Delivery of Lipid Micelles into Infarcted Myocardium Using a Lipid-Linked Matrix Metalloproteinase Targeting Peptide

Nanocarriers for gene delivery to the cardiovascular system

Cardiovascular diseases have posed a great threat to human health. Fortunately, gene therapy holds great promise in the fight against cardiovascular disease (CVD). In gene therapy, it is necessary to select the appropriate carriers to deliver the genes to the target cells of the target organs. There are usually two types of carriers, viral carriers and non-viral carriers. However, problems such as high immunogenicity, inflammatory response, and limited loading capacity have arisen with the use of viral carriers. Therefore, scholars turned their attention to non-viral carriers. Among them, nanocarriers are highly valued because of their easy modification, targeting, and low toxicity. Despite the many successes of gene therapy in the treatment of human diseases, it is worth noting that there are still many problems to be solved in the field of gene therapy for the treatment of cardiovascular diseases. In this review, we give a brief introduction to the common nanocarriers and several common cardiovascular diseases (arteriosclerosis, myocardial infarction, myocardial hypertrophy). On this basis, the application of gene delivery nanocarriers in the treatment of these diseases is introduced in detail.

Enhanced protection against hypoxia/reoxygenation-induced apoptosis in H9c2 cells by puerarin-loaded liposomes modified with matrix metalloproteinases-targeting peptide and triphenylphosphonium

Based on the inhibition of mitochondrial permeability transition pore (mPTP) opening, puerarin (PUE) has a good potential to reduce myocardial ischemia/reperfusion injury (MI/RI). However, the lack of targeting of free PUE makes it difficult to reach the mitochondria. In this paper, we constructed matrix metalloproteinase-targeting peptide (MMP-TP) and triphenylphosphonium (TPP) cation co-modified liposomes loaded with PUE (PUE@T/M-L) for mitochondria-targeted drug delivery. PUE@T/M-L had a favorable particle size of 144.9 ± 0.8 nm, an encapsulation efficiency of 78.9 ± 0.6%, and a sustained-release behavior. The results of cytofluorimetric experiments showed that MMP-TP and TPP double-modified liposomes (T/M-L) enhanced intracellular uptake, escaped lysosomal capture, and promoted drug targeting into mitochondria. In addition, PUE@T/M-L enhanced the viability of hypoxia-reoxygenation (H/R) injured H9c2 cells by inhibiting mPTP opening and reactive oxygen species (ROS) production, reducing Bax expression and increasing Bcl-2 expression. It was inferred that PUE@T/M-L delivered PUE into the mitochondria of H/R injured H9c2 cells, resulting in a significant increase in cellular potency. Based on the ability of MMP-TP to bind the elevated expression of matrix metalloproteinases (MMPs), T/M-L had excellent tropism for Lipopolysaccharide (LPS) -stimulated macrophages and can significantly reduce TNF-α and ROS levels, thus allowing both drug accumulation in ischemic cardiomyocytes and reducing inflammatory stimulation during MI/RI. Fluorescence imaging results of the targeting effect using a DiR probe also indicated that DiR@T/M-L could accumulate and retain in the ischemic myocardium. Taken together, these results demonstrated the promising application of PUE@T/M-L for mitochondria-targeted drug delivery to achieve maximum therapeutic efficacy of PUE.

ZipperCells Exhibit Enhanced Accumulation and Retention at the Site of Myocardial Infarction

There has been extensive interest in cellular therapies for the treatment of myocardial infarction, but bottlenecks concerning cellular accumulation and retention remain. Here, a novel system of in situ crosslinking mesenchymal stem cells (MSCs) for the formation of a living depot at the infarct site is reported. Bone marrow-derived mesenchymal stem cells that are surface decorated with heterodimerizing leucine zippers, termed ZipperCells, are engineered. When delivered intravenously in sequential doses, it is demonstrated that ZipperCells can migrate to the infarct site, crosslink, and show ≈500% enhanced accumulation and ≈600% improvement in prolonged retention at 10 days after injection compared to unmodified MSCs. This study introduces an advanced approach to creating noninvasive therapeutics depots using cellular crosslinking and provides the framework for future scaffold-free delivery methods for cardiac repair.

