local drug delivery strategies. This review examines approved and emerging endovascular devices, discussing drug release mechanisms and their impacts on arterial drug distribution. It emphasizes the crucial role of drug delivery in modern cardiovascular care and highlights how device technologies influence vascular behavior based on lesion morphology. The future holds promise for lesion-specific treatments, particularly in the superficial femoral artery, with recent CE-marked devices showing encouraging results. Exciting strategies and new patents focus on local drug delivery to prevent restenosis, shaping the future of interventional outcomes. In summary, as we navigate the ever-evolving landscape of cardiovascular intervention, it becomes increasingly evident that the future lies in tailoring treatments to the specific characteristics of each lesion. By leveraging cutting-edge technologies and harnessing the potential of localized drug delivery, we stand poised to usher in a new era of precision medicine in vascular intervention.

Coronary Drug-Coated Balloons for De Novo and In-Stent Restenosis Indications

Drug-coated balloons are approved outside the United States, not only for the treatment of peripheral arteries but also for coronary arteries. This review describes the technological basics, the scenarios of clinical application, and the current available data from clinical trials for the different coronary indications.

Intraplaque wiring enables drug-coated balloons to be utilized for percutaneous recanalization of chronically occluded coronary arteries

OBJECTIVES

This study aimed to determine whether drug-coated balloon (DCB) angioplasty following intraplaque wiring and the use of modified balloons is safe and effective in the percutaneous treatment of coronary chronic total occlusions (CTOs).

BACKGROUND

DCB is an alternative therapeutic option without the limitations of permanent vascular implants. However, its efficacy in CTOs has yet to be confirmed. The combination of modified balloons and DCB can be effectively applied when the intraplaque passage of the guidewire is achieved in CTOs.

METHODS

Data from 124 consecutive CTO lesions (105 patients) treated at our hospital between February 2016 and December 2020 were screened for inclusion and retrospectively analyzed. Among the 118 lesions successfully recanalized, intraplaque wiring was achieved in 108, and 85 were treated by the DCB-only approach following cutting/scoring balloon dilatation.

RESULTS

Follow-up data were available for 82 lesions (71 patients). The median occlusion length was 18.5 mm, and the J-CTO score was 1.7 ± 0.9. No in-hospital major adverse cardiac events occurred, including abrupt vessel closure. During the median 29-month follow-up period, target lesion revascularization was performed for 10 lesions. Follow-up coronary angiography (8.7 ± 3.9 months after the index procedure) was performed for 64 lesions, demonstrating late lumen loss of -0.15 mm (interquartile range -0.4 to 0.23 mm), binary restenosis (diameter stenosis ≥50%) in 12 lesions (18.8%), and late lumen enlargement in 37 (57.8%).

CONCLUSION

The DCB-only approach following the use of modified balloons is a promising strategy for coronary CTOs when intraplaque wiring is achieved.

The Ranger drug-coated balloon: advances in drug-coated technology for treatment of femoropopliteal segment arterial disease

Paclitaxel drug-coated balloons (DCBs) have been shown to improve patency and lower revascularization rates compared with plain old balloon angioplasty. DCBs continue to evolve by improving balloon-coating techniques that minimize the quantity of particles washed off into the bloodstream while maximizing drug retention and vascular-healing profile. Against this backdrop, it is clear that the future of antiproliferatives for the superficial femoral artery will focus on enhancements in device coating materials that will improve the efficiency of drug delivery. The Ranger DCB system recently gained US FDA approval for use. This review discusses the background of DCBs and how the Ranger DCB builds on these previous platforms based on experimental and clinical data.

Establishment of a Nomogram for Predicting the Suboptimal Angiographic Outcomes of Coronary De Novo Lesions Treated with Drug-Coated Balloons

INTRODUCTION

Factors affecting the angiographic outcomes of coronary de novo lesions treated with drug-coated balloons (DCBs) have not been well illustrated. The aim of the study is to establish a nomogram for predicting the risk of suboptimal diameter stenosis (DS) at angiographic follow-up.

METHODS

A retrospective analysis was performed on a cohort of patients who underwent DCB intervention for coronary de novo lesions with angiographic follow-up data. Multivariable logistic regression analysis was applied to determine the independent predictors of DS ≥ 30% at follow-up, and then a nomogram model was established and validated.

RESULTS

A total of 196 patients (313 lesions) were divided into the suboptimal (DS ≥ 30%) and optimal (DS < 30%) DS groups according to quantitative coronary angiography (QCA) measurements of the target lesions at follow-up. Seven independent factors including calcified lesions, true bifurcation lesions, immediate lumen gain rate (iLG%) < 20%, immediate diameter stenosis (iDS) ≥ 30%, DCB diameter/reference vessel diameter ratio (DCB/RVD) < 1.0, DCB length and mild dissection were identified. The area under the curve (AUC) (95% CI) of the receiver-operating characteristic (ROC) curve of the nomogram was 0.738 (0.683, 0.794). After the internal validation, the AUC (95% CI) was 0.740 (0.685, 0.795). The Hosmer-Lemeshow goodness of fit (GOF) test (χ² = 6.57, P = 0.766) and the calibration curve suggested a good predictive consistency of the nomogram.

CONCLUSIONS

The well-calibrated nomogram could efficiently predict the suboptimal angiographic outcomes at follow-up. This model may be helpful to optimize lesion preparation to achieve optimal outcomes.

