On the uncertainty of the correlation between nanoparticle avidity and biodistribution

The specific delivery of a drug to its site of action also known as targeted drug delivery is a topic in the field of pharmaceutics studied for decades. One approach extensively investigated in this context is the use ligand functionalized nanoparticles. These particles are modified to carry receptor specific ligands, enabling them to accumulate at a desired target site. However, while this concept initially appears straightforward to implement, in-depth research has revealed several challenges hindering target site specific particle accumulation - some of which remain unresolved to this day. One of these challenges consists in the still incomplete understanding of how nanoparticles interact with biological systems. This knowledge gap significantly compromises the predictability of particle distribution in biological systems, which is critical for therapeutic efficacy. One of the most crucial steps in delivery is the attachment of nanoparticles to cells at the target site. This attachment occurs via the formation of multiple ligand receptor bonds. A process also referred to as multivalent interaction. While multivalency has been described extensively for individual molecules and macromolecules respectively, little is known on the multivalent binding of nanoparticles to cells. Here, we will specifically introduce the concept of avidity as a measure for favorable particle membrane interactions. Also, an overview about nanoparticle and membrane properties affecting avidity will be given. Thereafter, we provide a thorough review on literature investigating the correlation between nanoparticle avidity and success in targeted particle delivery. In particular, we want to analyze the currently uncertain data on the existence and nature of the correlation between particle avidity and biodistribution.

Targeted Molecular Therapeutics for Pulmonary Diseases: Addressing the Need for Precise Drug Delivery

Respiratory diseases are a major concern in public health, impacting a large population worldwide. Despite the availability of therapies that alleviate symptoms, selectively addressing the critical points of pathopathways remains a major challenge. Innovative formulations designed for reaching these targets within the airways, enhanced selectivity, and prolonged therapeutic effects offer promising solutions. To provide insights into the specific medical requirements of chronic respiratory diseases, the initial focus of this chapter is directed on lung physiology, emphasizing the significance of lung barriers. Current treatments involving small molecules and the potential of gene therapy are also discussed. Additionally, we will explore targeting approaches, with a particular emphasis on nanoparticles, comparing targeted and non-targeted formulations for pulmonary administration. Finally, the potential of inhaled sphingolipids in the context of respiratory diseases is briefly discussed, highlighting their promising prospects in the field.

Fucoidan-mediated targeted delivery of dasatinib-loaded nanoparticles amplifies apoptosis and endows cytotoxic potential in triple-negative breast cancer

Dasatinib (DST) is a tyrosine kinase inhibitor with established antiproliferative activity in Triple-negative breast cancer. Conventional treatment strategies with DST have several pitfalls related to the development of resistance, lower cellular uptake and unwanted adverse effects. To address these issues, we have prepared P-selectin-targeted nanoparticles of DST with fucoidan (FUC) as a ligand. Poly lactide-co-glycolide nanoparticles of DST were coated with chitosan (CH) and FUC via electrostatic interaction (DST-CH-FUC-NPs). The mean particle size of 210.36 ± 0.66 nm and a polydispersity index of 0.234 ± 0.013 was observed for DST-CH-FUC-NPs. TEM and FTIR analysis proved CH coating followed by an FUC layer on nanoparticles. DST-CH-FUC-NPs showed a sustained release profile up to 120 h and 2.9 times less hemolytic potential than free DST suspension. DST-CH-FUC-NPs demonstrated 8-fold higher cytotoxicity compared to free DST in MDA-MB-231 cells. Rhodamine-CH-FUC- NPs showed 19 times and 3 times higher cellular uptake than free Rhodamine and Rhodamine-CH-NPs, respectively. DST-CH-FUC-NPs also displayed increased ROS production and mitochondrial membrane potential damage. Apoptosis study revealed a 7.5-fold higher apoptosis index for DST-CH-FUC-NPs than free DST. Subsequently, the DST-CH-FUC-NPs showed increased inhibition of cell migration, where approximately 5 % wound closure was noted. Further, DST-CH-FUC-NPs confirmed higher disruption of lysosomal membrane integrity, which is well correlated with apoptosis results. In addition, developed NPs were nontoxic on MCF 10 A normal cells. All these findings suggest that fabricated DST-CH-FUC-NPs are promising biocompatible carriers for tumor-targeted delivery and enhanced efficacy of dasatinib.

Nanotechnology in leukemia: diagnosis, efficient-targeted drug delivery, and clinical trials

Leukemia is a group of malignant disorders which affect the blood and blood-forming tissues in the bone marrow, lymphatic system, and spleen. Many types of leukemia exist; thus, their diagnosis and treatment are somewhat complicated. The use of conventional strategies for treatment such as chemotherapy and radiotherapy may develop many side effects and toxicity. Hence, modern research is concerned with the development of specific nano-formulations for targeted delivery of anti-leukemic drugs avoiding toxic effects on normal cells. Nanostructures can be applied not only in treatment but also in diagnosis. In this article, types of leukemia, its causes, diagnosis as well as conventional treatment of leukemia shall be reviewed. Then, the use of nanoparticles in diagnosis of leukemia and synthesis of nanocarriers for efficient delivery of anti-leukemia drugs being investigated in in vivo and clinical studies. Therefore, it may contribute to the discovery of novel and emerging nanoparticles for targeted treatment of leukemia with less side effects and toxicities.

Can targeted nanoparticles distinguish cancer metastasis from inflammation?

