Nanoengineered Macrophages Armed with TLR7/8 Agonist Enhance Remodeling of Immunosuppressive Tumor Microenvironment.

Although adoptive cell-based therapy is illuminated as one of the promising approaches in cancer immunotherapy, it shows low antitumor efficacy because transferred cells adapt and alter toward a pro-tumoral phenotype in response to the tumor's immunosuppressive milieu. Herein, nanoengineered macrophages anchored with functional liposome armed with cholesterol-conjugated Toll-like receptor 7/8 agonist (masked TLR7/8a, m7/8a) are generated to overcome the shortcomings of current macrophage-based therapies and enhance the remodeling of the immunosuppressive tumor microenvironment (TME). The liposome-anchored macrophages (LAMΦ-m7/8a), are fabricated by anchoring dibenzocyclooctyne-modified liposome(m7/8a) onto azido-expressing macrophages via a bio-orthogonal click reaction, are continuously invigorated due to the slow internalization of liposome(m7/8a) and sustained activation. LAMΦ-m7/8a secreted ≈3 and 33-fold more IL-6 and TNF-α than conventional M1-MΦ, maintained the M1 phenotype, and phagocytosed tumor cells for up to 48 h in vitro. Both intratumoral and intravenous injections of LAMΦ-m7/8a induced effective antitumor efficacy when treated in combination with doxorubicin-loaded liposomes in 4T1-tumor bearing mice. It not only increases the infiltration of antigen-specific CD8+ T cells secreting granzyme B, IFN-γ, and TNF-α within the TME, but also reduces myeloid-derived suppressor cells. These results suggest that LAMΦ-m7/8a may provide a suitable alternative to next-generation cell-based therapy platform.

Chemical Strategies to Enhance the Therapeutic Efficacy of Toll-like Receptor Agonist Based Cancer Immunotherapy.

Recent developments in the fields of biomedical chemistry and immune bioengineering have enabled innovative therapeutic approaches that can enhance the efficacy, accuracy, and safety of cancer immunotherapy. Among the numerous strategies utilized in cancer immunotherapy, Toll-like receptor (TLR) agonist-based approaches have been studied for a long time since they trigger the innate immune system and generate antigen-specific T cell responses to fight against tumors. In addition to these immunostimulatory functions, TLR agonists also contribute to the reprogramming of immune suppressive tumor microenvironments. Although TLR agonists are now being intensively studied in clinical trials due to their substantial immunomodulatory properties, they still show a low therapeutic index. Nonspecific and random stimulation of various immune cells produces excess levels of proinflammatory cytokines, resulting in cytokine storms and chronic diseases. Therefore, the development of chemical strategies to enhance the therapeutic efficacy as well as the safety of TLR agonist-based immunotherapy is essential and in high demand.In this Account, we summarize and discuss recent developments in biomedical chemistry and bioengineering techniques for the immunomodulation of TLR agonists that have addressed the limitations in current cancer immunotherapy. Immunomodulation of TLR agonists can be classified into two different approaches: (1) molecular modulation via chemical structure modification and (2) macroscopic modulation via an engineered drug delivery system. In molecular modulation, based on prodrug and antedrug principles, activity is modulated (active or inactive) through immolative chemical linkers that can respond to extrinsic or intrinsic biological stimulation and the plasmatic environment, respectively. To increase the effectiveness of TLR agonists as immunostimulatory agents, researchers have conjugated TLR agonists with other immunotherapeutic moieties (antigen, antibody, other TLR agonist, etc.). For macroscopic modulation, bioengineering of delivery carriers differing in size or with albumin hitchhiking moieties has been utilized to increase the efficiency of the targeting of these carriers to secondary lymphoid organs (lymph nodes (LNs) and spleen). The conjugation of specific targeting ligands and incorporation of stimulus-triggering moieties can promote the delivery of TLR agonists into specific cells or intracellular compartments. Implantable porous scaffolds for specific immune cell recruitment and in situ depot-forming gel systems for controlled release of immunomodulatory drugs can increase the therapeutic efficacy of TLR agonists while reducing systemic toxicity. Taken together, these findings show that well-designed and precisely controlled chemical strategies for the immunomodulation of TLR agonists at both the molecular and macroscopic levels are expected to play key roles in improving the therapeutic efficacy of cancer immunotherapy while minimizing immune-related toxicity.