Coronary artery aneurysm formation after paclitaxel-coated balloon-only intervention for de novo coronary chronic total occlusion

Background

Although coronary artery aneurysm (CAA) is an uncommon complication of drug-coated balloon (DCB) treatment, the incidence and mechanisms CAA formation after DCB intervention for chronic total occlusion (CTO) remains to be clarified. The aim of this study was to investigate the incidence of CAA after DCB intervention for the treatment of CTO of coronary arteries.

Materials and methods

This was a retrospective analysis of 82 patients, contributing 88 vessels, who underwent successful DCB-only treatment for de novo CTO lesions. Follow-up angiography was performed in all cases, at a mean 208.5 (interquartile range [IQR]: 174.8 to 337.5) days after the index procedure.

Results

CAA was identified in seven vessels, in seven patients, at the site of previous successful DCB-only treatment. Of these, six were fusiform in shape and one saccular, with a mean diameter of 4.2 ± 1.0 mm and length of 6.7 ± 2.6 mm. Six CAAs developed at the CTO inlet site, and all CAAs occurred at the lesions following dissection immediately after DCB treatment. CAAs were not associated with an increased risk of major clinical events over the median follow-up of 676.5 (IQR: 393.8 to 1,304.8) days.

Conclusion

The incidence of CAA after DCB-only treatment for CTO lesions was 8.0% in this study. Further research is warranted, using intravascular imaging, to clarify the mechanism of DCB-related CAA formation and prognosis.

Understudied factors in drug-coated balloon design and evaluation: A biophysical perspective

Drug-coated balloon (DCB) percutaneous interventional therapy allows for durable reopening of the narrowed lumen via physical tissue expansion and local anti-restenosis drug delivery, providing an alternative to traditional uncoated balloons or a permanent indwelling implant such as a conventional metallic drug-eluting stent. While DCB-based treatment of peripheral arterial disease (PAD) has been incorporated into clinical guidelines, DCB use has been recently curtailed due to reports that showed evidence of increased mortality risk in patients treated with paclitaxel (PTX)-coated balloons. Given the United States Food and Drug Administration's 2019 consequent warning regarding PTX-eluting DCBs and the subsequent marked reduction in clinical DCB use, there is now a critical need to better understand the compositional and mechanical factors underlying DCB efficacy and safety. Most work to date on DCB refinement has focused on designing both the enabling balloon catheter and alternate coatings composed of various drugs and excipients, followed by device evaluation in preclinical and clinical studies. We contend that improvement in DCB performance will require a better understanding of the biophysical factors operative during and following balloon deployment, and moreover that the elaboration and demonstrated control of these factors are needed to address current concerns with DCB use. This article provides a perspective on the biophysical interactions that govern DCB performance and offers new design strategies for the development of next-generation DCB devices.

Necrosis of Pedunculated Lipofibroma by Nab-Paclitaxel

We present a rare phenomenon of a soft tumor hanging on the woman's left upper arm that underwent necrosis from the distal aspect during chemotherapy for pancreatic cancer. The benign tumor, pedunculated lipofibroma, originally had normal color for 10 years and then became necrotic when she was treated with gemcitabine and nab-paclitaxel. Necrosis stopped in conjunction with chemotherapy cessation. Dermatologists must remember that nab-paclitaxel could develop necrosis of a skin tumor.

A multiphasic model for determination of water and solute transport across the arterial wall: effects of elastic fiber defects

Transport of solute across the arterial wall is a process driven by both convection and diffusion. In disease, the elastic fibers in the arterial wall are disrupted and lead to altered fluid and mass transport kinetics. A computational mixture model was used to numerically match previously published data of fluid and solute permeation experiments in groups of mouse arteries with genetic (knockout of fibulin-5) or chemical (treatment with elastase) disruption of elastic fibers. A biphasic model of fluid permeation indicated the governing property to be the hydraulic permeability, which was estimated to be 1.52×10^-9, 1.01×10^-8, and 1.07×10^-8 mm⁴/μN.s for control, knockout, and elastase groups, respectively. A multiphasic model incorporating solute transport was used to estimate effective diffusivities that were dependent on molecular weight, consistent with expected transport behaviors in multiphasic biological tissues. The effective diffusivity for the 4 kDA FITC-dextran solute, but not the 70 or 150 kDa FITC-dextran solutes, was dependent on elastic fiber structure, with increasing values from control to knockout to elastase groups, suggesting that elastic fiber disruption affects transport of lower molecular weight solutes. The model used here sets the groundwork for future work investigating transport through the arterial wall.

Comprehensive Assessment of Current Management Strategies for Patients With Diabetes and Chronic Limb-Threatening Ischemia

Chronic limb-threatening ischemia (CLTI) is the most severe form of peripheral artery disease. It is estimated that 60% of all nontraumatic lower-extremity amputations performed annually in the United States are in patients with diabetes and CLTI. The consequences of this condition are extraordinary, with substantial patient morbidity and mortality and high socioeconomic costs. Strategies that optimize the success of arterial revascularization in this unique patient population can have a substantial public health impact and improve patient outcomes. This article provides an up-to-date comprehensive assessment of management strategies for patients afflicted by both diabetes and CLTI.

