Rational Design of Lovastatin-Loaded Spherical Reconstituted High Density Lipoprotein for Efficient and Safe Anti-Atherosclerotic Therapy

Combination therapy and drug co-delivery systems for atherosclerosis

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of plaque within the arteries. Despite advances in therapeutic strategies including anti-inflammatory, antioxidant, and lipid metabolism modulation treatments over the past two decades, the treatment of atherosclerosis remains challenging, as arterial damage is the result of interconnected pathological factors. Therefore, current monotherapies often fail to address the complex nature of this disease, leading to insufficient therapeutic outcomes. This review addressed this paucity of effective treatment options by comprehensively exploring the potential for combination therapies and advanced drug co-delivery systems for the treatment of atherosclerosis. We investigated the pathological features of and risk factors for atherosclerosis, underscoring the importance of drug combination therapies for the treatment of atherosclerotic diseases. We discuss herein mathematical models for quantifying the efficacy of the combination therapies and provide a systematic summary of drug combinations for the treatment of atherosclerosis. We also provide a detailed review of the latest advances in nanoparticle-based drug co-delivery systems for the treatment of atherosclerosis, focusing on the design of carriers with high biocompatibility and efficacy. By exploring the possibilities and challenges inherent to this approach, we aim to highlight cutting-edge technologies that can foster the development of innovative strategies, optimize drug co-administration, improve treatment outcomes, and reduce the burden of atherosclerosis-related morbidity and mortality on the healthcare system.

Advances in nanocarriers for targeted drug delivery and controlled drug release

Nanocarrier-based drug delivery systems (nDDSs) present significant opportunities for improving disease treatment, offering advantages in drug encapsulation, solubilization, stability enhancement, and optimized pharmacokinetics and biodistribution. nDDSs, comprising lipid, polymeric, protein, and inorganic nanovehicles, can be guided by or respond to biological cues for precise disease treatment and management. Equipping nanocarriers with tissue/cell-targeted ligands enables effective navigation in complex environments, while functionalization with stimuli-responsive moieties facilitates site-specific controlled release. These strategies enhance drug delivery efficiency, augment therapeutic efficacy, and reduce side effects. This article reviews recent strategies and ongoing advancements in nDDSs for targeted drug delivery and controlled release, examining lesion-targeted nanomedicines through surface modification with small molecules, peptides, antibodies, carbohydrates, or cell membranes, and controlled-release nanocarriers responding to endogenous signals such as pH, redox conditions, enzymes, or external triggers like light, temperature, and magnetism. The article also discusses perspectives on future developments.

Recombinant high-density lipoprotein targeted delivery of celastrol to promote foam cells lipophagy against early atherosclerosis

INTRODUCTION

Atherosclerosis serving as the main underlying factor of cardiovascular disease (CVD) remains the primary cause of mortality and morbidity globally, while the deposition of massive cholesterol in macrophage-derived foam cells exerts pivotal roles in the occurrence and progression of atherosclerosis. Celastrol (CEL) is a bioactive ingredient owning potent capability to modulate lipid metabolism, whereas the poor bioavailability and potential toxicity limit its clinical application.

OBJECTIVES

This study aims to design a CEL-loaded recombinant high-density lipoprotein (rHDL) delivery platform for active targeting, which may effectively promote lipid degradation in foam cells and reversely transport excessive cholesterol to the liver for metabolism in time.

METHODS

The rHDL loaded with CEL (CEL-rHDL) was prepared by the thin film dispersion method. Then the anti-atherosclerotic efficacy and targeted delivery to foam cells of atherosclerotic lesions were verified both in vitro and in vivo. RNA-sequence was applied to reveal the potential mechanism against early atherosclerosis, which was further validated through several molecular biology experiments.

RESULTS

The prepared CEL-rHDL increased the targeting efficiency to foam cells of atherosclerotic lesions, mitigated its off-target toxicity, and improved anti-atherosclerotic efficacy. Importantly, CEL-rHDL decreased lipid storage in foam cells by triggering lipophagy via the activation of Ca2+/CaMKKβ/AMPK/mTOR signaling pathway and reverse cholesterol transport (RCT).

