Cancer immunotherapy: nanodelivery approaches for immune cell targeting and tracking

Platinum-based chemotherapy: trends in organic nanodelivery systems

Despite the investment in platinum drugs research, cisplatin, carboplatin and oxaliplatin are still the only Pt-based compounds used as first line treatments for several cancers, with a few other compounds being approved for administration in some Asian countries. However, due to the severe and worldwide impact of oncological diseases, there is an urge for improved chemotherapeutic approaches. Furthermore, the pharmaceutical application of platinum complexes is hindered by their inherent toxicity and acquired resistance. Nanodelivery systems rose as a key strategy to overcome these challenges, with recognized versatility and ability towards improving the safety, bioavailability and efficacy of the available drugs. Among the known nanocarriers, organic systems have been widely applied, taking advantage of their potential as drug vehicles. Researchers have mainly focused on the development of lipidic and polymeric carriers, including supramolecular structures, with an overall improvement of encapsulated platinum complexes. Herein, an overview of recent trends and strategies is presented, with the main focus on the encapsulation of platinum compounds into organic nanocarriers, showcasing the evolution in the design and development of these promising systems. This comprehensive review highlights formulation methods as well as characterization procedures, providing insights that may be helpful for the development of novel platinum nanocarriers aiming at future pharmaceutical applications.

Advancements in Photothermal Therapy Using Near-Infrared Light for Bone Tumors

Bone tumors, particularly osteosarcoma, are prevalent among children and adolescents. This ailment has emerged as the second most frequent cause of cancer-related mortality in adolescents. Conventional treatment methods comprise extensive surgical resection, radiotherapy, and chemotherapy. Consequently, the management of bone tumors and bone regeneration poses significant clinical challenges. Photothermal tumor therapy has attracted considerable attention owing to its minimal invasiveness and high selectivity. However, key challenges have limited its widespread clinical use. Enhancing the tumor specificity of photosensitizers through targeting or localized activation holds potential for better outcomes with fewer adverse effects. Combinations with chemotherapies or immunotherapies also present avenues for improvement. In this review, we provide an overview of the most recent strategies aimed at overcoming the limitations of photothermal therapy (PTT), along with current research directions in the context of bone tumors, including (1) target strategies, (2) photothermal therapy combined with multiple therapies (immunotherapies, chemotherapies, and chemodynamic therapies, magnetic, and photodynamic therapies), and (3) bifunctional scaffolds for photothermal therapy and bone regeneration. We delve into the pros and cons of these combination methods and explore current research focal points. Lastly, we address the challenges and prospects of photothermal combination therapy.

Emerging tendencies for the nano-delivery of gambogic acid: a promising approach in oncotherapy

Despite the advancements in cancer therapies during the past few years, chemo/photo resistance, severe toxic effects, recurrence of metastatic tumors, and non-selective targeting remain incomprehensible. Thus, much effort has been spent exploring natural anticancer compounds endowed with biosafety and high effectiveness in cancer prevention and therapy. Gambogic acid (GA) is a promising natural compound in cancer therapy. It is the major xanthone component of the dry resin extracted from the Garcinia hanburyi Hook. f. tree. GA has significant antiproliferative effects on different types of cancer, and it exerts its anticancer activities through various pathways. Nonetheless, the clinical translation of GA has been hampered, partly due to its water insolubility, low bioavailability, poor pharmacokinetics, rapid plasma clearance, early degradation in blood circulation, and detrimental vascular irritation. Lately, procedures have been invented demonstrating the ability of nanoparticles to overcome the challenges associated with the clinical use of natural compounds both in vitro and in vivo. This review sheds light on the recent emerging trends for the nanodelivery of GA to cancer cells. To the best of our knowledge, no similar recent review described the different nanoformulations designed to improve the anticancer therapeutic activity and targeting ability of GA.

Evolution of nanomedicine formulations for targeted delivery and controlled release

Nanotechnology research over the past several decades has been aimed primarily at improving the physicochemical properties of small molecules to produce druggable candidates as well as for tumor targeting of cytotoxic molecules. The recent focus on genomic medicine and the success of lipid nanoparticles for mRNA vaccines have provided additional impetus for the development of nanoparticle drug carriers for nucleic acid delivery, including siRNA, mRNA, DNA, and oligonucleotides, to create therapeutics that can modulate protein deregulation. Bioassays and characterizations, including trafficking assays, stability, and endosomal escape, are key to understanding the properties of these novel nanomedicine formats. We review historical nanomedicine platforms, characterization methodologies, challenges to their clinical translation, and key quality attributes for commercial translation with a view to their developability into a genomic medicine. New nanoparticle systems for immune targeting, as well as in vivo gene editing and in situ CAR therapy, are also highlighted as emerging areas.

Vaccine-like nanomedicine for cancer immunotherapy

The successful clinical application of immune checkpoint blockade (ICB) and chimeric antigen receptor T cells (CAR-T) therapeutics has attracted extensive attention to immunotherapy, however, their drawbacks such as limited specificity, persistence and toxicity haven't met the high expectations on efficient cancer treatments. Therapeutic cancer vaccines which instruct the immune system to capture tumor specific antigens, generate long-term immune memory and specifically eliminate cancer cells gradually become the most promising strategies to eradicate tumor. However, the disadvantages of some existing vaccines such as weak immunogenicity and in vivo instability have restricted their development. Nanotechnology has been recently incorporated into vaccine fabrication and exhibited promising results for cancer immunotherapy. Nanoparticles promote the stability of vaccines, as well as enhance antigen recognition and presentation owing to their nanometer size which promotes internalization of antigens by phagocytic cells. The surface modification with targeting units further permits the delivery of vaccines to specific cells. Meanwhile, nanocarriers with adjuvant effect can improve the efficacy of vaccines. In addition to classic vaccines composed of antigens and adjuvants, the nanoparticle-mediated chemotherapy, radiotherapy and certain other therapeutics could induce the release of tumor antigens in situ, which therefore effectively simulate antitumor immune responses. Such vaccine-like nanomedicine not only kills primary tumors, but also prevents tumor recurrence and helps eliminate metastatic tumors. Herein, we introduce recent developments in nanoparticle-based delivery systems for antigen delivery and in situ antitumor vaccination. We will also discuss the remaining opportunities and challenges of nanovaccine in clinical translation towards cancer treatment.