EFFECTS OF COATING PROPERTIES ON CONTROLLED DELIVERY FROM AN EMBEDDED DRUG-ELUTING STENT: A SIMULATION STUDY

The present investigation deals with the effects of biodegradable, biodurable and polymer-free coating of a stent on the release mechanism of the drug in a porous medium. The Brinkman equations for the interstitial fluid, the unsteady convection-diffusion-reaction equation for the transport of free drug in the tissue and the unsteady reaction equations for the bound as well as the internalized drug have been considered. In the coating, the transport of drug has been modeled as a diffusion process. Effects of different percentages of the embedment, convection and various coating properties of the stent on the transport of free drug, its retention and the internalization of the bound drug have been studied. Immersed Boundary Method (IBM) in the staggered grid formulation (IBM-MAC) has been used to tackle numerically the system of nonlinear governing equations. Simulated results predict the fastest release of drug from a biodegradable coating, but the averaged concentrations of all drug forms do reach a quasi-steady state in case of a biodurable coating irrespective of the degrees of embedment. Moreover, for all embedment levels of the stent, a biodegradable coating is superior to that of biodurable and polymer-free coating in the presence/absence of convection for larger times, but this superiority is lost for smaller times. Unlike biodurable coating, it is also predicted that the more the embedment level does not necessarily imply the more the effectiveness of delivery for biodegradable and polymer-free coatings of a stent.

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.

Stent conditioned media for in vitro evaluation of hydrophobic stent coatings

In vitro cell studies of hydrophobic drugs face difficulties associated with their low aqueous solubility. To study poorly soluble drugs in bio-relevant media, solubilizing agents are frequently used to make stock solutions before final reconstitution in media. This results in drug concentrations that are not representative of in vivo conditions and may pose adverse effects on cells' biological functions. This is especially true of typical hydrophobic stent coatings intended for vascular applications, where poor in vitro to in vivo correlation exists. To this end, a method for preparation of hydrophobic drug suspensions in bio-relevant media via stent conditioned media using paclitaxel (PTX) as a model drug is proposed. Since the drug is present as a suspension, this media was validated for its content uniformity and potency to induce formation of micronuclei, typical of cells undergoing prolonged mitotic arrest. Further, PTX uptake by endothelial cells was quantified and showed that the PTX stent conditioned media (at a theoretical concentration of 100 μM) suppressed cellular growth equivalent to the 0.1 μM DMSO dissolved PTX.

Contemporary technologies to modify calcified plaque in coronary artery disease

With aging society, one of the more challenging obstacles in percutaneous coronary interventions are calcified coronary lesions. Calcified lesions may impede stent delivery, limit balloon and stent expansion, cause uneven drug distribution, and hinder wire advancement. Even in the setting of acceptable procedural success, vessel calcification is independently associated with increased target lesion revascularization rates at follow-up and lower survival rates. In order to effectively manage such lesions, dedicated technologies have been developed. Atherectomy aims at excising tissue and debulking plaques, as well as compressing and reshaping the atheroma, generally referred to as lesion preparation that enables further balloon and/or stent expansion in contemporary clinical practice. In the current review, we will discuss the available methods for atherectomy, including rotational, orbital, and excimer laser coronary atherectomy, as well as intravascular lithotripsy. In addition, we will review the role of imaging in calcified lesions.

5FU encapsulated polyglycerol sebacate nanoparticles as anti-cancer drug carriers

The majority of anti-cancer drugs fail to reach clinical trials due to their low water solubility. A biocompatible drug delivery system that encapsulates and efficiently delivers hydrophobic drugs to the target site is the need of the hour. This study addresses the issue by focusing on a polymeric polyglycerol sebacate (PGS) nanoparticles loaded with 5-fluorouracil (5FU), a primary line chemotherapy drug for many types of cancers. The generated nanoparticle (PGS-NP) was biocompatible and had minimal cytotoxicity against the MDA-MB-231 and A549 cell lines, even at a high concentration of 100 μg mL-1. The cell viability post treatment with PGS nanoparticles encapsulated with 5FU (PGS-5FU) decreased to as low as around 40% whereas, in the case of treatment with 5FU, the viability percentage increased. The nanoparticles also showed controlled drug release when encapsulated with 5FU. This striking observation suggested that these nanoparticles can improve the efficacy of drug delivery to tumor sites. Apoptosis assay and caspase-3 activity quantification supported these data wherein PGS-5FU treatment showed almost three times caspase-3 activity as compared to control cells. Additionally, throughout all the experiments, MDA-MB-231 cells were more sensitive to PGS-5FU than A549 cells, indicating that these nanoparticles are ideal for breast cancer treatment. In summary, 5FU encapsulated PGS nanoparticles are a potential drug carrier to deliver 5FU efficiently to cancer cells.

Vascular Lesion-Specific Drug Delivery Systems: JACC State-of-the-Art Review

Drug delivery is central to modern cardiovascular care, where drug-eluting stents, bioresorbable scaffolds, and drug-coated balloons all aim to restore perfusion while inhibiting exuberant healing. The promise and enthusiasm of these devices has in some cases exceeded demonstration of efficacy and even understanding of driving mechanisms. The authors review the means of drug delivery in each device, outlining how the technologies affect vascular behavior. They focus on how drug retention and response are governed by lesion morphology: lipid displacing drug-specific binding sites, calcium inhibiting diffusion, blocking thrombi or promoting luminal washout, and vascular healing steering hyperplastic developments. In this regard, the authors outline the fundamental impact of vascular structure on drug delivery and review the development of contemporary and future devices for coronary and peripheral intervention. They look toward a future where incorporating information on lesion distribution is central to therapeutic success and envision a transition toward lesion-specific treatment for improved interventional outcomes.

