Extending antigen release from particulate vaccines results in enhanced antitumor immune response

Beyond Needles: Immunomodulatory Hydrogel-Guided Vaccine Delivery Systems

Vaccines are critical for combating infectious diseases, saving millions of lives worldwide each year. Effective immunization requires precise vaccine delivery to ensure proper antigen transport and robust immune activation. Traditional vaccine delivery systems, however, face significant challenges, including low immunogenicity and undesirable inflammatory reactions, limiting their efficiency. Encapsulating or binding vaccines within biomaterials has emerged as a promising strategy to overcome these limitations. Among biomaterials, hydrogels have gained considerable attention for their biocompatibility, ability to interact with biological systems, and potential to modulate immune responses. Hydrogels offer a materials science-driven approach for targeted vaccine delivery, addressing the shortcomings of conventional methods while enhancing vaccine efficacy. This review examines the potential of hydrogel-based systems to improve immunogenicity and explores their dual role as immunomodulatory adjuvants. Innovative delivery methods, such as microneedles, patches, and inhalable systems, are discussed as minimally invasive alternatives to traditional administration routes. Additionally, this review addresses critical challenges, including safety, scalability, and regulatory considerations, offering insights into hydrogel-guided strategies for eliciting targeted immune responses and advancing global immunization efforts.

Spatiotemporal coordination of antigen presentation and co-stimulatory signal for enhanced anti-tumor vaccination

Controlled-release systems enhance anti-tumor effects by leveraging local antigen persistence for antigen-presenting cells (APCs) recruitment and T cell engagement. However, constant antigen presentation alone tends to induce dysfunction in tumor-specific CD8+ T cells, neglecting the synergistic effects of co-stimulatory signal. To address this, we developed a soft particle-stabilized emulsion (SPE) to deliver lipopeptides with controlled release profiles by adjusting their hydrophobic chain lengths: C6-SPE (fast release), C10-SPE (medium release), and C16-SPE (slow release). Following administration, C6-SPE release antigen rapidly, inducing early antigen presentation, whereas C16-SPE's slow-release delays antigen presentation. Both scenarios missed the critical window for coordinating with the expression of CD86, leading to either T cell apoptosis or suboptimal activation. In contrast, C10-SPE achieved a spatiotemporally synergetic effect of the MHC-I-peptide complex and co-stimulatory signal (CD86), leading to effective dendritic cell (DC) activation, enhanced T cell activation, and tumor regression in EG7-OVA bearing mice. Additionally, co-delivery of cytosine-phosphate-guanine (CpG) with SPE provided a sustained expression of the CD86 window for DC activation, improving the immune response and producing robust anti-tumor effects with C6-SPE comparable to C10-SPE. These findings highlight that synchronizing the spatiotemporal dynamics of antigen presentation and APC activation may confer an optimal strategy for enhanced vaccinations.

Size Tuning of Mesoporous Silica Adjuvant for One-Shot Vaccination with Long-Term Anti-Tumor Effect

Despite recent clinical successes in cancer immunotherapy, it remains difficult to initiate a long-term anti-tumor effect. Therefore, repeated administrations of immune-activating agents are generally required in most cases. Herein, we propose an adjuvant particle size tuning strategy to initiate a long-term anti-tumor effect by one-shot vaccination. This strategy is based on the size-dependent immunostimulation mechanism of mesoporous silica particles. Hollow mesoporous silica (HMS) nanoparticles enhance the antigen uptake with dendritic cells around the immunization site in vivo. In contrast, hierarchically porous silica (HPS) microparticles prolong cancer antigen retention and release in vivo. The size tuning of the mesoporous silica adjuvant prepared by combining both nanoparticles and microparticles demonstrates the immunological properties of both components and has a long-term anti-tumor effect after one-shot vaccination. One-shot vaccination with HMS-HPS-ovalbumin (OVA)-Poly IC (PIC, a TLR3 agonist) increases CD4+ T cell, CD8+ T cell, and CD86+ cell populations in draining lymph nodes even 4 months after vaccination, as well as effector memory CD8+ T cell and tumor-specific tetramer+CD8+ T cell populations in splenocytes. The increases in the numbers of effector memory CD8+ T cells and tumor-specific tetramer+CD8+ T cells indicate that the one-shot vaccination with HMS-HPS-OVA-PIC achieved the longest survival time after a challenge with E.G7-OVA cells among all groups. The size tuning of the mesoporous silica adjuvant shows promise for one-shot vaccination that mimics multiple clinical vaccinations in future cancer immunoadjuvant development. This study may have important implications in the long-term vaccine design of one-shot vaccinations.