Targeting ligands have been widely used to increase the intratumoral accumulation of nanoparticles and their uptake by cancer cells. However, these ligands aim at targets that are often also upregulated in inflamed tissues. Here, we assessed the ability of targeted nanoparticles to distinguish metastatic cancer from sites of inflammation. Using common targeting ligands and a 60-nm liposome as a representative nanoparticle, we generated three targeted nanoparticle (NP) variants that targeted either fibronectin, folate, or αvβ3 integrin, whose deposition was compared against that of standard untargeted NP. Using fluorescently labeled NPs and ex vivo fluorescence imaging of organs, we assessed the deposition of the NPs into the lungs of mice modeling 4 different biological landscapes, including healthy lungs, aggressive metastasis in lungs, dormant/latent metastasis in lungs, and lungs with general pulmonary inflammation. Among the four NP variants, fibronectin-targeting NP and untargeted NP exhibited the highest deposition in lungs harboring aggressive metastases. However, the deposition of all targeted NP variants in lungs with metastasis was similar to the deposition in lungs with inflammation. Only the untargeted NP was able to exhibit higher deposition in metastasis than inflammation. Moreover, flow-cytometry analysis showed all NP variants accumulated predominantly in immune cells rather than cancer cells. For example, the number of NP+ macrophages and dendritic cells was 16-fold greater than NP+ cancer cells in the case of fibronectin-targeting NP. Overall, targeted NPs were unable to distinguish cancer metastasis from general inflammation, which may have clinical implications to the nanoparticle-mediated delivery of cancer drugs.

Impact of interferon-γ on the target cell tropism of nanoparticles

Interferon-γ (IFN-γ) is well known to reduce the infectivity of viral pathogens by altering their tissue tropism. This effect is induced by upregulation of cholesterol 25-hydroxylase (CH25H). Given the similarity of viral pathogens and ligand-functionalized nanoparticles in the underlying strategy of receptor-mediated cell recognition, it appears conceivable that IFN-γ exceeds similar effects on nanoparticles. Concretely, IFN-γ-induced activation of CH25H could decrease nanoparticle avidity for target cells via depletion of clathrin-coated pits. We hypothesized that this effect would cause deterioration of target-cell specific accumulation of nanoparticles. To prove our hypothesis, we investigated the cell tropism of angiotensin II functionalized nanoparticles (NPLys-Ang II) in a co-culture system of angiotensin II subtype 1 receptor (AT1R) positive rat mesangial target cells (rMCs) and AT1R-negative HeLa off-target cells. In the presence of IFN-γ we observed an up to 5-fold loss of target cell preference for NPLys-Ang II. Thus, our in vitro results suggest a strong influence of IFN-γ on nanoparticle distribution, which is relevant in the context of nanotherapeutic approaches to cancer treatment, as IFN-γ is strongly expressed in tumors. For the target cell tropism of viruses, our results provide a conclusive hypothesis for the underlying mechanism behind non-directed viral distribution in the presence of IFN-γ.

Functionalized zein nanoparticles targeting neonatal Fc receptor to enhance lung absorption of peptides

Peptides have a distinguished therapeutic potential for several chronic conditions, and more than 80 peptides exist in the global market. However, most of these marketed peptide drugs are currently delivered intravenously or subcutaneously due to their fast degradation and limited absorption through non-invasive routes. The pulmonary route is favored as a non-invasive route. Neonatal Fc receptor (FcRn) is expressed in adult human lungs and has a role in enhancing the pulmonary absorption of monoclonal antibodies. In this work, we developed and characterized candidate protein delivery systems for the pulmonary administration of peptides. The prepared bare and loaded zein nanoparticles (ZNPs), targeted, physically, and covalently PEGylated ZNPs showed hydrodynamic diameters between 137 and 155 nm and a narrow distribution index. Insulin, which was used as a protein model, showed an association efficiency of 72%, while the FcRn-targeted peptide conjugation efficiency was approximately 68%. The physically adsorbed poloxamer 407 on insulin-loaded ZNPs showed slower and controlled insulin release. The in vitro cell culture model consists of the NCI-H441 epithelial cell line, which confirmed its expression of the targeted receptor, FcRn. The safety of ZNPs was verified after incubation with both cell lines of the in vitro pulmonary model, namely NCI-H441 and HPMEC-ST1.6R, for 24 h. It was observed that targeted ZNPs enhanced insulin permeability by showing a higher apparent permeation coefficient than non-targeted ZNPs. Overall, both targeted PEGylated ZNPs showed to be suitable peptide carriers and adequately fit the demands of delivery systems designed for pulmonary administration.

Oral Targeted Delivery of Imatinib by pH Responsive Copolymer Modulates Liver Fibrosis in the Mice Model

Liver fibrosis is a significant cause of morbidity and mortality without approved treatment. The therapeutic effects of Imatinib as a tyrosine kinase inhibitor on reversing liver fibrosis have already been shown. However, considering the conventional route of Imatinib administration, the amount of drug to be used is very high, and its side effects are raised. Therefore, we designed an efficient pH-sensitive polymer for the targeted delivery of Imatinib in treating a carbon tetrachloride (CCl4)-induced liver fibrosis. This nanotherapeutic system-based Vitamin A (VA)-modified Imatinib-loaded poly (lactic-co-glycolic acid)/Eudragit S100 (PLGA-ES100) has been successfully fabricated by adapting the solvent evaporation technique. The applying ES100 on the surface of our desired nanoparticles (NPs) protects drug release at the acidic pH of the gastric and guarantees the effective release of Imatinib at a higher pH of the intestine. Besides, VA-functionalized NPs could be an ideal efficient drug delivery system due to the high capacity of hepatic cell lines to absorb VA. For induction of liver fibrosis, CCL4 was intraperitoneally (IP) injected twice a week for six weeks in BALB/c mice. Oral administration of VA-targeted PLGA-ES100 NPs loaded with Rhodamine Red™ by live animal imaging showed a preferential accumulation of the selected NPs in the liver of mice. Besides, administrating targeted Imatinib-loaded NPs significantly decreased serum levels of ALT, and AST, and also reduced the expression of extracellular matrix components, including collagen I, collagen III, and α-SMA, considerably. Interestingly, histopathological evaluation of liver tissues through H&E and Masson's trichrome staining showed that oral administration of targeted Imatinib-loaded NPs reduced hepatic damage by enhancing hepatic structure condition. Also, the Sirius-red staining indicated a reduction in collagen expression during treatment with targeted NP containing Imatinib. The immunohistochemistry result on liver tissue shows a significant decrease in the expression of α-SMA in groups treated with targeted NP. In the meantime, administration of a very scarce dose of Imatinib via targeted NP caused a substantial decline in the expression of fibrosis marker genes (Collagen I, Collagen III, α-SMA). Our results confirmed that novel pH-sensitive VA-targeted PLGA-ES100 NPs could efficiently deliver Imatinib to the liver cells. Loading Imatinib in the PLGA-ES100/VA might overcome many challenges facing conventional Imatinib therapy, including gastrointestinal pH, the low concentration at the target region, and toxicity.