Influence of Elongation of Paclitaxel-Eluting Electrospun-Produced Stent Coating on Paclitaxel Release and Transport through the Arterial Wall after Stenting

It was previously shown that polycaprolactone (PCL)-based electrospun-produced paclitaxel (PTX)-enriched matrices exhibit long-term drug release kinetics and can be used as coatings for drug-eluting stents (DES). The installation of vascular stents involves a twofold increase in stent diameter and, therefore, an elongation of the matrices covering the stents, as well as the arterial wall in a stented area. We studied the influence of matrix elongation on its structure and PTX release using three different electrospun-produced matrices. The data obtained demonstrate that matrix elongation during stent installation does not lead to fiber breaks and does not interfere with the kinetics of PTX release. To study PTX diffusion through the expanded artery wall, stents coated with 5%PCL/10%HSA/3%DMSO/PTX and containing tritium-labeled PTX were installed into the freshly obtained iliac artery of a rabbit. The PTX passing through the artery wall was quantified using a scintillator β-counter. The artery retained the PTX and decreased its release from the coating. The retention of PTX by the arterial wall was more efficient when incubated in blood plasma in comparison with PBS. The retention/accumulation of PTX by the arterial wall provides a prolonged drug release and allows for the reduction in the dose of the drugs in electrospun-produced stent coatings.

An ultralow dose paclitaxel coated drug balloon with an outer protective sheath for peripheral arterial disease treatment

Use of a drug-eluting coated balloon (DCB) represents a promising therapeutic method for peripheral arterial disease (PAD) due to its advantages such as no implant permanently retained in the patient and no inflammatory reaction and endothelialization barrier caused by a permanent stent. However, there is still a huge challenge of controlling the release of drugs from the DCB into vessel tissue. The uncontrolled release of drugs and high drug loading amounts could potentially lead to distal embolization and mortality events. In our study, an ultralow dose paclitaxel (PTX) coated DCB appended with an outer protective sheath was designed to treat peripheral vessel stenosis. An in vitro study demonstrated that the sheath could significantly reduce the drug loss during the delivery process and the meglumine matrix could effectively promote the transfer of PTX into vessel tissue. The pharmacokinetics study in the swine model also demonstrated that the PTX amount remaining in the vessel after being treated by our DCB was comparable to similar products on market although only less than a third of the PTX was used. The safety study indicated that the DCB treatment did not have any adverse impact on the physiological function of the vessel. Therefore, our ultralow dose PTX coated DCB could provide an effective and safe treatment for PAD.

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.

Possible mechanism of late lumen enlargement after treatment for de novo coronary lesions with drug-coated balloon

BACKGROUND

Drug-coated balloon (DCB) treatment for de novo coronary artery disease has demonstrated late lumen enlargement (LLE) in mid-term follow-up and it was considered as clinical benefit; however, its mechanism and the predictive factor remains unclear.

METHODS

This study enrolled 46 consecutive patients (54 lesions) treated with DCB, using intravascular ultrasound (IVUS) at the index procedure and at the 9-month follow-up. We measured IVUS parameters at 1-mm intervals and calculated the mean volume of the external elastic membrane (EEM), lumen, and plaque. We calculated the dissection index (DI) defined as summation of the following points, 2: dissection over EEM, 1: intra-EEM dissection, 0: no dissection at every 1-mm interval, and divided by lesion length.

RESULTS

IVUS showed that there was no flow limiting dissection just after DCB treatment, the mean EEM and lumen volume (LV) had significantly increased while mean plaque volume had significantly decreased at 9 months, and 74.1% lesions exhibited LLE. We divided the patients into three groups according to delta mean LV. Mean EEM volume significantly increased and mean plaque volume significantly decreased in the larger and smaller LLE groups, but not in the non-LLE group. The DI was higher in a descending order in the three groups. The multiple regression analysis demonstrated that the DI was the strongest predictor of the change in mean LV.

CONCLUSIONS

LLE after DCB treatment may be caused by vessel enlargement and plaque regression. The non-flow limiting larger dissection just after DCB treatment may strongly associate with the intending LLE.

Balloon-based drug coating delivery to the artery wall is dictated by coating micro-morphology and angioplasty pressure gradients

Paclitaxel coated balloon catheters (PCB) were developed as a polymer-free non-implantable alternative to drug eluting stents, delivering similar drug payloads in a matter of minutes. While PCB have shown efficacy in treating peripheral arterial disease in certain patient groups, restenosis rates remain high and there is no class effect. To help further optimize these devices, we developed a scanning electron microscopy (SEM) imaging technique and computational modeling approach that provide insights into the coating micromorphology dependence of in vivo drug transfer and retention. PCBs coated with amorphous/flaky or microneedle coatings were inflated for 60 sec in porcine femoral arteries. Animals were euthanized at 0.5, 24 and 72 h and treated arteries processed for SEM to image endoluminal coating distribution followed by paclitaxel quantification by mass spectrometry (MS). Endoluminal surfaces exhibited sparse coating patches at 0.5 h, predominantly protruding (13.71 vs 0.59%, P < 0.001), with similar micro-morphologies to nominal PCB surfaces. Microneedle coating covered a 1.5-fold endoluminal area (16.1 vs 10.7%, P = 0.0035) owing to higher proximal and distal delivery, and achieved 1.5-fold tissue concentrations by MS (1933 vs 1298 μg/g, P = 0.1745) compared to amorphous/flaky coating. Acute longitudinal coating distribution tracked computationally predicted microindentation pressure gradients (r = 0.9, P < 0.001), with superior transfer of the microneedle coatings attributed to their amplification of angioplasty contact pressures. By 24 h, paclitaxel concentration and coated tissue areas both declined by >93% even as nonprotruding coating levels were stable between 0.5 and 72 h, and 2.7-fold higher for microneedle vs flaky coating (0.64 vs 0.24%, P = 0.0195). Tissue retained paclitaxel concentrations at 24-72 h trended 1.7-fold higher post treatment with microneedle coating compared to the amorphous/flaky coating (69.9 vs 39.9 μg/g, P = 0.066). Thus, balloon based drug delivery is critically dependent on coating micromorphologies, with superior performance exhibited by micromorphologies that amplify angioplasty pressures.

