Biointerface engineering nanoplatforms for cancer-targeted drug delivery

Nature's carriers: leveraging extracellular vesicles for targeted drug delivery

With the rapid development of drug delivery systems, extracellular vesicles (EVs) have emerged as promising stars for improving targeting abilities and realizing effective delivery. Numerous studies have shown when compared to conventional strategies in targeted drug delivery (TDD), EVs-based strategies have several distinguished advantages besides targeting, such as participating in cell-to-cell communications and immune response, showing high biocompatibility and stability, penetrating through biological barriers, etc. In this review, we mainly focus on the mass production of EVs including the challenges and strategies for scaling up EVs production in a cost-effective and reproducible manner, the loading and active targeting methods, and examples of EVs as vehicles for TDD in consideration of potential safety and regulatory issues associated. We also conclude and discuss the rigor and reproducibility of EVs production, the current research status of the application of EVs-based strategies to targeted drug delivery, clinical conversion prospects, and existing chances and challenges.

A minimalist cancer cell membrane-shielded biomimetic nanoparticle for nasopharyngeal carcinoma active-targeting therapy

Nasopharyngeal carcinoma (NPC) is a common head and neck malignancy, which is characterized by high incidence and aggression with poor diagnosis and limited therapeutic opportunity. The innovative strategy for achieving precise NPC active-targeting drug delivery has emerged as a prominent focus in clinical research. Here, a minimalist cancer cell membrane (CCM) shielded biomimetic nanoparticle (NP) was designed for NPC active-targeting therapy. Chemotherapeutant model drug doxorubicin (DOX) was loaded in polyamidoamine (PAMAM) dendrimer. The PAMAM/DOX (PD) NP was further shielded by human CNE-2 NPC CCM. Characterization results verified that the biomimetic PAMAM/DOX@CCM (abbreviated as PDC) NPs had satisfactory physical properties with high DOX-loading and excellent stability. Cell experiments demonstrated that the CNE-2 membrane-cloaked PDC NPs presented powerful cellular uptake in the sourcing cells by homologous targeting and adhesive interaction. Further in vivo results confirmed that this biomimetic nanoplatform had extended circulation and remarkable tumor-targeting capability, and the PDC NPs effectively suppressed the progression of CNE-2 tumors by systemic administration. This CCM-shielded biomimetic NP displayed a minimalist paradigm nanoplatform for precise NPC therapy, and the strategy of CCM-shielded biomimetic drug delivery system (DDS) has great potential for extensive cancer active-targeting therapy.

Effect of zwitterionic sulfobetaine incorporation on blood behaviours, phagocytosis, and in vivo biodistribution of pH-responsive micelles with positive charges

pH-responsive micelles with positive charges are challenged by their significant effect on the cells/proteins and compromise their final fate due to electrostatic interactions. As one of the promising strategies, zwitterion incorporation in micelles has attracted considerable attention and displayed improved protein adsorption and blood circulation performances. However, previous reports in this field have been mostly limited in hemolysis for studying blood behaviour and lack a comprehensive understanding of their interactions with blood components. Herein, we present a prelimilary study on the effect of zwitterionic sulfobetaine incorporation on blood behaviour, phagocytosis, and in vivo biodistribution of pH-responsive micelles with positive charges. Amphiphilic triblock copolymers, namely poly(ε-caprolactone)-b-poly(N,N-diethylaminoethyl methacrylate)-(N-(3-sulfopropyl-N-methacryloxyethy-N,N-diethylammonium betaine)) (PCL-PDEAPSx, x = 2, 6, 10), containing different numbers of sulfobetaine groups were synthesized through four steps to prepare the pH-responsive micelles with positive charges. The effect of the sulfobetaine incorporation displayed different profiles, e.g., the micelles had no effect on RBC aggregation, thrombin time (TT), and platelet aggregation, while the cytotoxicity, hemolysis, RBC deformability, activated partial thromboplastin time (APTT), prothrombin time (PT), platelet activation, protein (albumin, fibrinogen, plasma) adsorption, phagocytosis, and in vivo biodistribution decreased with the increase in the sulfobetaine number, in which the transition mainly occurred at a sulfobetaine/tertiary amine group ratio of 3/7-1/1 compared to that of the mPEG control. In addition, the micelles displayed a strong inhibitory effect on the intrinsic coagulation pathway, which was associated with a significant decrease in the coagulation factor activity. Based on these findings, the related mechanism is discussed and proposed, which can aid the rational design of pH-responsive micelles for improved therapeutics.

Recent advances in zwitterionic nanoscale drug delivery systems to overcome biological barriers

Nanoscale drug delivery systems (nDDS) have been employed widely in enhancing the therapeutic efficacy of drugs against diseases with reduced side effects. Although several nDDS have been successfully approved for clinical use up to now, biological barriers between the administration site and the target site hinder the wider clinical adoption of nDDS in disease treatment. Polyethylene glycol (PEG)-modification (or PEGylation) has been regarded as the gold standard for stabilising nDDS in complex biological environment. However, the accelerated blood clearance (ABC) of PEGylated nDDS after repeated injections becomes great challenges for their clinical applications. Zwitterionic polymer, a novel family of anti-fouling materials, have evolved as an alternative to PEG due to their super-hydrophilicity and biocompatibility. Zwitterionic nDDS could avoid the generation of ABC phenomenon and exhibit longer blood circulation time than the PEGylated analogues. More impressively, zwitterionic nDDS have recently been shown to overcome multiple biological barriers such as nonspecific organ distribution, pressure gradients, impermeable cell membranes and lysosomal degradation without the need of any complex chemical modifications. The realization of overcoming multiple biological barriers by zwitterionic nDDS may simplify the current overly complex design of nDDS, which could facilitate their better clinical translation. Herein, we summarise the recent progress of zwitterionic nDDS at overcoming various biological barriers and analyse their underlying mechanisms. Finally, prospects and challenges are introduced to guide the rational design of zwitterionic nDDS for disease treatment.