CONCLUSION

A combination of hypolipidemic chemo-intervention with rHDL participated specific and reverse delivery may offer a promising strategy for biocompatible treatment of early atherosclerosis.

A Patent Analysis on Nano Drug Delivery Systems

BACKGROUND

A nano drug delivery system is an effective tool for drug delivery and controlled release, which is used for a variety of medical applications. In recent decades, nano drug delivery systems have been significantly developed with the emergence of new nanomaterials and nanotechnologies.

OBJECTIVE

This article aimed to provide insight into the technological development of nano drug delivery systems through patent analysis.

METHODS

3708 patent documents were used for patent analysis after retrieval from the Incopat patent database.

RESULTS

The number of patents on nano drug delivery systems has shown a rapid growth trend in the past two decades. At present, China and the United States have obvious contributions to the number of patents. According to the patent data, the nanomaterials used in nano drug delivery system are mainly inorganic nanomaterials, lipid-based nanomaterials, and macromolecules. In recent years, the highly cited patents (≥14) for nano drug delivery systems mainly involve lipid-based nanomaterials, indicating that their technology is mature and widely used. The inorganic nanomaterials in drug delivery have received increasing attention, and the number of related patents has increased significantly after 2016. The number of highly cited patents in the United States is 250, which is much higher than in other countries.

CONCLUSION

Even after decades of development, nano drug delivery systems remain a hot topic for researchers. The significant increase in patents since 2016 can be attributed to the large number of new patents from China. However, according to the proportion of highly cited patents in total, China's patented technologies in nano drug delivery systems are not advanced enough compared to developed countries, including the United States, Canada, Germany, and France. In the future, research on emerging nanomaterials for nano drug delivery systems, such as inorganic nanomaterials, may focus on developing new materials and optimising their properties. The lipid-based and polymer- based nanomaterials can be continuously improved for the development of new nanomedicines.

Research progress on the therapeutic effects of nanoparticles loaded with drugs against atherosclerosis

Presently, there are many drugs for the treatment of atherosclerosis (AS), among which lipid-lowering, anti-inflammatory, and antiproliferative drugs have been the most studied. These drugs have been shown to have inhibitory effects on the development of AS. Nanoparticles are suitable for AS treatment research due to their fine-tunable and modifiable properties. Compared with drug monotherapy, experimental results have proven that the effects of nanoparticle-encapsulated drugs are significantly enhanced. In addition to nanoparticles containing a single drug, there have been many studies on collaborative drug treatment, collaborative physical treatment (ultrasound, near-infrared lasers, and external magnetic field), and the integration of diagnosis and treatment. This review provides an introduction to the therapeutic effects of nanoparticles loaded with drugs to treat AS and summarizes their advantages, including increased targeting ability, sustained drug release, improved bioavailability, reduced toxicity, and inhibition of plaque and vascular stenosis.

Advancements in Macrophage-Targeted Drug Delivery for Effective Disease Management

Macrophages play a crucial role in tissue homeostasis and the innate immune system. They perform essential functions such as presenting antigens, regulating cytokines, and responding to inflammation. However, in diseases like cancer, cardiovascular disorders, and autoimmune conditions, macrophages undergo aberrant polarization, which disrupts tissue regulation and impairs their normal behavior. To address these challenges, there has been growing interest in developing customized targeted drug delivery systems specifically designed for macrophage-related functions in different anatomical locations. Nanomedicine, utilizing nanoscale drug systems, offers numerous advantages including improved stability, enhanced pharmacokinetics, controlled release kinetics, and precise temporal drug delivery. These advantages hold significant promise in achieving heightened therapeutic efficacy, specificity, and reduced side effects in drug delivery and treatment approaches. This review aims to explore the roles of macrophages in major diseases and present an overview of current strategies employed in targeted drug delivery to macrophages. Additionally, this article critically evaluates the design of macrophage-targeted delivery systems, highlighting limitations and discussing prospects in this rapidly evolving field. By assessing the strengths and weaknesses of existing approaches, we can identify areas for improvement and refinement in macrophage-targeted drug delivery.

