Magnetic Nanoparticle-Mediated Targeting of Cell Therapy Reduces In-Stent Stenosis in Injured Arteries

Nano revolution in cardiovascular health: Nanoparticles (NPs) as tiny titans for diagnosis and therapeutics

Cardiovascular diseases (CVDs) are known as life-threatening illnessescaused by severe abnormalities in the cardiovascular system. They are a leading cause of mortality and morbidity worldwide.Nanotechnology integrated substantialinnovations in cardiovascular diagnostic and therapeutic at the nanoscale. This in-depth analysis explores cutting-edge methods for diagnosing CVDs, including nanotechnological interventions and crucial components for identifying risk factors, developing treatment plans, and monitoring patients' progress with chronic CVDs.Intensive research has gone into making nano-carriers that can image and treat patients. To improve the efficiency of treating CVDs, the presentreview sheds light on a decision-tree-based solution by investigating recent and innovative approaches in CVD diagnosis by utilizing nanoparticles (NPs). Treatment choices for chronic diseases like CVD, whose etiology might take decades to manifest, are very condition-specific and disease-stage-based. Moreover, thisreview alsobenchmarks the changing landscape of employing NPs for targeted and better drug administration while examining the limitations of various NPs in CVD diagnosis, including cost, space, time, and complexity. To better understand and treatment of cardiovascular diseases, the conversation moves on to the nano-cardiovascular possibilities for medical research.We also focus on recent developments in nanoparticle applications, the ways they might be helpful, and the medical fields where they may find future use. Finally, this reviewadds to the continuing conversation on improved diagnosis and treatment approaches for cardiovascular disorders by discussing the obstacles and highlighting the revolutionary effects of nanotechnology.

Nanogold-coated stent facilitated non-invasive photothermal ablation of stent thrombosis and restoration of blood flow

In-stent restenosis (ISR) and stent thrombosis (ST) are the most serious complications of coronary angioplasty and stenting. Although the evolution of drug-eluting stents (DES) has significantly restricted the incidence of ISR, they are associated with an enhanced risk of ST. In the present study, we explore the photothermal ablation of a thrombus using a nano-enhanced thermogenic stent (NETS) as a modality for revascularization following ST. The photothermal activity of NETS, fabricated by coating bare metal stents with gold nanorods generating a thin plasmonic film of gold, was found to be effective in rarefying clots formed within the stent lumen in various in vitro assays including those under conditions mimicking blood flow. NETS implanted in the rat common carotid artery generated heat following exposure to a NIR-laser that led to effective restoration of blood flow within the occluded vessel in a model of ferric chloride-induced thrombosis. Our results present a proof-of-concept for a novel photothermal ablation approach by employing coated stents in the non-invasive management of ST.

Nanocrystals for Deep-Tissue In Vivo Luminescence Imaging in the Near-Infrared Region

In vivo imaging technologies have emerged as a powerful tool for both fundamental research and clinical practice. In particular, luminescence imaging in the tissue-transparent near-infrared (NIR, 700-1700 nm) region offers tremendous potential for visualizing biological architectures and pathophysiological events in living subjects with deep tissue penetration and high imaging contrast owing to the reduced light-tissue interactions of absorption, scattering, and autofluorescence. The distinctive quantum effects of nanocrystals have been harnessed to achieve exceptional photophysical properties, establishing them as a promising category of luminescent probes. In this comprehensive review, the interactions between light and biological tissues, as well as the advantages of NIR light for in vivo luminescence imaging, are initially elaborated. Subsequently, we focus on achieving deep tissue penetration and improved imaging contrast by optimizing the performance of nanocrystal fluorophores. The ingenious design strategies of NIR nanocrystal probes are discussed, along with their respective biomedical applications in versatile in vivo luminescence imaging modalities. Finally, thought-provoking reflections on the challenges and prospects for future clinical translation of nanocrystal-based in vivo luminescence imaging in the NIR region are wisely provided.