Computational model of stent-based delivery from a half-embedded two-layered coating

An attempt is made in the present investigation to develop a computational model for the purpose of studying the effect of interstitial flow in the porous media on the distribution of drug eluted from a half-embedded drug-eluting stent and its retention in the presence of two-layered coating of the stent. The transport of free drug inside the coatings is considered as an unsteady diffusion process while that in the tissue as an unsteady convection-diffusion-reaction process. The bound drug is governed by an unsteady reaction process only. Immersed boundary method (IBM) in the staggered grid formulation, popularly known as marker and cell (MAC) method, has been leveraged to tackle numerically the governing equations. This model highlights the benefits of consideration of two-layered coating and does predict underlying mechanism for better efficacy by tweaking the kinetics parameters. Comparisons are also made with the results available for stent-based delivery.

Customized Therapeutic Surface Coatings for Dental Implants

Dental implants are frequently used to support fixed or removable dental prostheses to replace missing teeth. The clinical success of titanium dental implants is owed to the exceptional biocompatibility and osseointegration with the bone. Therefore, the enhanced therapeutic effectiveness of dental implants had always been preferred. Several concepts for implant coating and local drug delivery had been developed during the last decades. A drug is generally released by diffusion-controlled, solvent-controlled, and chemical controlled methods. Although a range of surface modifications and coatings (antimicrobial, bioactive, therapeutic drugs) have been explored for dental implants, it is still a long way from designing sophisticated therapeutic implant surfaces to achieve the specific needs of dental patients. The present article reviews various interdisciplinary aspects of surface coatings on dental implants from the perspectives of biomaterials, coatings, drug release, and related therapeutic effects. Additionally, the various types of implant coatings, localized drug release from coatings, and how released agents influence the bone–implant surface interface characteristics are discussed. This paper also highlights several strategies for local drug delivery and their limitations in dental implant coatings as some of these concepts are yet to be applied in clinical settings due to the specific requirements of individual patients.

Mortality Assessment of Paclitaxel-Coated Balloons: Patient-Level Meta-Analysis of the ILLUMENATE Clinical Program at 3 Years

BACKGROUND

A recent summary-level meta-analysis comprising randomized, controlled trials (RCTs) of femoropopliteal paclitaxel-coated balloon and stent intervention identified excess late mortality in the paclitaxel-treated patients.

METHODS

We evaluated the safety of the Stellarex drug-coated balloon (DCB) for femoropopliteal artery disease with an independently performed meta-analysis of patient-level data from all patients in the Stellarex femoropopliteal clinical program. To compare mortality after DCB or uncoated percutaneous transluminal angioplasty (PTA), we aggregated data from 2 RCTs comprising 419 patients treated with DCB and 170 patients treated with PTA. In an additional analysis, data were aggregated from 6 poolable Stellarex DCB studies (2 RCTs, 3 single-arm studies, and 1 registry). All serious adverse events including deaths were adjudicated by a blinded, third-party, independent Clinical Events Committee. Kaplan-Meier estimates in the RCTs were compared with restricted mean survival time. Predictors of death were assessed with hazard ratios (HRs) and Cox proportional hazards modeling.

RESULTS

Baseline characteristics were similar in the patients treated with DCB and PTA in the pooled RCT analysis, with the exception that the DCB cohort was younger (67.4±9.7 versus 69.4±9.4 years, P=0.02), smoked more frequently (86.6% versus 78.8%, P=0.02), and were less often treated for recurrent lesions (8.8% versus 14.7%, P=0.04). In the RCTs, patients treated with DCB had all-cause mortality rates that were not different from those of patients treated with PTA (Kaplan-Meier estimates 1.8±0.7% versus 1.3±0.9%, 6.5±1.2% versus 5.9±1.9%, and 9.3±1.5% versus 9.9±2.4% at 1, 2, and 3 years, respectively, P=0.86). All-cause mortality rates were similar in a 1906-patient pooled nonrandomized DCB data set (Kaplan-Meier estimates of 2.1%, 4.9%, and 7.0% at 1, 2, and 3 years, respectively). Clinical Events Committee-adjudicated causes of death were balanced between the DCB and PTA cohorts. Multivariable Cox modeling identified age (HR, 1.06; 95% CI, 1.04-1.08; P<0.001), diabetes mellitus (HR, 1.42; 95% CI, 1.01-2.00; P=0.04), congestive heart failure (HR, 1.88; 95% CI, 1.12-3.16; P=0.02), and renal insufficiency (HR, 2.00; 95% CI, 1.33-3.01; P<0.001) as predictors of mortality. Paclitaxel exposure was unrelated to mortality (HR, 1.04; 95% CI, 0.98-1.10; P=0.23).