Targeted drug delivery to the brain endothelium dominates over passive delivery via vascular leak in experimental intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is one of the most common causes of fatal stroke, yet has no specific drug therapies. Many attempts at passive intravenous (IV) delivery in ICH have failed to deliver drugs to the salvageable area around the hemorrhage. The passive delivery method assumes vascular leak through the ruptured blood-brain barrier will allow drug accumulation in the brain. Here we tested this assumption using intrastriatal injection of collagenase, a well-established experimental model of ICH. Fitting with hematoma expansion in clinical ICH, we showed that collagenase-induced blood leak drops significantly by 4 h after ICH onset and is gone by 24 h. We observed passive-leak brain accumulation also declines rapidly over ∼4 h for 3 model IV therapeutics (non-targeted IgG; a protein therapeutic; PEGylated nanoparticles). We compared these passive leak results with targeted brain delivery by IV monoclonal antibodies (mAbs) that actively bind vascular endothelium (anti-VCAM, anti-PECAM, anti-ICAM). Even at early time points after ICH induction, where there is high vascular leak, brain accumulation via passive leak is dwarfed by brain accumulation of endothelial-targeted agents: At 4 h after injury, anti-PECAM mAbs accumulate at 8-fold higher levels in the brain vs. non-immune IgG; anti-VCAM nanoparticles (NPs) deliver a protein therapeutic (superoxide dismutase, SOD) at 4.5-fold higher levels than the carrier-free therapeutic at 24 h after injury. These data suggest that relying on passive vascular leak provides inefficient delivery of therapeutics even at early time points after ICH, and that a better strategy might be targeted delivery to the brain endothelium, which serves as the gateway for the immune attack on the peri-hemorrhage inflamed brain region.

CD44-targeted nanoparticles with GSH-responsive activity as powerful therapeutic agents against breast cancer

DOX-loaded nanoparticles able to actively target CD44-receptors and respond to redox stimuli were proposed as non-conventional chemotherapeutic strategy in breast cancer. A covalent conjugate of human serum albumin and hyaluronic acid was prepared and assembled by a GSH-mediated desolvation in disulfide-crosslinked solid nanoparticles with mean diameter of 120 nm ± 3.4. The effective internalization of nanoparticles in cancer cells via CD44-receptors, together with the more efficient intracellular release, resulted in a significant increase of drug efficacy, with IC₅₀ reduced from 0.9959 and 2.516 μg mL^-1 to 0.4014 and 0.3094 μg mL^-1 for MCF-7 and MDA-MB-231, respectively. Conversely, no enhancement in drug toxicity was recorded in healthy MCF-10A cells. The efficacy of the proposed formulation was further investigated in the different biological steps involved in metastasis process, paving the way for further in vivo experiments.

Mechanisms of chemotherapeutic resistance and the application of targeted nanoparticles for enhanced chemotherapy in colorectal cancer

Colorectal cancer is considered one of the major malignancies that threaten the lives and health of people around the world. Patients with CRC are prone to post-operative local recurrence or metastasis, and some patients are advanced at the time of diagnosis and have no chance for complete surgical resection. These factors make chemotherapy an indispensable and important tool in treating CRC. However, the complex composition of the tumor microenvironment and the interaction of cellular and interstitial components constitute a tumor tissue with high cell density, dense extracellular matrix, and high osmotic pressure, inevitably preventing chemotherapeutic drugs from entering and acting on tumor cells. As a result, a novel drug carrier system with targeted nanoparticles has been applied to tumor therapy. It can change the physicochemical properties of drugs, facilitate the crossing of drug molecules through physiological and pathological tissue barriers, and increase the local concentration of nanomedicines at lesion sites. In addition to improving drug efficacy, targeted nanoparticles also reduce side effects, enabling safer and more effective disease diagnosis and treatment and improving bioavailability. In this review, we discuss the mechanisms by which infiltrating cells and other stromal components of the tumor microenvironment comprise barriers to chemotherapy in colorectal cancer. The research and application of targeted nanoparticles in CRC treatment are also classified.

Targeted delivery of protein arginine deiminase-4 inhibitors to limit arterial intimal NETosis and preserve endothelial integrity

AIMS

Recent evidence suggests that 'vulnerable plaques', which have received intense attention as underlying mechanism of acute coronary syndromes over the decades, actually rarely rupture and cause clinical events. Superficial plaque erosion has emerged as a growing cause of residual thrombotic complications of atherosclerosis in an era of increased preventive measures including lipid lowering, antihypertensive therapy, and smoking cessation. The mechanisms of plaque erosion remain poorly understood, and we currently lack validated effective diagnostics or therapeutics for superficial erosion. Eroded plaques have a rich extracellular matrix, an intact fibrous cap, sparse lipid, and few mononuclear cells, but do harbour neutrophil extracellular traps (NETs). We recently reported that NETs amplify and propagate the endothelial damage at the site of arterial lesions that recapitulate superficial erosion in mice. We showed that genetic loss of protein arginine deiminase (PAD)-4 function inhibited NETosis and preserved endothelial integrity. The current study used systemic administration of targeted nanoparticles to deliver an agent that limits NETs formation to probe mechanisms of and demonstrate a novel therapeutic approach to plaque erosion that limits endothelial damage.