A Novel Combined Dry Powder Inhaler Comprising Nanosized Ketoprofen-Embedded Mannitol-Coated Microparticles for Pulmonary Inflammations: Development, In Vitro-In Silico Characterization, and Cell Line Evaluation

Pulmonary inflammations such as chronic obstructive pulmonary disease and cystic fibrosis are widespread and can be fatal, especially when they are characterized by abnormal mucus accumulation. Inhaled corticosteroids are commonly used for lung inflammations despite their considerable side effects. By utilizing particle engineering techniques, a combined dry powder inhaler (DPI) comprising nanosized ketoprofen-embedded mannitol-coated microparticles was developed. A nanoembedded microparticle system means a novel advance in pulmonary delivery by enhancing local pulmonary deposition while avoiding clearance mechanisms. Ketoprofen, a poorly water-soluble anti-inflammatory drug, was dispersed in the stabilizer solution and then homogenized by ultraturrax. Following this, a ketoprofen-containing nanosuspension was produced by wet-media milling. Furthermore, co-spray drying was conducted with L-leucine (dispersity enhancer) and mannitol (coating and mucuactive agent). Particle size, morphology, dissolution, permeation, viscosity, in vitro and in silico deposition, cytotoxicity, and anti-inflammatory effect were investigated. The particle size of the ketoprofen-containing nanosuspension was ~230 nm. SEM images of the spray-dried powder displayed wrinkled, coated, and nearly spherical particles with a final size of ~2 µm (nano-in-micro), which is optimal for pulmonary delivery. The mannitol-containing samples decreased the viscosity of 10% mucin solution. The results of the mass median aerodynamic diameter (2.4-4.5 µm), fine particle fraction (56-71%), permeation (five-fold enhancement), and dissolution (80% release in 5 min) confirmed that the system is ideal for local inhalation. All samples showed a significant anti-inflammatory effect and decreased IL-6 on the LPS-treated U937 cell line with low cytotoxicity. Hence, developing an innovative combined DPI comprising ketoprofen and mannitol by employing a nano-in-micro approach is a potential treatment for lung inflammations.

A multifunctional integrated biomimetic spore nanoplatform for successively overcoming oral biological barriers

The biological barriers have seriously restricted the efficacious responses of oral delivery system in diseases treatment. Utilizing a carrier based on the single construction means is hard to overcome these obstacles simultaneously because the complex gastrointestinal tract environment requires carrier to have different or even contradictory properties. Interestingly, spore capsid (SC) integrates many unique biological characteristics, such as high resistance, good stability etc. This fact offers a boundless source of inspiration for the construction of multi-functional oral nanoplatform based on SC without further modification. Herein, we develop a type of biomimetic spore nanoplatform (SC@DS NPs) to successively overcome oral biological barriers. Firstly, doxorubicin (DOX) and sorafenib (SOR) are self-assembled to form carrier-free nanoparticles (DS NPs). Subsequently, SC is effectively separated from probiotic spores and served as a functional vehicle for delivering DS NPs. As expect, SC@DS NPs can efficaciously pass through the rugged stomach environment after oral administration and further be transported to the intestine. Surprisingly, we find that SC@DS NPs exhibit a significant improvement in the aspects of mucus penetration and transepithelial transport, which is related to the protein species of SC. This study demonstrates that SC@DS NPs can efficiently overcome multiple biological barriers and improve the therapeutic effect.

Biomimetic Nanoparticles Loaded with Ulinastatin for the Targeted Treatment of Acute Pancreatitis

Ulinastatin is commonly used in the clinic to treat acute pancreatitis (AP), but its therapeutic effect was limited by the presence of the blood-pancreas barrier (BPB) and low specificity. Here, we prepared a macrophage biomimetic nanoparticle (MU) that delivered ulinastatin to address the above issues. Macrophage membrane was used as a shell for a mixture of PEG-PLGA and ulinastatin. It was found that MU showed good stability and biocompatibility in vitro and in vivo. According to in vivo fluorescence imaging, MU displayed a great inflammation targeting effect both in a subcutaneous inflammation model and in situ pancreatitis mouse model, which was ascribed to the presence of adhesion proteins. In vitro and in vivo results demonstrated that MU have a superior AP treatment effect by inhibiting pro-inflammatory factors and keeping cells viability. It was suggested the MU could provide a new strategy for targeted AP treatment.

Polymer Nanoantidotes

Intoxication is one of the most common causes of accidental death globally. Although some antidotes capable of neutralizing the toxicity of certain xenobiotics have become well established, the current reality is that clinicians primarily rely on nonspecific extracorporeal techniques to remove toxins. Nano-intervention strategies in which nanoantidotes neutralize toxicity in situ via physical interaction, chemical bonding, or biomimetic clearance have begun to show clinical potential. However, most nanoantidotes remain in the proof-of-concept stage, and the difficulty of constructing clinical relevance models and the unclear pharmacokinetics of nanoantidotes hinder their translation to clinic. This Concept reviews the detoxification mechanisms of polymer nanoantidotes and predicts the opportunities and challenges associated with their clinical application.

Biomimetic and bioinspired nano-platforms for cancer vaccine development

The advent of immunotherapy has revolutionized the treating modalities of cancer. Cancer vaccine, aiming to harness the host immune system to induce a tumor-specific killing effect, holds great promises for its broad patient coverage, high safety, and combination potentials. Despite promising, the clinical translation of cancer vaccines faces obstacles including the lack of potency, limited options of tumor antigens and adjuvants, and immunosuppressive tumor microenvironment. Biomimetic and bioinspired nanotechnology provides new impetus for the designing concepts of cancer vaccines. Through mimicking the stealth coating, pathogen recognition pattern, tissue tropism of pathogen, and other irreplaceable properties from nature, biomimetic and bioinspired cancer vaccines could gain functions such as longstanding, targeting, self-adjuvanting, and on-demand cargo release. The specific behavior and endogenous molecules of each type of living entity (cell or microorganism) offer unique features to cancer vaccines to address specific needs for immunotherapy. In this review, the strategies inspired by eukaryotic cells, bacteria, and viruses will be overviewed for advancing cancer vaccine development. Our insights into the future cancer vaccine development will be shared at the end for expediting the clinical translation.