Nanocarrier-Based Targeted Therapies for Myocardial Infarction

Myocardial infarction is a major cause of morbidity and mortality worldwide. Due to poor inherent regeneration of the adult mammalian myocardium and challenges with effective drug delivery, there has been little progress in regenerative therapies. Nanocarriers, including liposomes, nanoparticles, and exosomes, offer many potential advantages for the therapy of myocardial infarction, including improved delivery, retention, and prolonged activity of therapeutics. However, there are many challenges that have prevented the widespread clinical use of these technologies. This review aims to summarize significant principles and developments in the field, with a focus on nanocarriers using ligand-based or cell mimicry-based targeting. Lastly, a discussion of limitations and potential future direction is provided.

Regenerative strategies for the consequences of myocardial infarction: Chronological indication and upcoming visions

Heart muscle injury and an elevated troponin level signify myocardial infarction (MI), which may result in defective and uncoordinated segments, reduced cardiac output, and ultimately, death. Physicians apply thrombolytic therapy, coronary artery bypass graft (CABG) surgery, or percutaneous coronary intervention (PCI) to recanalize and restore blood flow to the coronary arteries, albeit they were not convincingly able to solve the heart problems. Thus, researchers aim to introduce novel substitutional therapies for regenerating and functionalizing damaged cardiac tissue based on engineering concepts. Cell-based engineering approaches, utilizing biomaterials, gene, drug, growth factor delivery systems, and tissue engineering are the most leading studies in the field of heart regeneration. Also, understanding the primary cause of MI and thus selecting the most efficient treatment method can be enhanced by preparing microdevices so-called heart-on-a-chip. In this regard, microfluidic approaches can be used as diagnostic platforms or drug screening in cardiac disease treatment. Additionally, bioprinting technique with whole organ 3D printing of human heart with major vessels, cardiomyocytes and endothelial cells can be an ideal goal for cardiac tissue engineering and remarkable achievement in near future. Consequently, this review discusses the different aspects, advancements, and challenges of the mentioned methods with presenting the advantages and disadvantages, chronological indications, and application prospects of various novel therapeutic approaches.

Delivering more for less: nanosized, minimal-carrier and pharmacoactive drug delivery systems

Traditional nanoparticle carriers such as liposomes, micelles, and polymeric vehicles improve drug delivery by protecting, stabilizing, and increasing the circulatory half-life of the encapsulated drugs. However, traditional drug delivery systems frequently suffer from poor drug loading and require an excess of carrier materials. This carrier material excess poses an additional systemic burden through accumulation, if not degradable the need for metabolism, and potential toxicity. To address these shortcomings, minimal-carrier nanoparticle systems and pharmacoactive carrier materials have been developed. Both solutions provide drug delivery systems in which the majority of the nanoparticle is pharmacologically active. While minimal-carrier and pharmacoactive drug delivery systems can improve drug loading, they can also suffer from poor stability. Here, we review minimal-carrier and pharmacoactive delivery systems, discuss ongoing challenges and outline opportunities to translate minimal-carrier and pharmacoactive drug delivery systems into the clinic.

Nanoparticles: Promising Tools for the Treatment and Prevention of Myocardial Infarction

Despite several recent advances, current therapy and prevention strategies for myocardial infarction are far from satisfactory, owing to limitations in their applicability and treatment effects. Nanoparticles (NPs) enable the targeted and stable delivery of therapeutic compounds, enhance tissue engineering processes, and regulate the behaviour of transplants such as stem cells. Thus, NPs may be more effective than other mechanisms, and may minimize potential adverse effects. This review provides evidence for the view that function-oriented systems are more practical than traditional material-based systems; it also summarizes the latest advances in NP-based strategies for the treatment and prevention of myocardial infarction.