TLR7 Agonist-Loaded Gadolinium Oxide Nanotubes Promote Anti-Tumor Immunity by Activation of Innate and Adaptive Immune Responses

Improving the delivery of biomolecules to DCs and lymph nodes is critical to increasing their anti-tumor efficacy, reducing their off-target side effects, and improving their safety. In this study, Gd2O3 nanotubes with lengths of 70-80 nm, diameters of 20-30 nm, and pore sizes of up to 18 nm were synthesized using a facile one-pot solvothermal method. The Gd2O3 nanotubes showed good adsorption capacity of OVA and TLR7a, with a loading efficiency of about 100%. The Gd2O3 nanotubes showed pH-sensitive degradation and biomolecule release properties; the release of gadolinium ions, OVA, and TLR7a was slow at pH 7.4 and fast at pH 5. The Gd2O3 nanotubes showed 2.6-6.0 times higher payload retention around the injection site, 3.1 times higher cellular uptake, 1.7 times higher IL1β secretion, 1.4 times higher TNFα secretion by BMDCs, and markedly enhanced draining lymph node delivery properties. The combination of OVA, TLR7a, and Gd2O3 nanotubes significantly inhibited tumor growth and increased survival rate compared with only OVA-TLR7a, only OVA, and saline. The Gd2O3 nanotubes are biocompatible and can also be used as radiation sensitizers.

A single-shot prophylactic tumor vaccine enabled by an injectable biomembrane hydrogel

Prophylactic tumor vaccines hold great promise against tumor occurrence. However, their clinical efficacy remains low due to inadequate activation of strong-sustainable immunity. Herein, a biomembrane hydrogel was designed as a powerful single-shot prophylactic tumor vaccine. Mannose-decorated hybrid biomembrane (MHCM) modified with oxidized sodium alginate (OSA) was designed as a gelator (O-MHCM), where the hybrid biomembrane (HCM) is a hybridization of bacterial outer membrane vesicles (OMV) and tumor cell membranes (TCM). The O-MHCM enables quick gelation subcutaneously where the cysteine protease inhibitor E64 is encapsulated in hydrogel micropores. After a single vaccination of E64@O-MHCM hydrogel, MHCM and E64 are released sustainably due to OSA moiety degradation. The MHCM enables active targeting to dendritic cells (DC) and effective DC maturation. Meanwhile, the E64 enables sufficient antigen availability for subsequent cross presentation. Ultimately, strong and sustainable T lymphocyte-mediated immunity was elicited, demonstrating a strong prophylactic effect against breast tumors. This study provides a long-lasting platform to prevent tumor occurrence, opening an innovative avenue for the design of a single-shot prophylactic tumor vaccine. STATEMENT OF SIGNIFICANCE: Developing a single-shot prophylactic tumor vaccine to elicit strong-sustainable immunity is of great interest clinically. Here, a prophylactic tumor vaccine was designed using an injectable biomembrane hydrogel for achieving strong-sustainable immunity. The mannose-tailored hybrid biomembrane was modified with oxidized sodium alginate to result in a gelator, which enabled the formation of the hydrogel after subcutaneous injection. Cysteine protease inhibitor E64 was incorporated into the micropores of the hydrogel. The hydrogel induced strong-sustainable immunity through the continuous release of active components. This was facilitated by the mannose moiety, which enabled active targeting, as well as the antigen and adjuvant function of biomembrane, and the E64-enabled suppression of antigen degradation. The biomembrane hydrogel demonstrated powerful prevention of 4T1 breast tumors. This study offers an attractive strategy for designing a single-shot prophylactic tumor vaccine.