CONCLUSIONS

The mortality rates for patients treated with the DCB and uncoated PTA were indistinguishable over 3-year follow-up. Additional patient-level, adequately powered meta-analyses with larger RCT data sets will be needed to confirm the generalizability of these findings.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifiers: NCT02110524, NCT01858363, NCT01858428, NCT03421561, NCT01912937, NCT01927068, and NCT02769273.

Electrospun Produced 3D Matrices for Covering of Vascular Stents: Paclitaxel Release Depending on Fiber Structure and Composition of the External Environment

Paclitaxel is a natural, highly lipophilic anti proliferative drug widely used in medicine. We have studied the release of tritium-labeled paclitaxel (³H-PTX) from matrices destined for the coating of vascular stents and produced by the electrospinning method from the solutions of polycaprolactone (PCL) with paclitaxel (PTX) in hexafluoisopropanol (HFIP) and/or solutions of PCL with PTX and human serum albumin (HSA) in HFIP or HIFP-dimethyl sulphoxide (DMSO) blend. The release of PTX has been shown to depend on the composition of electrospinning solution, as well as the surrounding medium, particularly the concentration of free PTX and PTX-binding biomolecules present in human serum. It was shown that 3D matrices can completely release PTX without weight loss. Two-phase PTX release from optimized 3D matrices was obtained: ~27% of PTX was released in the first day, another 8% were released over the next 26 days. Wherein ~2.8%, ~2.3%, and ~0.25% of PTX was released on day 3, 9, and 27, respectively. Considering PTX toxicity, the rate of its diffusion through the arterial wall, and the data obtained the minimum cytostatic dose of the drug in the arterial wall will be maintained for at least three months.

Strategic Pentablock Copolymer Nanomicellar Formulation for Paclitaxel Delivery System

Nanomicelles (NM) enhance solubility and absorption of active pharmaceutical ingredients (APIs). Various polymers and non-polymers are utilized to prepare nanomicellar formulations to achieve high absorption and delivery of drugs. The main purpose of this study was to develop drug-loaded nanomicelles with pentablock copolymers for paclitaxel delivery. Monomers of lactide, ε-caprolactone, and polyethylene-glycol were utilized to prepare pentablock copolymer by ring opening technique. The pentablock nanomicelles (PBNM) were formulated by evaporation and rehydration. Both copolymers and nanomicelles were analyzed by H-NMR, FTIR, and XRD. Nanomicelles were further analyzed for size and zeta potential using dynamic light scattering (DLS) and by H-NMR and TEM. The XRD, FTIR, and H-NMR analyses confirmed the structures of the pentablock copolymers. Average size was 20 nm ± 5.00 nm, and ζ-potential is around zero. H-NMR and FTIR analyses for Paclitaxel-PBNM indicated peaks of paclitaxel and the polymer, confirming successful encapsulation. TEM showed spherical morphology and size range similar to that obtained by DLS. In vitro release studies revealed slow first-order paclitaxel release rate from pentablock nanomicelles in phosphate buffer solution (PBS). Confocal laser scanning microscopy analysis with coumarin-6-loaded in PBNM indicated that pentablock nanomicelles were efficiently taken into prostate cancer (PC-3) cells. Cell proliferation assay showed that nanomicelles were able to ferry adequate amounts of paclitaxel drug into PC-3 cells and subsequently inhibiting PC-3 cell proliferation significantly. Results confirmed that pentablock copolymer can generate drug-loaded nanomicelles with desirable sizes and zeta potential. These demonstrate potentiality of pentablock nanomicelles as carrier for anticancer delivery.

Drug-eluting stents for the treatment of complex femoro-popliteal disease: a systematic review and meta-analysis

INTRODUCTION

Endovascular methods have emerged as an appealing alternative to bypass for the treatment of patients not suitable for surgery. Drug eluting stents (DES) have been developed to address the limitations of angioplasty and stenting. There is a paucity of data in the literature on their performance for the treatment of patients with long femoro- popliteal segment lesions. We aimed to analyse the evidence supporting the use of DES in patients with complex femoro-popliteal disease.

EVIDENCE ACQUISITION

A systematic review and meta-analysis was conducted according to the recommendations of the Preferred Reporting Items for Systematic reviews and Meta- Analyses (PRISMA) statement.

EVIDENCE SYNTHESIS

A total of 1255 potentially relevant articles were initially selected. After reviewing at title or abstract level, 22 articles were read in full and 10 were included. These studies reported on the use of DES for 1539 patients. In all studies the DES that was employed was a paclitaxel-eluting stent (Zilver PTX, Cook Medical). Average lesion length ranged from 114mm to 400mm. The pooled technical success rate was 0.964 (95% confidence interval [CI]: 0.936 - 0.980). The pooled estimate of limb loss at 12 months was 0.019 (95% CI: 0.012 - 0.030), stent fracture at 12 months 0.035 (95% CI: 0.007 - 0.155), primary patency at 12 months 0.705 (95% CI: 0.576 - 0.807) and secondary patency at 12 months 0.898 (95% CI: 0.815 - 0.946).

CONCLUSIONS

The short-term outcomes of DES for TASC C & D femoro-popliteal lesions are encouraging. Caution is advised in extrapolating the results of the included studies due to the large heterogeneity and lack of reporting of subgroup specific outcomes.