Disulfiram Enhances the Antineoplastic Activity and Sensitivity of Murine Hepatocellular Carcinoma to 5-FU via Redox Management

The efficacy of anticancer drug 5-FU is suppressed due to various factors, including severe side effects and decreased insensitivity during prolonged chemotherapy. Elevated endogenous copper (Cu) levels are one of the prominent hallmark features of cancer cells. In the present investigation, this feature was targeted in diethyl nitrosamine-phenobarbital-induced hepatocellular carcinoma (HCC) in a rat model system by an established anticancer drug, 5-FU, co-administered with copper and its chelating agent, disulfiram. After treatment with the test chemicals in HCC-induced rats, blood and liver samples were subjected to biochemical, molecular, and histopathological analyses. The analysis revealed that reactive oxygen species-mediated oxidative stress is the crucial etiological reason for the pathogenesis of HCC in rats, as evidenced by the significantly compromised activity of major antioxidant enzymes and elevated levels of oxidative damaged products with major histological alterations compared to the control. However, the combination of 5-FU with DSF demonstrated a significant improvement in most of the parameters, followed by 5-FU-Cu in the combination-treated groups. The combination treatment improved the histological details and triggered apoptosis in the cancer cells to a remarkable extent, as the levels of cleaved PARP and caspase-3 were significantly higher than those in the HCC rats treated with the drug alone. The present study envisages that manipulating the Cu-level greatly enhances the antineoplastic activity of 5-FU and sensitizes cancer cells to the increased efficacy of the drug.

Immune-Enhancing Effects of Co-treatment With Kalopanax pictus Nakai Bark and Nelumbo nucifera Gaertner Leaf Extract in a Cyclophosphamide-Induced Immunosuppressed Rat Model

Objective

Immune system disorders can result in various pathological conditions, such as infections and cancer. Identifying therapies that enhance the immune response might be crucial for immunocompromised individuals. Therefore, we assessed the immune-enhancing effect of co-treatment with Kalopanax pictus Nakai Bark and Nelumbo nucifera Gaertner leaf extract (KPNN) in a cyclophosphamide (Cy)-induced immunosuppressed rat model.

Materials and Methods

For in vitro studies, macrophages and splenocytes were treated with various KPNN doses in the presence or absence of Cy. Macrophage viability, nitric oxide production, splenocyte viability, cytokine production and natural killer (NK) cell activity were analyzed. For in vivo studies, analysis of weekly body weight, dietary intake, tissue weight, immune-related blood cell count, cytokine levels, and spleen biopsy was performed in a Cy-induced immunocompromised animal model.

Results

KPNN significantly increased phospho-NF-κB and phospho-ERK protein levels and cell viability in macrophages. KPNN significantly increased the NK cell activity in splenocytes compared to that in the control. Cy treatment decreased tumor necrosis factor (TNF)-α, interleukin (IL)-6, and interferon-γ production. In the Cy-induced immunosuppression rat model, KPNN-treated rats had significantly higher body weights and tissue weights than the Cy-treated rats. Additionally, KPNN treatment restored the immune-related factors, such as total leukocyte, lymphocyte, and intermediate cell contents, to their normal levels in the blood. The blood cytokines (TNF-α and IL-6) were increased, and spleen tissue damage was significantly alleviated.

Conclusions

Collectively, KPNN exerts an immune-enhancing effect suggesting their potential as an immunostimulatory agent or functional food.

How Did Conventional Nanoparticle-Mediated Photothermal Therapy Become "Hot" in Combination with Cancer Immunotherapy?

Simple Summary

Photothermal therapy (PTT) has become effective through the development of nanoparticle-based photoabsorbers with various functions, such as targeting properties, high light-to-heat conversion, and photostability. Conventional nanoparticle-mediated PTT has attained localized efficiency in cancer treatment by heat-induced apoptosis or necrosis of cancer cells. Currently, such treatment methods evolve into cancer immunotherapy through the induction of immunogenic cell death (ICD). Damage-associated molecular patterns from dead cells by nanoparticle-mediated PTT activate immune cells for systemic anti-cancer effect. In this review, we investigate various nanoparticle-based PTT and compare its methodology to clarify how it undergoes a transition from thermotherapy to immunotherapy.

Abstract

One of the promising cancer treatment methods is photothermal therapy (PTT), which has achieved good therapeutic efficiency through nanoparticle-based photoabsorbers. Because of the various functions of nanoparticles, such as targeting properties, high light-to-heat conversion, and photostability, nanoparticle-mediated PTT successfully induces photothermal damage in tumor tissues with minimal side effects on surrounding healthy tissues. The therapeutic efficacy of PTT originates from cell membrane disruption, protein denaturation, and DNA damage by light-induced heat, but these biological impacts only influence localized tumor areas. This conventional nanoparticle-mediated PTT still attracts attention as a novel cancer immunotherapy, because PTT causes immune responses against cancer. PTT-induced immunogenic cell death activates immune cells for systemic anti-cancer effect. Additionally, the excellent compatibility of PTT with other treatment methods (e.g., chemotherapy and immune checkpoint blockade therapy) reinforces the therapeutic efficacy of PTT as combined immunotherapy. In this review, we investigate various PTT agents of nanoparticles and compare their applications to reveal how nanoparticle-mediated PTT undergoes a transition from thermotherapy to immunotherapy.

Irradiation immunity interactions

The immune system can influence cancer development by both impeding and/or facilitating tumour growth and spread. A better understanding of this complex relationship is fundamental to optimise current and future cancer therapeutic strategies. Although typically regarded as a localised and immunosuppressive anti‐cancer treatment modality, radiation therapy has been associated with generating profound systemic effects beyond the intended target volume. These systemic effects are immune‐driven suggesting radiation therapy can enhance anti‐tumour immunosurveillance in some instances. In this review, we summarise how radiation therapy can positively and negatively affect local and systemic anti‐tumour immune responses, how co‐administration of immunotherapy with radiation therapy may help promote anti‐tumour immunity, and how the use of immune biomarkers may help steer radiation therapy‐immunotherapy personalisation to optimise clinical outcomes.

Enhanced Immune Responses by Virus-Mimetic Polymeric Nanostructures Against Infectious Diseases

Intermittent outbreaks of global pandemic disease have spurred new sensors and medicines development for the prevention of disease spread. This perspective specifically covers recent advances, challenges, and future directions in virus-mimetic polymeric nanostructures and their application in biological medicines with a special emphasis on subunit vaccine development. With tailorable compositions and properties, polymers facilitate the ingenious design of various polymeric nanostructures. As one type of polymeric nanostructures, virus-mimetic polymeric nanostructures have been developed as an attractive platform for enhanced immune responses, since they combine the merits of polymer nanocores with the biomimetic characteristic of virus which displays multivalent epitopes on their surfaces. This perspective also provides an applicative approach to rationally design virus-mimetic polymeric platforms based on nanostructures that are self-assembled by using polymers as templates and the antigens and metal oxide clusters loaded on their surface to mimic viruses in size and surface antigenicity. Sub-200 nm virus-mimetic polymeric nanostructures are in a relatively lower level of endotoxins and can promote the antigens to elicit potent humoral and cellular immune responses against pathogenic bacteria. The promising development of virus-mimetic polymeric nanostructures will continue to protect human health from common pathogens and emerging infectious threats.