The recent applications of nanotechnology in the diagnosis and treatment of common cardiovascular diseases

Almost a third of all fatalities may be attributed to cardiovascular disease (CVD), making it a primary cause of mortalities worldwide. Better diagnostic tools and secure, non-invasive imaging techniques are needed to offer accurate information on CVD progression. Several elements contribute to the success of CVD personalized therapy, and two of the most crucial are accurate diagnosis and early detection. The therapy options available for conditions with a pathogenesis that unfold over decades, such as CVD, are very condition-specific and disease-stage based. Nanotechnology is increasingly being used as a therapeutic tool in the biomedical area, where they are used in various contexts, including diagnostics, biosensing, and drug administration. This review article provides an overview of the most recent applications of nanotechnology in the detection and management of prevalent CVDs.

Intraprocedural endothelial cell seeding of arterial stents via biotin/avidin targeting mitigates in-stent restenosis

Impaired endothelialization of endovascular stents has been established as a major cause of in-stent restenosis and late stent thrombosis. Attempts to enhance endothelialization of inner stent surfaces by pre-seeding the stents with endothelial cells in vitro prior to implantation are compromised by cell destruction during high-pressure stent deployment. Herein, we report on the novel stent endothelialization strategy of post-deployment seeding of biotin-modified endothelial cells to avidin-functionalized stents. Acquisition of an avidin monolayer on the stent surface was achieved by consecutive treatments of bare metal stents (BMS) with polyallylamine bisphosphonate, an amine-reactive biotinylation reagent and avidin. Biotin-modified endothelial cells retain growth characteristics of normal endothelium and can express reporter transgenes. Under physiological shear conditions, a 50-fold higher number of recirculating biotinylated cells attached to the avidin-modified metal surfaces compared to bare metal counterparts. Delivery of biotinylated endothelial cells to the carotid arterial segment containing the implanted avidin-modified stent in rats results in immediate cell binding to the stent struts and is associated with a 30% reduction of in-stent restenosis in comparison with BMS.

Fabrication and Hemocompatibility Evaluation of a Robust Honeycomb Nanostructure on Medical Pure Titanium Surface

Thrombosis induced by blood-contacting medical devices is still a major clinical problem, resulting in some serious complications such as infarction, irreversible tissue damage, and even death. Therefore, seeking an effective and safe surface modification approach to improve the hemocompatibility of the material is still urgent. In this research, a novel and facile approach was proposed to fabricate a robust honeycomb nanostructure on medical pure titanium surface by two-step anodic oxidation, which effectively enhanced the physicochemical performance and hemocompatibility of the material. Especially, the honeycomb nanostructure that underwent annealing treatment at 500 °C (HN-Ti-500 °C) presented significant performance to suppress the coagulation cascade in the in vitro tests, the reason mainly ascribed to an overall repulsive interaction between the protein molecule related to thrombosis and material surface based on an extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory analysis. Furthermore, a vessel stent fabricated by HN-Ti-500 °C was implanted into the left carotid artery of rabbits for 1 month. The antithrombotic mechanism and biocompatibility of the modified surface were further verified. The results presented that no thrombus generated and adhered onto the inner surface of the modified stent, and no obvious disorder hyperplasia and inflammation were observed in the intima tissue of the vessel at the implantation site, which indicated that the modified surface could effectively decrease the risk of in-stent restenosis and thrombosis. This work offers a promising strategy for surface modification of blood-contacting medical titanium material to address the clinical complications associated with restenosis and thrombosis.

Small-angle X-ray scattering to quantify the incorporation and analyze the disposition of magnetic nanoparticles inside cells

Access to detailed information on cells loaded with nanoparticles with nanoscale precision is of a long-standing interest in many areas of nanomedicine. In this context, designing a single experiment able to provide statistical mean data from a large number of living unsectioned cells concerning information on the nanoparticle size and aggregation inside cell endosomes and accurate nanoparticle cell up-take is of paramount importance. Small-angle X-ray scattering (SAXS) is presented here as a tool to achieve such relevant data. Experiments were carried out in cultures of B16F0 murine melanoma and A549 human lung adenocarcinoma cell lines loaded with various iron oxide nanostructures displaying distinctive structural characteristics. Five systems of water-dispersible magnetic nanoparticles (MNP) of different size, polydispersity and morphology were analyzed, namely, nearly monodisperse MNP with 11 and 13 nm mean size coated with meso-2,3-dimercaptosuccinic acid, more polydisperse 6 nm colloids coated with citric acid and two nanoflowers (NF) systems of 24 and 27 nm in size resulting from the aggregation of 8 nm MNP. Up-take was determined for each system using B16F0 cells. Here we show that SAXS pattern provides high resolution information on nanoparticles disposition inside endosomes of the cytoplasm through the structure factor analysis, on nanoparticles size and dispersity after their incorporation by the cell and on up-take quantification from the extrapolation of the intensity in absolute scale to null scattering vector. We also report on the cell culture preparation to reach sensitivity for the observation of MNP inside cell endosomes using high brightness SAXS synchrotron source. Our results show that SAXS can become a valuable tool for analyzing MNP in cells and tissues.