Predicting patient exposure to nickel released from cardiovascular devices using multi-scale modeling

Many cardiovascular device alloys contain nickel, which if released in sufficient quantities, can lead to adverse health effects. However, in-vivo nickel release from implanted devices and subsequent biodistribution of nickel ions to local tissues and systemic circulation are not well understood. To address this uncertainty, we have developed a multi-scale (material, tissue, and system) biokinetic model. The model links nickel release from an implanted cardiovascular device to concentrations in peri-implant tissue, as well as in serum and urine, which can be readily monitored. The model was parameterized for a specific cardiovascular implant, nitinol septal occluders, using in-vitro nickel release test results, studies of ex-vivo uptake into heart tissue, and in-vivo and clinical measurements from the literature. Our results show that the model accurately predicts nickel concentrations in peri-implant tissue in an animal model and in serum and urine of septal occluder patients. The congruity of the model with these data suggests it may provide useful insight to establish nickel exposure limits and interpret biomonitoring data. Finally, we use the model to predict local and systemic nickel exposure due to passive release from nitinol devices produced using a wide range of manufacturing processes, as well as general relationships between release rate and exposure. These relationships suggest that peri-implant tissue and serum levels of nickel will remain below 5 μg/g and 10 μg/l, respectively, in patients who have received implanted nitinol cardiovascular devices provided the rate of nickel release per device surface area does not exceed 0.074 μg/(cm² d) and is less than 32 μg/d in total.

STATEMENT OF SIGNIFICANCE

The uncertainty in whether in-vitro tests used to evaluate metal ion release from medical products are representative of clinical environments is one of the largest roadblocks to establishing the associated patient risk. We have developed and validated a multi-scale biokinetic model linking nickel release from cardiovascular devices in-vivo to both peri-implant and systemic levels. By providing clinically relevant exposure estimates, the model vastly improves the evaluation of risk posed to patients by the nickel contained within these devices. Our model is the first to address the potential for local and systemic metal ion exposure due to a medical device and can serve as a basis for future efforts aimed at other metal ions and biomedical products.

Positive Vessel Remodelling

Since its introduction, the success of percutaneous transluminal coronary angioplasty (PTCA) has been jeopardised by recoil, neointima proliferation, and luminal renarrowing; however, the benefit of positive remodelling has not gained widespread attention. While vessels will remodel positively up to a certain stage in the development of atherosclerosis, the therapeutic application of this process remains low. The prevention of vessel shrinkage during the healing process, which represents the predominant mechanism of restenosis after PTCA, is a prerequisite of long-term success in PTCA. The antiproliferative drugs that are currently used mainly on stents are known to be capable of this. Primary clinical studies have reported that positive remodelling leads to beneficial effects in coronary and peripheral angioplasty if no foreign body is inserted, and a paradigm change in percutaneous coronary intervention towards far fewer implants is within reach.

Intimal and medial contributions to the hydraulic resistance of the arterial wall at different pressures: a combined computational and experimental study

The hydraulic resistances of the intima and media determine water flux and the advection of macromolecules into and across the arterial wall. Despite several experimental and computational studies, these transport processes and their dependence on transmural pressure remain incompletely understood. Here, we use a combination of experimental and computational methods to ascertain how the hydraulic permeability of the rat abdominal aorta depends on these two layers and how it is affected by structural rearrangement of the media under pressure. Ex vivo experiments determined the conductance of the whole wall, the thickness of the media and the geometry of medial smooth muscle cells (SMCs) and extracellular matrix (ECM). Numerical methods were used to compute water flux through the media. Intimal values were obtained by subtraction. A mechanism was identified that modulates pressure-induced changes in medial transport properties: compaction of the ECM leading to spatial reorganization of SMCs. This is summarized in an empirical constitutive law for permeability and volumetric strain. It led to the physiologically interesting observation that, as a consequence of the changes in medial microstructure, the relative contributions of the intima and media to the hydraulic resistance of the wall depend on the applied pressure; medial resistance dominated at pressures above approximately 93 mmHg in this vessel.

Calcified plaque modification alters local drug delivery in the treatment of peripheral atherosclerosis

BACKGROUND

Calcific atherosclerosis is a major challenge to intraluminal drug delivery in peripheral artery disease (PAD).

OBJECTIVES

We evaluated the effects of orbital atherectomy on intraluminal paclitaxel delivery to human peripheral arteries with substantial calcified plaque.

METHODS

Diagnostic angiography and 3-D rotational imaging of five fresh human lower limbs revealed calcification in all main arteries. The proximal or distal segment of each artery was treated using an orbital atherectomy system (OAS) under simulated blood flow and fluoroscopy. Explanted arterial segments underwent either histomorphometric assessment of effect or tracking of ¹⁴C-labeled or fluorescent-labeled paclitaxel. Radiolabeled drug quantified bulk delivery and fluorescent label established penetration of drug over finer spatial domain in serial microscopic sections. Results were interpreted using a mathematical model of binding-diffusion mediated arterial drug distribution.

RESULTS

Lesion composition affected paclitaxel absorption and distribution in cadaveric human peripheral arteries. Pretreatment imaging calcium scores in control femoropopliteal arterial segments correlated with a log-linear decline in the bulk absorption rate-constant of ¹⁴C-labeled, declining 5.5-fold per calcified quadrant (p=0.05, n=7). Compared to controls, OAS-treated femoropopliteal segments exhibited 180μm thinner intima (p<0.001), 45% less plaque calcification, and 2 log orders higher paclitaxel bulk absorption rate-constants. Correspondingly, fluorescent paclitaxel penetrated deeper in OAS-treated femoropopliteal segments compared to controls, due to a 70% increase in diffusivity (p<0.001).