Immune-regulating camouflaged nanoplatforms: A promising strategy to improve cancer nano-immunotherapy

Although nano-immunotherapy has advanced dramatically in recent times, there remain two significant hurdles related to immune systems in cancer treatment, such as (namely) inevitable immune elimination of nanoplatforms and severely immunosuppressive microenvironment with low immunogenicity, hampering the performance of nanomedicines. To address these issues, several immune-regulating camouflaged nanocomposites have emerged as prevailing strategies due to their unique characteristics and specific functionalities. In this review, we emphasize the composition, performances, and mechanisms of various immune-regulating camouflaged nanoplatforms, including polymer-coated, cell membrane-camouflaged, and exosome-based nanoplatforms to evade the immune clearance of nanoplatforms or upregulate the immune function against the tumor. Further, we discuss the applications of these immune-regulating camouflaged nanoplatforms in directly boosting cancer immunotherapy and some immunogenic cell death-inducing immunotherapeutic modalities, such as chemotherapy, photothermal therapy, and reactive oxygen species-mediated immunotherapies, highlighting the current progress and recent advancements. Finally, we conclude the article with interesting perspectives, suggesting future tendencies of these innovative camouflaged constructs towards their translation pipeline.

Insights into Lipid-Based Delivery Nanosystems of Protein-Tyrosine Kinase Inhibitors for Cancer Therapy

According to the WHO, cancer caused almost 10 million deaths worldwide in 2020, i.e., almost one in six deaths. Among the most common are breast, lung, colon and rectal and prostate cancers. Although the diagnosis is more perfect and spectrum of available drugs is large, there is a clear trend of an increase in cancer that ends fatally. A major advance in treatment was the introduction of gentler antineoplastics for targeted therapy-tyrosine kinase inhibitors (TKIs). Although they have undoubtedly revolutionized oncology and hematology, they have significant side effects and limited efficacy. In addition to the design of new TKIs with improved pharmacokinetic and safety profiles, and being more resistant to the development of drug resistance, high expectations are placed on the reformulation of TKIs into various drug delivery lipid-based nanosystems. This review provides an insight into the history of chemotherapy, a brief overview of the development of TKIs for the treatment of cancer and their mechanism of action and summarizes the results of the applications of self-nanoemulsifying drug delivery systems, nanoemulsions, liposomes, solid lipid nanoparticles, lipid-polymer hybrid nanoparticles and nanostructured lipid carriers used as drug delivery systems of TKIs obtained in vitro and in vivo.

Nanotechnology: A Promising Approach for Cancer Diagnosis, Therapeutics and Theragnosis

Cancer remains the most devastating disease and the major cause of mortality worldwide. Although early diagnosis and treatment are the key approach in fighting against cancer, the available conventional diagnostic and therapeutic methods are not efficient. Besides, ineffective cancer cell selectivity and toxicity of traditional chemotherapy remain the most significant challenge. These limitations entail the need for the development of both safe and effective cancer diagnosis and treatment options. Due to its robust application, nanotechnology could be a promising method for in-vivo imaging and detection of cancer cells and cancer biomarkers. Nanotechnology could provide a quick, safe, cost-effective, and efficient method for cancer management. It also provides simultaneous diagnosis and treatment of cancer using nano-theragnostic particles that facilitate early detection and selective destruction of cancer cells. Updated and recent discussions are important for selecting the best cancer diagnosis, treatment, and management options, and new insights on designing effective protocols are utmost important. This review discusses the application of nanotechnology in cancer diagnosis, therapeutics, and theragnosis and provides future perspectives in the field.

Poly(ε-Caprolactone)-Methoxypolyethylene Glycol (PCL-MPEG)-Based Micelles for Drug-Delivery: The Effect of PCL Chain Length on Blood Components, Phagocytosis, and Biodistribution

Background

The main challenge of polymeric micelles as drug delivery systems is that the actual delivery efficiency is not as high as expected, which is closely related with the interactions with the complex biological environments such as blood components, phagocytosis, and biodistribution. Herein, we expect to understand these concerns for the clinically relevant micelles that composed of methoxypolyethylene glycol (MPEG) with identical chain length And poly(ε-caprolactone) (PCL) with tunable chain length (PCLn-MPEG) (n=20, 30, and 40) wherein doxorubicin was encapsulated as a model drug.

Methods

The doxorubicin-loaded PCLn-MPEG micelles were prepared by a dialysis method and characterized by dynamic light scattering and transmission electron microscopy. The surface PEG density and chain conformation were investigated by dissipative particle dynamics simulation. The stability of the micelles was detected by nanoparticle tracking analysis. The effects of PCL chain length on the blood components, phagocytosis, and biodistribution were assayed in vitro and in vivo.

Results

The micelles exhibited spherical morphology with a diameter about 30nm. The PEG chain conformation from "mushroom-like" to "brush-like" was evident. The micelles have no remarkable effect on the red blood cells, blood coagulation, and platelet activation. Interestingly, the protein adsorption was affected and dependent on the chain conformation, with lowest adsorption for PCL30-MPEG, which also has the loWest phagocytosis. The stability of the micelles was in the order of PCL40-MPEG>PCL30-MPEG>PCL20-MPEG which was dependent on the PCL chain length. The micelles mainly accumulated in liver, with the order consistent with their stability, indicating that, besides the phagocytosis, the stability of the micelle plays an important role in biodistribution as well. The related mechanisms were proposed and discussed.

Conclusion

Manipulating the PEG/PCL ratio of the micelle is an effective approach to modulate the protein adsorption, phagocytosis, and biodistribution, which may be a prerequisite for clinical applications.