Iron Oxide Nanoparticles in Regenerative Medicine and Tissue Engineering

In recent years, many promising nanotechnological approaches to biomedical research have been developed in order to increase implementation of regenerative medicine and tissue engineering in clinical practice. In the meantime, the use of nanomaterials for the regeneration of diseased or injured tissues is considered advantageous in most areas of medicine. In particular, for the treatment of cardiovascular, osteochondral and neurological defects, but also for the recovery of functions of other organs such as kidney, liver, pancreas, bladder, urethra and for wound healing, nanomaterials are increasingly being developed that serve as scaffolds, mimic the extracellular matrix and promote adhesion or differentiation of cells. This review focuses on the latest developments in regenerative medicine, in which iron oxide nanoparticles (IONPs) play a crucial role for tissue engineering and cell therapy. IONPs are not only enabling the use of non-invasive observation methods to monitor the therapy, but can also accelerate and enhance regeneration, either thanks to their inherent magnetic properties or by functionalization with bioactive or therapeutic compounds, such as drugs, enzymes and growth factors. In addition, the presence of magnetic fields can direct IONP-labeled cells specifically to the site of action or induce cell differentiation into a specific cell type through mechanotransduction.

Stent strut streamlining and thickness reduction promote endothelialization

Stent thrombosis (ST) carries a high risk of myocardial infarction and death. Lack of endothelial coverage is an important prognostic indicator of ST after stenting. While stent strut thickness is a critical factor in ST, a mechanistic understanding of its effect is limited and the role of haemodynamics is unclear. Endothelialization was tested using a wound-healing assay and five different stent strut models ranging in height between 50 and 150 µm for circular arc (CA) and rectangular (RT) geometries and a control without struts. Under static conditions, all stent strut surfaces were completely endothelialized. Reversing pulsatile disturbed flow caused full endothelialization, except for the stent strut surfaces of the 100 and 150 µm RT geometries, while fully antegrade pulsatile undisturbed flow with a higher mean wall shear stress caused only the control and the 50 µm CA geometries to be fully endothelialized. Modest streamlining and decrease in height of the stent struts improved endothelial coverage of the peri-strut and stent strut surfaces in a haemodynamics dependent manner. This study highlights the impact of the stent strut height (thickness) and geometry (shape) on the local haemodynamics, modulating reendothelialization after stenting, an important factor in reducing the risk of stent thrombosis.

Targeting and deep-penetrating delivery strategy for stented coronary artery by magnetic guidance and ultrasound stimulation

Stent placement is an effective treatment for atherosclerosis, but is suffered from in-stent restenosis (ISR) caused by stent mechanical damage. Conventional ISR treatment such as drug-eluting stents (DES) is challenged by the low therapeutic efficacy and severe complications, unchangeable drug dosage for individuals, and limited drug penetration in the vascular tissue. We hypothesize that magnetic targeting and deep-penetrating delivery strategy by magnetic guidance and ultrasound stimulation might be an effective approach for ISR treatment. In the present study, antiproliferative drug (paclitaxel, PTX) loaded poly (lactide-co-glycolide) (PLGA) nanoparticles (PLGA-PTX) were embedded within the shells of the magnetic nanoparticle coated microbubbles (MMB-PLGA-PTX). Once being targeted to the stent under a magnetic field, a low intensity focused ultrasound (LIFU) is applied to activate stable microbubble oscillations, thereby triggering the release of PLGA-PTX. The generated mechanical force and microstreaming facilitate the penetration of released PLGA-PTX into the thickened vascular tissue and enhance their internalization by smooth muscle cells (SMCs), thereby reducing the clearance by blood flow. In an ex vivo experiment, magnetic targeting improved the accumulation amount of MMB-PLGA-PTX by 10 folds, while the LIFU facilitated the penetration of released PLGA-PTX into the tunica media region of the porcine coronary artery, resulting in prolonged retention time at the stented vascular tissue. With the combination effects, this strategy holds great promise in the precision delivery of antiproliferative drugs to the stented vascular tissue for ISR treatment.