Lipid-Based Drug Delivery Systems in Regenerative Medicine

The most important goal of regenerative medicine is to repair, restore, and regenerate tissues and organs that have been damaged as a result of an injury, congenital defect or disease, as well as reversing the aging process of the body by utilizing its natural healing potential. Regenerative medicine utilizes products of cell therapy, as well as biomedical or tissue engineering, and is a huge field for development. In regenerative medicine, stem cells and growth factor are mainly used; thus, innovative drug delivery technologies are being studied for improved delivery. Drug delivery systems offer the protection of therapeutic proteins and peptides against proteolytic degradation where controlled delivery is achievable. Similarly, the delivery systems in combination with stem cells offer improvement of cell survival, differentiation, and engraftment. The present review summarizes the significance of biomaterials in tissue engineering and the importance of colloidal drug delivery systems in providing cells with a local environment that enables them to proliferate and differentiate efficiently, resulting in successful tissue regeneration.

Preparation of Nanocomposite Peptide and Its Inhibitory Effect on Myocardial Injury in Type-II Diabetic Rats

Complications of diabetes are the main cause of death and disability in diabetic patients. Cardiovascular diseases, especially diabetic cardiomyopathy, are one of the major complications and causes of death in type 2 diabetes. Peptide drugs have a better effect on improving cellular oxidative damage, reducing tissue inflammation and inhibiting intracellular calcium overload. The application of nanotechnology to the preparation of peptide drugs and myocardial injury can effectively improve myocardial stun, arrhythmia and myocardial systolic dysfunction in patients with type 2 diabetes. The use of nanotechnology to develop more stable Glucagon-like peptide 1 analogues or sustained-release preparations, improve patient compliance and improve the efficacy of diabetes, is of great significance for the prevention and treatment of diabetic cardiomyopathy. Therefore, this study used nanotechnology to prepare PLGA-GLP-1 nanoparticles using polyglycolic acid glycolic acid as a drug carrier, which achieved long-acting drug and its morphology by transmission electron microscopy. At the same time, this study explored the anti-cardiomyocyte injury and anti-myocardial damage of PLGA-GLP-1 nanocomposite peptide and its molecular mechanism by using animal models and cell models. Experimental studies have shown that PLGA-GLP-1 nanocomposite peptide has a protective effect on myocardial injury in diabetic rats. Its mechanism is related to the PLGA-GLP-1 nanocomposite peptide enhancing the body's antioxidant capacity, anti-cardiomyocyte apoptosis, and promoting mitochondrial DNA repair in cardiomyocytes.

Multiscale Live Imaging Using Förster Resonance Energy Transfer (FRET) for Evaluating the Biological Behavior of Nanoparticles as Drug Carriers

To develop targeted drug delivery systems using nanoparticles for treating various diseases, the evaluation of nanoparticle behavior in biological environments is necessary. In the present study, the biological behavior of polymeric nanoparticles was directly traced in living mice and cells. The dissociation of nanoparticles was detected by Förster resonance energy transfer (FRET) imaging. DiR and DiD were encapsulated in the nanoparticles for near-infrared FRET imaging, and they were traced using in vivo FRET imaging and intravital FRET imaging at the whole-body and tissue scales, respectively. In vivo FRET imaging revealed that the nanoparticles dissociated over time following intravenous administration. Intravital FRET imaging revealed that the nanoparticles dissociated in the liver and blood vessels following intravenous administration. DiI and DiO were encapsulated in nanoparticles for FRET imaging using confocal microscopy, and they were traced using in vitro FRET imaging in HepG2 cells. In vitro FRET imaging revealed that the nanoparticles dissociated and released fluorescent dyes that distributed in the cell membrane. Finally, live imaging was performed using FRET at the whole-body, tissue, and cellular scales. This method is suitable for obtaining information regarding the biological kinetic properties of nanoparticles and their use in targeted drug delivery.

MiR-101a loaded extracellular nanovesicles as bioactive carriers for cardiac repair

Myocardial infarction (MI) remains a major cause of mortality worldwide. Despite significant advances in MI treatment, many who survive the acute event are at high risk of chronic cardiac morbidity. Here we developed a cell-free therapeutic that capitalizes on the antifibrotic effects of micro(mi)RNA-101a and exploits the multi-faceted regenerative activity of mesenchymal stem cell (MSC) extracellular nanovesicles (eNVs). While the majority of MSC eNVs require local delivery via intramyocardial injection to exert therapeutic efficacy, we have developed MSC eNVs that can be administered in a minimally invasive manner, all while remaining therapeutically active. When loaded with miR-101a, MSC eNVs substantially decreased infarct size (9.2 ± 1.7% vs. 20.0 ± 6.5%) and increased ejection fraction (53.6 ± 7.6% vs. 40.3 ± 6.0%) and fractional shortening (23.6 ± 4.3% vs. 16.6 ± 3.0%) compared to control. These findings are significant as they represent an advance in the development of minimally invasive cardio-therapies.