Aptamer Nanomaterials for Ovarian Cancer Target Theranostics

Ovarian cancer is among the leading causes of gynecological cancer-related mortality worldwide. Early and accurate diagnosis and an effective treatment strategy are the two primary means of improving the prognosis of patients with ovarian cancer. The development of targeted nanomaterials provides a potentially efficient strategy for ovarian cancer theranostics. Aptamer nanomaterials have emerged as promising nanoplatforms for accurate ovarian cancer diagnosis by recognizing relevant biomarkers in the serum and/or on the surface of tumor cells, as well as for effective ovarian cancer inhibition via target protein blockade on tumor cells and targeted delivery of various therapeutic agents. In this review, we summarize recent advances in aptamer nanomaterials as targeted theranostic platforms for ovarian cancer and discusses the challenges and opportunities for their clinical application. The information presented in this review represents a valuable reference for creation of a new generation of aptamer nanomaterials for use in the precise detection and treatment of ovarian cancer.

Engineered mesenchymal stem cell-derived exosomes with high CXCR4 levels for targeted siRNA gene therapy against cancer

Gene therapy has been used in a variety of diseases and shows brilliant anticancer or cancer suppression effects. Gene therapy is gradually evolving as the most compelling frontier hotspot in the field of cancer therapy. The current vehicles used in gene therapy have poor safety and low delivery efficiency, and thus, it is urgent to develop novel delivery vehicles for gene therapy. Due to the excellent stability and biosafety of exosomes, their use as drug carriers for novel nucleic acid therapy is in full swing, revealing huge prospects for clinical application. Mesenchymal stem cells (MSCs) have a natural homing property and can spontaneously accumulate at injury sites, inflammation sites, and even tumour sites. This feature is attributed to a variety of tropism factors expressed on their surface; for example, CXC chemokine receptor type 4 (CXCR4) can specifically bind to the highly expressed stromal cell derived factor-1 (SDF-1) on the tumour surface, which is essential for accumulation of MSCs at the tumour site. The mesenchymal stem cells used in this study were genetically engineered to obtain exosomes with high CXCR4 expression as carriers for targeted gene-drug delivery, and then, the Survivin gene was loaded via electrotransformation to construct a brand-new gene-drug delivery system (CXCR4^high Exo/si-Survivin). Finally, related in vivo and in vitro experiments were conducted. We observed that the new delivery system can efficiently aggregate at the tumour site and release siRNA into tumour cells, knocking down the Survivin gene in tumour cells in vivo and thereby inhibiting tumour growth. This new gene-drug delivery system has tremendous clinical transformation value and provides a new strategy for clinical treatment of tumours.

Intracellular Reduction-Responsive Molecular Targeted Nanomedicine for Hepatocellular Carcinoma Therapy

The stimuli-responsive polymer-based platform for controlled drug delivery has gained increasing attention in treating hepatocellular carcinoma (HCC) owing to the fascinating biocompatibility and biodegradability, improved antitumor efficacy, and negligible side effects recently. Herein, a disulfide bond-contained polypeptide nanogel, methoxy poly(ethylene glycol)-poly(l-phenylalanine-co-l-cystine) [mPEG-P(LP-co-LC)] nanogel, which could be responsive to the intracellular reduction microenvironments, was developed to deliver lenvatinib (LEN), an inhibitor of multiple receptor tyrosine kinases, for HCC therapy. The lenvatinib-loaded nanogel (NG/LEN) displayed concise drug delivery under the stimulus of glutathione in the cancer cells. Furthermore, the intracellular reduction-responsive nanomedicine NG/LEN showed excellent antitumor effect and almost no side effects toward both subcutaneous and orthotopic HCC tumor-allografted mice in comparison to free drug. The excellent tumor-inhibition efficacy with negligible side effects demonstrated the potential of NG/LEN for clinical molecular targeted therapy of gastrointestinal carcinoma in the future.

Recent progress of macrophage vesicle-based drug delivery systems

Nanoparticle drug delivery systems (NDDSs) are promising platforms for efficient delivery of drugs. In the past decades, many nanomedicines have received clinical approval and completed translation. With the rapid advance of nanobiotechnology, natural vectors are emerging as novel strategies to carry and delivery nanoparticles and drugs for biomedical applications. Among diverse types of cells, macrophage is of great interest for their essential roles in inflammatory and immune responses. Macrophage-derived vesicles (MVs), including exosomes, microvesicles, and those from reconstructed membranes, may inherit the chemotactic migration ability and high biocompatibility. The unique properties of MVs make them competing candidates as novel drug delivery systems for precision nanomedicine. In this review, the advantages and disadvantages of existing NDDSs and MV-based drug delivery systems (MVDDSs) were compared. Then, we summarized the potential applications of MVDDSs and discuss future perspectives. The development of MVDDS may provide avenues for the treatment of diseases involving an inflammatory process.

Recent advances on biomedical applications of bacterial outer membrane vesicles

Nanoscale and non-self-replicating outer membrane vesicles (OMVs) are naturally secreted by some bacteria with their structures and compositions similar to that of the outer membrane of parental bacteria. With some...

Enhanced Anticancer Efficacy of Chemotherapy by Amphiphilic Y-Shaped Polypeptide Micelles

Although the treatment modalities of cancers are developing rapidly, chemotherapy is still the primary treatment strategy for most solid cancers. The progress in nanotechnology provides an opportunity to upregulate the tumor suppression efficacy and decreases the systemic toxicities. As a promising nanoplatform, the polymer micelles are fascinating nanocarriers for the encapsulation and delivery of chemotherapeutic agents. The chemical and physical properties of amphiphilic co-polymers could significantly regulate the performances of the micellar self-assembly and affect the behaviors of controlled release of drugs. Herein, two amphiphilic Y-shaped polypeptides are prepared by the ring-opening polymerization of cyclic monomer l-leucine N-carboxyanhydride (l-Leu NCA) initiated by a dual-amino-ended macroinitiator poly(ethylene glycol) [mPEG-(NH2)2]. The block co-polypeptides with PLeu8 and PLeu16 segments could form spontaneously into micelles in an aqueous solution with hydrodynamic radii of 80.0 ± 6.0 and 69.1 ± 4.8 nm, respectively. The developed doxorubicin (DOX)-loaded micelles could release the payload in a sustained pattern and inhibit the growth of xenografted human HepG2 hepatocellular carcinoma with decreased systemic toxicity. The results demonstrated the great potential of polypeptide micellar formulations in cancer therapy clinically.