Immune cell targeting nanoparticles: a review

Immune cells are attractive targets for therapy as they are direct participants in a variety of diseases. Delivering a therapeutic agent only to cells that act on a disease by distinguishing them from other cells has the advantage of concentrating the therapeutic effect and lowering systemic side effects. Distinguishing each immune cell from other immune cells to deliver substances, including drugs and genes, can be achieved using nanotechnology. And also nanoparticles can ensure in vivo stability and sustained drug release. In addition, there is an ease of surface modification, which is an important characteristic that can be utilized in targeted drug delivery systems. This characteristic allows us to utilize various properties that are specifically expressed in each immune cell. A number of studies have delivered various substances specifically to immune cells through surface engineering with active target ligands that can target each immune cell and enzyme-responsive coating, and demonstrated high therapeutic effects compared to conventional treatments. Progress in research on target delivery has been suggested to be a breakthrough for the treatments of various diseases, including cancer treatment.

Interaction of Supramolecular Congo Red and Congo Red-Doxorubicin Complexes with Proteins for Drug Carrier Design

Targeted immunotherapy has expanded to simultaneous delivery of drugs, including chemotherapeutics. The aim of the presented research is to design a new drug carrier system. Systems based on the use of proteins as natural components of the body offer the chance to boost safety and efficacy of targeted drug delivery and excess drug removal. Congo red (CR) type supramolecular, self-assembled ribbon-like structures (SRLS) were previously shown to interact with some proteins, including albumin and antibodies complexed with antigen. CR can intercalate some chemotherapeutics including doxorubicin (Dox). The goal of this work was to describe the CR-Dox complexes, to analyze their interaction with some proteins, and to explain the mechanism of this interaction. In the present experiments, a model system composed of heated immunoglobulin light chain Lλ capable of CR binding was used. Heat aggregated immunoglobulins (HAI) and albumin were chosen as another model system. The results of experiments employing methods such as gel filtration chromatography and dynamic light scattering confirmed the formation of the CR-Dox complex of large size and properties different from the free CR structures. Electrophoresis and chromatography experiments have shown the binding of free CR to heated Lλ while CR-Dox mixed structures were not capable of forming such complexes. HAI was able to bind both free CR and CR-Dox complexes. Albumin also bound both CR and its complex with Dox. Additionally, we observed that albumin-bound CR-Dox complexes were transferred from albumin to HAI upon addition of HAI. DLS analyses showed that interaction of CR with Dox distinctly increased the hydrodynamic diameter of CR-Dox compared with a free CR supramolecular structure. To our knowledge, individual small proteins such as Lλ may bind upon heating a few molecules of Congo red tape penetrating protein body due to the relatively low cohesion of the dye micelle. If, however, the compactness is high (in the case of, e.g., CR-Dox) large ribbon-like, micellar structures appear. They do not divide easily into smaller portions and cannot attach to proteins where there is no room for binding large ligands. Such binding is, however, possible by albumin which is biologically adapted to form complexes with different large ligands and by tightly packed immune complexes and heat aggregated immunoglobulin-specific protein complex structures of even higher affinity for Congo red than albumin. The CR clouds formed around them also bind the CR-Dox complexes. The presented research is essential in the search for optimum solutions for SRLS application in immuno-targeting therapeutic strategies, especially with the use of chemotherapeutics.

Bioactive nanotherapeutic trends to combat triple negative breast cancer

The management of aggressive breast cancer, particularly, triple negative breast cancer (TNBC) remains a formidable challenge, despite treatment advancement. Although newer therapies such as atezolizumab, olaparib, and sacituzumab can tackle the breast cancer prognosis and/or progression, but achieved limited survival benefit(s). The current research efforts are aimed to develop and implement strategies for improved bioavailability, targetability, reduce systemic toxicity, and enhance therapeutic outcome of FDA-approved treatment regimen. This review presents various nanoparticle technology mediated delivery of chemotherapeutic agent(s) for breast cancer treatment. This article also documents novel strategies to employ cellular and cell membrane cloaked (biomimetic) nanoparticles for effective clinical translation. These technologies offer a safe and active targeting nanomedicine for effective management of breast cancer, especially TNBC.

Polysaccharide-based nanomedicines for cancer immunotherapy: A review

Cancer immunotherapy is an effective antitumor approach through activating immune systems to eradicate tumors by immunotherapeutics. However, direct administration of "naked" immunotherapeutic agents (such as nucleic acids, cytokines, adjuvants or antigens without delivery vehicles) often results in: (1) an unsatisfactory efficacy due to suboptimal pharmacokinetics; (2) strong toxic and side effects due to low targeting (or off-target) efficiency. To overcome these shortcomings, a series of polysaccharide-based nanoparticles have been developed to carry immunotherapeutics to enhance antitumor immune responses with reduced toxicity and side effects. Polysaccharides are a family of natural polymers that hold unique physicochemical and biological properties, as they could interact with immune system to stimulate an enhanced immune response. Their structures offer versatility in synthesizing multifunctional nanocomposites, which could be chemically modified to achieve high stability and bioavailability for delivering therapeutics into tumor tissues. This review aims to highlight recent advances in polysaccharide-based nanomedicines for cancer immunotherapy and propose new perspectives on the use of polysaccharide-based immunotherapeutics.

Active Ingredients from Euodia ruticarpa Steam Distilled Essential Oil Inhibit PC-3 Prostate Cancer Cell Growth via Direct Action and Indirect Immune Cells Conditioned Media In Vitro

Active constituents isolated from Euodia ruticarpa (ER) steam distilled essential oil (SDEO) against PC-3 prostate cancer cell growth remain unclear. To clarify the puzzle, ER SDEO was extracted and further resolved into six isolated fractions ERF1–F6 with Sephadex LH-20 gel filtration chromatography to analyze their biological activities. Active ingredients in the isolated fractions were analyzed with GC-MS. Potential isolated fractions were selected to treat PC-3 cells with direct action and indirect treatment by mouse splenocyte- (SCM) and macrophage-conditioned media (MCM). The relationship between PC-3 cell viabilities and corresponding total polyphenols, flavonoid contents as well as Th1/Th2 cytokine profiles in SCM was analyzed using the Pearson product–moment correlation coefficient (r). As a result, ERF1–F3 was abundant in total polyphenols and flavonoids contents with diverse active ingredients. Treatments with ERF1–F3 at appropriate concentrations more or less inhibit PC-3 cell growth in a direct action manner. Only SCM, respectively, cultured with ER SDEO and ERF1–F3 markedly enhanced the effects to inhibit PC-3 cell growth, suggesting that secretions by splenocytes might involve anti-PC-3 effects. There are significantly negative correlations between PC-3 cell viabilities and IL-2, IL-10 as well as IL-10/IL-2 ratios in the corresponding SCM. Total polyphenol and flavonoid contents in the media cultured with ER SDEO isolated fractions positively correlated with IL-10 (Th2) and IL-10/IL-2 (Th2/Th1) cytokine secretion ratios by splenocytes, indicating that polyphenol and flavonoid components in ER SDEO isolated fractions promote Th2-polarized and anti-inflammatory characteristics. These new findings concluded that the inhibitory effects against PC-3 prostate cancer cell growth are attributed to active anti-inflammatory ingredients in ER SDEO and its active ERF1–F3 fractions through direct action and indirect treatment by modulating splenocytes’ cytokine secretion profiles.