Dynamically Programmable Magnetic Fields for Controlled Movement of Cells Loaded with Iron Oxide Nanoparticles

Cell-based therapies are becoming increasingly prominent in numerous medical contexts, particularly in regenerative medicine and the treatment of cancer. However, since the efficacy of the therapy is largely dependent on the concentration of therapeutic cells at the treatment area, a major challenge associated with cell-based therapies is the ability to move and localize therapeutic cells within the body. In this article, a technique based on dynamically programmable magnetic fields is successfully demonstrated to noninvasively aggregate therapeutic cells at a desired location. Various types of therapeutically relevant cells (neural stem cells, monocytes/macrophages, and chimeric antigen receptor T cells) are loaded with iron oxide nanoparticles and then focused at a particular site using externally controlled electromagnets. These experimental results serve as a readily scalable prototype for designing an apparatus that patients can wear to focus therapeutic cells at the anatomical sites needed for treatment.

Experimental Single-Platform Approach to Enhance the Functionalization of Magnetically Targetable Cells

Magnetic guidance shows promise as a strategy for improving the delivery and performance of cell therapeutics. However, clinical translation of magnetically guided cell therapy requires cell functionalization protocols that provide adequate magnetic properties in balance with unaltered cell viability and biological function. Existing methodologies for characterizing cells functionalized with magnetic nanoparticles (MNP) produce aggregate results, both distorted and unable to reflect variability in either magnetic or biological properties within a preparation. In the present study, we developed an inverted-plate assay allowing determination of these characteristics using a single-platform approach, and applied this method for a comparative analysis of two loading protocols providing highly uniform vs. uneven MNP distribution across cells. MNP uptake patterns remarkably different between the two protocols were first shown by fluorimetry carried out in a well-scan mode on endothelial cells (EC) loaded with BODIPY558/568-labeled MNP. Using the inverted-plate assay we next demonstrated that, in stark contrast to unevenly loaded cells, more than 50% of uniformly functionalized EC were captured within 5 min over a broad range of MNP doses. Furthermore, magnetically captured cells exhibited unaltered viability, substrate attachment, and proliferation rates. Conducted in parallel, magnetophoretic mobility studies corroborated the markedly superior guidance capacity of uniformly functionalized cells, confirming substantially faster cell capture kinetics on a clinically relevant time scale. Taken together, these results emphasize the importance of optimizing cell preparation protocols with regard to loading uniformity as key to efficient site-specific delivery, engraftment, and expansion of the functionalized cells, essential for both improving performance and facilitating translation of targeted cell therapeutics.

Characterization of Photoluminescent Polylactone-Based Nanoparticles for Their Applications in Cardiovascular Diseases