PEGylated Doxorubicin Prodrug-Forming Reduction-Sensitive Micelles With High Drug Loading and Improved Anticancer Therapy

Significant efforts on the design and development of advanced drug delivery systems for targeted cancer chemotherapy continue to be a major challenge. Here, we reported a kind of reduction-responsive PEGylated doxorubicin (DOX) prodrug via the simple esterification and amidation reactions, which self-assembled into the biodegradable micelles in solutions. Since there was an obvious difference in the reduction potentials between the oxidizing extracellular milieu and the reducing intracellular fluids, these PEG-disulfide-DOX micelles were localized intracellularly and degraded rapidly by the stimulus to release the drugs once reaching the targeted tumors, which obviously enhanced the therapeutic efficacy with low side effects. Moreover, these reduction-sensitive micelles could also physically encapsulate the free DOX drug into the polymeric cargo, exhibiting a two-phase programmed drug release behavior. Consequently, it showed a potential to develop an intelligent and multifunctional chemotherapeutic payload transporter for the effective tumor therapy.

Functional Nanomedicines for Targeted Therapy of Bladder Cancer

Bladder cancer is one of most common malignant urinary tract tumor types with high incidence worldwide. In general, transurethral resection of non-muscle-invasive bladder cancer followed by intravesical instillation of chemotherapy is the standard treatment approach to minimize recurrence and delay progression of bladder cancer. However, conventional intravesical chemotherapy lacks selectivity for tumor tissues and the concentration of drug is reduced with the excretion of urine, leading to frequent administration and heavy local irritation symptoms. While nanomedicines can overcome all the above shortcomings and adhere to the surface of bladder tumors for a long time, and continuously and efficiently release drugs to bladder cancers. The rapid advances in targeted therapy have led to significant improvements in drug efficacy and precision of targeted drug delivery to eradicate tumor cells, with reduced side-effects. This review summarizes the different available nano-systems of targeted drug delivery to bladder cancer tissues. The challenges and prospects of targeted therapy for bladder cancer are additionally discussed.

Nanomedicine potentiates mild photothermal therapy for tumor ablation

The booming photothermal therapy (PTT) has achieved great progress in non-invasive oncotherapy, and paves a novel way for clinical oncotherapy. Of note, mild temperature PTT (mPTT) of 42–45 °C could avoid treatment bottleneck of the traditional PTT, including nonspecific injury to normal tissues, vasculature and host antitumor immunity. However, cancer cells can resist mPTT via heat shock response and autophagy, thus leading to insufficient mPTT monotherapy to ablate tumor. To overcome the deficient antitumor efficacy caused by thermo-resistance of cancer cells and mono mPTT, synergistic therapies towards cancer cells have been conducted with mPTT. This review summarizes the recent advances in nanomedicine-potentiated mPTT for cancer treatment, including strategies for enhanced single-mode mPTT and mPTT plus synergistic therapies. Moreover, challenges and prospects for clinical translation of nanomedicine-potentiated mPTT are discussed.

Multistage targeted "Photoactive neutrophil" for enhancing synergistic photo-chemotherapy

Cell-based drug delivery system holds a great promise in anticancer treatment, due to its potential of maximizing therapeutic efficacy while minimizing adverse effects. However, current cell system can only deliver drugs in tumor lesions, but lack an ability to target subcellular locus of therapeutic actions, thereby compromising anticancer efficacy. Herein, we bioengineered living neutrophils as a novel type of "Photoactive neutrophil" (PAN) with capabilities of self-amplified multistage targeting and inflammation response for enhancing mitochondria-specific photo-chemotherapy. PAN encapsulated multifunctional nanocomplex (RA/Ce6) of RGD-apoptotic peptide conjugate (RA) decorated liposomal photosensitizer Ce6, and could overcome tumor barriers to selectively release RA/Ce6 within tumor. Consequently, RA/Ce6 actively entered cancer cells and accumulated in mitochondria to trigger combined photodynamic therapy (PDT) and RA-induced mitochondrial membrane disruption, resulting in enhanced therapeutic effects. Importantly, PAN exhibited inflammation amplified tumor targeting after PDT, and initiated combined photo-chemotherapy to suppress tumor growth without adverse effects, leading to prolonged mice survival. Therefore, PAN represents the first multistage targeted cell therapy, and brings new insights into cancer treatment.

Design and Encapsulation of Immunomodulators onto Gold Nanoparticles in Cancer Immunotherapy

The aim of cancer immunotherapy is to reactivate autoimmune responses to combat cancer cells. To stimulate the immune system, immunomodulators, such as adjuvants, cytokines, vaccines, and checkpoint inhibitors, are extensively designed and studied. Immunomodulators have several drawbacks, such as drug instability, limited half-life, rapid drug clearance, and uncontrolled immune responses when used directly in cancer immunotherapy. Several strategies have been used to overcome these limitations. A simple and effective approach is the loading of immunomodulators onto gold-based nanoparticles (GNPs). As gold is highly biocompatible, GNPs can be administered intravenously, which aids in increasing cancer cell permeability and retention time. Various gold nanoplatforms, including nanospheres, nanoshells, nanorods, nanocages, and nanostars have been effectively used in cancer immunotherapy. Gold nanostars (GNS) are one of the most promising GNP platforms because of their unusual star-shaped geometry, which significantly increases light absorption and provides high photon-to-heat conversion efficiency due to the plasmonic effect. As a result, GNPs are a useful vehicle for delivering antigens and adjuvants that support the immune system in killing tumor cells by facilitating or activating cytotoxic T lymphocytes. This review represents recent progress in encapsulating immunomodulators into GNPs for utility in a cancer immunotherapeutic regimen.