Therapeutic efficacy of cancer vaccine adjuvanted with nanoemulsion loaded with TLR7/8 agonist in lung cancer model.

Although immune checkpoint inhibitors have significantly improved clinical outcomes in various malignant cancers, only a small proportion of patients reap benefits, likely due to the low number of T cells and high number of immunosuppressive cells in the tumor microenvironment (TME) of patients with advanced disease. We developed a cancer vaccine adjuvanted with nanoemulsion (NE) loaded with TLR7/8 agonist (R848) and analyzed its therapeutic effect alone or in combination with immune checkpoint inhibitors, on antitumor immune responses and the reprogramming of suppressive immune cells in the TME. NE (R848) demonstrated robust local and systemic antitumor immune responses in both subcutaneous and orthotopic mouse lung cancer models, inducing tumor-specific T cell activation and mitigating T cell exhaustion. Combination with anti-PD-1 antibodies showed synergistic effects with respect to therapeutic efficacy and survival rate. Thus, NE (R848)-based cancer vaccines could prevent tumor recurrence and prolong survival by activating antitumor immunity and reprogramming immunosuppression.

Improved Sensitivity of Intramolecular Strand Displacement Based on Localization of Probes.

Effective intermolecular interaction is required between probe and target molecules for successful detection of biomarkers. Here, we demonstrate that localization of probes on DNA nanostructures improves detection sensitivity and reaction rate. The structural flexibility of DNA nanostructures enabled frequent intramolecular interactions among the localized probes. The Smoluchowski coagulation method and the coarse-grained molecular dynamic software oxDNA were used for theoretical estimation of inter- and intramolecular behaviors of the DNA nanostructures as well as adequate experiments verifying the improvements in sensitivity with probe localization. Remarkably, the probe-localized DNA nanostructure had an increased sensitivity up to 274 times higher than that of the same probes without localization. We believe this achievement represents a wide applicability as a potential design strategy for robust, reliable, and sensitive biosensors.

Protein Nanoparticle Fabrication for Optimized Reticuloendothelial System Evasion and Tumor Accumulation.

Nanoparticles (NPs) of protein-based materials have become one of the most promising candidates for drug carriers in drug-delivery systems because of their in vivo nontoxicity, biodegradability, compatibility with hydrophilic drugs, and adaptability to the human body. Many studies have investigated the fabrication of protein NPs from human serum albumin (HSA) as a new drug carrier. It is important for these NPs to remain in the blood until they reach their therapeutic target to achieve the desired effect; the quicker the clearance of drugs from the body, the shorter is the residence time of drugs in the body, which eventually reduces drug efficacy. Macrophage uptake is a major mechanism for clearance of NPs from the body, so, reducing the degree of macrophage uptake is a major challenge in drug-delivery systems. Original studies of HSA NP uptake by macrophages showed that denatured HSA and HSA NPs synthesized with 80% (v/v) ethanol showed a high degree of macrophage uptake. We found that HSA NPs synthesized with lower ethanol content at pH 7 showed lower macrophage uptake in in vitro macrophage cellular uptake experiments. The effects of the preparation parameters of ethanol concentration, pH, and glutaraldehyde on the macrophage uptake of NPs were thoroughly studied. This newly developed protein NP with lower macrophage uptake has potential application as a drug carrier for many delivery systems.

Programming of Influenza Vaccine Broadness and Persistence by Mucoadhesive Polymer-Based Adjuvant Systems.