Biomimetic nanomedicines for precise atherosclerosis theranostics

Atherosclerosis (AS) is a leading cause of the life-threatening cardiovascular disease (CVD), creating an urgent need for efficient, biocompatible therapeutics for diagnosis and treatment. Biomimetic nanomedicines (bNMs) are moving closer to fulfilling this need, pushing back the frontier of nano-based drug delivery systems design. This review seeks to outline how these nanomedicines (NMs) might work to diagnose and treat atherosclerosis, to trace the trajectory of their development to date and in the coming years, and to provide a foundation for further discussion about atherosclerotic theranostics.

ROS-Responsive Prodrug Micelle Co-Delivery System for Synergistic Antiatherosclerotic Therapy

Tanshinone IIA (TS-IIA) and salvianic acid A (SAA) are the main pharmacological active constituents of Danshen, which exhibit potent effects on atherosclerosis. A combination of TS-IIA and SAA might exert a synergistic antiatherosclerotic effect. However, the opposite solubility profiles of TS-IIA and SAA might lead to difficulty in achieving a synergistic combined effect of the two active components. Therefore, in this work, we fabricated a ROS-responsive prodrug micelle for the codelivery of TS-IIA and SAA (TS-IIA-PM) by self-assembling amphiphilic block copolymer PEG5000-SAA/PLA10000-APBA. The amphiphilic polymer was characterized by 1H NMR, FTIR, and alizarin red S competition tests. The ROS responsiveness of TS-IIA-PM was evidenced by time-course monitoring of particle size and morphology changes and drug release behavior in the presence of 1 mM H2O2. We found TS-IIA-PM was stable according to its critical micelle concentration and the unchanged particle sizes in 10% FBS for 7 days. The results of in vitro and in vivo tests revealed that TS-IIA-PM was safe and biocompatible. Furthermore, it was observed that TS-IIA and prodrug micelle could produce synergistic antiatherosclerotic effect based on the results of the antioxidant study, which was further confirmed by a series of pharmocodynamics studies, such as in vitro DiI-oxLDL uptake study, oil red O staining, cholesterol efflux study, inflammatory cytokine analysis, in vivo CD68 immunostaining, and lipid disposition staining studies. Collectively, TS-IIA-PM holds great potential for the safe and efficient codelivery of TS-IIA and SAA for synergistic antiatherosclerosis.

Polyketides from the fungus Pochonia chlamydosporia and their bioactivities

Three previously undescribed griseofulvin derivatives, namely pochonichlamydins A-C, one small polyketide, namely pochonichlamydin D, together with nine known compounds, have been isolated from cultures of the fungus Pochonia chlamydosporia. Their structures with absolute configurations were elucidated on the basis of extensive spectrometric methods and single-crystal X-ray diffraction. Dechlorogriseofulvin and griseofulvin exhibited inhibitory activities against Candida albicans at the concentration of 100 μM, with inhibition rates of 69.1% and 56.3%, respectively. Meanwhile, pochonichlamydin C showed mild cytotoxicity against the human cancer MCF-7 cell line with an IC₅₀ value of 33.1 μM.

Diterpenoids inhibit ox-LDL-induced foam cell formation in RAW264.7 cells by promoting ABCA1 mediated cholesterol efflux