CONCLUSIONS

These data illustrate that calcified plaque limited intravascular drug delivery, and controlled OAS treatment of calcific plaques resulted in greater drug permeability and improved adjunct drug delivery to diseased arteries.

Erythromycin Modification That Improves Its Acidic Stability while Optimizing It for Local Drug Delivery

The antibiotic erythromycin has limited efficacy and bioavailability due to its instability and conversion under acidic conditions via an intramolecular dehydration reaction. To improve the stability of erythromycin, several analogs have been developed—such as azithromycin and clarithromycin—which decrease the rate of intramolecular dehydration. We set out to build upon this prior work by developing a conjugate of erythromycin with improved pH stability, bioavailability, and preferential release from a drug delivery system directly at the low pH of an infection site. To develop this new drug conjugate, adamantane-1-carbohydrazide was covalently attached to erythromycin via a pH-degradable hydrazone bond. Since Staphylococcus aureus infection sites are slightly acidic, the hydrazone bond will undergo hydrolysis liberating erythromycin directly at the infection site. The adamantane group provides interaction with the drug delivery system. This local delivery strategy has the potential of reducing off-target and systemic side-effects. This work demonstrates the synthesis of a pH-cleavable, erythromycin conjugate that retains the inherent antimicrobial activity of erythromycin, has an increased hydrophobicity, and improved stability in acidic conditions; thereby enhancing erythromycin’s bioavailability while simultaneously reducing its toxicity.

First-in-man experience of self-expanding nitinol stents combined with drug-coated balloon in the treatment of femoropopliteal occlusive disease

Purpose

The present study aimed to determine the safety and efficacy of a drug-coated balloon inflated within a thin-strut self-expanding bare-metal stent in patients with severe and complex femoropopliteal occlusive disease.

Methods

This prospective study used the Pulsar-self-expanding stent and Passeo-18 Lux drug-coated balloon in patients with severe and complex femoropopliteal occlusive disease. The primary endpoint was the 12-month primary patency, and the secondary endpoints included 24-month primary patency, assisted primary patency, secondary patency, and clinically associated target lesion revascularisation.

Results

The study included 44 patients (51 limbs). The mean age of the patients was 67.6 ± 10.2 years, with 73% men. Chronic limb severity was classified as Rutherford Category III in 41% of the patients, stage IV in 31%, and stage V in 27%. Lesions were predominantly Trans-Atlantic Inter-Society Consensus (TASC 2007) D (51%) and C (45%), with 32 (63%) chronic total occlusions. Procedural success was obtained in all cases. The mean lesion length was 200 ± 74.55 mm (95% CI = 167.09–208.01) with a mean number of stents per limb used of 1.57 ± 0.70 (95% CI = 1.37–1.76). Distal embolisation occurred in two patients. The primary patency rates at the 12- and 24-month follow-up were 94% (95% CI = 82.9–98.1) and 88% (95% CI = 75.7–94.5), respectively. The assisted primary was 94% (95% CI = 82.9–98.1) and secondary patency was 96% (95% CI = 85.2–99.0) at 24-month follow-up. The cumulative stent fracture rate at the 24-month follow-up was 10%. Freedom from clinically driven target lesion revascularisation was 94% (95% CI = 83–98%) at 12-month follow-up and 88% (95% CI = 76–94%) at 24-month follow-up, with two patients requiring a bypass graft.

Conclusion

Our novel approach involving the combination of a thin-strut bare-metal stent and a drug-coated balloon may be safe and effective, with sustainable and promising clinical outcomes up to 24 months after treatment.

Mechanisms Underlying Drug Delivery to Peripheral Arteries

Delivery of drugs onto arterial targets via endovascular devices commands several principles: dissolution, diffusion, convection, drug binding, barriers to absorption, and interaction between the drug, delivery vehicle, and accepting arterial wall. The understanding of drug delivery in the coronary vasculature is vast; there is ongoing work needed in the peripheral arteries. There are differences that account for some failures of application of coronary technology into the peripheral vascular space. Breakthroughs in peripheral vascular interventional techniques building on current technologies require investigators willing to acknowledge the similarities and differences between these different vascular territories, while developing technologies adapted for peripheral arteries.

[Drug-coated balloons in the treatment of peripheral artery disease (PAD). History and current level of evidence]

BACKGROUND

Despite initially encouraging technical success after femoropopliteal PTA, restenosis remains the major challenge in patients with peripheral artery disease (PAD). The main cause of restenosis is neointimal hyperplasia which can be suppressed by antiproliferative drugs. Drug-coated balloons (DCB) or drug-eluting stents (DES) are used for the inhibition of restenosis.

OBJECTIVES

The present article gives an overview of DCB development, actual DCB systems for femoro- and infrapopliteal use, displays the outcomes of randomized clinical trials and the discusses the evidence for the DCB treatment in PAD.

METHODS

A systematic literature search was performed in i) medical journals (i. e. MEDLINE), ii) in international registers for clinical studies (i. e. www.clinicaltrials.gov ) and in iii) scientific session abstracts.

RESULTS

The clinical evidence of the PTX-DCB of the first and following generation has been shown in several controlled randomized trials.

CONCLUSIONS

Major advantages of the DCBs lie in leaving no stent scaffold behind, the immediate release of high drug concentrations with a single dosage, their efficacy in areas, where stents have been contra-indicated until now and its use for secondary interventions. As their effect seems to be limited in severely calcified lesions, prior plaque preconditioning or removal could be advantageous. First positive results data supporting this hypothesis do exist.