The development of an anti-influenza vaccine with the potential for cross-protection against seasonal drift variants as well as occasionally emerging reassortant viruses is essential. In this study, we successfully generated a novel anti-influenza vaccine system combining conserved matrix protein 2 (sM2) and stalk domain of hemagglutinin (HA2) fusion protein (sM2HA2) and poly-γ-glutamic acid (γ-PGA)-based vaccine adjuvant systems that can act as a mucoadhesive delivery vehicle of sM2HA2 as well as a robust strategy for the incorporation of hydrophobic immunostimulatory 3-O-desacyl-4'-monophosphoryl lipid A (MPL) and QS21. Intranasal coadministration of sM2HA2 and the combination adjuvant γ-PGA/MPL/QS21 (CA-PMQ) was able to induce a high degree of protective mucosal, systemic, and cell-mediated immune responses. The sM2HA2/CA-PMQ immunization was able to prevent disease symptoms, confering complete protection against lethal infection with divergent influenza subtypes (H5N1, H1N1, H5N2, H7N3, and H9N2) that lasted for at least 6 mo. Therefore, our data suggest that mucosal administration of sM2HA2 in combination with CA-PMQ could be a potent strategy for a broad cross-protective influenza vaccine, and CA-PMQ as a mucosal adjuvant could be used for effective mucosal vaccines.

RAP80 regulates epithelial-mesenchymal transition related with metastasis and malignancy of cancer.

Epithelial-mesenchymal transition (EMT) has been closely related with invasive and metastatic properties of cancer. Recently, the convergence of DNA damage response and EMT in cancer development has received a great amount of scientific attention. Here, we showed that EMT is induced by the downregulation of RAP80, a well-known regulator for DNA damage response. The knockdown of RAP80 leads to EMT-like morphological changes and the increase of tumor sphere formation in non-adhesive culture. Mechanistically, RAP80 controls a reciprocal regulatory axis of ZEB1 (for EMT activation) and miR200c (for EMT inhibition). The downregulation of RAP80 increases ZEB1 protein and decreases miR200c expression to activate EMT signaling in the form of drastic inhibitions of E-cadherin, p16 and p21 expression. Using in vivo metastasis analysis, RAP80 knockdown cells are shown to dramatically metastasize into the lung and generate more malignant phenotype compared to controls. Interestingly, the expression level of RAP80 was positively correlated with the survival rate in lung adenocarcinoma and breast cancer patients. These findings indicate that RAP80 is a critical gatekeeper in impeding EMT-induced metastasis and malignant phenotypes of cancer as well as preserving DNA integrity.

Injectable and Pathogen-Mimicking Hydrogels for Enhanced Protective Immunity against Emerging and Highly Pathogenic Influenza Virus.

Seasonal emerging infectious diseases such as influenza A impose substantial risk and need new translational strategies to achieve active immunomodulation. Here, a novel injectable pathogen-mimicking hydrogel (iPMH) that can enhance both cellular and humoral immune responses is suggested. By the help of poly(γ-glutamic acid) that has abundant carboxylate groups and dispersion helper function, hydrophobic immunostimulatory 3-O-desacyl-4'-monophosphoryl lipid A (MPLA) molecules and viral antigens (PR8, W150) can be successfully combined as pathogen-mimicking adjuvants. Polyelectrolyte complex between the poly(γ-glutamic acid)-based adjuvants and collagens generate in situ gel-forming hydrogel at physiological temperature. When the iPMH are immunized, they act as a pathogen-mimicking (MPLA, H1N1, H5N1) immune priming center and a depot for continuous stimulation of immune system, resulting in the induction of high levels (8.5 times higher) of antigen-specific IgG titers in the sera of mice and the increased number of IFN-γ-producing cells (7.3 times higher) compared with those in the groups immunized with antigen plus clinically used aluminum gels. Following the intranasal infection of the mouse adapted virus (emerging infectious 2009 H1N1 and highly pathogenic 2006 H5N1) at 50 times the 50% lethal dose, the mice immunized with viral antigens plus iPMH exhibit 100% protective immunity against lethal virus challenge.

An Electrostatically Self-Assembled Ternary Nanocomplex as a Non-Viral Vector for the Delivery of Plasmid DNA into Human Adipose-Derived Stem Cells.