Introduction: Atherosclerosis is the main cause of many cardiovascular diseases and contributes to morbidity and mortality worldwide. The formation of macrophage-derived foam cells plays a critical role in the early stage of atherosclerosis pathogenesis. Diterpenoids found in the flowers of Callicarpa rubella Lindl., a traditional Chinese medicine, have been reported to have anti-inflammatory activity. However, little is known about the effects of these diterpenoids on macrophage foam cell formation. Methods: A macrophage-derived foam cell formation model was established by treating RAW264.7 cells with oxidized low-density lipoprotein (ox-LDL) for 24 h. Oil red O staining were used to detect the intracellular lipids. The cholesterol efflux capacity was assayed by labeling cells with 22-NBD-cholesterol. Western blots and real-time PCRs were performed to quantify protein and mRNA expressions. Results: Two diterpenoid molecules, 14α-hydroxyisopimaric acid (C069002) and isopimaric acid (C069004), extracted from the flowers of Callicarpa rubella Lindl., significantly attenuated ox-LDL-induced foam cell formation in RAW264.7 macrophages. Further investigation showed that these two diterpenoids could promote cholesterol efflux from RAW264.7 macrophages to apolipoprotein A-I or high-density lipoproteins, which was associated with upregulated expression of ATP-binding cassette A1/G1 (ABCA1/G1), liver X receptor-α (LXRα), and peroxisome proliferator-activated receptor-γ (PPARγ). Unexpectedly, the diterpenoids C069002 and C069004 failed to enhance the mRNA transcription of the ABCG1 gene in macrophage-derived foam cells induced by ox-LDL. To evaluate the effects of diterpenoids on macrophage foam cell formation and determine the underlying mechanism, two drugs (lovastatin and rosiglitazone) were used as positive controls. Although both drugs could reduce macrophage foam cell formation and promote cholesterol efflux, they each had distinctive abilities to modulate the expression of cholesterol efflux-related genes. In contrast to lovastatin, rosiglitazone showed a similar influence on the expression of cholesterol efflux-related genes (including ABCA1, LXRα, and PPARγ) as the diterpenoids regardless of the presence or absence of ox-LDL, implying a similar mechanism by which they may exert atheroprotective effects. Conclusion: Our research indicates that diterpenoids effectively inhibit ox-LDL-induced macrophage foam cell formation by promoting cholesterol efflux from macrophages via the PPARγ-LXRα-ABCA1 pathway. Further investigation of diterpenoids as potential drugs for the treatment of atherosclerosis is warranted.

Targeting the Microenvironment of Vulnerable Atherosclerotic Plaques: An Emerging Diagnosis and Therapy Strategy for Atherosclerosis

Atherosclerosis is considered one of the primary causes of cardiovascular diseases (CVDs). Unpredictable rupture of the vulnerable atherosclerotic plaques triggers adverse cardiovascular events such as acute myocardial syndrome and even sudden cardiac death. Therefore, assessing the vulnerability of atherosclerotic plaques and early intervention are of significance in reducing CVD mortality. Nanomedicine possesses tremendous advantages in achieving the integration of the diagnosis and therapy of atherosclerotic plaques because of its magnetic, optical, thermal, and catalytic properties. Based on the pathological characteristics of vulnerable plaques, stimuli-responsive nanoplatforms and surface-functionalized nanoagents are designed and have drawn great attention for accomplishing the precise imaging and treatment of vulnerable atherosclerotic plaques due to their superior properties, such as high bioavailability, lesion-targeting specificity, on-demand cargo release, and low off-target damage. Here, the characteristics of vulnerable plaques are generalized, and some targeted strategies for boosting the accuracy of plaque vulnerability evaluation by imaging and the efficacy of plaque stabilization therapy (including antioxidant therapy, macrophage depletion therapy, regulation of lipid metabolism therapy, anti-inflammation therapy, etc.) are systematically summarized. In addition, existing challenges and prospects in this field are discussed, and it is believed to provide new thinking for the diagnosis and treatment of CVDs in the near future.

