Disease-microenvironment modulation by bare- or engineered-exosome for rheumatoid arthritis treatment.

BACKGROUND: Exosomes are extracellular vesicles secreted by eukaryotic cells and have been extensively studied for their surface markers and internal cargo with unique functions. A deeper understanding of exosomes has allowed their application in various research areas, particularly in diagnostics and therapy. MAIN BODY: Exosomes have great potential as biomarkers and delivery vehicles for encapsulating therapeutic cargo. However, the limitations of bare exosomes, such as rapid phagocytic clearance and non-specific biodistribution after injection, pose significant challenges to their application as drug delivery systems. This review focuses on exosome-based drug delivery for treating rheumatoid arthritis, emphasizing pre/post-engineering approaches to overcome these challenges. CONCLUSION: This review will serve as an essential resource for future studies to develop novel exosome-based therapeutic approaches for rheumatoid arthritis. Overall, the review highlights the potential of exosomes as a promising therapeutic approach for rheumatoid arthritis treatment.

Curvature-sensing peptide inhibits tumour-derived exosomes for enhanced cancer immunotherapy.

Tumour-derived exosomes (T-EXOs) impede immune checkpoint blockade therapies, motivating pharmacological efforts to inhibit them. Inspired by how antiviral curvature-sensing peptides disrupt membrane-enveloped virus particles in the exosome size range, we devised a broadly useful strategy that repurposes an engineered antiviral peptide to disrupt membrane-enveloped T-EXOs for synergistic cancer immunotherapy. The membrane-targeting peptide inhibits T-EXOs from various cancer types and exhibits pH-enhanced membrane disruption relevant to the tumour microenvironment. The combination of T-EXO-disrupting peptide and programmed cell death protein-1 antibody-based immune checkpoint blockade therapy improves treatment outcomes in tumour-bearing mice. Peptide-mediated disruption of T-EXOs not only reduces levels of circulating exosomal programmed death-ligand 1, but also restores CD8+ T cell effector function, prevents premetastatic niche formation and reshapes the tumour microenvironment in vivo. Our findings demonstrate that peptide-induced T-EXO depletion can enhance cancer immunotherapy and support the potential of peptide engineering for exosome-targeting applications.

Spin Swapping Effect of Band Structure Origin in Centrosymmetric Ferromagnets.

We theoretically demonstrate the spin swapping effect of band structure origin in centrosymmetric ferromagnets. It is mediated by an orbital degree of freedom but does not require inversion asymmetry or impurity spin-orbit scattering. Analytic and tight-binding models reveal that it originates mainly from k points where bands with different spins and different orbitals are nearly degenerate, and thus it has no counterpart in normal metals. First-principle calculations for centrosymmetric 3d transition-metal ferromagnets show that the spin swapping conductivity of band structure origin can be comparable in magnitude to the intrinsic spin Hall conductivity of Pt. Our theory generalizes transverse spin currents generated by ferromagnets and emphasizes the important role of the orbital degree of freedom in describing spin-orbit-coupled transport in centrosymmetric materials.

Sulfisoxazole Elicits Robust Antitumour Immune Response Along with Immune Checkpoint Therapy by Inhibiting Exosomal PD-L1.

Despite their potent antitumor activity, clinical application of immune checkpoint inhibitors has been significantly limited by their poor response rates (<30%) in cancer patients, primarily due to immunosuppressive tumor microenvironments. As a representative immune escape mechanism, cancer-derived exosomes have recently been demonstrated to exhaust CD8+ cytotoxic T cells. Here, it is reported that sulfisoxazole, a sulfonamide antibacterial, significantly decreases the exosomal PD-L1 level in blood when orally administered to the tumor-bearing mice. Consequently, sulfisoxazole effectively reinvigorates exhausted T cells, thereby eliciting robust antitumor effects in combination with anti-PD-1 antibody. Overall, sulfisoxazole regulates immunosuppression through the inhibition of exosomal PD-L1, implying its potential to improve the response rate of anti-PD-1 antibodies.

Orbital torque in magnetic bilayers.