Nanoparticle-Mediated Drug Delivery for Treatment of Ischemic Heart Disease

The regenerative capacity of an adult cardiac tissue is insufficient to repair the massive loss of heart tissue, particularly cardiomyocytes (CMs), following ischemia or other catastrophic myocardial injuries. The delivery methods of therapeutics agents, such as small molecules, growth factors, exosomes, cells, and engineered tissues have significantly advanced in medical science. Furthermore, with the controlled release characteristics, nanoparticle (NP) systems carrying drugs are promising in enhancing the cardioprotective potential of drugs in patients with cardiac ischemic events. NPs can provide sustained exposure precisely to the infarcted heart via direct intramyocardial injection or intravenous injection with active targets. In this review, we present the recent advances and challenges of different types of NPs loaded with agents for the repair of myocardial infarcted heart tissue.

Therapy for myocardial infarction: In vitro and in vivo evaluation of puerarin-prodrug and tanshinone co-loaded lipid nanoparticulate system

Myocardial infarction (MI) is the leading cause of morbidity and mortality worldwide. Nanoparticle systems carrying drugs have already been developed to treat MI. To improve the efficiency of tanshinone (TAN), and to achieve the synergistic effect of TAN and puerarin (PUE), PUE-prodrug and TAN co-loaded solid lipid nanoparticles (SLN) was structured and utilized for MI treatment in the present research. PUE-prodrug was synthesized by an esterification reaction. PUE-prodrug and TAN co-loaded SLN (PUEp/TAN-SLN) were prepared by a single emulsification followed by a solvent evaporation method. The physicochemical properties of SLN were characterized and the in vivo infarct therapy effects were evaluated in MI rats. PUE-prodrug and TAN contained SLN showed a size of 112.6 ± 3.1 nm. The SLN encapsulation reduced the cytotoxicity of drugs and was a safer system. PUEp-SLN exhibited a 1.7-fold increase in comparison to PUE-SLN (21.2 ± 2.1 versus 12.5 ± 1.5 mg/L), in the mean time a 3.4-fold increase compared with free PUE in heart drug concentration (21.2 ± 2.1 versus 6.3 ± 0.9 mg/L). In vivo infarct therapy efficiency of double drugs loaded PUEp/TAN-SLN (17 ± 1.9%) was significantly better than the single drug loaded PUEp-SLN (31 ± 1.6%) and TAN-SLN (40 ± 2.2%). PUE-prodrug contained, double drugs co-loaded SLN can be utilized as promising candidate delivery system for cardioprotective drugs in treatment of myocardial infarction.

Biologics and Cardiovascular Disease

The advent of biologic therapy has enhanced our ability to augment disease in an increasingly targeted manner. The use of biologics in cardiovascular disease (CVD) has steadily increased over the past several decades. Much of the early data on biologics and CVD were derived from their use in rheumatologic populations. Atherosclerosis, myocardial infarction, and heart failure have been closely linked to the inflammatory response. Accordingly, cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 have been targeted. Noninflammatory mediators, such as proprotein convertase subtilisin kexin type 9 (PCSK9), have been selected for therapeutic intervention as well. Furthermore, RNA interference (RNAi) therapy has emerged and may serve as another targeted therapeutic mechanism. Herein, we will review the history, obstacles, and advances in using biologic therapy for CVD.

Effect of CCR2 inhibitor-loaded lipid micelles on inflammatory cell migration and cardiac function after myocardial infarction

Background

After myocardial infarction (MI), inflammatory cells infiltrate the infarcted heart in response to secreted stimuli. Monocytes are recruited to the infarct via CCR2 chemokine receptors along a CCL2 concentration gradient. While infiltration of injured tissue with monocytes is an important component of the reparatory response, excessive or prolonged inflammation can adversely affect left ventricular remodeling and worsen clinical outcomes.