A green and highly efficient method to deliver hydrophilic polyphenols of Salvia miltiorrhiza and Carthamus tinctorius for enhanced anti-atherosclerotic effect via metal-phenolic network

Salvia miltiorrhiza and Carthamus tinctorius are traditional Chinese medicines that have been widely used for the treatment of cardiovascular disease. Salvianic acid A (SAA), salvianic acid B (SAB), protocatechuic aldehyde (PCA) and hydroxysafflor yellow A (HSYA) are the major hydrophilic polyphenols of Salvia miltiorrhiza and Carthamus tinctorius, all of which have been documented as active compounds for the prevention and treatment of atherosclerosis (AS). However, high aqueous solubility, low permeability and poor stability properties of the four hydrophilic polyphenols might influence their bioavailability and thus hinder their clinical potential. In this work, we introduced a green and highly efficient method for the efficient delivery of the four hydrophilic components via metal-phenolic network. The four coordination polymers of SAA, SAB, PCA and HSYA were successfully fabricated, and confirmed by UV-vis, FTIR, XPS, ICP-MS and dynamic light scattering analysis. We found all of them displayed potent antioxidant activity, good biocompatibility and stability. Impressively, the four coordination polymers showed remarkably enhanced anti-atherosclerotic effect compared with free drugs. Collectively, metal-phenolic network-based coordination polymer might show great potential for safe and efficient delivery of the hydrophilic polyphenols of Salvia miltiorrhiza and Carthamus tinctorius for anti-atherosclerotic therapy.

A ROS and shear stress dual-sensitive bionic system with cross-linked dendrimers for atherosclerosis therapy

Atherosclerosis is an important pathological basis for cardiovascular disease. Thus, the treatment of atherosclerosis can effectively improve the prognosis and reduce the mortality of cardiovascular diseases. In this study, we developed simvastatin acid (SA)-loaded cross-linked dendrimer nanoparticles (SA PAM) that were adsorbed to the surface of red blood cells (RBCs) to obtain SA PAM@RBCs, a ROS and shear stress dual response drug delivery system for the treatment of atherosclerosis. SA PAM could continuously release SA in an H₂O₂-triggered manner, and effectively eliminate excessive H₂O₂ in LPS-stimulated RAW 264.7 cells, achieving the target of using the special microenvironment at the plaque to release drugs. At the same time, the shear sensitive model also proved that only 12.4% of SA PAM detached from the RBCs under low shear stress (20 dynes per cm²), while 61.3% SA PAM desorbed from the RBCs under a high shear stress (100 dynes per cm²) stimulus, revealing that SA PAM could desorb in response to the shear stress stimulus. Both the FeCl₃ model and ApoE^-/- model showed that SA PAM@RBCs had better therapeutic effects than free SA, and with excellent safety in vivo. Therefore, a biomimetic drug delivery system with dual sensitivity to ROS and shear stress would become a promising strategy for the treatment of atherosclerosis.

Advanced and Innovative Nano-Systems for Anticancer Targeted Drug Delivery

The encapsulation of therapeutic agents into nano-based drug delivery system for cancer treatment has received considerable attention in recent years. Advancements in nanotechnology provide an opportunity for efficient delivery of anticancer drugs. The unique properties of nanoparticles not only allow cancer-specific drug delivery by inherent passive targeting phenomena and adopting active targeting strategies, but also improve the pharmacokinetics and bioavailability of the loaded drugs, leading to enhanced therapeutic efficacy and safety compared to conventional treatment modalities. Small molecule drugs are the most widely used anticancer agents at present, while biological macromolecules, such as therapeutic antibodies, peptides and genes, have gained increasing attention. Therefore, this review focuses on the recent achievements of novel nano-encapsulation in targeted drug delivery. A comprehensive introduction of intelligent delivery strategies based on various nanocarriers to encapsulate small molecule chemotherapeutic drugs and biological macromolecule drugs in cancer treatment will also be highlighted.

(r)HDL in theranostics: how do we apply HDL's biology for precision medicine in atherosclerosis management?

High-density lipoproteins (HDL) are key players in cholesterol metabolism homeostasis since they are responsible for transporting excess cholesterol from peripheral tissues to the liver. Imbalance in this process, due to either excessive accumulation or impaired clearance, results in net cholesterol accumulation and increases the risk of cardiovascular disease (CVD). Therefore, significant effort has been focused on the development of therapeutic tools capable of either directly or indirectly enhancing HDL-guided reverse cholesterol transport (RCT). More recently, in light of the emergence of precision nanomedicine, there has been renewed research interest in attempting to take advantage of the development of advanced recombinant HDL (rHDL) for both therapeutic and diagnostic purposes. In this review, we provide an update on the different approaches that have been developed using rHDL, focusing on the rHDL production methodology and rHDL applications in theranostics. We also compile a series of examples highlighting potential future perspectives in the field.