The orbital Hall effect describes the generation of the orbital current flowing in a perpendicular direction to an external electric field, analogous to the spin Hall effect. As the orbital current carries the angular momentum as the spin current does, injection of the orbital current into a ferromagnet can result in torque on the magnetization, which provides a way to detect the orbital Hall effect. With this motivation, we examine the current-induced spin-orbit torques in various ferromagnet/heavy metal bilayers by theory and experiment. Analysis of the magnetic torque reveals the presence of the contribution from the orbital Hall effect in the heavy metal, which competes with the contribution from the spin Hall effect. In particular, we find that the net torque in Ni/Ta bilayers is opposite in sign to the spin Hall theory prediction but instead consistent with the orbital Hall theory, which unambiguously confirms the orbital torque generated by the orbital Hall effect. Our finding opens a possibility of utilizing the orbital current for spintronic device applications, and it will invigorate researches on spin-orbit-coupled phenomena based on orbital engineering.

Temperature dependence of intrinsic and extrinsic contributions to anisotropic magnetoresistance.

Electrical conduction in magnetic materials depends on their magnetization configuration, resulting in various magnetoresistances (MRs). The microscopic mechanisms of MR have so far been attributed to either an intrinsic or extrinsic origin, yet the contribution and temperature dependence of either origin has remained elusive due to experimental limitations. In this study, we independently probed the intrinsic and extrinsic contributions to the anisotropic MR (AMR) of a permalloy film at varying temperatures using temperature-variable terahertz time-domain spectroscopy. The AMR induced by the scattering-independent intrinsic origin was observed to be approximately 1.5% at T = 16 K and is virtually independent of temperature. In contrast, the AMR induced by the scattering-dependent extrinsic contribution was approximately 3% at T = 16 K but decreased to 1.5% at T = 155 K, which is the maximum temperature at which the AMR can be resolved using THz measurements. Our results experimentally quantify the temperature-dependent intrinsic and extrinsic contributions to AMR, which can stimulate further theoretical research to aid the fundamental understanding of AMR.

Repurposing macitentan with nanoparticle modulates tumor microenvironment to potentiate immune checkpoint blockade.

Immune checkpoint therapy (ICT), which reinvigorates cytotoxic T cells, provides clinical benefits as an alternative to conventional cancer therapies. However, its clinical response rate is too low to treat an immune-excluded tumor, owing to the presence of abundant stromal elements impeding the penetration of immune cells. Here, we report that macitentan, a dual endothelin receptor antagonist approved by the FDA to treat pulmonary arterial hypertension, can be repositioned to modulate the desmoplastic tumor microenvironment (TME). In the 4T1 orthotopic tumor model, the polymeric nanoparticles bearing macitentan (M-NPs) prevent fibrotic progression by regulating the function of cancer-associated fibroblasts, attenuate the biogenesis of cancer cell-derived exosomes, and modulate the T cell subsets and distribution in TME. These results demonstrate that the M-NPs effectively reorganize the immunosuppressive TME by targeting the endothelin-1 axis and consequently exhibit synergistic antitumor effects in combination with ICT.

Reactive oxygen species-responsive dendritic cell-derived exosomes for rheumatoid arthritis.

Although tolerogenic dendritic cell-derived exosomes (TolDex) have emerged as promising therapeutics for rheumatoid arthritis (RA), their clinical applications have been hampered by their poor in vivo disposition after systemic administration. Herein, we report the development of stimuli-responsive TolDex that induces lesion-specific immunoregulation in RA. Responsiveness to reactive oxygen species (ROS), a physiological stimulus in the RA microenvironment, was conferred on TolDex by introducing a thioketal (TK) linker-embedded poly(ethylene glycol) (PEG) on TolDex surface via hydrophobic insertion. The detachment of PEG following overproduction of ROS facilitates the cellular uptake of ROS-responsive TolDex (TKDex) into activated immune cells. Notably, TolDex and TKDex downregulated CD40 in mature dendritic cells (mDCs) and regulated secretion of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin-6 (IL-6) at the cellular level. In the collagen-induced arthritis (CIA) mouse model, PEG prolonged the blood circulation of TKDex following intravenous administration and enhanced their accumulation in the joints. In addition, TKDex decreased IL-6, increased transforming growth factor-ß, and induced the CD4+CD25+Foxp3+ regulatory T cells in CIA mice. Overall, ROS-responsive TolDex might have potential as therapeutic agents for RA. STATEMENT OF SIGNIFICANCE: Tolerogenic dendritic cell-derived exosomes (TolDex) are emerging immunoregulators of autoimmune diseases, including rheumatoid arthritis (RA). However, their lack of long-term stability and low targetability are still challenging. To overcome these issues, we developed reactive oxygen species (ROS)-responsive TolDex (TKDex) by incorporating the ROS-sensitive functional group-embedded poly(ethylene glycol) linker into the exosomal membrane of TolDex. Surface-engineered TKDex were internalized in mature DCs because of high ROS-sensitivity and enhanced accumulation in the inflamed joint in vivo. Further, for the first time, we investigated the potential mechanism of action of TolDex relevant to CD40 downregulation and attenuation of tumor necrosis factor (TNF)-α secretion. Our strategy highlighted the promising nanotherapeutic effects of stimuli-sensitive TolDex, which induces immunoregulation.