In situ vaccination with nanoparticles for cancer immunotherapy: understanding the immunology

FDA approval of anti-CTLA4 in 2011 for melanoma immunotherapy was paradigm shifting and dramatically accelerated cancer immunotherapy research. The investment and effort have been exceptionally large, with a commensurate impressive pace of discovery. Historical and current research has validated the following key points: tumors are recognized by the immune system; tumors develop an immunosuppressive environment which suppresses the antitumor immune response; successful immunotherapy must overcome that tumor-mediated immunosuppression. While cancer immunotherapy research expanded, a parallel effort developing nanoparticles (NP) for cancer diagnosis and therapy also received major investment and expanded. Initially the two efforts appeared to have minimal synergy. Systemically administered nanoparticles are rapidly ingested by phagocytic leukocytes, and therefore nanotechnologists developed strategies to avoid NP ingestion by leukocytes in order to accomplish nanoparticle accumulation in tumors rather than liver and spleen. Recently, nanotechnology and cancer immunotherapy have increasingly merged since phagocytic leukocytes are the key to reversing the local tumor immunosuppression and the tendency of NP to be phagocytosed can be exploited to manipulate phagocytes for immunotherapy. This review focuses on in situ vaccination (ISV), an immunotherapy approach that can utilize direct injection of immunostimulatory reagents, including NPs, into tumors to disrupt the local immunosuppression, stimulate effective immune response against the treated tumor, and most importantly, generate a systemic antitumor immune response to eliminate metastatic tumors. While there are many specific options for using NP for ISV (reviewed further in this special issue), this review focuses on immunology concepts needed to understand and design successful NP ISV approaches.

Recent strategies for nano-based PTT combined with immunotherapy: from a biomaterial point of view

Cancer has been a great threat to humans for decades. Due to the limitations of monotherapy, combinational therapies such as photothermal therapy (PTT) and immunotherapy have gained increasing attention with expectation to overcome the shortfalls of each other and obtain satisfactory therapeutic outcomes. PTT can inhibit primary tumors by thermal ablation but usually fails to achieve complete eradication and cannot prevent metastasis and recurrence. Meanwhile, the efficacy of immunotherapy is usually attenuated by the weak immunogenicity of tumor and the immunosuppressive tumor microenvironment (ITM). Therefore, many recent studies have attempted to synergize PTT with immunotherapy in order to enhance the therapeutic efficacy. In this review, we aim to summarize the cutting-edge strategies in combining nano-based PTT with immunotherapy for cancer treatment. Herein, the combination strategies were mainly classified into four categories, including 1) nano-based PTT combined with antigens to induce host immune responses; 2) nano-based PTT in combination with immune adjuvants acting as in situ vaccines; 3) nano-based PTT synergized with immune checkpoint blockade or other regulators to relieve the ITM; 4) nano-based PTT combined with CAR-T therapy or cytokine therapy for tumor treatment. The characteristics of various photothermal agents and nanoplatforms as well as the immunological mechanisms for the synergism were also introduced in detail. Finally, we discussed the existing challenges and future prospects in combined PTT and immunotherapy.

Preclinical models and technologies to advance nanovaccine development

The remarkable success of targeted immunotherapies is revolutionizing cancer treatment. However, tumor heterogeneity and low immunogenicity, in addition to several tumor-associated immunosuppression mechanisms are among the major factors that have precluded the success of cancer vaccines as targeted cancer immunotherapies. The exciting outcomes obtained in patients upon the injection of tumor-specific antigens and adjuvants intratumorally, reinvigorated interest in the use of nanotechnology to foster the delivery of vaccines to address cancer unmet needs. Thus, bridging nano-based vaccine platform development and predicted clinical outcomes the selection of the proper preclinical model will be fundamental. Preclinical models have revealed promising outcomes for cancer vaccines. However, only few cases were associated with clinical responses. This review addresses the major challenges related to the translation of cancer nano-based vaccines to the clinic, discussing the requirements for ex vivo and in vivo models of cancer to ensure the translation of preclinical success to patients.

Nanomaterials Synthesis through Microfluidic Methods: An Updated Overview

Microfluidic devices emerged due to an interdisciplinary "collision" between chemistry, physics, biology, fluid dynamics, microelectronics, and material science. Such devices can act as reaction vessels for many chemical and biological processes, reducing the occupied space, equipment costs, and reaction times while enhancing the quality of the synthesized products. Due to this series of advantages compared to classical synthesis methods, microfluidic technology managed to gather considerable scientific interest towards nanomaterials production. Thus, a new era of possibilities regarding the design and development of numerous applications within the pharmaceutical and medical fields has emerged. In this context, the present review provides a thorough comparison between conventional methods and microfluidic approaches for nanomaterials synthesis, presenting the most recent research advancements within the field.

Potential therapeutic applications of phytoconstituents as immunomodulators: Pre-clinical and clinical evidences

Autoimmune and infectious diseases are the major public health issues and have gained great attention in the last few years for the search of new agents with therapeutic benefits on the host immune functions. In recent years, natural products (NPs) have been studied broadly for their multi-targeted activities under pathological conditions. Interestingly, several attempts have been made to outline the immunomodulatory properties of NPs. Research on in-vitro and in-vivo models have shown the immunomodulatory activity of NPs, is due to their antiinflammatory property, induction of phagocytosis and immune cells stimulation activity. Moreover, studies on humans have suggested that phytomedicines reduce inflammation and could provide appropriate benefits either in single form or complex combinations with other agents preventing disease progression, subsequently enhancing the efficacy of treatment to combat multiple malignancies. However, the exact mechanism of immunomodulation is far from clear, warranting more detailed investigations on their effectiveness. Nevertheless, the reduction of inflammatory cascades is considered as a prime protective mechanism in a number of inflammation regulated autoimmune diseases. Altogether, this review will discuss the biological activities of plant-derived secondary metabolites, such as polyphenols, alkaloids, saponins, polysaccharides and so forth, against various diseases and their potential use as an immunomodulatory agent under pathological conditions.

Emerging advances in cationic liposomal cancer nanovaccines: opportunities and challenges

Advancements in the field of cancer therapeutics have witnessed a recent surge in the use of liposomes. The physicochemical characteristics of the liposomes and their components, including the lipid phase transition temperature, vesicular size and size distribution, surface properties, and route of administration, play a significant role in the modulation of the immune response as an adjuvant and for loaded antigen (Ag). Cationic liposomes, concerning their potential ability to amplify the immunogenicity of the loaded Ag/adjuvant, have received enormous interest as a promising vaccine delivery platform for cancer immunotherapy. In the present review, the physicochemical considerations for the development of Ag/adjuvant-loaded liposomes and the cationic liposomes' effectiveness for promoting cancer immunotherapy have been summarized.