Materials and methods

Here, we developed poly(ethylene glycol) (PEG)-distearoylphos-phatidylethanolamine (PEG-DSPE) micelles loaded with a small molecule CCR2 antagonist to inhibit monocyte recruitment to the infarcted myocardium. To specifically target CCR2-expressing cells, PEG-DSPE micelles were further surface decorated with an anti-CCR2 antibody.

Results

Targeted PEG-DSPE micelles showed eight-fold greater binding to CCR2-expressing RAW 264.7 monocytes than plain, non-targeted PEG-DSPE micelles. In a mouse model of MI, CCR2-targeting PEG-DSPE micelles loaded with a CCR2 small molecule antagonist significantly decreased the number of Ly6C^high inflammatory cells to 3% of total compared with PBS-treated controls. Furthermore, CCR2-targeting PEG-DSPE micelles significantly reduced the infarct size based on epicardial and endocardial infarct arc lengths.

Conclusion

Both non-targeted and CCR2-targeting PEG-DSPE micelles showed a trend toward improving cardiac function. As such, PEG-DSPE micelles represent a promising cardiac therapeutic platform.

Modulating Macrophage Polarization through CCR2 Inhibition and Multivalent Engagement

Excessive or prolonged recruitment of inflammatory monocytes to damaged tissue can significantly worsen patient outcomes. Monocytes migrate to sites of tissue inflammation in response to high local concentrations of CCL2, a chemokine that binds to and signals through the CCR2 receptor. While the role of CCR2 in cellular migration is well studied, it is unclear how CCR2 inhibition affects macrophage polarization and if multivalency can increase downstream signaling effects. Using affinity selection with a phage library, we identified a novel single-chain variable fragment (scFv) (58C) that binds specifically and with high affinity to the N-terminal domain of CCR2 ( KD = 59.8 nM). The newly identified 58C-scFv bound to native CCR2 expressed on macrophages and MDA-MB-231 cells, inhibited migration, and induced a pro-inflammatory M1-phenotype in macrophages. The M1/M2 macrophage phenotype ratio for monomeric 58C-scFv was significantly increased over the negative control by 1.0 × 104-fold (iNOS/Arg-1), 5.1 × 104-fold (iNOS/Mgl2), 3.4 × 105-fold (IL-6/Arg-1), and 1.7 × 106-fold (IL-6/Mgl2). The multivalent display of 58C-scFv on liposomes further reduced migration of both cell types by 25-40% and enhanced M1 polarization by 200% over monomeric 58C-scFv. These studies demonstrate that CCR2 inhibition polarizes macrophages toward an inflammatory M1 phenotype, and that multivalent engagement of CCR2 increases the effects of 58C-scFv on polarization and migration. These data provide important insights into the role of multivalency in modulating binding, downstream signaling, and cellular fate.

Atrial natriuretic peptide modified oleate adenosine prodrug lipid nanocarriers for the treatment of myocardial infarction: in vitro and in vivo evaluation

Purpose

Myocardial infarction is a major cause of mortality and heart failure worldwide. One of the most effective methods of this injury is direct delivery of cardioprotective drugs to ischemia–reperfusion (IR) myocardium. The aim of the present study was to fabricate an adenosine (Ade) prodrug-based, atrial natriuretic peptide (ANP)-modified nanosystem for the treatment of myocardial infarction.

Materials and methods

Oleate adenosine prodrug (Ade-OA) and ANP-distearoylphosphatidylethanolamine-polyethylene glycol were synthesized. ANP-modified Ade-loaded lipid nanocarriers (ANP Ade/LNCs) were then self-assembled by using solvent evaporation method. In vitro drug release in the presence of plasma was evaluated. In vivo inhibition effect on infarct size, tissue distribution, and pharmacokinetics were investigated in rats with ischemic myocardium after intravenous injection.