Necroptosis-Inducible Polymeric Nanobubbles for Enhanced Cancer Sonoimmunotherapy.

Necroptosis, caspase-independent programmed necrosis, has emerged as a therapeutic target to make dying cancer cells stimulants for antitumor immune responses. The clinical translations exploiting necroptosis, however, have been limited since most cancer cells downregulate receptor-interacting protein kinase 3 (RIPK3) as a key enzyme for necroptosis. Herein, nanobubbles (NBs) that can trigger RIPK3-independent necroptosis, facilitating cell-membrane rupture via the acoustic cavitation effect are reported. The NBs, imbibing perfluoropentane as the gas precursor, are prepared using an amphiphilic polymer conjugate, composed of PEGylated carboxymethyl dextran as the hydrophilic backbone and chlorin e6 as the hydrophobic sonosensitizer. When exposed to ultrasound, the NBs efficiently promote the release of biologically active damage-associated molecular patterns by inducing burst-mediated cell-membrane disintegration. Consequently, the necroptosis-inducible NBs significantly improve antitumor immunity by maturation of dendritic cells and activation of CD8+ cytotoxic T cells both in vitro and in vivo. In addition, the combination of NBs and immune checkpoint blockade leads to complete regression of the primary tumor and beneficial therapeutic activity against metastatic tumors in an RIPK3-deficient CT26 tumor-bearing mouse model. Overall, the innovative NB that causes immunogenic cell death of cancer via RIPK3-independent necroptosis is a promising enhancer for cancer immunotherapy.

Metal-Phenolic Network-Coated Hyaluronic Acid Nanoparticles for pH-Responsive Drug Delivery.

Although self-assembled nanoparticles (SNPs) have been used extensively for targeted drug delivery, their clinical applications have been limited since most of the drugs are released into the blood before they reach their target site. In this study, metal-phenolic network (MPN)-coated SNPs (MPN-SNPs), which consist of an amphiphilic hyaluronic acid derivative, were prepared to be a pH-responsive nanocarrier to facilitate drug release in tumor microenvironments (TME). Due to their amphiphilic nature, SNPs were capable of encapsulating doxorubicin (DOX), chosen as the model anticancer drug. Tannic acid and FeCl3 were added to the surface of the DOX-SNPs, which allowed them to be readily coated with MPNs as the diffusion barrier. The pH-sensitive MPN corona allowed for a rapid release of DOX and effective cellular SNP uptake in the mildly acidic condition (pH 6.5) mimicking TME, to which the hyaluronic acid was exposed to facilitate receptor-mediated endocytosis. The DOX-loaded MPN-SNPs exhibited a higher cytotoxicity for the cancer cells, suggesting their potential use as a drug carrier in targeted cancer therapy.

Nanomedicines for Reactive Oxygen Species Mediated Approach: An Emerging Paradigm for Cancer Treatment.