18F-ASEM Imaging for Evaluating Atherosclerotic Plaques Linked to α7-Nicotinic Acetylcholine Receptor

Background

Atherosclerosis is a chronic vascular inflammatory procedure alongside with lipid efflux disorder and foam cell formation. α7-Nicotinic acetylcholine receptor (α7nAChR) is a gated-calcium transmembrane channel widely expressed in neuron and non-neuron cells, such as monocytes and macrophages, activated T cells, dendritic cells, and mast cells. ¹⁸F-ASEM is an inhibitor targeted to α7nAChR that had been successfully applied in nervous system diseases. Previous studies had highlighted that α7nAChR was related to the emergency of vulnerable atherosclerotic plaques with excess inflammation cells. Thus, ¹⁸F-ASEM could be a complementary diagnostic approach to atherosclerotic plaques.

Materials and Methods

The synthesis of ASEM precursor and ¹⁸F-labeling had been performed successfully. We had established the ApoE^–/– mice atherosclerotic plaques model (fed with western diet) and New Zealand rabbits atherosclerotic models (balloon-sprained experiment and western diet). After damage of endothelial cells and primary plaque formation, ¹⁸F-ASEM imaging of atherosclerotic plaques linked to α7nAChR had been conducted. In vivo micro-PET/CT imaging of ApoE^–/– mice and the control group was performed 1 h after injection of ¹⁸F-ASEM (100–150 μCi); PET/CT imaging for rabbits with atherosclerotic plaques and control ones was also performed. Meanwhile, we also conducted CT scan on the abdominal aorta of these rabbits. After that, the animals were sacrificed, and the carotid and abdominal aorta were separately taken out for circular sections. The paraffin-embedded specimens were sectioned with 5 μm thickness and stained with hematoxylin–eosin (H&E) and oil red.

Results

In vivo vessel binding of ¹⁸F-ASEM and α7nAChR expression in the model group with atherosclerosis plaques was significantly higher than that in the control group. PET/CT imaging successfully identified the atherosclerotic plaques in ApoE^–/– mice and model rabbits, whereas no obvious signals were detected in normal mice or rabbits. Compared with ¹⁸F-FDG, ¹⁸F-ASEM had more significant effect on the early monitoring of inflammation in carotid atherosclerotic plaques of ApoE^–/– mice and model rabbits. ¹⁸F-ASEM had relatively more palpable effect on the imaging of abdominal aorta with atherosclerosis in rabbits. H&E and oil red staining identified the formation of atherosclerotic plaques in model animals, which provided pathological basis for the evaluation of imaging effects.

Conclusion

We first confirmed ¹⁸F-ASEM as radiotracer with good imaging properties for precise identification of atherosclerotic diseases.

Delivery of nanoparticle antigens to antigen-presenting cells: from extracellular specific targeting to intracellular responsive presentation

An appropriate delivery system can improve the immune effects of antigens against various infections or tumors. Antigen-presenting cells (APCs) are specialized to capture and process antigens in vivo, which link the innate and adaptive immune responses. Functionalization of vaccine delivery systems with targeting moieties to APCs is a promising strategy for provoking potent immune responses. Additionally, the internalization and intracellular distribution of antigens are closely related to the initiation of downstream immune responses. With a deeper understanding of the intracellular microenvironment and the mechanisms of antigen presentation, vehicles designed to respond to endogenous and external stimuli can modulate antigen processing and presentation pathways, which are critical to the types of immune response. Here, an overview of extracellular targeting delivery of antigens to APCs and intracellular stimulus-responsiveness strategies is provided, which might be helpful for the rational design of vaccine delivery systems.

Molecular Targeted Agent and Immune Checkpoint Inhibitor Co-Loaded Thermosensitive Hydrogel for Synergistic Therapy of Rectal Cancer

Molecular targeted therapy has been proved effective in treatment of rectal cancer. Up-regulated expression of programmed death ligand-1 (PD-L1) was observed after the management of molecular targeted therapy, which made the therapeutic effect discounted. Tumors with higher PD-L1 expression were more sensitive and responsive to treatment of PD-L1 inhibitor. Therefore, the combination of molecular targeted therapy and immune checkpoint blockade makes sense. In this study, the copolymers of poly (ethylene glycol)-block-poly (_L-leucine) (PEG-PLLeu) were synthesized as a thermosensitive hydrogel composite for consecutive release of regorafenib (REG) and BMS202. The mechanical properties of PEG-PLLeu were investigated, confirming that PEG-PLLeu (5 wt.%) was suitable for in situ injection as drug-delivery composite at low temperature and stable after sol-gel transition at body temperature. Importantly, the double drug loaded hydrogel showed superior antitumour activity over single drugs in an orthotopic rectal cancer model (CT26-Luc). Further analysis of the tumor tissues suggested that REG upregulated the expression of PD-L1 in tumor tissues. In addition, the immunosuppressive tumor microenvironment of CT26-Luc tumor was distinctly relieved under the effect of BMS202, as characterized by increased infiltration of CD8⁺ T cells in tumors and enhanced secretion of antitumour cytokines (IFN-γ and TNF-α). Moreover, the drug-loaded composite showed no obvious toxicity in histological analysis. Taken together, the administration of REG and BMS202 in the PEG-PLLeu composite could induce a synergistic effect in in situ treatment of rectal cancer without obvious toxicity, and thus represented a potential strategy for enhanced in situ therapeutic modality.