Advanced subunit vaccine delivery technologies: From vaccine cascade obstacles to design strategies

Designing and manufacturing safe and effective vaccines is a crucial challenge for human health worldwide. Research on adjuvant-based subunit vaccines is increasingly being explored to meet clinical needs. Nevertheless, the adaptive immune responses of subunit vaccines are still unfavorable, which may partially be attributed to the immune cascade obstacles and unsatisfactory vaccine design. An extended understanding of the crosstalk between vaccine delivery strategies and immunological mechanisms could provide scientific insight to optimize antigen delivery and improve vaccination efficacy. In this review, we summarized the advanced subunit vaccine delivery technologies from the perspective of vaccine cascade obstacles after administration. The engineered subunit vaccines with lymph node and specific cell targeting ability, antigen cross-presentation, T cell activation properties, and tailorable antigen release patterns may achieve effective immune protection with high precision, efficiency, and stability. We hope this review can provide rational design principles and inspire the exploitation of future subunit vaccines.

Hydrogel-guided strategies to stimulate an effective immune response for vaccine-based cancer immunotherapy

Cancer vaccines have attracted widespread interest in tumor therapy because of the potential to induce an effective antitumor immune response. However, many challenges including weak immunogenicity, off-target effects, and immunosuppressive microenvironments have prevented their broad clinical translation. To overcome these difficulties, effective delivery systems have been designed for cancer vaccines. As carriers in cancer vaccine delivery systems, hydrogels have gained substantial attention because they can encapsulate a variety of antigens/immunomodulators and protect them from degradation. This enables hydrogels to simultaneously reverse immunosuppression and stimulate the immune response. Meanwhile, the controlled release properties of hydrogels allow for precise temporal and spatial release of loads in situ to further enhance the immune response of cancer vaccines. Therefore, this review summarizes the classification of cancer vaccines, highlights the strategies of hydrogel-based cancer vaccines, and provides some insights into the future development of hydrogel-based cancer vaccines.

Therapeutic Cancer Vaccines—Antigen Discovery and Adjuvant Delivery Platforms

For decades, vaccines have played a significant role in protecting public and personal health against infectious diseases and proved their great potential in battling cancers as well. This review focused on the current progress of therapeutic subunit vaccines for cancer immunotherapy. Antigens and adjuvants are key components of vaccine formulations. We summarized several classes of tumor antigens and bioinformatic approaches of identification of tumor neoantigens. Pattern recognition receptor (PRR)-targeting adjuvants and their targeted delivery platforms have been extensively discussed. In addition, we emphasized the interplay between multiple adjuvants and their combined delivery for cancer immunotherapy.

Symphony of nanomaterials and immunotherapy based on the cancer-immunity cycle

The immune system is involved in the initiation and progression of cancer. Research on cancer and immunity has contributed to the development of several clinically successful immunotherapies. These immunotherapies often act on a single step of the cancer–immunity cycle. In recent years, the discovery of new nanomaterials has dramatically expanded the functions and potential applications of nanomaterials. In addition to acting as drug-delivery platforms, some nanomaterials can induce the immunogenic cell death (ICD) of cancer cells or regulate the profile and strength of the immune response as immunomodulators. Based on their versatility, nanomaterials may serve as an integrated platform for multiple drugs or therapeutic strategies, simultaneously targeting several steps of the cancer–immunity cycle to enhance the outcome of anticancer immune response. To illustrate the critical roles of nanomaterials in cancer immunotherapies based on cancer–immunity cycle, this review will comprehensively describe the crosstalk between the immune system and cancer, and the current applications of nanomaterials, including drug carriers, ICD inducers, and immunomodulators. Moreover, this review will provide a detailed discussion of the knowledge regarding developing combinational cancer immunotherapies based on the cancer–immunity cycle, hoping to maximize the efficacy of these treatments assisted by nanomaterials.