Growth in the knowledge of cancer biology has led to the emergence and evolution of cancer nanomedicines by providing the rationale for leveraging nanotechnology to develop better treatment options. The discovery of nanometer-sized intercellular openings in the defective angiogenic tumor vasculature contributed to the development of an idea for the well-known cancer passive targeting regime, enhanced permeability and retention (EPR) effect, of the nanomedicines. Recently, reactive oxygen species (ROS) have been highlighted as one of the key players that underlie the acquisition of the various hallmarks of cancer. As ROS are associated with all stages of cancer, their applications in cancer treatment based on the following concentration-dependent implications have attracted much attention: (1) low to moderate levels of ROS as key signaling molecules, (2) elevated levels of ROS in cancer cells as one of the unique characteristics of cancer, and (3) excessive levels of ROS as cytotoxic agents. Considering ROS from a different point of view, various cancer nanomedicines have been designed to achieve spatiotemporal control of therapeutic action, the main research focus in this area. This Account includes our efforts and preclinical achievements in development of nanomedicines for a range of ROS-mediated cancer therapies. It begins with general background regarding cancer nanomedicines, the significance of ROS in cancer, and a brief overview of ROS-mediated approaches for cancer therapy. Then, this Account highlights the two key roles of ROS that define therapeutic purposes of cancer nanomedicines: (1) ROS as drug delivery enhancers and (2) ROS as cell death inducers. The former inspired us to develop nitric oxide-generating nanoparticles for improved EPR effect, endogenous ROS-responsive polymeric micelles for enhanced intracellular drug delivery, and exogenous ROS-activated micelles for subcellular localization via photochemical internalization. While refining conventional chemotherapy, recent researches also have focused on the latter, the cytotoxic ROS, to advance alternative treatment modalities such as oxidation therapy, photodynamic therapy (PDT), and sonodynamic therapy (SDT). In particular, we have been motivated to develop polymeric nanoreactors containing enzymes to produce H2O2 for oxidation therapy, photosensitizer-loaded gold-nanoclustered polymeric nanoassemblies for photothermally activated PDT overcoming the oxygen dependency of PDT, and hydrophilized TiO2 nanoparticles and Au-TiO2 nanocomposites as novel sonosensitizers for improved SDT efficiency. The integration of nanomedicine and ROS-mediated therapy has emerged as the new paradigm in the treatment of cancer, based on promising proof-of-concept demonstrations in preclinical studies. Further efforts to ensure clinical translation along with more sophisticated cancer nanomedicines to address relevant challenges are expected to be made in the coming years.

Bulk Dzyaloshinskii-Moriya interaction in amorphous ferrimagnetic alloys.

Symmetry breaking is a fundamental concept that prevails in many branches of physics1-5. In magnetic materials, broken inversion symmetry induces the Dzyaloshinskii-Moriya interaction (DMI), which results in fascinating physical behaviours6-14 with the potential for application in future spintronic devices15-17. Here, we report the observation of a bulk DMI in GdFeCo amorphous ferrimagnets. The DMI is found to increase linearly with an increasing thickness of the ferrimagnetic layer, which is a clear signature of the bulk nature of DMI. We also found that the DMI is independent of the interface between the heavy metal and ferrimagnetic layer. This bulk DMI is attributed to an asymmetric distribution of the elemental content in the GdFeCo layer, with spatial inversion symmetry broken throughout the layer. We expect that our experimental identification of a bulk DMI will open up additional possibilities to exploit this interaction in a wide range of materials.

Recent Advances in Polymeric Nanomedicines for Cancer Immunotherapy.

Immunotherapy has emerged as a promising approach to treat cancer, since it facilitates eradication of cancer by enhancing innate and/or adaptive immunity without using cytotoxic drugs. Of the immunotherapeutic approaches, significant clinical potentials are shown in cancer vaccination, immune checkpoint therapy, and adoptive cell transfer. Nevertheless, conventional immunotherapies often involve immune-related adverse effects, such as liver dysfunction, hypophysitis, type I diabetes, and neuropathy. In an attempt to address these issues, polymeric nanomedicines are extensively investigated in recent years. In this review, recent advances in polymeric nanomedicines for cancer immunotherapy are highlighted and thoroughly discussed in terms of 1) antigen presentation, 2) activation of antigen-presenting cells and T cells, and 3) promotion of effector cells. Also, the future perspectives to develop ideal nanomedicines for cancer immunotherapy are provided.

Recent Progress and Advances in Stimuli-Responsive Polymers for Cancer Therapy.

The conventional chemotherapeutic agents, used for cancer chemotherapy, have major limitations including non-specificity, ubiquitous biodistribution, low concentration in tumor tissue, and systemic toxicity. In recent years, owing to their unique features, polymeric nanoparticles have been widely used for the target-specific delivery of drugs in the body. Although polymeric nanoparticles have addressed a number of important issues, the bioavailability of drugs at the disease site, and especially upon cellular internalization, remains a challenge. A polymer nanocarrier system with a stimuli-responsive property (e.g., pH, temperature, or redox potential), for example, would be amenable to address the intracellular delivery barriers by taking advantage of pH, temperature, or redox potentials. With a greater understanding of the difference between normal and pathological tissues, there is a highly promising role of stimuli-responsive nanocarriers for drug delivery in the future. In this review, we highlighted the recent advances in different types of stimuli-responsive polymers for drug delivery.

Ultrasmall gold nanosatellite-bearing transformable hybrid nanoparticles for deep tumor penetration.