Loading and Releasing Behavior of Selenium and Doxorubicin Hydrochloride in Hydroxyapatite with Different Morphologies

Doxorubicin (Dox)-loaded or selenium-substituted hydroxyapatite (HA) has been developed to achieve anti-osteosarcoma or bone regeneration in a number of studies. However, currently, there is a lack of studies on the combination of Dox and selenium loading in/on HA and comparative research studies on which form and size of HA are more suitable for drug loading and release in the treatment osteogenesis after osteosarcoma resection. Herein, selenium-doped rod-shaped nano-HA (n-HA) and spherical mesoporous HA (m-HA) were successfully prepared. The doping efficiency of selenium and the Dox loading capacity of selenium-doped HA with different morphologies were studied. The release kinetics of Dox and the selenium element in phosphate-buffered saline with different pH values was also comparatively investigated. The drug loading results showed that n-HA exhibited 3 times higher selenium doping amount than m-HA, and the Dox entrapment efficiency of selenium-doped n-HA (0.1Se-n-HA) presented 20% higher than that of selenium-doped m-HA (0.1Se-m-HA). The Dox release behaviors of HA in two different morphologies showed similar release kinetics, with almost the same Dox releasing ratio but slightly more Dox releasing amount in selenium-doped HA than in HA without selenium. The selenium release from selenium-doped n-HA-D (0.1Se-n-HA-D) particles was 2 times as much as that of selenium-doped m-HA-D (0.1Se-m-HA) particles. Our study indicated that n-HA loaded with Dox and selenium may be a promising drug delivery strategy for inhibition of osteosarcoma recurrence and promoting osteogenesis simultaneously.

Schiff-Linked PEGylated Doxorubicin Prodrug Forming pH-Responsive Nanoparticles With High Drug Loading and Effective Anticancer Therapy

Developing efficacious drug delivery systems for targeted cancer chemotherapy remains a major challenge. Here we demonstrated a kind of pH-responsive PEGylated doxorubicin (DOX) prodrug via the effective esterification and Schiff base reactions, which could self-assemble into the biodegradable micelles in aqueous solutions. Owing to low pH values inside the tumor cells, these PEG-Schiff-DOX nanoparticles exhibited high drug loading ability and pH-responsive drug release behavior within the tumor cells or tissues upon changes in physical and chemical environments, but they displayed good stability at physiological conditions for a long period. CCK-8 assay showed that these PEGylated DOX prodrugs had a similar cytotoxicity to the MCF-7 tumor cells as the free DOX drug. Moreover, this kind of nanoparticle could also encapsulate small DOX drugs with high drug loading, sufficient drug release and enhanced therapeutic effects toward MCF-7 cells, which will be benefited for developing more drug carriers with desirable functions for clinical anticancer therapy.

Dual pH- and Glutathione-Responsive CO2-Generating Nanodrug Delivery System for Contrast-Enhanced Ultrasonography and Therapy of Prostate Cancer

Ultrasonography (US) contrast imaging using US contrast agents has been widely applied for the diagnosis and differential diagnosis of tumors. Commercial US contrast agents have limited applications because of their large size and shorter imaging time. At the same time, the desired therapeutic purpose cannot be achieved by applying only conventional US contrast agents. The development of nanoscale US agents with US imaging and therapeutic functions has attracted increasing attention. In this study, we successfully developed DOX-loaded poly-1,6-hexanedithiol-sodium bicarbonate nanoparticles (DOX@HADT-SS-NaHCO3 NPs) with pH-responsive NaHCO3 and GSH-responsive disulfide linkages. DOX@HADT-SS-NaHCO3 NPs underwent acid-triggered decomposition of NaHCO3 to generate CO2 bubbles and a reduction of disulfide linkages to further promote the release of CO2 and DOX. The potential of DOX@HADT-SS-NaHCO3 NPs for contrast-enhanced US imaging and therapy of prostate cancer was thoroughly evaluated using in vitro agarose gel phantoms and a C4-2 tumor-bearing nude mice model. These polymeric NPs displayed significantly enhanced US contrast at acidic pH and antitumor efficacy. Therefore, the NaHCO3 and DOX-encapsulated polymeric NPs hold tremendous potential for effective US imaging and therapy of prostate cancer.

The Availability of the α7-Nicotinic Acetylcholine Receptor in Early Identification of Vulnerable Atherosclerotic Plaques: A Study Using a Novel 18F-Label Radioligand PET

Background: It has been confirmed that the α7-nicotinic acetylcholine receptor (α7nAChR) is an important target for identifying vulnerable atherosclerotic plaques. Previously, we successfully designed and synthesized a series of ¹⁸F-labeled PET molecular probes targeting α7nAChR, which are mainly used in the diagnosis of Alzheimer's disease. Based on the characteristics of α7nAChR in blood vessels, we have firstly screened for a suitable novel ¹⁸F-labeled PET molecular probe ([¹⁸F]YLF-DW), with high selectivity for α7nAChR over α4β2nAChR and a good effect for the imaging of atherosclerotic animal models, to effectively identify vulnerable atherosclerotic plaques at an early stage. Meanwhile, we compared it with the “gold standard” pathological examination of atherosclerosis, to verify the reliability of [¹⁸F]YLF-DW in early diagnosis of atherosclerosis.

Methods: The vulnerable atherosclerotic plaques model of ApoE-/-mice were successfully established. Then based on the methods of 3D-QSAR and molecular docking, we designed oxazolo[4,5-b] pyridines and fluorenone compounds, which are targeted at α7nAChR. Through further screening, a novel alpha7 nicotinic acetylcholine receptor radioligand ([¹⁸F]YLF-DW) was synthesized and automatically ¹⁸F-labeled using a Stynthra RNplus module. Subsequently, we employed [¹⁸F]YLF-DW for the targeting of α7nAChR in atherosclerotic plaques and control group, using a micro-PET/CT respectively. After imaging, the mice were sacrificed by air embolism and the carotid arteries taken out for making circular sections. The paraffin embedded specimens were sectioned with 5 μm thickness and stained with oil red. After staining, immunohistochemistry experiment was carried out to verify the effect of micro-PET/CT imaging.

Results: The micro-PET/CT imaging successfully identified the vulnerable atherosclerotic plaques in the carotid arteries of ApoE-/-mice; whereas, no signal was observed in normal control mice. In addition, compared with the traditional imaging agent [¹⁸F]FDG, [¹⁸F]YLF-DW had a significant effect on the early plaques imaging of carotid atherosclerosis. The results of oil red staining and immunohistochemistry also showed early formations of carotid plaques in ApoE-/-mice and provided pathological bases for the evaluation of imaging effect.