METHODS AND RESULTS

We developed Collagen IV-targeted nanoparticles (Col IV NP) to deliver PAD4 inhibitors selectively to regions of endothelial cell sloughing and collagen IV-rich basement membrane exposure. We assessed the binding capability of the targeting ligand in vitro and evaluated Col IV NP targeting to areas of denuded endothelium in vivo in a mouse preparation that recapitulates features of superficial erosion. Delivery of the PAD4 inhibitor GSK484 reduced NET accumulation at sites of intimal injury and preserved endothelial continuity.

CONCLUSIONS

NPs directed to Col IV show selective uptake and delivery of their payload to experimentally eroded regions, illustrating their translational potential. Our results further support the role of PAD4 and NETs in superficial erosion.

Clofazimine functionalized polymeric nanoparticles for brain delivery in the tuberculosis treatment

Central nervous system tuberculosis (CNS-TB) is the most severe form of the disease especially due to the inability of therapeutics to cross the blood-brain barrier (BBB). Clofazimine (CFZ) stands out for presenting high in vitro activity against multi-drug resistant strains of Mycobacterium tuberculosis, however, CFZ physicochemical and pharmacokinetics properties limit drug penetration into the CNS and, consequently, its clinical use. The aim of this work was to develop polymeric nanoparticles (NPs) of poly(lactic-co-glycolic acid) (PLGA) and polyethylene glycol (PEG) loaded with CFZ and functionalized with a transferrin receptor (TfR)-binding peptide, aiming brain drug delivery for CNS-TB treatment by the intravenous route. The poor water solubility and high lipophilicity of CFZ was overcome through its entrapment into PLGA-PEG NPs manufactured by both conventional and microfluidic techniques using the nanoprecipitation principle. In vitro studies in brain endothelial hCMEC/D3 cells demonstrated that CFZ incorporation into the NPs was advantageous to reduce drug cytotoxicity. The TfR-binding peptide-functionalized NPs showed superior cell interaction and higher CFZ permeability across hCMEC/D3 cell monolayers compared to the non-functionalized NP control, thus indicating the efficacy of the functionalization strategy on providing CFZ transport through the BBB in vitro. The functionalized NPs demonstrate suitability for CFZ biological administration, suggested with low plasma protein binding, off-target biodistribution and precise delivery of CFZ towards the brain parenchyma.

Recent advances in nano delivery systems for blood-brain barrier (BBB) penetration and targeting of brain tumors

Gliomas constitute about 80% of brain tumors and have a meager two-year survival rate. The treatment options available are very few because of poor prognosis and a lack of targeted nanodelivery systems that can cross the blood-brain barrier (BBB) and the blood-tumor barrier. This short review attempts to clarify the challenges for delivery systems designed to cross the BBB, and provides a brief description of the different types of targeted nanodelivery system that have shown potential for success in delivering drugs to the brain. Further, this review describes the most recent studies that have developed nanoparticles for brain delivery in the past five years. We also provide an insight into the most recent clinical trials designed to assess the efficacy of these nanodelivery systems for glioma.

Emerging insights into mitochondria-specific targeting and drug delivering strategies: Recent milestones and therapeutic implications

Mitochondria are a major intracellular organelle for drug targeting due to its functional roles in cellular metabolism and cell signaling for proliferation and cell death. Mitochondria-targeted treatment strategy could be promising to improve the therapeutic efficacy of cancer while minimizing the adverse side effects. Over the last decades, several studies have explored and focused on mitochondrial functions, which has led to the emergence of mitochondria-specific therapies. Molecules in the mitochondria are considered to be prime targets, and a wide range of molecular strategies have been designed for targeting mitochondria compared with that of the cytosol. In this review, we focused on the molecular mechanisms of mitochondria-specific ligand targeting and selective drug action strategies for targeting mitochondria, including those premised on mitochondrial targeting of signal peptides (MTS), cell-penetrating peptides (CPPs), and use of lipophilic cations. Furthermore, most research has concentrated on specific conjugation of ligands to therapeutic molecules to enhance their effectiveness. There are several variations for the ideal design and development for mitochondrial-targeted drugs, such as selecting a suitable ligand and linker targets. However, some challenges related to drug solubility and selectivity could be resolved using the nanocarrier system. Nanoparticles yield excellent advantages for targeting and transmitting therapeutic drugs, and they offer elegant platforms for mitochondria-specific drug delivery. We explain many of the advanced and proven strategies for multifunctional mitochondria-specific targets, which should contribute to achieving better anticancer therapies in a promising future.

Targeting nanoparticles for diagnosis and therapy of bone tumors: Opportunities and challenges

A variety of targeted nanoparticles were developed for the diagnosis and therapy of orthotopic and metastatic bone tumors during the past decade. This critical review will focus on principles and methods in the design of these bone-targeted nanoparticles. Ligands including bisphosphonates, aspartic acid-rich peptides and synthetic polymers were grafted on nanoparticles such as PLGA nanoparticles, liposomes, dendrimers and inorganic nanoparticles for bone targeting. Besides, other ligands such as monoclonal antibodies, peptides and aptamers targeting biomarkers on tumor/bone cells were identified for targeted diagnosis and therapy. Examples of targeted nanoparticles for the early detection of bone metastatic tumors and the ablation of cancer via chemotherapy, photothermal therapy, gene therapy and combination therapy will be intensively reviewed. The development of multifunctional nanoparticles to break down the "vicious" cycle between tumor cell proliferation and bone resorption, and the challenges and perspectives in this area will be discussed.

uMUC1-Targeting Magnetic Resonance Imaging of Therapeutic Response in an Orthotropic Mouse Model of Colon Cancer

PURPOSE

Noninvasive assessment of chemotherapeutic response in colon cancer would tremendously aid in therapeutic intervention of cancer patients and improve outcomes. The aim of the study was to evaluate the feasibility of a noninvasive assessment of chemotherapeutic response by magnetic resonance imaging utilizing underglycosylated mucin 1 (uMUC1) tumor antigen as a biomarker of therapeutic response in a colon cancer mouse model.