Since delivering drugs to an entire tumoral region leads to high therapeutic efficacy and good prognosis, achieving deep tumoral penetration of drugs is a major issue in cancer treatment. In this regard, conventional nanomedicines (>50 nm) have shown limitations in cancer therapy, primarily attributed to the heterogeneous distribution of drugs because of the physiological barrier of the tumor interstitial space. To address this issue, we prepared transformable hybrid nanoparticles (TNPs) consisting of a pH-responsive nanocarrier (PEG-PBAE) and doxorubicin (DOX)-conjugated ultrasmall (<3 nm) gold nanoparticles (nanosatellites). It has been shown that PEG-PBAE can serve as a reservoir for nanosatellites and release them in mildly acidic conditions (pH 6.5), mimicking the tumor microenvironment. When DOX-loaded TNPs (DOX-TNPs) were intravenously injected into tumor-bearing mice, they successfully accumulated and dissociated at the extracellular level of the tumor, leading to the disclosure of nanosatellites and free DOX. While the free DOX accumulated in tumor tissue near blood vessels, the deeply diffused nanosatellites were taken up by the tumor cell, followed by the release of DOX via cleavage of pH-responsive ester linkages in the nanosatellites at the intracellular level. Consequently, the DOX-TNPs effectively suppressed tumor growth through improved tumor penetration of DOX, suggesting their promising potential as a cancer nanomedicine. STATEMENT OF SIGNIFICANCE: Deep tumor penetration of anticancer drug is an important issue for high therapeutic efficacy. If the drugs cannot reach cancer cells in a sufficient concentration, their effectiveness will be limited. In this regard, conventional nanomedicine showed only modest therapeutic efficacy since they cannot deliver their payloads to the deep site of tumor tissue. This heterogeneous distribution of the drug is primarily attributed to the physiological barriers of the tumor microenvironment, including a dense extracellular matrix. To surmount this challenge, we developed tumor acidity-triggered transformable nanoparticles. By encapsulating doxorubicin-conjugated ultrasmall gold nanosatellites into the nanoparticles, the drug was not significantly bound to genetic materials, resulting in its minimal sequestration near the vasculature and deep tumor penetration. Our strategy could resolve not only the poor penetration issue of the drug but also its restricted tumor accumulation, suggesting the potential as an effective nanotherapeutics.

A carboxymethyl dextran-based polymeric conjugate as the antigen carrier for cancer immunotherapy.

BACKGROUND: Antigen-specific cytotoxic T lymphocytes (CTLs), which eliminate target cells bearing antigenic peptides presented by surface major histocompatibility complex (MHC) class I molecules, play a key role in cancer immunotherapy. However, the majority of tumors are not immunologically rejected since they express self-antigens which are not recognized by CTLs as foreign. To foreignize these tumors for CTL-mediated immunological rejection, it is essential to develop carriers that can effectively deliver foreign antigens to cancer cells. METHODS: A polymeric conjugate, composed of a carboxymethyl dextran (CMD) as the backbone and ovalbumin (OVA) as a model foreign antigen, was prepared to investigate its potential as the antigen carrier for cancer immunotherapy. RESULTS: An in vitro cellular uptake study showed that the conjugate was successfully taken up by TC-1 cervical cancer cells. When CMD-OVA was systemically administered to tumor-bearing mice, the strong fluorescence signal was observed at the tumor site over the whole period of time period, suggesting high tumor targetability of the conjugate. Compared to free OVA, CMD-OVA induced significantly higher antigen presentation at the tumor site. CONCLUSIONS: The CMD-OVA conjugate can effectively deliver the antigen to the tumor site, implying its high potential as the antigen carrier for cancer immunotherapy.

Intracellularly Activatable Nanovasodilators To Enhance Passive Cancer Targeting Regime.

Conventional cancer targeting with nanoparticles has been based on the assumed enhanced permeability and retention (EPR) effect. The data obtained in clinical trials to date, however, have rarely supported the presence of such an effect. To address this challenge, we formulated intracellular nitric oxide-generating nanoparticles (NO-NPs) for the tumor site-specific delivery of NO, a well-known vasodilator, with the intention of boosting EPR. These nanoparticles are self-assembled under aqueous conditions from amphiphilic copolymers of poly(ethylene glycol) and nitrated dextran, which possesses inherent NO release properties in the reductive environment of cancer cells. After systemic administration of the NO-NPs, we quantitatively assessed and visualized increased tumor blood flow as well as enhanced vascular permeability than could be achieved without NO. Additionally, we prepared doxorubicin (DOX)-encapsulated NO-NPs and demonstrated consequential improvement in therapeutic efficacy over the control groups with considerably improved DOX intratumoral accumulation. Overall, this proof of concept study implies a high potency of the NO-NPs as an EPR enhancer to achieve better clinical outcomes.