Targeting macrophages using nanoparticles: a potential therapeutic strategy for atherosclerosis

Atherosclerosis is one of the leading causes of vascular diseases, with high morbidity and mortality worldwide. Macrophages play a critical role in the development and local inflammatory responses of atherosclerosis, contributing to plaque rupture and thrombosis. Considering their central roles, macrophages have gained considerable attention as a therapeutic target to attenuate atherosclerotic progression and stabilize existing plaques. Nanoparticle-based delivery systems further provide possibilities to selectively and effectively deliver therapeutic agents into intraplaque macrophages. Although challenges are numerous and clinical application is still distant, the design and development of macrophage-targeting nanoparticles will generate new knowledge and experiences to improve therapeutic outcomes and minimize toxicity. Hence, the review aims to discuss various strategies for macrophage modulation and the development and evaluation of macrophage targeting nanomedicines for anti-atherosclerosis.

Shuttle/sink model composed of β-cyclodextrin and simvastatin-loaded discoidal reconstituted high-density lipoprotein for enhanced cholesterol efflux and drug uptake in macrophage/foam cells

Targeting drug delivery to macrophage/foam cells is challenged owing to the poor cell permeability and fluidity resulting from the massive accumulation of intracellular cholesterol in atherosclerosis (AS). Discoidal reconstituted high-density lipoprotein (d-rHDL) has been well regarded as a potential drug delivery system for AS by virtue of its plaque-targeting and cholesterol removal abilities, while the latter is compromised by the high activation energy of cholesterol efflux. It is reported that a low concentration of β-cyclodextrin (β-CD) can function as a cholesterol shuttle to promote cholesterol efflux from cells to the extracellular acceptors (cholesterol sink, such as HDL particles), but it is still unknown whether the combination of β-CD with a drug-loaded d-rHDL can function as a shuttle/sink model to promote the remodeling and drug release of the d-rHDL carrier after accelerating the cholesterol efflux. Furthermore, it is interesting to investigate whether enhanced cholesterol efflux can improve the cellular drug uptake by restoring the permeability and fluidity of the cell membrane. Here, simvastatin-loaded d-rHDL (ST-d-rHDL) was combined with different concentrations of β-CD. Compared with ST-d-rHDL alone, the cholesterol removal ability of ST-d-rHDL combined with 0.5 mM of β-CD increased by 31-fold after incubation for 6 h and the cumulative drug release of ST-d-rHDL increased by two-fold during the initial 1 h in an acellular mimetic system. In macrophage/foam cells, 0.5 mM of β-CD showed superior promoting effects in the cholesterol removal ability and remodeling of ST-d-rHDL compared to 0.1 mM of β-CD. The high concentration of β-CD at 2 mM displayed a low efficiency for accelerating cholesterol efflux, which might function as a cholesterol sink rather than a cholesterol shuttle. Moreover, the permeability and fluidity of the cell membrane were improved by combining 0.5 mM of β-CD with ST-d-rHDL, which exhibited an enhanced cellular drug uptake and inhibiting effect on the intracellular lipid deposition and secretion of inflammatory cytokine. Collectively, combination of β-CD and ST-d-rHDL as a shuttle/sink model could enhance cholesterol efflux and drug uptake to suppress inflammation in macrophage/foam cells.