PROCEDURES

The study was performed by applying molecular imaging approach based on targeting uMUC1 with specific dual-modality imaging probe (MN-EPPT). The probe consisted of dextran-coated iron oxide nanoparticles conjugated to the near infrared fluorescent dye Cy5.5 and to a uMUC1-specific peptide (EPPT) and was used for magnetic resonance imaging (MRI) and fluorescence optical imaging. An orthotopic murine model of colon cancer expressing human uMUC1 peptide (MC38 MUC1) was created along with the control model devoid of the antigen (MC38 neo). Animals received chemotherapy with 5-fluorouracil (5-FU) followed by MN-EPPT-enhanced MR and optical imaging.

RESULTS

In vivo imaging of animals with uMUC1 expressing tumors after 5-FU therapy showed that the average deltaT2 was reduced by 7.27 ms (p = 0.045) compared with animals in control groups indicating lower accumulation of MN-EPPT caused by uMUC1 downregulation. In vivo optical imaging, biodistribution, and fluorescence microscopy confirmed the MRI findings. Interestingly, we found that the group of animals that did not respond to chemotherapy ("progressive disease" per RECIST) showed higher accumulation of MN-EPPT compared to the group of responders ("stable disease") consistent with proliferating tumor cells and increased antigen availability.

CONCLUSIONS

We believe that in application to over 50 % of human cancers expressing uMUC1, our results could provide insight into overall assessment of therapeutic response based on its expression as defined by non-invasive MN-EPPT-enhanced MRI.

Inhibition of the adenosinergic pathway: the indispensable part of oncological therapy in the future

In recent years, immunotherapy has produced many unexpected breakthroughs in oncological therapy; however, it still has many deficiencies. For example, the number of patients who are unresponsive to anti-programmed death-ligand 1 (PD-L1), anti-cytotoxic T-like antigen-4 (CTLA4), and anti-programmed death-1 (PD1) therapies cannot be ignored, and the search for an undiscovered immunosuppressive pathway is imminent. Five decades ago, researchers found that activation of the adenosinergic pathway was negatively correlated with prognosis in many cancers. This review describes the entire process of the adenosinergic pathway in the tumor microenvironment and the mechanism of immunosuppression, which promotes tumor metastasis and drug resistance. Additionally, the review explores factors that regulate this pathway, including signaling factors secreted by the tumor microenvironment and certain anti-tumor drugs. Additionally, the combination of adenosinergic pathway inhibitors with chemotherapy, checkpoint blockade therapy, and immune cell-based therapy is summarized. Finally, certain issues regarding treatment via inhibition of this pathway and the use of targeted nanoparticles to reduce adverse reactions in patients are put forward in this review. Graphical Abstract The inhibitors of adenosinergic pathway loaded nanoparticles enter tumor tissue through EPR effect, and inhibit adenosinergic pathway to enhance or restore the effect of immune checkpoint blockade therapy, chemotherapies and immune cell-based therapy. Note: EPR means enhanced penetration and retention, × means blockade.

Surface modification of pH-sensitive honokiol nanoparticles based on dopamine coating for targeted therapy of breast cancer

At present, there is a higher demand for the efficacy of nanoparticle drugs. It is hoped that more drugs will reach the tumor site and that the drug will be less harmful to other normal cells of the body before reaching the tumor site. Most target research for nanomedicine can achieve better positioning through complex processes, such as synthesis. To overcome these difficulties, such as the complexity of the preparation method and lack of good targeting, we used simple polydopamine (PDA) as a pH-sensitive targeting anchor for nanoparticles (NPs). We successfully conjugated folic acid (FA) to the surface of honokiol (HK) nanoparticles coated with PDA using a typical surface modifier. After preparation into HK-PDA-FA-NPs, we characterized the particle size, potential and transmission electron microscope (TEM). The targeted nanoparticles (HK-PDA-FA-NPs) can be stably present in various physiological media and exhibit pH sensitivity during drug release in vitro. HK-PDA-FA-NPs have better targeting ability to 4T1 cells than HK-NPs. Targeted nanoparticles have a tumor inhibition rate of greater than 80% in vivo, which is significantly higher than ordinary HK-NPs. This experiment shows that surface modification of HK-NPs coated with PDA is a promising preparation method for targeted therapy.

Molecular Recognition Force Spectroscopy for Probing Cell Targeted Nanoparticles In Vitro

In the development and design of cell targeted nanoparticle-based systems the density of targeting moieties plays a fundamental role in allowing maximal cell-specific interaction. Here, we describe the use of molecular recognition force spectroscopy as a valuable tool for the characterization and optimization of targeted nanoparticles toward attaining cell-specific interaction. By tailoring the density of targeting moieties at the nanoparticle surface, one can correlate the unbinding event probability between nanoparticles tethered to an atomic force microscopy tip and cells to the nanoparticle vectoring capacity. This novel approach allows for a rapid and cost-effective design of targeted nanomedicines reducing the need for long and tedious in vitro tests.