Results

In vivo inhibition effect on infarct size, tissue distribution, and pharmacokinetics studies in acute myocardial infarction (AMI) rats showed that ANP Ade/LNCs exhibited better efficiency than non-modified Ade/LNCs and free Ade in all respects.

Conclusion

These results indicated that the ANP Ade/LNCs can be used as a promising system for the treatment of cardiovascular diseases.

Precision engineering of targeted nanocarriers

Since their introduction in 1980, the number of advanced targeted nanocarrier systems has grown considerably. Nanocarriers capable of targeting single receptors, multiple receptors, or multiple epitopes have all been used to enhance delivery efficiency and selectivity. Despite tremendous progress, preclinical studies and clinically translatable nanotechnology remain disconnected. The disconnect in targeting efficacy may stem from poorly-understood factors such as receptor clustering, spatial control of targeting ligands, ligand mobility, and ligand architecture. Further, the relationship between receptor distribution and ligand architecture remains elusive. Traditionally, targeted nanocarriers were engineered assuming a "static" target. However, it is becoming increasingly clear that receptor expression patterns change in response to external stimuli and disease progression. Here, we discuss how cutting-edge technologies will enable a better characterization of the spatiotemporal distribution of membrane receptors and their clustering. We further describe how this will enable the design of new nanocarriers that selectively target the site of disease. Ultimately, we explore how the precision engineering of targeted nanocarriers that adapt to receptor dynamics will have the potential to drive nanotechnology to the forefront of therapy and make targeted nanomedicine a clinical reality. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Biology-Inspired Nanomaterials > Lipid-Based Structures Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.

In Situ Imaging of Tissue Remodeling with Collagen Hybridizing Peptides

Collagen, the major structural component of nearly all mammalian tissues, undergoes extensive proteolytic remodeling during developmental states and a variety of life-threatening diseases such as cancer, myocardial infarction, and fibrosis. While degraded collagen could be an important marker of tissue damage, it is difficult to detect and target using conventional tools. Here, we show that a designed peptide (collagen hybridizing peptide: CHP), which specifically hybridizes to the degraded, unfolded collagen chains, can be used to image degraded collagen and inform tissue remodeling activity in various tissues: labeled with 5-carboxyfluorescein and biotin, CHPs enabled direct localization and quantification of collagen degradation in isolated tissues within pathologic states ranging from osteoarthritis and myocardial infarction to glomerulonephritis and pulmonary fibrosis, as well as in normal tissues during developmental programs associated with embryonic bone formation and skin aging. The results indicate the general correlation between the level of collagen remodeling and the amount of denatured collagen in tissue and show that the CHP probes can be used across species and collagen types, providing a versatile tool for not only pathology and developmental biology research but also histology-based disease diagnosis, staging, and therapeutic screening. This study lays the foundation for further testing CHP as a targeting moiety for theranostic delivery in various animal models.

Protective effects on myocardial infarction model: delivery of schisandrin B using matrix metalloproteinase-sensitive peptide-modified, PEGylated lipid nanoparticles

Purpose

Schisandrin B (Sch B) is clinically applied for the treatment of hepatitis and ischemic disease. However, its clinical efficacy is limited due to the poor solubility and low bioavailability. This study aimed to develop matrix metalloproteinase (MMP)-sensitive peptide-modified, polyethylene glycol (PEG)-modified (PEGylated) solid lipid nanoparticles (SLNs) for loading Sch B (MMP-Sch B SLNs), and to evaluate the therapeutic effect in the myocardial infarction model.

Methods

PEG lipid and MMP-targeting peptide conjugate were synthesized. MMP-Sch B SLNs were prepared by solvent displacement technique. The physicochemical properties and pharmacokinetics of SLNs were investigated. In vivo effects on infarct size was evaluated in rats.

Results

The successful synthesis of lipid-peptide conjugate was confirmed. MMP-Sch B SLNs had a particle size of 130 nm, a zeta potential of 18.3 mV, and a sustained-release behavior. Higher heart drug concentration and longer blood circulation times were achieved by Sch B loaded SLNs than the drug solution according to the pharmacokinetic and biodistribution results. The best therapeutic efficacy was exhibited by MMP-Sch B SLNs by reducing the infarction size to the greatest extent.