Cardiovascular diseases (CVD) affect a large number of the population across the globe and are the leading cause of death worldwide. Nanotechnology-based drug delivery has currently offered novel therapeutic options to treat these diseases, yet combination of both diagnostic and therapeutic abilities is further needed to understand factors and/or mechanisms that affect the treatment in order to design better therapies to challenge CVD. Biodegradable photoluminescent polylactones (BPLPLs) enable to bridge this gap as these materials exhibit a stable, long-term intrinsic fluorescence as well as offers excellent cytocompatibility and biodegradability properties. Herein, we formulated three different BPLPL based nanoparticles (NPs), including BPLP-co-poly (L-lactic acid) (BPLPL-PLLA), BPLP-co-poly (lactic-co-glycolic acid) copolymers with lactic acid and glycolic acid ratios of 75:25 (BPLPL-PLGA75:25) and 50:50 (BPLPL-PLGA50:50), and extensively evaluated their suitability as theranostic nanocarriers for CVD applications. All BPLPL based NPs were <160 nm in size and had photoluminescence characteristics and tunable release kinetics of encapsulated protein model depending on polylactones copolymerized with BPLP materials. Compared to BPLPL-PLLA NPs, BPLPL-PLGA NPs demonstrated excellent stability in various formulations including deionized water, serum, saline, and simulated body fluid over 2 days. In vitro cell studies with human umbilical vein derived endothelial cells showed dose-dependent accumulation of BPLPL-based NPs, and BPLPL-PLGA NPs presented superior compatibility with endothelial cells in terms of viability with minimal effects on cellular functions such as nitric oxide production. Furthermore, all BPLPL NPs displayed hemocompatibility with no effect on whole blood kinetic profiles, were non-hemolytic, and consisted of comparable platelet responses such as platelet adhesion and activation to those of PLGA, an FDA approved material. Overall, our results demonstrated that BPLPL-PLGA based NPs have better physical and biological properties than BPLPL-PLLA; hence they have potential to be utilized as functional nanocarriers for therapy and diagnosis of CVD.

From design to the clinic: practical guidelines for translating cardiovascular nanomedicine

Cardiovascular diseases (CVD) account for nearly half of all deaths in Europe and almost 30% of global deaths. Despite the improved clinical management, cardiovascular mortality is predicted to rise in the next decades due to the increasing impact of aging, obesity, and diabetes. The goal of emerging cardiovascular nanomedicine is to reduce the burden of CVD using nanoscale medical products and devices. However, the development of novel multicomponent nano-sized products poses multiple technical, ethical, and regulatory challenges, which often obstruct their road to successful approval and use in clinical practice. This review discusses the rational design of nanoparticles, including safety considerations and regulatory issues, and highlights the steps needed to achieve efficient clinical translation of promising nanomedicinal products for cardiovascular applications.

Magnetically Assisted Control of Stem Cells Applied in 2D, 3D and In Situ Models of Cell Migration

The success of cell therapy approaches is greatly dependent on the ability to precisely deliver and monitor transplanted stem cell grafts at treated sites. Iron oxide particles, traditionally used in vivo for magnetic resonance imaging (MRI), have been shown to also represent a safe and efficient in vitro labelling agent for mesenchymal stem cells (MSCs). Here, stem cells were labelled with magnetic particles, and their resulting response to magnetic forces was studied using 2D and 3D models. Labelled cells exhibited magnetic responsiveness, which promoted localised retention and patterned cell seeding when exposed to magnet arrangements in vitro. Directed migration was observed in 2D culture when adherent cells were exposed to a magnetic field, and also when cells were seeded into a 3D gel. Finally, a model of cell injection into the rodent leg was used to test the enhanced localised retention of labelled stem cells when applying magnetic forces, using whole body imaging to confirm the potential use of magnetic particles in strategies seeking to better control cell distribution for in vivo cell delivery.

Silica-coated magnetic nanoparticles labeled endothelial progenitor cells alleviate ischemic myocardial injury and improve long-term cardiac function with magnetic field guidance in rats with myocardial infarction

Low retention of endothelial progenitor cells (EPCs) in the infarct area has been suggested to be responsible for the poor clinical efficacy of EPC therapy for myocardial infarction (MI). This study aimed to evaluate whether magnetized EPCs guided through an external magnetic field could augment the aggregation of EPCs in an ischemia area, thereby enhancing therapeutic efficacy. EPCs from male rats were isolated and labeled with silica‐coated magnetic iron oxide nanoparticles to form magnetized EPCs. Then, the proliferation, migration, vascularization, and cytophenotypic markers of magnetized EPCs were analyzed. Afterward, the magnetized EPCs (1 × 10⁶) were transplanted into a female rat model of MI via the tail vein at 7 days after MI with or without the guidance of an external magnet above the infarct area. Cardiac function, myocardial fibrosis, and the apoptosis of cardiomyocytes were observed at 4 weeks after treatment. In addition, EPC retention and the angiogenesis of ischemic myocardium were evaluated. Labeling with magnetic nanoparticles exhibited minimal influence to the biological functions of EPCs. The transplantation of magnetized EPCs guided by an external magnet significantly improved the cardiac function, decreased infarction size, and reduced myocardial apoptosis in MI rats. Moreover, enhanced aggregations of magnetized EPCs in the infarcted border zone were observed in rats with external magnet‐guided transplantation, accompanied by the significantly increased density of microvessels and upregulated the expression of proangiogenic factors, when compared with non‐external‐magnet‐guided rats. The magnetic field‐guided transplantation of magnetized EPCs was associated with the enhanced aggregation of EPCs in the infarcted border zone, thereby improving the therapeutic efficacy of MI.