Fabrication and Applications of Microfluidic Devices: A Review

Microfluidics is a relatively newly emerged field based on the combined principles of physics, chemistry, biology, fluid dynamics, microelectronics, and material science. Various materials can be processed into miniaturized chips containing channels and chambers in the microscale range. A diverse repertoire of methods can be chosen to manufacture such platforms of desired size, shape, and geometry. Whether they are used alone or in combination with other devices, microfluidic chips can be employed in nanoparticle preparation, drug encapsulation, delivery, and targeting, cell analysis, diagnosis, and cell culture. This paper presents microfluidic technology in terms of the available platform materials and fabrication techniques, also focusing on the biomedical applications of these remarkable devices.

Personalized medicine and back-allogeneic exosomes for cancer immunotherapy

Extracellular vesicles, especially exosomes, have been explored for cancer immunotherapy. The initial studies made use of autologous B-cell or dendritic cell-derived exosomes, with the idea that MHC-peptide complexes on the exosomal surface would stimulate an MHC-restricted cancer-specific immune response. This was also verified in mouse systems, whilst the effects in human clinical systems were more modest. Several studies have explored the mechanisms for exosomal T-cell activation, and a picture emerges where the antigen-presenting cells, possibly both B cells and dendritic cells of the recipient, are needed to induce a potent T-cell response to exosomes. Therefore, the exosomes function more as an adjuvant-like delivery system of antigens, and we need to further understand the exact components that trigger the most broad and potent immune responses. Here, we describe the grounds for using allogeneic exosomes for cancer therapy, something that would greatly improve the feasibility of new exosome-based immunotherapeutic approaches to cure cancer.

Sequential Modulations of Tumor Vasculature and Stromal Barriers Augment the Active Targeting Efficacy of Antibody-Modified Nanophotosensitizer in Desmoplastic Ovarian Carcinoma

Active-targeted nanoparticles are attractive carriers due to their potentials to facilitate specific delivery of drugs into tumor cells while sparing normal cells. However, the therapeutic outcomes of active-targeted nanomedicines are hampered by the multiple physiological barriers in the tumor microenvironment (TME). Herein, an epidermal growth factor receptor-targeted ultra-pH-sensitive nanophotosensitizer is fabricated, and the regulation of the TME to augment the active targeting ability and therapeutic efficacy is pinpointed. The results reveal that tumor vasculature normalization with thalidomide indiscriminately enhance the tumor accumulation of passive and active targeted nanoparticles, both of which are sequestered in the stromal bed of tumor mass. Whereas, photoablation of stromal cells located in perivascular regions significantly improves the accessibility of antibody-modified nanophotosensitizer to receptor-overexpressed cancer cells. After sequential regulation of TME, the antitumor efficacy of antibody-modified nanophotosensitizer is drastically enhanced through synergistic enhancements of tumor accumulation and cancer cell accessibility of active-targeted nanoparticles. The study offers deep insights about the intratumoral barriers that hinder the active-targeted nanoparticles delivery, and provides a basis for developing more effective strategies to accelerate the clinical translation of active-targeted nanomedicines.

Nanomedicine-Combined Immunotherapy for Cancer

BACKGROUND

Immunotherapy for cancer includes Chimeric Antigen Receptor (CAR)-T cells, CAR-natural Killer (NK) cells, PD1, and the PD-L1 inhibitor. However, the proportion of patients who respond to cancer immunotherapy is not satisfactory. Concurrently, nanotechnology has experienced a revolution in cancer diagnosis and therapy. There are few clinically approved nanoparticles that can selectively bind and target cancer cells and incorporate molecules, although many therapeutic nanocarriers have been approved for clinical use. There are no systematic reviews outlining how nanomedicine and immunotherapy are used in combination to treat cancer.

OBJECTIVE

This review aims to illustrate how nanomedicine and immunotherapy can be used for cancer treatment to overcome the limitations of the low proportion of patients who respond to cancer immunotherapy and the rarity of nanomaterials in clinical use.

METHODS

A literature review of MEDLINE, PubMed / PubMed Central, and Google Scholar was performed. We performed a structured search of literature reviews on nanoparticle drug-delivery systems, which included photodynamic therapy, photothermal therapy, photoacoustic therapy, and immunotherapy for cancer. Moreover, we detailed the advantages and disadvantages of the various nanoparticles incorporated with molecules to discuss the challenges and solutions associated with cancer treatment.

CONCLUSION

This review identified the advantages and disadvantages associated with improving health care and outcomes. The findings of this review confirmed the importance of nanomedicinecombined immunotherapy for improving the efficacy of cancer treatment. It may become a new way to develop novel cancer therapeutics using nanomaterials to achieve synergistic anticancer immunity.

Nanoparticles in cancer immunotherapies: An innovative strategy

Cancer has been one of the most significant causes of mortality, worldwide. Cancer immunotherapy has recently emerged as a competent, cancer-fighting clinical strategy. Nevertheless, due to the difficulty of such treatments, costs, and off-target adverse effects, the implementation of cancer immunotherapy described by the antigen-presenting cell (APC) vaccine and chimeric antigen receptor T cell therapy ex vivo in large clinical trials have been limited. Nowadays, the nanoparticles theranostic system as a promising target-based modality provides new opportunities to improve cancer immunotherapy difficulties and reduce their adverse effects. Meanwhile, the appropriate engineering of nanoparticles taking into consideration nanoparticle characteristics, such as, size, shape, and surface features, as well as the use of these physicochemical properties for suitable biological interactions, provides new possibilities for the application of nanoparticles in cancer immunotherapy. In this review article, we focus on the latest state-of-the-art nanoparticle-based antigen/adjuvant delivery vehicle strategies to professional APCs and engineering specific T lymphocyte required for improving the efficiency of tumor-specific immunotherapy.

Nanotechnology Solutions for Controlled Cytokine Delivery: An Applied Perspective

Around 200 cytokines with roles in cell signaling have been identified and studied, with the vast majority belonging to the four-α-helix bundle family. These proteins exert their function by binding to specific receptors and are implicated in many diseases. The use of several cytokines as therapeutic targets has been approved by the FDA, however their rapid clearance in vivo still greatly limits their efficacy. Nano-based drug delivery systems have been widely applied in nanomedicine to develop safe, specific and controlled delivery techniques. Nevertheless, each nanomaterial has its own specifications and their suitability towards the biochemical and biophysical properties of the selected drug needs to be determined, weighing in the final choice of the ideal nano drug delivery system. Nanoparticles remain the most used vehicle for cytokine delivery, where polymeric carriers represent the vast majority of the studied systems. Liposomes and gold or silica nanoparticles are also explored and discussed in this review. Additionally, surface functionalization is of great importance to facilitate the attachment of a wide variety of molecules and modify features such as bioavailability. Since the monitoring of cytokine levels has an important role in early clinical diagnosis and for assessing therapeutic efficacy, nanotechnological advances are also valuable for nanosensor development.