Conclusion

The modified SLNs may be a good choice for delivery of Sch B for the treatment of myocardial infarction.

Flow arrest intra-arterial delivery of small TAT-decorated and neutral micelles to gliomas

The cell-penetrating trans-activator of transcription (TAT) is a cationic peptide derived from human immunodeficiency virus-1. It has been used to facilitate macromolecule delivery to various cell types. This cationic peptide is capable of crossing the blood-brain barrier and therefore might be useful for enhancing the delivery of drugs that target brain tumors. Here we test the efficiency with which relatively small (20 nm) micelles can be delivered by an intra-arterial route specifically to gliomas. Utilizing the well-established method of flow-arrest intra-arterial injection we compared the degree of brain tumor deposition of cationic TAT-decorated micelles versus neutral micelles. Our in vivo and post-mortem analyses confirm glioma-specific deposition of both TAT-decorated and neutral micelles. Increased tumor deposition conferred by the positive charge on the TAT-decorated micelles was modest. Computational modeling suggested a decreased relevance of particle charge at the small sizes tested but not for larger particles. We conclude that continued optimization of micelles may represent a viable strategy for targeting brain tumors after intra-arterial injection. Particle size and charge are important to consider during the directed development of nanoparticles for intra-arterial delivery to brain tumors.

RGD modified and PEGylated lipid nanoparticles loaded with puerarin: Formulation, characterization and protective effects on acute myocardial ischemia model

CONTEXT

Puerarin has been widely used as a therapeutic agent for the treatment of cardiovascular diseases. However, its rapid elimination half-life in plasma and poor water solubility limits its clinical efficacy.

OBJECTIVE

RGD modified and PEGylated solid lipid nanoparticles loaded with puerarin (RGD/PEG-PUE-SLN) were developed to improve bioavailability of PUE, to prolong retention time in vivo and to enhance its protective effect on acute myocardial ischemia model.

METHODS

In the present study, RGD-PEG-DSPE was synthesized. RGD/PEG-PUE-SLN were prepared by the solvent evaporation method with some modifications. The physicochemical properties of NPs were characterized, the pharmacokinetics, biodistribution, pharmacodynamic behavior of RGD/PEG-PUE-SLN were evaluated in acute MI rats.

RESULTS

The mean diameter, zeta potential, entrapment efficiency and drug loading capacity for RGD/PEG-PUE-SLN were observed as 110.5nm, -26.2mV, 85.7% and 16.5% respectively. PUE from RGD/PEG-PUE-SLN exhibited sustained drug release with a burst release during the initial 12h and a followed sustained release. Pharmacokinetics results indicated that AUC increased from 52.93 (μg/mLh) for free PUE to 176.5 (μg/mLh) for RGD/PEG-PUE-SLN. Similarly, T_1/2 increased from 0.73h for free PUE to 2.62h for RGD/PEG-PUE-SLN. RGD/PEG-PUE-SLN exhibited higher drug concentration in the heart and plasma compared with other PUE formulations. It can be clearly seen that the infarct size of RGD/PEG-PUE-SLN is the lowest among all the formulation.

CONCLUSION

We conclude that RGD modified and PEGylated SLN are promising candidate delivery vehicles for cardioprotective drugs in treatment of myocardial infarction.

A DNA-directed covalent conjugation fluorescence probe for in vitro detection of functional matrix metalloproteinases

Matrix metalloproteinases (MMPs) have been considered to contribute to the progression of tumorigenesis and tumor invasion; MMP-9 in particular, has been regarded as a priority target in cancer treatment due to its massive up-regulation in malignant tissues and its ability to degrade type IV collagen. In this work, we employed a DNA-directed covalent conjugation method to design a fluorescence probe for in vitro detection of functional matrix metalloproteinases, by which a nitrilotriacetic acid (NTA)-modified DNA probe can combine with the Zn²⁺ in the active site of MMPs, and then a molecule beacon (MB) modified FITC and BHQ1 can open to bond with their complementary base, NTA-modified DNA. We can evaluate the amount of MMPs in the medium according to the fluorescence intensity. The detection procedure can be finished in 30 min with good selectivity, cheap reagents and easy preparation. All the results and the amount of secreted MMPs under three different cell culture conditions are in accordance with previous reports. Satisfactory results are obtained. Furthermore, owing to the importance of MMP-9, we designed an approach to achieve the desired selectivity and specificity of our work, using dual amplification for improving fluorescence intensity based on RCA to detect the amount of MMP-9.