Integrating plant molecular farming and materials research for next-generation vaccines

Biologics - medications derived from a biological source - are increasingly used as pharmaceuticals, for example, as vaccines. Biologics are usually produced in bacterial, mammalian or insect cells. Alternatively, plant molecular farming, that is, the manufacture of biologics in plant cells, transgenic plants and algae, offers a cheaper and easily adaptable strategy for the production of biologics, in particular, in low-resource settings. In this Review, we discuss current vaccination challenges, such as cold chain requirements, and highlight how plant molecular farming in combination with advanced materials can be applied to address these challenges. The production of plant viruses and virus-based nanotechnologies in plants enables low-cost and regional fabrication of thermostable vaccines. We also highlight key new vaccine delivery technologies, including microneedle patches and material platforms for intranasal and oral delivery. Finally, we provide an outlook of future possibilities for plant molecular farming of next-generation vaccines and biologics.

Integrating plant molecular farming and materials research for next-generation vaccines

Biologics - medications derived from a biological source - are increasingly used as pharmaceuticals, for example, as vaccines. Biologics are usually produced in bacterial, mammalian or insect cells. Alternatively, plant molecular farming, that is, the manufacture of biologics in plant cells, transgenic plants and algae, offers a cheaper and easily adaptable strategy for the production of biologics, in particular, in low-resource settings. In this Review, we discuss current vaccination challenges, such as cold chain requirements, and highlight how plant molecular farming in combination with advanced materials can be applied to address these challenges. The production of plant viruses and virus-based nanotechnologies in plants enables low-cost and regional fabrication of thermostable vaccines. We also highlight key new vaccine delivery technologies, including microneedle patches and material platforms for intranasal and oral delivery. Finally, we provide an outlook of future possibilities for plant molecular farming of next-generation vaccines and biologics.

Engineering Vaccines for Tissue-Resident Memory T Cells

In recent years, tissue-resident memory T cells (TRM) have attracted significant attention in the field of vaccine development. Distinct from central and effector memory T cells, TRM cells take up residence in home tissues such as the lung or urogenital tract and are ideally positioned to respond quickly to pathogen encounter. TRM have been found to play a role in the immune response against many globally important infectious diseases for which new or improved vaccines are needed, including influenza and tuberculosis. It is also increasingly clear that TRM play a pivotal role in cancer immunity. Thus, vaccines that can generate this memory T cell population are highly desirable. The field of immunoengineering-that is, the application of engineering principles to study the immune system and design new and improved therapies that harness or modulate immune responses-is ideally poised to provide solutions to this need for next-generation TRM vaccines. This review covers recent developments in vaccine technologies for generating TRM and protecting against infection and cancer, including viral vectors, virus-like particles, and synthetic and natural biomaterials. In addition, it offers critical insights on the future of engineering vaccines for tissue-resident memory T cells.

Polymeric nanoparticle vaccines to combat emerging and pandemic threats

Subunit vaccines are more advantageous than live attenuated vaccines in terms of safety and scale-up manufacture. However, this often comes as a trade-off to their efficacy. Over the years, polymeric nanoparticles have been developed to improve vaccine potency, by engineering their physicochemical properties to incorporate multiple immunological cues to mimic pathogenic microbes and viruses. This review covers recent advances in polymeric nanostructures developed toward particulate vaccines. It focuses on the impact of microbe mimicry (e.g. size, charge, hydrophobicity, and surface chemistry) on modulation of the nanoparticles’ delivery, trafficking, and targeting antigen-presenting cells to elicit potent humoral and cellular immune responses. This review also provides up-to-date progresses on rational designs of a wide variety of polymeric nanostructures that are loaded with antigens and immunostimulatory molecules, ranging from particles, micelles, nanogels, and polymersomes to advanced core-shell structures where polymeric particles are coated with lipids, cell membranes, or proteins.