Carboxymethyl dextran-based hypoxia-responsive nanoparticles for doxorubicin delivery.

In an attempt to develop the hypoxia-responsive nanoparticles for cancer therapy, a polymer conjugate, consisting of carboxymethyl dextran (CMD) and black hole quencher 3 (BHQ3), was prepared. The polymer conjugate can self-assemble into nanoparticles (CMD-BHQ3 NPs) under aqueous conditions. The anticancer drug, doxorubicin (DOX), was loaded in CMD-BHQ3 NPs to prepare DOX@CMD-BHQ3 NPs. The CMD-BHQ3 NPs released DOX in a sustained manner under physiological conditions, whereas the release rate of DOX remarkably increased under hypoxic conditions throughout the cleavage of the azo bond in BHQ3. In vitro cytotoxicity study revealed that DOX@CMD-BHQ3 NPs showed higher toxicity under hypoxic conditions than normoxic conditions. Confocal microscopic images indicated oxygen-dependent intracellular release of DOX from DOX@CMD-BHQ3. In vivo biodistribution study demonstrated that CMD-BHQ3 NPs were preferentially accumulated in the tumor after systemic administration into tumor-bearing mice. Overall, CMD-BHQ3 might be a promising carrier for selective drug release in the hypoxic tumor.

Anti-Trop2 antibody-conjugated bioreducible nanoparticles for targeted triple negative breast cancer therapy.

Trop2, a transmembrane glycoprotein, has emerged as a biomarker for targeted cancer therapy since it is overexpressed in 80% of triple negative breast cancer (TNBC) patients. For the site-specific delivery of the anticancer drug into TNBC, anti-Trop2 antibody-conjugated nanoparticles (ST-NPs) were prepared as the potential nanocarrier, composed of carboxymethyl dextran (CMD) derivatives with bioreducible disulfide bonds. Owing to its amphiphilicity, the CMD derivatives were self-assembled into nano-sized particles in an aqueous condition. Doxorubicin (DOX), chosen as a model anticancer drug, was effectively encapsulated into the nanoparticles. DOX-loaded ST-NPs (DOX-ST-NPs) rapidly released DOX in the presence of 10mM glutathione (GSH), whereas the DOX release is significantly retarded in the physiological condition (PBS, pH 7.4). Confocal microscopic images and flow cytometry analysis demonstrated that DOX-ST-NPs were selectively taken up by MDA-MB-231 as the representative Trop2-expressing TNBC cells. Consequently, DOX-ST-NPs exhibited higher toxicity to Trop2-positive MDA-MB-231 cancer cells, compared to DOX-loaded control nanoparticles without the disulfide bond or anti-Trop2 antibody. Overall, ST-NPs might be a promising carrier of DOX for targeted TNBC therapy.

Effects of tumor microenvironments on targeted delivery of glycol chitosan nanoparticles.

In cancer theranostics, the main strategy of nanoparticle-based targeted delivery system has been understood by enhanced permeability and retention (EPR) effect of macromolecules. Studies on diverse nanoparticles provide a better understanding of different EPR effects depending on their structure, physicochemical properties, and chemical modifications. Recently the tumor microenvironment has been considered as another important factor for determining tumor-targeted delivery of nanoparticles, but the correlation between EPR effects and tumor microenvironment has not yet been fully elucidated. Herein, ectopic subcutaneous tumor models presenting different tumor microenvironments were established by inoculation of SCC7, U87, HT29, PC3, and A549 cancer cell lines into athymic nude mice, respectively. In the five different types of tumor-bearing mice, tumor-targeted delivery of self-assembled glycol chitosan nanoparticles (CNPs) were comparatively evaluated to identify the correlation between the tumor microenvironments and targeted delivery of CNPs. As a result, neovascularization and extents of intratumoral extracellular matrix (ECM) were both important in determining the tumor targeted delivery of CNPs. The EPR effect was maximized in the tumors which include large extent of angiogenic blood vessels and low intratumoral ECM content. This comprehensive study provides substantial evidence that the EPR effects based tumor-targeted delivery of nanoparticles can be different depending on the tumor microenvironment in individual tumors. To overcome current limitations in clinical nanomedicine, the tumor microenvironment of the patients and EPR effects in clinical tumors should also be carefully studied.