Drug delivery to atherosclerotic plaques using superparamagnetic iron oxide nanoparticles

INTRODUCTION

Magnetic drug targeting utilizes superparamagnetic iron oxide nanoparticles (SPIONs) to accumulate drugs in specified vasculature regions.

METHODS

We produced SPIONs conjugated with dexamethasone phosphate (SPION-DEXA). The efficacy of magnetic drug targeting was investigated in a rabbit model of atherosclerosis induced by balloon injury and high cholesterol diet.

RESULTS

In vitro, SPION-DEXA were well-tolerated by endothelial cells. SPION-DEXA were internalized by human peripheral blood mononuclear cells and induced CD163 expression comparable with the free drug. In vivo, magnetic targeting of SPIONs to abdominal aorta was confirmed by histology. Upon vascular injury followed by high-cholesterol diet, early administration of SPION-DEXA enhanced the inflammatory burden in the plaques. Increased macrophage content and larger intima- media thickness were observed in animals treated with SPION-DEXA compared with controls. In advanced atherosclerosis, no beneficial effect of local glucocorticoid therapy was detectable.

CONCLUSION

Magnetic drug targeting represents an efficient platform to deliver drugs to diseased arteries in vivo. However, targeting of vascular injury in the lipid-rich environment using dexamethasone-conjugated SPIONs may cause accelerated inflammatory response.

Synergistically regulated spontaneous calcium signaling is attributed to cartilaginous extracellular matrix metabolism

Ca²⁺ has been recognized as a key molecule for chondrocytes, however, the role and mechanism of spontaneous [Ca ²⁺ ] _i signaling in cartilaginous extracellular matrix (ECM) metabolism regulation are unclear. Here we found that spontaneous Ca ²⁺ signal of in-situ porcine chondrocytes was [Ca ²⁺ ] _o dependent, and mediated by [Ca ²⁺ ] _i store release. T-type voltage-dependent calcium channel (T-VDCC) mediated [Ca ²⁺ ] _o influx was associated with decreased cell viability and expression levels of ECM deposition genes. Further analysis revealed that chondrocytes expressed both inositol 1,4,5-trisphosphate receptor (InsP3R) and Orai isoforms. Inhibition of endoplasmic reticulum (ER) Ca ²⁺ release and store-operated calcium entry significantly abolished spontaneous [Ca ²⁺ ] _i signaling of in-situ chondrocytes. Moreover, blocking ER Ca ²⁺ release with InsP3R inhibitors significantly upregulated ECM degradation enzymes production, and was accompanied by decreased proteoglycan and collagen type II intensity. Taken together, our data provided evidence that spontaneous [Ca ²⁺ ] _i signaling of in-situ porcine chondrocytes was tightly regulated by [Ca ²⁺ ] _o influx, InsP3Rs mediated [Ca ²⁺ ] _i store release, and Orais mediated calcium release-activated calcium channels activation. Both T-VDCC mediated [Ca ²⁺ ] _o influx and InsP3Rs mediated ER Ca ²⁺ release were found crucial to cartilaginous ECM metabolism through distinct regulatory mechanisms.