Laser-assisted skin delivery of immunocontraceptive rabies nanoparticulate vaccine in poloxamer gel

A painless skin delivery of vaccine for disease prevention is of great advantage in improving compliance in patients. To test this idea as a proof of concept, we utilized a pDNA vaccine construct, pDNAg333-2GnRH that has a dual function of controlling rabies and inducing immunocontraception in animals. The pDNA was administered to mice in a nanoparticulate form delivered through the skin using the P.L.E.A.S.E.® (Precise Laser Epidermal System) microporation laser device. Laser application was well tolerated, and mild skin reaction was healed completely in 8 days. We demonstrated that adjuvanted nanoparticulate pDNA vaccine significantly upregulated the expression of co-stimulatory molecules in dendritic cells. After topical administration of the adjuvanted nano-vaccine in mice, the high avidity serum for GnRH antibodies were induced and maintained up to 9 weeks. The induced immune response was of a mixed Th1/Th2 profile as measured by IgG subclasses (IgG2a and IgG1) and cytokine levels (IFN-γ and IL-4). Using flow cytometry, we revealed an increase of CD8+ T-cells and CD45R B cells upon the administration of the adjuvanted vaccine. Our previous study used the same pDNA nanoparticulate vaccine through an IM route, and a comparable immune response was induced using P.L.E.A.S.E. However, the vaccine dose in the current study was four-fold less than what was applied through the IM route.We concluded that laser-assisted skin vaccination has a potential of becoming a safe and reliable vaccination tool for rabies vaccination in animals or even in humans for pre- or post-exposure prophylaxis.

Leveraging the modularity of biomaterial carriers to tune immune responses

Biomaterial carriers offer modular features to control the delivery and presentation of vaccines and immunotherapies. This tunability is a distinct capability of biomaterials. Understanding how tunable material features impact immune responses is important to improve vaccine and immunotherapy design, as well as clinical translation. Here we discuss the modularity of biomaterial properties as a means of controlling encounters with immune signals across scales - tissue, cell, molecular, and time - and ultimately, to direct stimulation or regulation of immune function. We highlight these advances using illustrations from recent literature across infectious disease, cancer, and autoimmunity. As the immune engineering field matures, informed design criteria could support more rational biomaterial carriers for vaccination and immunotherapy.

Cancer Nanomedicines in an Evolving Oncology Landscape

Nanomedicine represents an important class of cancer therapy. Clinical translation of cancer nanomedicine has significantly reduced the toxicity and adverse consequences of standard-of-care chemotherapy. Recent advances in new cancer treatment modalities (e.g., gene and immune therapies) are profoundly changing the oncology landscape, bringing with them new requirements and challenges for next-generation cancer nanomedicines. We present an overview of cancer nanomedicines in four emerging oncology-associated fields: (i) gene therapy, (ii) immunotherapy, (iii) extracellular vesicle (EV) therapy, and (iv) machine learning-assisted therapy. We discuss the incorporation of nanomedicine into these emerging disciplines, present prominent examples, and evaluate their advantages and challenges. Finally, we discuss future opportunities for next-generation cancer nanomedicines.

Cationic Liposome/DNA Complexes Mediate Antitumor Immunotherapy by Promoting Immunogenic Tumor Cell Death and Dendritic Cell Activation

Immunotherapy has been successfully used in the treatment of multiple malignancies, but clinical studies revealed low response rates. Thus, the development of new effective immunotherapeutic modalities is urgently needed. Successfully inducing tumor cell death with enhanced antigenicity is important for the expansion and differentiation of tumor-specific CD8⁺ cytotoxic T lymphocytes. Cationic liposome/DNA complexes (CLN/DNA), which usually have obvious cytotoxic effects, may improve the antitumor immunity through enhancing the immunogenicity of dying tumor cells. Herein, we report that a plasmid DNA-encapsulated cationic lipid nanoparticle formulated with cholesterol, DOTAP, and DSPE-mPEG₂₀₀₀ significantly increases the tumor cell death with high antigenicity in vitro. Furthermore, the cationic liposome/DNA complex (CLN/DNA) treatment promotes the activation of dendritic cells (DCs). We also find that the intratumorally injected CLN/DNA successfully promoted the activation of DCs in the tumor-draining lymph node. Importantly, both local tumor growth and distant tumor formation were significantly inhibited by T cell-dependent antitumor immune responses after intratumoral injection of CLN/DNA. This study presents a simple and effective strategy for improving the cancer immunotherapy.