Distribution of Systemically Administered Nanoparticles Reveals a Size-Dependent Effect Immediately following Cardiac Ischaemia-Reperfusion Injury

Nanoparticles represent an attractive option for systemic delivery of therapeutic compounds to the heart following myocardial infarction. However, it is well known that physicochemical properties of nanoparticles such as size, shape and surface modifications can vastly alter the distribution and uptake of injected nanoparticles. Therefore, we aimed to provide an examination of the rapid size-dependent uptake of fluorescent PEG-modified polystyrene nanoparticles administered immediately following cardiac ischaemia-reperfusion injury in mice. By assessing the biodistribution of nanoparticles with core diameters between 20 nm and 2 μm 30 minutes after their administration, we conclude that 20-200 nm diameter nanoparticles are optimal for passive targeting of the injured left ventricle.

Cationizable lipid micelles as vehicles for intraarterial glioma treatment

The relative abundance of anionic lipids on the surface of endothelia and on glioma cells suggests a workable strategy for selective drug delivery by utilizing cationic nanoparticles. Furthermore, the extracellular pH of gliomas is relatively acidic suggesting that tumor selectivity could be further enhanced if nanoparticles can be designed to cationize in such an environment. With these motivating hypotheses the objective of this study was to determine whether nanoparticulate (20 nm) micelles could be designed to improve their deposition within gliomas in an animal model. To test this, we performed intra-arterial injection of micelles labeled with an optically quantifiable dye. We observed significantly greater deposition (end-tissue concentration) of cationizable micelles as compared to non-ionizable micelles in the ipsilateral hemisphere of normal brains. More importantly, we noted enhanced deposition of cationizable as compared to non-ionizable micelles in glioma tissue as judged by semiquantitative fluorescence analysis. Micelles were generally able to penetrate to the core of the gliomas tested. Thus we conclude that cationizable micelles may be constructed as vehicles for facilitating glioma-selective delivery of compounds after intraarterial injection.

Enzyme-Responsive Nanoparticles for Targeted Accumulation and Prolonged Retention in Heart Tissue after Myocardial Infarction

A method for targeting to and retaining intravenously injected nanoparticles at the site of acute myocardial infarction in a rat model is described. Enzyme-responsive peptide-polymer amphiphiles are assembled as spherical micellar nanoparticles, and undergo a morphological transition from spherical-shaped, discrete materials to network-like assemblies when acted upon by matrix metalloproteinases (MMP-2 and MMP-9), which are up-regulated in heart tissue post-myocardial infarction.

Targeting delivery of Radix Ophiopogonis polysaccharide to ischemic/reperfused rat myocardium by long-circulating macromolecular and liposomal carriers

Drug delivery to ischemic myocardium is an enormous challenge. This work aimed to characterize cardiac delivery behaviors of mono-polyethylene glycosylated (PEGylated) conjugates and long-circulating liposomes (L-Lps) with Radix Ophiopogonis polysaccharide (ROP) as drug. The results showed that compared to native ROP, 32-, 52-, and 45-fold increases in blood half-life were achieved by 20-kDa PEG mono-modified ROP (P_20k-R), 40-kDa PEG mono-modified ROP (P_40k-R), and ROP-loaded L-Lp, respectively. With comparable blood pharmacokinetics, ROP-loaded L-Lp showed both significantly higher targeting efficacy and drug exposure in infarcted myocardium than P_40k-R. With regard to P_20k-R, both its targeting efficacy and its level in infarcted myocardium at 3 hours postdose were comparable to P_40k-R, but its level in blood and myocardium reduced obviously faster. As a whole, the results indicate that both loading in L-Lps and mono-PEGylation are effective in targeting drug to ischemic myocardium, but the former appears to induce stronger effects.