Heat-Killed Lactobacillus brevis Enhances Phagocytic Activity and Generates Immune-Stimulatory Effects through Activating the TAK1 Pathway

There is an increasing interest in using inactivated probiotics to modulate the host immune system and protect against pathogens. As the immunomodulatory function of heat-killed Lactobacillus brevis KCTC 12777BP (LBB) and its mechanism is unclear, we investigated the effect of LBB on immune response based on the hypothesis that LBB might exert stimulatory effects on immunity. In the current study, we demonstrate that administration of LBB can exert immune-stimulatory effects and promote clearance of foreign matters through enhancing phagocytosis. Treatment with LBB induced the production of TNF-α, IL-6, and nitric oxide in macrophages. Importantly, LBB directly increased the phagocytic activity of macrophages against bacterial particles. LBB was able to promote the production of TNF-α in bone marrow-derived macrophages and splenocytes and also increase the proliferation rate of splenocytes, suggesting that the immune-stimulating activity of LBB can be observed in primary immune cells. Investigation into the molecular mechanism responsible revealed that LBB upregulates TAK1 activity and its downstream ERK, p38, and JNK signaling pathways. To further confirm the immunomodulatory capability of LBB in vivo, we orally administered LBB to mice and assessed the effect on primary splenocytes. Splenocytes isolated from LBB-treated mice exhibited higher TNF-α expression and proliferative capacity. These results show that heat-killed L. brevis, a wildly consumed probiotic, may provide protection against pathogens through enhancing host immunity.

Advanced polymeric nanotechnology to augment therapeutic delivery and disease diagnosis

Therapeutic and diagnostic payloads are usually associated with properties that compromise their efficacy, such as poor aqueous solubility, short half-life, low bioavailability, nonspecific accumulation and diverse side effects. Nanotechnological solutions have emerged to circumvent some of these drawbacks, augmenting therapeutic and/or diagnostic outcomes. Nanotechnology has benefited from the rise in polymer science research for the development of novel nanosystems for therapeutic and diagnostic purposes. Polymers are a widely used class of biomaterials, with a considerable number of regulatory approvals for application in clinics. In addition to their versatility in production and functionalization, several synthetic and natural polymers demonstrate biocompatible properties that dictate their successful biological performance. This article highlights the physicochemical characteristics of a variety of natural and synthetic biocompatible polymers, as well as their role in the manufacture of nanotechnology-based systems, state-of-art applications in disease treatment and diagnosis, and current challenges in finding a way to clinics.

Exosomes-based cell-free cancer therapy: a novel strategy for targeted therapy

Exosomes are cell-derived nano-sized, phospholipid vehicles that function to transport prodigious amounts of bioactive molecules to specific recipient tissues. Several hallmarks of cancer are impacted by this exosome-mediated cell-to-cell communication, including, remodeling the architecture of the extracellular matrix, endowing cancer cells with characteristics of drug resistance, or even modulating immune responses. Owing to their immunomodulatory potential and endogenous functionalities, exosomes may also be exploited in various innovative immunological approaches to activate adaptive and innate immune effector cells to mount an effective anticancer immunosurveillance. The review highlights the recent advances in state-of-the-art technologies and protocols for using exosomes as an effective and promising application for cancer immunotherapy.

Nanoparticle cancer vaccines: Design considerations and recent advances

Vaccines therapeutics manipulate host's immune system and have broad potential for cancer prevention and treatment. However, due to poor immunogenicity and limited safety, fewer cancer vaccines have been successful in clinical trials. Over the past decades, nanotechnology has been exploited to deliver cancer vaccines, eliciting long-lasting and effective immune responses. Compared to traditional vaccines, cancer vaccines delivered by nanomaterials can be tuned towards desired immune profiles by (1) optimizing the physicochemical properties of the nanomaterial carriers, (2) modifying the nanomaterials with targeting molecules, or (3) co-encapsulating with immunostimulators. In order to develop vaccines with desired immunogenicity, a thorough understanding of parameters that affect immune responses is required. Herein, we discussed the effects of physicochemical properties on antigen presentation and immune response, including but not limited to size, particle rigidity, intrinsic immunogenicity. Furthermore, we provided a detailed overview of recent preclinical and clinical advances in nanotechnology for cancer vaccines, and considerations for future directions in advancing the vaccine platform to widespread anti-cancer applications.

Immunostimulatory Activity of Black Rice Bran in Cyclophosphamide-Induced Immunosuppressed Rats

Black rice bran extract (BRBE), containing various biologically active compounds, such as anthocyanin, has antioxidant activity and numerous pharmacological effects. Here, we aimed to confirm the immunostimulatory effects of BRBE in cyclophosphamide (CP)-induced immunosuppressed cells. Our results confirmed that BRBE exerted an immunostimulatory effect. In vitro, BRBE treatment enhanced cell proliferation, activity of natural killer cells and cytotoxic T lymphocytes, and production of CP-repressed cytokines, such as tumor necrosis factor-α, interferon-γ, interleukin (IL)-2, and IL-12, and immunoglobulins G and A in isolated splenocytes. Additionally, in vivo, BRBE treatment increased the number of immune cells, such as white blood cells, lymphocyte counts, mid-range absolute counts, and neutrophils in CP-induced immunosuppressed rats. Furthermore, BRBE increased the serum levels of abovementioned inflammatory cytokines and immunoglobulins in CP-induced immunosuppressed rats. In addition, BRBE protected against CP-mediated spleen and thymic tissue damage. Our findings suggest that BRBE could be potentially used as a component of functional food for immunity enhancement.

Genetically engineered mesenchymal stem cells: targeted delivery of immunomodulatory agents for tumor eradication

Cancer immunotherapy emerged as a novel therapeutic option that employs enhanced or amended native immune system to create a robust response against malignant cells. The systemic therapies with immune-stimulating cytokines have resulted in substantial dose-limiting toxicities. Targeted cytokine immunotherapy is being explored to overcome the heterogeneity of malignant cells and tumor cell defense with a remarkable reduction of systemic side effects. Cell-based strategies, such as dendritic cells (DCs), fibroblasts or mesenchymal stem cells (MSCs) seek to minimize the numerous toxic side effects of systemic administration of cytokines for extended periods of time. The usual toxicities comprised of a vascular leak, hypotension, and respiratory insufficiency. Natural and strong tropism of MSCs toward malignant cells made them an ideal systemic delivery vehicle to direct the proposed therapeutic genes to the vicinity of a tumor where their expression could evoke an immune reaction against the tumor. Compared with other methods, the delivery of cytokines via engineered MSCs is safer and renders a more practical, and promising strategy. Large numbers of genes code for cytokines have been utilized to reengineer MSCs as therapeutic cells. This review highlights the recent findings on the cytokine gene therapy for human malignancies by focusing on MSCs application in cancer immunotherapy.