In this study, we developed electrostatically self-assembled ternary nanocomplexes as a safe and effective non-viral vector for the delivery of plasmid DNA (pDNA) into human adipose-derived stem cells (hASCs). Although polyethylenimine (PEI) polymers initially showed excellent performance as gene delivery carriers, their broad use has been limited by cytotoxicity resulting from their strong positive charge. To reduce the cytotoxicity, we utilized anionic hyaluronic acid (HA) as a corona layer material for pDNA/PEI binary nanocomplexes. HA was also introduced to increase the targeting efficiency of pDNA/PEI nanocomplexes because HA has can bind CD44 that is highly expressed on the surface of hASCs. We confirmed that the addition of HA changed the surface charge of pDNA/PEI nanocomplexes from positive to negative. The pDNA/PEI/HA ternary nanocomplexes showed high transfection efficiency and low cytotoxicity compared with commercially available products. When hASCs were pretreated with HA to passivate CD44, the transfection efficiency of pDNA/PEI/HA nanocomplexes was significantly reduced. These results suggest that HA that can act as a targeting ligand to CD44 contributed to the improved transfection of pDNA into hASCs. Our novel pDNA/PEI/HA nanocomplexes may be used as an effective non-viral pDNA delivery system for hASCs.

Evaluation of the novel near-infrared fluorescence tracers pullulan polymer nanogel and indocyanine green/γ-glutamic acid complex for sentinel lymph node navigation surgery in large animal models.

BACKGROUND: This study aimed to examine tracers designed to overcome the disadvantages of indocyanine green (ICG), which disperses quickly to multiple lymph nodes, using a near-infrared (NIR) imaging system in animal models. METHODS: Diluted ICG, ICG/poly-γ-glutamic acid (PGA) complex, and IRDye900-conjugated pullulan-cholesterol nanoprobe "near-infrared polynagogel" (NIR-PNG) were injected into the stomachs of dogs and pigs, and the patterns of dispersion were observed using an NIR imaging system. To compare retention times, fluorescence signals were evaluated in the stomach and small bowel of animals 1 week after injection. RESULTS: A diluted concentration (~0.1 mg/ml) of ICG was optimal for NIR imaging compared with the conventional concentration (5 mg/ml) for visual inspection. When injected into the stomach, the signals of ICG and ICG/PGA complex were relatively large at the injection site, and signals were detected at multiple sentinel nodes and lymph nodes beyond them. The NIR-PNG signal intensity was relatively small at the injection site and limited to only one sentinel node with no additional node. When evaluated 1 week after injection, only the NIR-PNG signal was detected in the canine stomach, and the signal intensity at the lymph nodes of the porcine small bowel was the highest with NIR-PNG, followed by ICG/PGA complex and finally ICG. CONCLUSION: NIR-PNG showed the best characteristics of less dispersion and longer retention in the sentinel nodes, and ICG/PGA complex remained longer than diluted ICG. These tracers could potentially be used as optimal tracers for sentinel node navigation surgery in gastric cancer.

Indocyanine green as a near-infrared fluorescent agent for identifying parathyroid glands during thyroid surgery in dogs.

BACKGROUND: Surgical procedures involving the thyroid gland require identification of the parathyroid glands. Indocyanine green (ICG) is a near-infrared (NIR) fluorescent contrast agent used for a variety of procedures such as intraoperative angiography, extrahepatic cholangiography, and lymph node mapping. In this study, we used a canine model to evaluate ICG for NIR fluorescent imaging of the parathyroid gland. METHODS: Three dogs were used for the study. The dogs were administered general anesthesia, and after surgical dissection, each dog received a series of intravenous ICG doses ranging from 12.5 to 100 µg/kg ICG. The excitation light source used to illuminate the operating field was a NIR laser (λ = 785 nm). Intravascular ICG fluorescence (λ = 835/45 nm) was recorded using a charge-coupled device that employed optical filtering to block ambient and laser light. Fluorescent imaging was assessed after injection of each dose of ICG. RESULTS: NIR fluorescent imaging visualized the parathyroid glands. The intensity curves showing the peak and plateau of fluorescence are similar regardless of the concentration of ICG. The time to peak fluorescent intensity was 50.2 ± 2.0 s after injection of ICG. Taking into consideration background fluorescent intensity, the estimated optimal dose of ICG was 18.75 µg/kg. At 106.7 ± 5.8 s, the parathyroid glands lost much of their fluorescence, although they remained sufficiently fluorescent to be distinguishable. There was a positive correlation of fluorescent intensity with ICG dose escalation up to 25 µg/kg. CONCLUSIONS: ICG NIR fluorescent imaging was useful in detecting the parathyroid glands of dogs. By allowing detection of parathyroid glands, the current technique shows promise for use by endocrine surgeons performing thyroidectomies.