Endocytic recycling as cellular trafficking fate of simvastatin-loaded discoidal reconstituted high-density lipoprotein to coordinate cholesterol efflux and drug influx

Reconstituted high-density lipoproteins (rHDLs) hold promise as nanocarriers for atherosclerosis-targeted delivery, with biofunctions typified by mediating cholesterol efflux. The paradox is how rHDL offloads the delivered drugs into atherosclerotic foam cells, while simultaneously transferring cholesterol out of cells. Herein, simvastatin-loaded discoidal rHDL (ST-d-rHDL), constructed based on established paradigms, was employed to investigate its basic trafficking mechanism in foam cells. As proved, ST-d-rHDL was resecreted via lysosomal and Golgi apparatus-recycling endosome-mediated pathways following clathrin-mediated endocytosis. And the resecretion ratio reached 60% within 6-h chase with excessive ST-d-rHDLs. During the rHDL resecretion, 39% of cellular cholesterol efflux was detected, accompanied by 85% of the encapsulated cargo released intracellularly. Furthermore, the recycling rate was demonstrated to be promoted by smaller rHDL size and higher cellular lipid contents. Collectively, endocytic recycling confers the synergism in ST-d-rHDL to coordinate cholesterol efflux and intracellular drug release, providing new insights into design of biofunctional rHDL.

Lipoprotein-based drug delivery

Lipoproteins (LPs) are circulating heterogeneous nanoparticles produced by the liver and intestines. LPs play a major role in the transport of dietary and endogenous lipids to target cells through cell membrane receptors or cell surface-bound lipoprotein lipase. The stability, biocompatibility, and selective transport of LPs make them promising delivery vehicles for various therapeutic and imaging agents. This review discusses isolation, manufacturing, and drug loading techniques used for LP-based drug delivery, as well as recent applications for diagnosis and treatment of cancer, atherosclerosis, and other life-threatening diseases.

Drug delivery to macrophages: A review of targeting drugs and drug carriers to macrophages for inflammatory diseases

Macrophages play a key role in defending against foreign pathogens, healing wounds, and regulating tissue homeostasis. Driving this versatility is their phenotypic plasticity, which enables macrophages to respond to subtle cues in tightly coordinated ways. However, when this coordination is disrupted, macrophages can aid the progression of numerous diseases, including cancer, cardiovascular disease, and autoimmune disease. The central link between these disorders is aberrant macrophage polarization, which misguides their functional programs, secretory products, and regulation of the surrounding tissue microenvironment. As a result of their important and deterministic roles in both health and disease, macrophages have gained considerable attention as targets for drug delivery. Here, we discuss the role of macrophages in the initiation and progression of various inflammatory diseases, summarize the leading drugs used to regulate macrophages, and review drug delivery systems designed to target macrophages. We emphasize strategies that are approved for clinical use or are poised for clinical investigation. Finally, we provide a prospectus of the future of macrophage-targeted drug delivery systems.

Dynamically enhancing plaque targeting via a positive feedback loop using multifunctional biomimetic nanoparticles for plaque regression

A paradigm shift from preventive therapy to aggressive plaque regression and eventual eradication is much needed to address increasing atherosclerotic burden and risks. Herein, we report a biologically inspired dual-targeting multifunctional recombinant high-density lipoprotein (rHDL)-mimicking core-shell nanoplatform. It is composed of an ATP-responsive ternary polyplexes core for SR-A siRNA and catalase complexation, and a phosphatidylserine-modified rHDL-based outer shell for SR-BI and CD36 targeting, in which pitavastatin is packaged. We demonstrated that dual-targeting biomimetic core-shell nanoparticles dynamically enhanced macrophage CD36 targeting in the plaques by establishing a positive feedback loop via the reciprocal regulation of SR-A and CD36. Positive feedback-enabled accumulation of the nanoparticles in the atherosclerotic plaques increased by 3.3-fold following 4-week repeated administration. A 3-month dosage regimen of the dual-targeting rHDL-mimicking nanoparticles reduced plaque areas by 65.8%, and decreased macrophages by 57.3%. Collectively, this work shows that dynamically enhancing plaque targeting via a positive feedback loop and dual action of cholesterol deposition inhibition and efflux enhancement accomplished with our novel multifunctional biomimetic nanoparticles provides a new way to regress plaques and alleviate the atherosclerotic burden.