Nanomedicine for improvement of dendritic cell-based cancer immunotherapy

Dendritic cell (DC)-based cancer immunotherapy has shown impressive outcomes, including the development of the first FDA-approved anti-cancer vaccine. However, the clinical application of DC-based cancer immunotherapy is associated with various challenges. Promising novel tools for the administration of cancer vaccines has emerged from recent developments in nanoscale biomaterials. One current strategy to enhance targeted drug delivery, while minimizing drug-related toxicities, is the use of nanoparticles (NPs). These can be utilized for antigen delivery into DCs, which have been shown to provide potent T cell-stimulating effects. Therefore, NP delivery represents one promising approach for creating an effective and stable immune response without toxic side effects. The current review surveys cancer immunotherapy with particular attention toward NP-based delivery methods that target DCs.

Cell Tracking in Cancer Immunotherapy

The impressive development of cancer immunotherapy in the last few years originates from a more precise understanding of control mechanisms in the immune system leading to the discovery of new targets and new therapeutic tools. Since different stages of disease progression elicit different local and systemic inflammatory responses, the ability to longitudinally interrogate the migration and expansion of immune cells throughout the whole body will greatly facilitate disease characterization and guide selection of appropriate treatment regiments. While using radiolabeled white blood cells to detect inflammatory lesions has been a classical nuclear medicine technique for years, new non-invasive methods for monitoring the distribution and migration of biologically active cells in living organisms have emerged. They are designed to improve detection sensitivity and allow for a better preservation of cell activity and integrity. These methods include the monitoring of therapeutic cells but also of all cells related to a specific disease or therapeutic approach. Labeling of therapeutic cells for imaging may be performed in vitro, with some limitations on sensitivity and duration of observation. Alternatively, in vivo cell tracking may be performed by genetically engineering cells or mice so that may be revealed through imaging. In addition, SPECT or PET imaging based on monoclonal antibodies has been used to detect tumors in the human body for years. They may be used to detect and quantify the presence of specific cells within cancer lesions. These methods have been the object of several recent reviews that have concentrated on technical aspects, stressing the differences between direct and indirect labeling. They are briefly described here by distinguishing ex vivo (labeling cells with paramagnetic, radioactive, or fluorescent tracers) and in vivo (in vivo capture of injected radioactive, fluorescent or luminescent tracers, or by using labeled antibodies, ligands, or pre-targeted clickable substrates) imaging methods. This review focuses on cell tracking in specific therapeutic applications, namely cell therapy, and particularly CAR (Chimeric Antigen Receptor) T-cell therapy, which is a fast-growing research field with various therapeutic indications. The potential impact of imaging on the progress of these new therapeutic modalities is discussed.

A quantitativeex vivostudy of the interactions between reconstituted high-density lipoproteins and human leukocytes

Knowledge of the interactions between nanoparticles and immune cells is required for optimal design of nanoparticle-based drug delivery systems, either when aiming to avoid phagocytic clearance of the nanoparticles or promote an immune response by delivering therapeutic agents to specific immune cells. Several studies have suggested that reconstituted high-density lipoproteins (rHDL) are attractive drug delivery vehicles. However, detailed studies of rHDL interactions with circulating leukocytes are limited. Here, we evaluated the association of discoidal rHDL with leukocytes in human whole blood (HWB) using quantitative approaches. We found that while the rHDL of various lipid compositions associated preferentially with monocytes, the degree of association depended on the lipid composition. However, consistent with the long circulation half-life of rHDL, we show that only a minor fraction of the rHDL associated with the leukocytes. Furthermore, we used three-dimensional fluorescence microscopy and imaging flow cytometry to evaluate the possible internalization of rHDL cargo into the cells, and we show increased internalization of rHDL cargo in monocytes relative to granulocytes. The preferential rHDL association with monocytes and the internalization of rHDL cargo could possibly be mediated by the scavenger receptor class B type 1 (SR-BI), which we show is expressed to a higher extent on monocytes than on the other major leukocyte populations. Our work implies that drug-loaded rHDL can deliver its cargo to monocytes in circulation, which could lead to some off-target effects when using rHDL for systemic drug delivery, or it could pave the way for novel immunotherapeutic treatments aiming to target the monocytes.

We used novel quantitative methods to study the interactions between reconstituted high-density lipoproteins (rHDL) and human leukocytes – showing that rHDL cargo are preferentially taken up by monocytes.

Polyethylenimine Hybrid Thin-Shell Hollow Mesoporous Silica Nanoparticles as Vaccine Self-Adjuvants for Cancer Immunotherapy

Conventional adjuvants (e.g., aluminum) are insufficient to trigger cell-mediated immunity, which plays a crucial role in triggering specific immunity against cancer. Therefore, developing appropriate adjuvants for cancer vaccines is a central way to stimulate the antitumor immune response. Hollow mesoporous silica nanoparticles (HMSNs) have been proven to stimulate Th1 antitumor immunity in vivo and promote immunological memory in the formulation of novel cancer vaccines. Yet, immune response rates of existing HMSNs for anticancer immunity still remain low. Here, we demonstrate the generation of polyethylenimine (PEI)-incorporated thin-shell HMSNs (THMSNs) through a facile PEI etching strategy for cancer immunotherapy. Interestingly, incorporation of PEI and thin-shell hollow structures of THMSNs not only improved the antigen-loading efficacy and sustained drug release profiles but also enhanced the phagocytosis efficiency by dendritic cells (DCs), enabled DC maturation and Th1 immunity, and sustained immunological memory, resulting in the enhancement of the adjuvant effect of THMSNs. Moreover, THMSNs vaccines without significant side effects can significantly reduce the potentiality of tumor growth and metastasis in tumor challenge and rechallenge models, respectively. THMSNs are considered to be promising vehicles and excellent adjuvants for the formulation of cancer vaccines for immunotherapy.

ENS, Boer JC, Ferji K, Six JL, Chen X, Elkord E, Plebanski M, Mohamud R. Synergistic Effects of Nanomedicine Targeting TNFR2 and DNA Demethylation Inhibitor-An Opportunity for Cancer Treatment

Tumor necrosis factor receptor 2 (TNFR2) is expressed on some tumor cells, such as myeloma, Hodgkin lymphoma, colon cancer and ovarian cancer, as well as immunosuppressive cells. There is increasingly evidence that TNFR2 expression in cancer microenvironment has significant implications in cancer progression, metastasis and immune evasion. Although nanomedicine has been extensively studied as a carrier of cancer immunotherapeutic agents, no study to date has investigated TNFR2-targeting nanomedicine in cancer treatment. From an epigenetic perspective, previous studies indicate that DNA demethylation might be responsible for high expressions of TNFR2 in cancer models. This perspective review discusses a novel therapeutic strategy based on nanomedicine that has the capacity to target TNFR2 along with inhibition of DNA demethylation. This approach may maximize the anti-cancer potential of nanomedicine-based immunotherapy and, consequently, markedly improve the outcomes of the management of patients with malignancy.