Self-assembled polyelectrolyte nanoparticles as fluorophore-free contrast agents for multicolor optical imaging.

In this work, we describe the fabrication of self-assembled polyelectrolyte nanoparticles that provide a multicolor optical imaging modality. Poly(γ-glutamic acid)(γ-PGA) formed self-assembled nanoparticles through electrostatic interactions with two different cationic polymers: poly(L-lysine)(PLL) and chitosan. The self-assembled γ-PGA/PLL and γ-PGA/chitosan nanoparticles were crosslinked by glutaraldehyde. Crosslinking of the ionic self-assembled nanoparticles with glutaraldehyde not only stabilized the nanoparticles but also generated a strong autofluorescence signal. Fluorescent Schiff base bonds (C=N) and double bonds (C=C) were generated simultaneously by crosslinking of the amine moiety of the cationic polyelectrolytes with monomeric glutaraldehyde or with polymeric glutaraldehyde. The unique optical properties of the nanoparticles that resulted from the crosslinking by glutaraldehyde were analyzed using UV/Vis and fluorescence spectroscopy. We observed that the fluorescence intensity of the nanoparticles could be regulated by adjusting the crosslinker concentration and the reaction time. The nanoparticles also exhibited high performance in the labeling and monitoring of therapeutic immune cells (macrophages and dendritic cells). These self-assembled nanoparticles are expected to be a promising multicolor optical imaging contrast agent for the labeling, detection, and monitoring of cells.

Multivalent Polymer Nanocomplex Targeting Endosomal Receptor of Immune Cells for Enhanced Antitumor and Systemic Memory Response.

We have designed and synthesized linear polymer-based nanoconjugates and nanocomplexes bearing multivalent immunostimulatory ligands and also demonstrated that the synthetic multivalent nanocomplexes led to an enhanced stimulation of immune cells in vitro and antitumor and systemic immune memory response in vivo. We have developed hyaluronic acid (HA)-based multivalent nanoconjugates and nanocomplexes for enhanced immunostimulation through the combination of multivalent immune adjuvants with CpG ODNs (as a TLR9 ligand) and cationic poly(L-lysine) (PLL; for the enhancement of cellular uptake). The multivalent HA-CpG nanoconjugate efficiently stimulated the antigen-presenting cells and the multivalent PLL/HA-CpG nanocomplex also led to an enhanced cellular uptake as well as continuous stimulation of endosomal TLR9. The mice vaccinated with dendritic cells treated with the multivalent nanocomplex exhibited tumor growth inhibition as well as a strong antitumor memory response.

Targeted theranostic nanoparticles: receptor-mediated entry into cells, pH-induced signal generation and cytosolic delivery.

Virus-like theranostic nanoparticles: virus-like poly(amino acid) nanoparticles are synthesized that can be internalized via receptor-mediated endocytosis, resulting in encapsulated pH-activatable fluorescence probes that can be turned on in acidic environments but otherwise remain undetectable. The encapsulated anticancer drugs are also released into cytosol by endosome disruption.

In vivo imaging of islet transplantation using PLGA nanoparticles containing iron oxide and indocyanine green.