Cationic carrier peptide enhances cerebrovascular targeting of nanoparticles in Alzheimer's disease brain

Accumulation of amyloid beta (Aβ) peptides in the cerebral vasculature, referred to as cerebral amyloid angiopathy (CAA), is widely observed in Alzheimer's disease (AD) brain and was shown to accelerate cognitive decline. There is no effective method for detecting cerebrovascular amyloid (CVA) and treat CAA. The targeted nanoparticles developed in this study effectively migrated from the blood flow to the vascular endothelium as determined by using quartz crystal microbalance with dissipation monitoring (QCM-D) technology. We also improved the stability, and blood-brain barrier (BBB) transcytosis of targeted nanoparticles by coating them with a cationic BBB penetrating peptide (K16ApoE). The K16ApoE-Targeted nanoparticles demonstrated specific targeting of vasculotropic DutchAβ40 peptide accumulated in the cerebral vasculature. Moreover, K16ApoE-Targeted nanoparticles demonstrated significantly greater uptake into brain and provided specific MRI contrast to detect brain amyloid plaques.

Fine tuning neuronal targeting of nanoparticles by adjusting the ligand grafting density and combining PEG spacers of different length

Poly(ethylene glycol) (PEG) has been extensively used to coat the surface of nanocarriers to improve their physicochemical properties and allow the grafting of targeting moieties. Still, to date there is no common agreement on the ideal PEG coverage-density or length to be used for optimum vector performance. In this study, we aimed to investigate the impact of both PEG density and length on the vectoring capacity of neuron-targeted gene-carrying trimethyl chitosan nanoparticles. The non-toxic fragment from the tetanus toxin (HC) was coupled to a 5 kDa heterobifunctional PEG (HC-PEG_5k) reactive for the thiol groups inserted into the polymer backbone and grafted at different densities onto the nanoparticles. Internalization and transfection studies on neuronal versus non-neuronal cell lines allowed to determine the PEG density of 2 mol% of PEG chains per mol of primary amine groups as the one with superior biological performance. To enhance HC exposure and maximize cell-nanoparticle specific interaction, NPs containing different ratios of HC-PEG_5k and 2 kDa methoxy-PEG at the same grafting density were produced. By intercalating HC-PEG_5k with methoxy-PEG_2k we attained the best performance in terms of internalization (higher payload delivery into cells) and transfection efficiency, using twice lower amount of HC. This outcome highlights the need for fine-tuning of PEG-modified nanoparticles towards the achievement of optimal targeting.

STATEMENT OF SIGNIFICANCE

The amount and exposure of targeting moieties at a nanoparticle surface are critical parameters regarding the targeting potential of nanosized delivery vectors. However, to date, few studies have considered fundamental aspects impacting the ligand-receptor pair interaction, such as the effect of spacer chain length, flexibility or conformation. By optimizing the PEG spacer density and chain length grafted into nanoparticles, we were able to establish the formulation that maximizes cell-nanoparticle specific interaction and has superior biological performance. Our work shows that the precise adjustment of the PEG coverage-density presents a significant impact on the selectivity and bioactivity of the developed formulation, emphasizing the need for the fine-tuning of PEG-modified nanoparticles for the successful development of the next-generation nanomedicines.

Carcinoembryonic antigen-targeted nanoparticles potentiate the delivery of anticancer drugs to colorectal cancer cells

Bioengineered functionalized nanoparticles have extensively been proposed in recent years to efficiently deliver anti-cancer drugs to the tumour site, by targeting the cancer cells and improving the therapeutic efficiency of active molecules. In this work, polymeric poly (lactic-co- glycolic)-polyethyleneglycol (PLGA-PEG) nanoparticles were produced by nanoprecipitation and loaded with paclitaxel, following surface-functionalized with a monoclonal antibody targeting the carcinoembryonic antigen (CEA) of intestinal epithelial cells. Physicochemical properties, cytotoxicity and targeting ability of the nanoparticles against two intestine epithelial carcinoma cell lines, CEA-expressing Caco-2 clone and non-CEA-expressing SW480, were assessed. Results showed successful production of nanoparticles around 200 nm, and close to charge neutrality, encapsulating up to 99% of paclitaxel. Functionalized nanoparticles were further constructed, demonstrating to be non-cytotoxic against intestinal cells. The targeting ability of functionalized nanoparticles to Caco-2 CEA expressing cells was confirmed by flow cytometry, in opposite to SW480 cells. Overall, the surface-modified PLGA-PEG nanoparticles with the CEA-targeting antibody were successfully developed as nanocarriers for paclitaxel and interacted with CEA expressing cells. This specific interaction provide these particles ability to be used as targeted systems for colorectal cancer therapeutics.

[Establishment of myocardial targeted nanoparticles and preliminary evaluation of its effects on prevention and treatment of myocardial injury]