Nanoparticle Delivery of Immunostimulatory Agents for Cancer Immunotherapy

Immunostimulatory agents, including adjuvants, cytokines, and monoclonal antibodies, hold great potential for the treatment of cancer. However, their direct administration often results in suboptimal pharmacokinetics, vulnerability to biodegradation, and compromised targeting. More recently, encapsulation into biocompatible nanoparticulate carriers has become an emerging strategy for improving the delivery of these immunotherapeutic agents. Such approaches can address many of the challenges facing current treatment modalities by endowing additional protection and significantly elevating the bioavailability of the encapsulated payloads. To further improve the delivery efficiency and subsequent immune responses associated with current nanoscale approaches, biomimetic modifications and materials have been employed to create delivery platforms with enhanced functionalities. By leveraging nature-inspired design principles, these biomimetic nanodelivery vehicles have the potential to alter the current clinical landscape of cancer immunotherapy.

Targeted co-delivery of Trp-2 polypeptide and monophosphoryl lipid A by pH-sensitive poly (β-amino ester) nano-vaccines for melanoma

Dendritic cell (DC)-targeted vaccines based on nanotechnology are a promising strategy to efficiently induce potent immune responses. We synthesized and manufactured a mannose-modified poly (β-amino ester) (PBAE) nano-vaccines with easily tuneable and pH-sensitive characteristics to co-deliver the tumor-associated antigen polypeptide Trp-2 and the TLR4 agonist monophosphoryl lipid A (MPLA). To reduce immunosuppression in the tumor microenvironment, an immune checkpoint inhibitor, PD-L1 antagonist, was administrated along with PBAE nano-vaccines to delay melanoma development. We found that mannosylated Trp-2 and MPLA-loaded PBAE nano-vaccines can target and mature DCs, consequently boosting antigen-specific cytotoxic T lymphocyte activity against melanoma. The prophylactic study indicates that combination therapy with PD-L1 antagonist further enhanced anti-tumor efficacy by 3.7-fold and prolonged median survival time by 1.6-fold more than free Trp-2/MPLA inoculation. DC-targeting PBAE polymers have a great potential as a nanotechnology platform to design vaccines and achieve synergistic anti-tumor effects with immune checkpoint therapy.

Drug Delivery for Cancer Immunotherapy and Vaccines

Cancer cells are able to avoid immune surveillance and exploit the immune system to grow and metastasize. With the development of nano- and micro-particles, there has been a growing number of immunotherapy delivery systems developed to elicit innate and adaptive immune responses to eradicate cancer cells. This can be accomplished by training resident immune cells to recognize and eliminate cells with tumor-associated antigens or by providing external stimuli to enhance tumor cell apoptosis in the immunosuppressive tumor microenvironment (TME). In this review we will focus on nano- and micro-particle (NP and MP) based immunotherapies and vaccines used to elicit a potent and sustained antitumor immune response.

Conjugation of a Small-Molecule TLR7 Agonist to Silica Nanoshells Enhances Adjuvant Activity

Stimulation of Toll-like receptors (TLRs) and/or NOD-like receptors on immune cells initiates and directs immune responses that are essential for vaccine adjuvants. The small-molecule TLR7 agonist, imiquimod, has been approved by the FDA as an immune response modifier but is limited to topical application due to its poor pharmacokinetics that causes undesired adverse effects. Nanoparticles are increasingly used with innate immune stimulators to mitigate side effects and enhance adjuvant efficacy. In this study, a potent small-molecule TLR7 agonist, 2-methoxyethoxy-8-oxo-9-(4-carboxybenzyl)adenine (1V209), was conjugated to hollow silica nanoshells (NS). Proinflammatory cytokine (IL-6, IL-12) release by mouse bone-marrow-derived dendritic cells and human peripheral blood mononuclear cells revealed that the potency of silica nanoshells-TLR7 conjugates (NS-TLR) depends on nanoshell size and ligand coating density. Silica nanoshells of 100 nm diameter coated with a minimum of ∼6000 1V209 ligands/particle displayed 3-fold higher potency with no observed cytotoxicity when compared to an unconjugated TLR7 agonist. NS-TLR activated the TLR7-signaling pathway, triggered caspase activity, and stimulated IL-1β release, while neither unconjugated TLR7 ligands nor silica shells alone produced IL-1β. An in vivo murine immunization study, using the model antigen ovalbumin, demonstrated that NS-TLR increased antigen-specific IgG antibody induction by 1000× with a Th1-biased immune response, compared to unconjugated TLR7 agonists. The results show that the TLR7 ligand conjugated to silica nanoshells is capable of activating an inflammasome pathway to enhance both innate immune-stimulatory and adjuvant potencies of the TLR7 agonist, thereby broadening applications of innate immune stimulators.

In vivo targeting of DNA vaccines to dendritic cells using functionalized gold nanoparticles

The clinical success of dendritic cell (DC)-based genetic immunization remains critically dependent on the availability of effective and safe nano-carriers for targeting antigen-encoded DNA vaccines to DCs, the most potent antigen-presenting cells in the human body in vivo. Recent studies revealed the efficacies of mannose receptor-mediated in vivo DC-targeted genetic immunization by liposomal DNA vaccine carriers containing both mannose-mimicking shikimoyl and transfection enhancing guanidinyl functionalities. However, to date, the efficacies of this approach have not been examined for metal-based nanoparticle DNA vaccine carriers. Herein, we report for the first time, the design, synthesis, physico-chemical characterization and bioactivities of gold nanoparticles covalently functionalized with a thiol ligand containing both shikimoyl and guanidinyl functionalities (Au-SGSH). We show that Au-SGSH nanoparticles can deliver DNA vaccines to mouse DCs under in vivo conditions. Subcutaneous administration of near infrared (NIR) dye-labeled Au-SGSH showed significant accumulation of the NIR dye in the DCs of the nearby lymph nodes compared to that for the non-targeting NIR-labeled Au-GSH nanoconjugate containing only a covalently tethered guanidinyl group, not the shikimoyl-functionality. Under prophylactic settings, in vivo immunization (s.c.) with the Au-SGSH-pCMV-MART1 nanoplex induced a long-lasting (180 days) immune response against murine melanoma. Notably, mannose receptor-mediated in vivo DC-targeted immunization (s.c.) with the Au-SGSH-MART1 nanoplex significantly inhibited established melanoma growth and increased the overall survivability of melanoma-bearing mice under therapeutic settings. The Au-SGSH nanoparticles reported herein have potential use for in vivo DC-targeted genetic immunization against cancer and infectious diseases.