PURPOSE: We determined whether poly(lactic-co-glycolic acid) nanoparticles would be a useful reagent for the successful monitoring of isolated islets by magnetic resonance imaging and optical imaging systems, without clinically relevant toxicity in vitro or in vivo. METHODS: We used iron oxide for MR imaging and a cyanide dye approved by the Food and Drug Administration (indocyanine green) for optical imaging and estimated the in vivo detection of transplanted pancreatic islets. RESULTS: The poly(lactic-co-glycolic acid) nanoparticles were associated with the islets in vitro and were successfully detected by 4.7 T (MR) and optical imaging, without other toxic effects. When labeled islets were transplanted under the mouse kidney capsule, in vivo T2/ T2*-weighted scans with 4.7 T MR detected as few as 300 labeled islets by 4 weeks. Optical in vivo imaging revealed indocyanine green fluorescence by 2 and 4 days after transplantation of islets containing 250 and 500 µg/mL poly(lactic-co-glycolic acid) nanoparticles, respectively. These results were further supported by the immunohistochemical results for insulin and iron in the recipient mouse kidney and pancreas. CONCLUSIONS: Taken together, these data indicate that poly(lactic-co-glycolic acid) nanoparticles may be used to label transplanted islets and may be imaged with in vivo MR and optical imaging systems.

Molecular Masking of Synthetic Immunomodulator Evokes Antitumor Immunity With Reduced Immune Tolerance and Systemic Toxicity by Temporal Activity Recovery and Sustained Stimulation.

Activation of the innate immune system counteracts tumor-induced immunosuppression. Hence, small molecule-based toll-like receptor 7/8 agonists (TLR7/8a), which can modulate immunosuppression in the tumor microenvironment along with the activation of innate immunity, are emerging as essential components of cancer immunotherapy. However, the clinical application of synthetic TLR7/8a therapies is limited by systemic immune-associated toxicity and immune tolerance induced by uncontrolled stimulatory activities and repeated treatments. To address these limitations, a dynamic immunomodulation strategy incorporating masking and temporal recovery of the activity of TLR7/8a through prodrug-like TLR7/8a (pro-TLR7/8a) at the molecular level and a sustained and controlled release of active TLR7/8a from nanoliposome (pro-TLR7/8a) (NL(pro-TLR7/8)) in a macroscale depot are designed. Immunization with cationic NL(pro-TLR7/8) and anionic antigens triggers robust activation of innate immune cells as well as antigen-specific T cell responses, eliciting reprogramming of immunosuppressive cells into tumor-suppressive cells, with decreased systemic adverse effects and immune tolerance. Combination treatment with NL(pro-TLR7/8a) and immune checkpoint inhibitors (anti-CTLA-4 plus anti-PD-L1) or nanoliposomes (Doxorubicin) has synergistic effects on antitumor immunity in various tumor models. The concept of pro-TLR7/8a suggested herein may facilitate the advancement of small-molecule-based immunomodulators for clinical translation and safe and effective cancer immunotherapy.

A biospecies-derived genomic DNA hybrid gel electrolyte for electrochemical energy storage.

Intrinsic impediments, namely weak mechanical strength, low ionic conductivity, low electrochemical performance, and stability have largely inhibited beyond practical applications of hydrogels in electronic devices and remains as a significant challenge in the scientific world. Here, we report a biospecies-derived genomic DNA hybrid gel electrolyte with many synergistic effects, including robust mechanical properties (mechanical strength and elongation of 6.98 MPa and 997.42%, respectively) and ion migration channels, which consequently demonstrated high ionic conductivity (73.27 mS/cm) and superior electrochemical stability (1.64 V). Notably, when applied to a supercapacitor the hybrid gel-based devices exhibit a specific capacitance of 425 F/g. Furthermore, it maintained rapid charging/discharging with a capacitance retention rate of 93.8% after ∼200,000 cycles while exhibiting a maximum energy density of 35.07 Wh/kg and a maximum power density of 193.9 kW/kg. This represents the best value among the current supercapacitors and can be immediately applied to minicars, solar cells, and LED lightning. The widespread use of DNA gel electrolytes will revolutionize human efforts to industrialize high-performance green energy.

Bioconjugated Antibody-Trojan Immune Converter Enhance Cancer Immunotherapy with Minimized Toxicity by Programmed Two-Step Immunomodulation of Myeloid Cells.