Nanoparticle-Mediated Cell Capture Enables Rapid Endothelialization of a Novel Bare Metal Stent

Incomplete endothelialization of intracoronary stents has been associated with stent thrombosis and recurrent symptoms, whereas prolonged use of dual antiplatelet therapy increases bleeding-related adverse events. Facilitated endothelialization has the potential to improve clinical outcomes in patients who are unable to tolerate dual antiplatelet therapy. The objective of this study was to demonstrate the feasibility of magnetic cell capture to rapidly endothelialize intracoronary stents in a large animal model. A novel stent was developed from a magnetizable duplex stainless steel (2205 SS). Polylactic-co-glycolic acid and magnetite (Fe₃O₄) were used to synthesize biodegradable superparamagnetic iron oxide nanoparticles, and these were used to label autologous blood outgrowth endothelial cells. Magnetic 2205 SS and nonmagnetic 316L SS control stents were implanted in the coronary arteries of pigs (n = 11), followed by intracoronary delivery of magnetically labeled cells to 2205 SS stents. In this study, we show extensive endothelialization of magnetic 2205 SS stents (median 98.4% cell coverage) within 3 days, whereas the control 316L SS stents exhibited significantly less coverage (median 48.9% cell coverage, p < 0.0001). This demonstrates the ability of intracoronary delivery of magnetic nanoparticle labeled autologous endothelial cells to improve endothelialization of magnetized coronary stents within 3 days of implantation.

Smart multifunctional nanoagents for in situ monitoring of small molecules with a switchable affinity towards biomedical targets

The great diversity of nanomaterials provides ample opportunities for constructing effective agents for biomedical applications ranging from biosensing to drug delivery. Multifunctional nanoagents that combine several features in a single particle are of special interest due to capabilities that substantially exceed those of molecular drugs. An ideal theranostic agent should simultaneously be an advanced biosensor to identify a disease and report the diagnosis and a biomedical actuator to treat the disease. While many approaches were developed to load a nanoparticle with various drugs for actuation of the diseased cells (e.g., to kill them), the nanoparticle-based approaches for the localized biosensing with real-time reporting of the marker concentration severely lag behind. Here, we show a smart in situ nanoparticle-based biosensor/actuator system that dynamically and reversibly changes its structural and optical properties in response to a small molecule marker to allow real-time monitoring of the marker concentration and adjustment of the system ability to bind its biomedical target. Using the synergistic combination of signal readout based on the localized surface plasmon resonance and an original method of fabrication of smart ON/OFF-switchable nanoagents, we demonstrate reversible responsiveness of the system to a model small molecule marker (antibiotic chloramphenicol) in a wide concentration range. The proposed approach can be used for the development of advanced multifunctional nanoagents for theranostic applications.

Magnetic-targeting of polyethylenimine-wrapped iron oxide nanoparticle labeled chondrocytes in a rabbit articular cartilage defect model

Osteoarthritis (OA) is the most prevalent form of joint disease and lacks effective treatment. Cell-based therapy through intra-articular injection holds great potential for effective intervention at its early stage. Despite the promising outcomes, major barriers for successful clinical application such as lack of specific targeting of transplanted cells still remain. Here, novel polyethylenimine-wrapped iron oxide nanoparticles (PEI/IONs) were utilized as a magnetic agent, and the in vitro efficiency of PEI/ION labeling, and the influence on the chondrogenic properties of chondrocytes were evaluated; the in vivo feasibility of magnetic-targeting intra-articular injection with PEI/ION labeled autologous chondrocytes was investigated using a rabbit articular cartilage defect model. Our data showed that chondrocytes were conveniently labeled with PEI/IONs in a time- and dose-dependent manner, while the viability was unaffected. No significant decrease in collagen type-II synthesis of labeled chondrocytes was observed at low concentration. Macrographic and histology evaluation at 1 week post intra-articular injection revealed efficient cell delivery at chondral defect sites in the magnetic-targeting group. In addition, chondrocytes in the defect area presented a normal morphology, and the origin of cells within was confirmed by immunohistochemistry staining against BrdU and Prussian blue staining. The present study shows proof of concept experiments in magnetic-targeting of PEI/ION labeled chondrocytes for articular cartilage repair, which might provide new insight to improve current cartilage repair strategies.

Magnetic-targeting outcome in the knee joint of experimental rabbit model at 1 week post intra-articular injection.