Objective: To establish 3-{4-[2-hydroxyl-(1-methylethylamino) propoxy] phenyl} propionic acid cetylesters (PAC) modified nanoparticles, and preliminarily explore its cardiomyocyte-targeting function and protection effects on myocardium. Methods: (1) HL-1 myocardial cells were divided into cyanidin-3 (Cy3) marked non-targeted small interference RNA (Cy3-siNC) group and Cy3 marked small interference RNA designed for the nuclear factor kappa B (NF-κB)-p65 gene (Cy3-si435) group according to the random number table, with 3 wells in each group. Cells in Cy3-siNC group were transfected with Cy3-siNC, while cells in Cy3-si435 group were transfected with Cy3-si435. At transfection hour 24, the mRNA expression of NF-κB-p65 of cells was determined by real-time fluorescent quantitative polymerase chain reaction. (2) Multiple emulsificating solvent evaporating method was adopted to prepare PAC modified nanoparticles carried with Cy3-siNC (Cy3-siNC-PAC) and PAC modified nanoparticles carried with Cy3-si435 (Cy3-si435-PAC). The morphology of Cy3-si435-PAC nanoparticles was observed with scanning electron microscope, and the size and potential of Cy3-si435-PAC nanoparticles were detected by nanometer particle size and zeta potential analyzer. The entrapment efficiency and drug loadings of Cy3-si435-PAC nanoparticle were determined with ultraviolet spectrophotometer. The release of Cy3-si435 of Cy3-si435-PAC nanoparticles was determined by dialysis method. (3) Another batch of HL-1 cells were divided into 4 groups according to the random number table, with 9 wells in each group. Cells in negative control group were added with 5 μL phosphate buffer. Cells in 25, 50, and 100 mg/mL Cy3-si435-PAC nanoparticles groups were added with 5 μL 25, 50, and 100 mg/mL Cy3-si435-PAC nanoparticles, respectively. At transfection hour 6, 12, and 24, proliferation activity of cells in 3 wells of each group was detected by methyl thiazolyl tetrazolium method, respectively. (4) Another batch of HL-1 cells were cultured for 24 h, and then treated with 100 μL Cy3-si435-PAC nanoparticles. At transfection hour 0, 4, 8, 12, and 24, the percentage of cells uptaking Cy3-si435-PAC nanoparticles in 3 wells were detected by flow cytometry, respectively. (5) Another batch of HL-1 cells were divided into 2 groups according to the random number table, with 3 wells in each group. Cells in Cy3-siNC-PAC group were added with 100 μL Cy3-siNC-PAC nanoparticles, while cells in Cy3-si435-PAC group were added with 100 μL Cy3-si435-PAC nanoparticles. At transfection hour 24, the mRNA expression of NF-κB-p65 of cells was determined by real-time fluorescent quantitative polymerase chain reaction. (6) Six male C57BL/6J mice were divided into 2 groups according to the random number table, with 3 mice in each group. Mice in Cy3-siNC-lipopolysaccharide (LPS) group and Cy3-si435-LPS group were respectively injected with 500 μL Cy3-siNC-PAC nanoparticles and Cy3-si435-PAC nanoparticles (50 mg/mL) in the tail vein. At injection hour 24, mice in the two groups were intraperitoneally injected with 10 mg/kg LPS to induce myocardial injury. At post injury hour 24, the distribution of nanoparticles in mice was detected with small animal imager. (7) Another 9 male C57BL/6J mice were divided into 3 groups according to the random number table, with 3 mice in each group. Mice in Cy3-siNC-normal saline (NS) group and Cy3-siNC-LPS group were injected with 500 μL 50 mg/mL Cy3-siNC-PAC nanoparticles in the tail vein, while mice in Cy3-si435-LPS group were injected with 500 μL 50 mg/mL Cy3-si435-PAC nanoparticles. At injection hour 24, mice in Cy3-siNC-NS group were intraperitoneally injected with NS, while mice in Cy3-siNC-LPS group and Cy3-si435-LPS group were injected with 10 mg/kg LPS to induce myocardial injury. At post injury hour 24, pathological changes of myocardium of mice in each group were observed with HE staining. Data were processed with t test and one-way analysis of variance. Results: (1) The mRNA expression of NF-κB-p65 of cells in Cy3-si435 group was 0.183±0.004, significantly lower than 1.003±0.092 in Cy3-siNC group (t=15.46, P<0.01). (2) The form of prepared Cy3-si435-PAC nanoparticles was good, with particle size of 146.0 nm, potential of -29.2 mV, entrapment efficiency of (86.9±1.1) %, drug loadings of (25.4±0.9) %, and stable Cy3-si435 release. (3) At transfection hour 6, 12, and 24, there were no statistically significant differences in proliferation activity of cells in the 4 groups (with F values from 0.129 to 2.512, P values above 0.05). (4) At transfection hour 0, 4, 8, 12, and 24, the percentages of cells uptaking Cy3-si435-PAC nanoparticles were (0.79±0.06)%, (31.04±1.59)%, (51.64±2.67)%, (68.15±2.60)%, and (83.68±4.67)%, respectively. (5) The mRNA expression of NF-κB-p65 of cells in Cy3-si435-PAC group was 0.286±0.015, significantly lower than 1.002±0.073 in Cy3-siNC-PAC group (t=16.62, P<0.01). (6) At post injury hour 24, uniform distribution of nanoparticles could be observed in cardiomyocytes of mice in Cy3-siNC-LPS group and Cy3-si435-LPS group. (7) The structure of myocardial fibers of mice in Cy3-siNC-NS group was dense, with no inflammatory cells infiltration and uniform distribution of cytoplasm. The structure of myocardial fibers of mice in Cy3-siNC-LPS group were loose, with inflammatory cells infiltration and scattered distribution of cytoplasm. The structure of myocardial fibers of mice in Cy3-si435-LPS group was denser, with no obvious inflammatory cells infiltration and uniform distribution of cytoplasm. Conclusions: Cy3-si435-PAC nanoparticles have good morphology, uniform particle size, normal potential distribution, and no cell cytotoxicity. Cy3-si435-PAC nanoparticles can be effectively uptaked by HL-1 cells and suppress NF-κB-p65 mRNA expression. They also can effectively target to mice cardiomyocytes to reduce inflammatory cells infiltration and alleviate the myocardial injury of mice induced by LPS.