Conclusion: We innovated to apply the novel molecular probe ([¹⁸F]YLF-DW) to the identification of vulnerable atherosclerotic plaques in carotid arteries, to detect atherosclerosis early inflammatory response and provide powerful input for the early diagnosis of atherosclerotic lesions, which may play an early warning role in cardiovascular acute events.

Role of intravital imaging in nanomedicine-assisted anti-cancer therapy

Although nanomedicines have provided promising anti-tumor effects in cancer animal models, their clinical success remains limited. One of the most significant barriers in the clinical translation of nanomedicines is that they consist of multiple components, each of which may have different toxicities and therapeutic effects. Intravital imaging provides high spatial and temporal resolution for visualizing nanomedicine-mediated interactions between immune cells and tumor cells in real-time. Intravital imaging can facilitate the in vivo evaluation of the properties and effects of nanomedicines, such as their ability to cross the tumor vasculature, specifically eliminate the cancer cells, and modulate the immune cells found in the tumor microenvironment (TME). Thus, intravital imaging can provide direct evidence of nanomedicine's intravital behavior to better understand mechanism and accelerate clinical translation. In this review, we summarize several applications and latest advances in intravital imaging in nanomedicine-assisted anti-cancer therapy and discuss future perspectives in the field.

Progress of Cancer Nanotechnology as Diagnostics, Therapeutics, and Theranostics Nanomedicine: Preclinical Promise and Translational Challenges

Early detection, right therapeutic intervention, and simultaneous effectiveness mapping are considered the critical factors in successful cancer therapy. Nevertheless, these factors experience the limitations of conventional cancer diagnostics and therapeutics delivery approaches. Along with providing the targeted therapeutics delivery, advances in nanomedicines have allowed the combination of therapy and diagnostics in a single system (called cancer theranostics). This paper discusses the progress in the pre-clinical and clinical development of therapeutics, diagnostics, and theranostics cancer nanomedicines. It has been well evident that compared to the overabundance of works that claimed success in pre-clinical studies, merely 15 and around 75 cancer nanomedicines are approved, and currently under clinical trials, respectively. Thus, we also brief the critical bottlenecks in the successful clinical translation of cancer nanomedicines.

Research Progress and Prospect of Nanoplatforms for Treatment of Oral Cancer

Oral cancers refer to malignant tumors associated with high morbidity and mortality, and oral squamous cell carcinoma accounts for the majority of cases. It is an important part of head and neck, and oral cancer is one of the six most common cancers in the world. At present, the traditional treatment methods for oral cancer include surgery, radiation therapy, and chemotherapy. However, these methods have many disadvantages. In recent years, nanomedicine, the delivery of drugs through nanoplatforms for the treatment of cancer, has become a promising substitutive therapy. The use of nanoplatforms can reduce the degradation of the drug in the body and accurately deliver it to the tumor site. This minimizes the distribution of the drug to other organs, thereby reducing its toxicity and allowing higher drug concentration at the tumor site. This review introduces polymer nanoparticles, lipid-based nanoparticles, metal nanoparticles, hydrogels, exosomes, and dendrimers for the treatment of oral cancer, and discusses how these nanoplatforms play an anti-cancer effect. Finally, the review gives a slight outlook on the future prospects of nanoplatforms for oral cancer treatment.

Implantable and Injectable Biomaterial Scaffolds for Cancer Immunotherapy

Cancer immunotherapy has become an emerging strategy recently producing durable immune responses in patients with varieties of malignant tumors. However, the main limitation for the broad application of immunotherapies still to reduce side effects by controlling and regulating the immune system. In order to improve both efficacy and safety, biomaterials have been applied to immunotherapies for the specific modulation of immune cells and the immunosuppressive tumor microenvironment. Recently, researchers have constantly developed biomaterials with new structures, properties and functions. This review provides the most recent advances in the delivery strategies of immunotherapies based on localized biomaterials, focusing on the implantable and injectable biomaterial scaffolds. Finally, the challenges and prospects of applying implantable and injectable biomaterial scaffolds in the development of future cancer immunotherapies are discussed.

Novel Honokiol-eluting PLGA-based scaffold effectively restricts the growth of renal cancer cells

Renal Cell Carcinoma (RCC) often becomes resistant to targeted therapies, and in addition, dose-dependent toxicities limit the effectiveness of therapeutic agents. Therefore, identifying novel drug delivery approaches to achieve optimal dosing of therapeutic agents can be beneficial in managing toxicities and to attain optimal therapeutic effects. Previously, we have demonstrated that Honokiol, a natural compound with potent anti-tumorigenic and anti-inflammatory effects, can induce cancer cell apoptosis and inhibit the growth of renal tumors in vivo. In cancer treatment, implant-based drug delivery systems can be used for gradual and sustained delivery of therapeutic agents like Honokiol to minimize systemic toxicity. Electrospun polymeric fibrous scaffolds are ideal candidates to be used as drug implants due to their favorable morphological properties such as high surface to volume ratio, flexibility and ease of fabrication. In this study, we fabricated Honokiol-loaded Poly(lactide-co-glycolide) (PLGA) electrospun scaffolds; and evaluated their structural characterization and biological activity. Proton nuclear magnetic resonance data proved the existence of Honokiol in the drug loaded polymeric scaffolds. The release kinetics showed that only 24% of the loaded Honokiol were released in 24hr, suggesting that sustained delivery of Honokiol is feasible. We calculated the cumulative concentration of the Honokiol released from the scaffold in 24hr; and the extent of renal cancer cell apoptosis induced with the released Honokiol is similar to an equivalent concentration of direct application of Honokiol. Also, Honokiol-loaded scaffolds placed directly in renal cell culture inhibited renal cancer cell proliferation and migration. Together, we demonstrate that Honokiol delivered through electrospun PLGA-based scaffolds is effective in inhibiting the growth of renal cancer cells; and our data necessitates further in vivo studies to explore the potential of sustained release of therapeutic agents-loaded electrospun scaffolds in the treatment of RCC and other cancer types.