Plasmon-actuated nano-assembled microshells

We present three-dimensional microshells formed by self-assembly of densely-packed 5 nm gold nanoparticles (AuNPs). Surface functionalization of the AuNPs with custom-designed mesogenic molecules drives the formation of a stable and rigid shell wall, and these unique structures allow encapsulation of cargo that can be contained, virtually leakage-free, over several months. Further, by leveraging the plasmonic response of AuNPs, we can rupture the microshells using optical excitation with ultralow power (<2 mW), controllably and rapidly releasing the encapsulated contents in less than 5 s. The optimal AuNP packing in the wall, moderated by the custom ligands and verified using small angle x-ray spectroscopy, allows us to calculate the heat released in this process, and to simulate the temperature increase originating from the photothermal heating, with great accuracy. Atypically, we find the local heating does not cause a rise of more than 50 °C, which addresses a major shortcoming in plasmon actuated cargo delivery systems. This combination of spectral selectivity, low power requirements, low heat production, and fast release times, along with the versatility in terms of identity of the enclosed cargo, makes these hierarchical microshells suitable for wide-ranging applications, including biological ones.

Optimizing endothelial cell functionalization for cell therapy of vascular proliferative disease using a direct contact co-culture system

Increased susceptibility to thrombosis, neoatherosclerosis, and restenosis due to incomplete regrowth of the protective endothelial layer remains a critical limitation of the interventional strategies currently used clinically to relieve atherosclerotic obstruction. Rapid recovery of endothelium holds promise for both preventing the thrombotic events and reducing post-angioplasty restenosis, providing the rationale for developing cell delivery strategies for accelerating arterial reendothelialization. The successful translation of experimental cell therapies into clinically viable treatment modalities for restoring vascular endothelium critically depends on identifying strategies for enhancing the functionality of endothelial cells (EC) derived from high cardiovascular risk patients, the target group for the majority of angioplasty procedures. Enhancing EC-associated nitric oxide (NO) synthesis by inducing overexpression of NO synthase (NOS) has shown promise as a way of increasing paracrine activity and restoring function of EC. In the present study, we developed a direct contact co-culture approach compatible with highly labile effectors, such as NO, and applied it for determining the effect of EC functionalization via NOS gene transfer on the growth of co-cultured arterial smooth muscle cells (A10 cell line) exhibiting the defining characteristics of neointimal cells. Bovine aortic endothelial cells magnetically transduced with inducible NOS-encoding adenovirus (Ad) formulated in zinc oleate-based magnetic nanoparticles (MNP[_iNOSAd]) strongly suppressed growth of proliferating A10 and attenuated the stimulatory effect of a potent mitogen, platelet-derived growth factor (PDGF-BB), whereas EC functionalization with free _iNOSAd or MNP formulated with a different isoform of the enzyme, endothelial NOS, was associated with lower levels of NO synthesis and less pronounced antiproliferative activity toward co-cultured A10 cells. These results show feasibility of applying magnetically facilitated gene transfer to potentiate therapeutically relevant effects of EC for targeted cell therapy of restenosis. The direct contact co-culture methodology provides a sensitive and reliable tool with potential utility for a variety of biomedical applications.

Nanomedicine in coronary artery disease

Nanomedicine is one of the most promising therapeutic modalities researchers are working on. It involves development of drugs and devices that work at the nanoscale (10-9m). Coronary artery disease (CAD) is responsible for more than a third of all deaths in age group >35 years. With such a huge burden of mortality, CAD is one of the diseases where nanomedicine is being employed for preventive and therapeutic interventions. Nanomedicine can effectively deliver focused drug payload at sites of local plaque formation. Non-invasive strategies include thwarting angiogenesis, intra-arterial thrombosis and local inflammation. Invasive strategies following percutaneous coronary intervention (PCI) include anti-restenosis and healing enhancement. However, before practical application becomes widespread, many challenges need to be dealt with. These include manufacturing at the nanoscale, direct nanomaterial cellular toxicity and visualization.

An efficient strategy to synthesize a multifunctional ferroferric oxide core@dye/SiO2@Au shell nanocomposite and its targeted tumor theranostics

Regular spheric magnetic ferroferric oxide nanoclusters have been developed and used for the targeted photothermal therapy of colorectal cancer cells after conjugation with SW620-specific phage fusion proteins.