Improved antitumor activity of epirubicin-loaded CXCR4-targeted polymeric nanoparticles in liver cancers

A liver-targeted drug delivery system (CX-EPNP) composed of PLGA/TPGS was prepared and characterized. The surface of nanoparticle was conjugated with LFC131 peptide to increase the specific interaction of carrier with CXCR4 overexpressing liver cancers to enhance the Epirubicin (EPI) delivery to tumors. The particles were nanosized with size than 150 nm and portrayed a sustained release kinetics suggesting its suitability for cancer targeting. The in vitro cell uptake results showed that the introduction of LFC131 to the nanoparticles could increase significantly the affinity to human hepatic carcinoma cells (HepG2) with approximately a 3-fold improvement in cellular uptake than non-targeted one. A specific receptor-mediated uptake was observed by confocal laser scanning microscopy. In addition, CX-EPNP showed remarkable cytotoxicity towards HepG2 cells, and could effectively inhibit tumor growth. The more significant EPI accumulation from CX-EPNP in the cancer cells gave rise to the enhanced EPI cytotoxicity and cell apoptosis. The CX-EPNP distributed mostly in the xenograft tumor after intravenous administration to mice and adequately remained in the blood for at least 24h. It seemed that CX-EPNP upon intravenous injection avoided rapid recognition by Kupffer cells and adequately remained in the blood. These findings suggest that CX-EPNP could effectively inhibit the growth of liver tumors in situ and could potentially reduce the systemic side effects. However, extensive investigation is still needed to assess the possible applications of the CX-EPNP in humans.

Thrombosis: Novel nanomedical concepts of diagnosis and treatment

Intravascular thrombosis, a critical pathophysiological feature of many cardiovascular disorders, leads to the formation of life-threatening obstructive blood clots within the vessels. Rapid recanalization of occluded vessels is essential for the patients’ outcome, but the currently available systemic fibrinolytic therapy is associated with low efficacy and tremendous side effects. Additionally, many patients are ineligible for systemic thrombolytic therapy, either due to delayed admission to the hospital after symptom onset, or because of recent surgery, or bleeding. In order to improve the treatment efficacy and to limit the risk of hemorrhagic complications, both precise imaging of the affected vascular regions, and the localized application of fibrinolytic agents, are required. Recent years have brought about considerable advances in nanomedical approaches to thrombosis. Although these thrombus-targeting imaging agents and nanotherapies are not yet implemented in humans, substantial amount of successful in vivo applications have been reported, including animal models of stroke, acute arterial thrombosis, and pulmonary embolism. It is evident that the future progress in diagnosis and treatment of thrombosis will be closely bound with the development of novel nanotechnology-based strategies. This Editorial focuses on the recently reported approaches, which hold a great promise for personalized, disease-targeted treatment and reduced side effects in the patients suffering from this life-threatening condition.

Minimizing the non-specific binding of nanoparticles to the brain enables active targeting of Fn14-positive glioblastoma cells

A major limitation in the treatment of glioblastoma (GBM), the most common and deadly primary brain cancer, is delivery of therapeutics to invading tumor cells outside of the area that is safe for surgical removal. A promising way to target invading GBM cells is via drug-loaded nanoparticles that bind to fibroblast growth factor-inducible 14 (Fn14), thereby potentially improving efficacy and reducing toxicity. However, achieving broad particle distribution and nanoparticle targeting within the brain remains a significant challenge due to the adhesive extracellular matrix (ECM) and clearance mechanisms in the brain. In this work, we developed Fn14 monoclonal antibody-decorated nanoparticles that can efficiently penetrate brain tissue. We show these Fn14-targeted brain tissue penetrating nanoparticles are able to (i) selectively bind to recombinant Fn14 but not brain ECM proteins, (ii) associate with and be internalized by Fn14-positive GBM cells, and (iii) diffuse within brain tissue in a manner similar to non-targeted brain penetrating nanoparticles. In addition, when administered intracranially, Fn14-targeted nanoparticles showed improved tumor cell co-localization in mice bearing human GBM xenografts compared to non-targeted nanoparticles. Minimizing non-specific binding of targeted nanoparticles in the brain may greatly improve the access of particulate delivery systems to remote brain tumor cells and other brain targets.

Targeted nanotechnology for cancer imaging

Targeted nanoparticle imaging agents provide many benefits and new opportunities to facilitate accurate diagnosis of cancer and significantly impact patient outcome. Due to the highly engineerable nature of nanotechnology, targeted nanoparticles exhibit significant advantages including increased contrast sensitivity, binding avidity and targeting specificity. Considering the various nanoparticle designs and their adjustable ability to target a specific site and generate detectable signals, nanoparticles can be optimally designed in terms of biophysical interactions (i.e., intravascular and interstitial transport) and biochemical interactions (i.e., targeting avidity towards cancer-related biomarkers) for site-specific detection of very distinct microenvironments. This review seeks to illustrate that the design of a nanoparticle dictates its in vivo journey and targeting of hard-to-reach cancer sites, facilitating early and accurate diagnosis and interrogation of the most aggressive forms of cancer. We will report various targeted nanoparticles for cancer imaging using X-ray computed tomography, ultrasound, magnetic resonance imaging, nuclear imaging and optical imaging. Finally, to realize the full potential of targeted nanotechnology for cancer imaging, we will describe the challenges and opportunities for the clinical translation and widespread adaptation of targeted nanoparticles imaging agents.

Peptide-functionalized nanoparticles for selective targeting of pancreatic tumor

Chemotherapy for pancreatic cancer is hampered by the tumor's physio-pathological complexity. Here we show a targeted nanomedicine using a new ligand, the CKAAKN peptide, which had been identified by phage display, as an efficient homing device within the pancreatic pathological microenvironment. Taking advantage of the squalenoylation platform, the CKAAKN peptide was conjugated to squalene (SQCKAAKN) and then co-nanoprecipitated with the squalenoyl prodrug of gemcitabine (SQdFdC) giving near monodisperse nanoparticles (NPs) for safe intravenous injection. By interacting with a novel target pathway, the Wnt-2, the CKAAKN functionalization enabled nanoparticles: (i) to specifically interact with both tumor cells and angiogenic vessels and (ii) to simultaneously promote pericyte coverage, thus leading to the normalization of the vasculature likely improving the tumor accessibility for therapy. All together, this approach represents a unique targeted nanoparticle design with remarkable selectivity towards pancreatic cancer and multiple mechanisms of action.