Current immune checkpoint blockade therapy (ICBT) predominantly targets T cells to harness the antitumor effects of adaptive immune system. However, the effectiveness of ICBT is reduced by immunosuppressive innate myeloid cells in tumor microenvironments (TMEs). Toll-like receptor 7/8 agonists (TLR7/8a) are often used to address this problem because they can reprogram myeloid-derived suppressor cells (MDSCs) and tumor-associated M2 macrophages, and boost dendritic cell (DC)-based T-cell generation; however, the systemic toxicity of TLR7/8a limits its clinical translation. Here, to address this limitation and utilize the effectiveness of TLR7/8a, this work suggests a programmed two-step activation strategy via Antibody-Trojan Immune Converter Conjugates (ATICC) that specifically targets myeloid cells by anti-SIRPα followed by reactivation of transiently inactivated Trojan TLR7/8a after antibody-mediated endocytosis. ATICC blocks the CD47-SIRPα ("don't eat me" signal), enhances phagocytosis, reprograms M2 macrophages and MDSCs, and increases cross-presentation by DCs, resulting in antigen-specific CD8+ T-cell generation in tumor-draining lymph nodes and TME while minimizing systemic toxicity. The local or systemic administration of ATICC improves ICBT responsiveness through reprogramming of the immunosuppressive TME, increased infiltration of antigen-specific CD8+ T cells, and antibody-dependent cellular phagocytosis. These results highlight the programmed and target immunomodulation via ATICC could enhance cancer immunotherapy with minimized systemic toxicities.

Noninvasive assessment of myocardial inflammation by cardiovascular magnetic resonance in a rat model of experimental autoimmune myocarditis.

BACKGROUND: Limited availability of noninvasive and biologically precise diagnostic tools poses a challenge for the evaluation and management of patients with myocarditis. METHODS AND RESULTS: The feasibility of cardiovascular magnetic resonance (CMR) imaging with magneto-fluorescent nanoparticles (MNPs) for detection of myocarditis and its effectiveness in discriminating inflammation grades were assessed in experimental autoimmune myocarditis (EAM) (n=65) and control (n=10) rats. After undergoing CMR, rats were administered with MNPs, followed by a second CMR 24 hours later. Head-to-head comparison of MNP-CMR with T(2)-weighted, early and late gadolinium enhancement CMR was performed in additional EAM (n=10) and control (n=5) rats. Contrast-to-noise ratios were measured and compared between groups. Flow cytometry and microscopy demonstrated that infiltrating inflammatory cells engulfed MNPs, resulting in altered myocardial T(2)* effect. Changes in contrast-to-noise ratio between pre- and post-MNP CMR were significantly greater in EAM rats (1.08 ± 0.10 versus 0.48 ± 0.20; P<0.001). In addition, contrast-to-noise ratio measurement in MNP-CMR clearly detected the extent of inflammation (P<0.001) except for mild inflammation. Compared with conventional CMR, MNP-CMR provided better image contrast (CNR change 8% versus 46%, P<0.001) and detectability of focal myocardial inflammation. Notably, MNP-CMR successfully tracked the evolution of myocardial inflammation in the same EAM rats. CONCLUSIONS: Magneto-fluorescent nanoparticle CMR permitted effective visualization of myocardial inflammatory cellular infiltrates and distinction of the extent of inflammation compared with conventional CMR in a preclinical model of EAM. Magneto-fluorescent nanoparticle CMR performs best in EAM rats with at least moderate inflammatory response.

Biodegradable microparticles with surface dimples as a bi-modal imaging contrast agent.

Fabrication of physically engineered colloids and their application to the biological fields is emerging importance because of their potential to provide an enhanced performance without altering the chemical properties of biomaterials used. A facile approach is reported to fabricate sub-10-µm-sized PLGA microparticle with small dimples covering the surface by droplet imprinting. Optical and magnetic resonance bioimaging agents are easily co-encapsulated inside the microparticles to obtain a bi-modal imaging agent. Cell internalization efficacy of dimpled particles in DC 2.4 cell is enhanced compared with conventional smooth round-shaped colloids. Our result indicates that morphology-controlled microparticles show promise as a cell labeling with improved cell interaction.