Pulmonary Delivery of Nanoparticle-Bound Toll-like Receptor 9 Agonist for the Treatment of Metastatic Lung Cancer

CpG oligodeoxynucleotides are potent toll-like receptor (TLR) 9 agonists and have shown promise as anticancer agents in preclinical studies and clinical trials. Binding of CpG to TLR9 initiates a cascade of innate and adaptive immune responses, beginning with activation of dendritic cells and resulting in a range of secondary effects that include the secretion of pro-inflammatory cytokines, activation of natural killer cells, and expansion of T cell populations. Recent literature suggests that local delivery of CpG in tumors results in superior antitumor effects as compared to systemic delivery. In this study, we utilized PRINT (particle replication in nonwetting templates) nanoparticles as a vehicle to deliver CpG into murine lungs through orotracheal instillations. In two murine orthotopic metastasis models of non-small-cell lung cancer-344SQ (lung adenocarcinoma) and KAL-LN2E1 (lung squamous carcinoma), local delivery of PRINT-CpG into the lungs effectively promoted substantial tumor regression and also limited systemic toxicities associated with soluble CpG. Furthermore, cured mice were completely resistant to tumor rechallenge. Additionally, nanodelivery showed extended retention of CpG within the lungs as well as prolonged elevation of antitumor cytokines in the lungs, but no elevated levels of proinflammatory cytokines in the serum. These results demonstrate that PRINT-CpG is a potent nanoplatform for local treatment of lung cancer that has collateral therapeutic effects on systemic disease and an encouraging toxicity profile and may have the potential to treat lung metastasis of other cancer types.

Artificially cloaked viral nanovaccine for cancer immunotherapy

Virus-based cancer vaccines are nowadays considered an interesting approach in the field of cancer immunotherapy, despite the observation that the majority of the immune responses they elicit are against the virus and not against the tumor. In contrast, targeting tumor associated antigens is effective, however the identification of these antigens remains challenging. Here, we describe ExtraCRAd, a multi-vaccination strategy focused on an oncolytic virus artificially wrapped with tumor cancer membranes carrying tumor antigens. We demonstrate that ExtraCRAd displays increased infectivity and oncolytic effect in vitro and in vivo. We show that this nanoparticle platform controls the growth of aggressive melanoma and lung tumors in vivo both in preventive and therapeutic setting, creating a highly specific anti-cancer immune response. In conclusion, ExtraCRAd might serve as the next generation of personalized cancer vaccines with enhanced features over standard vaccination regimens, representing an alternative way to target cancer.

Cancer therapy using oncolytic virus has shown pre-clinical and clinical efficacy. Here, the authors report ExtraCRAd, an oncolytic virus cloaked with tumour cell membrane and report its therapeutic effects in vitro and in vivo in multiple mouse tumour models.

Mucosal Immunization with a pH-Responsive Nanoparticle Vaccine Induces Protective CD8+ Lung-Resident Memory T Cells

Tissue-resident memory T cells (T_RM) patrol nonlymphoid organs and provide superior protection against pathogens that commonly infect mucosal and barrier tissues, such as the lungs, intestine, liver, and skin. Thus, there is a need for vaccine technologies that can induce a robust, protective T_RM response in these tissues. Nanoparticle (NP) vaccines offer important advantages over conventional vaccines; however, there has been minimal investigation into the design of NP-based vaccines for eliciting T_RM responses. Here, we describe a pH-responsive polymeric nanoparticle vaccine for generating antigen-specific CD8⁺ T_RM cells in the lungs. With a single intranasal dose, the NP vaccine elicited airway- and lung-resident CD8⁺ T_RM cells and protected against respiratory virus challenge in both sublethal (vaccinia) and lethal (influenza) infection models for up to 9 weeks after immunization. In elucidating the contribution of material properties to the resulting T_RM response, we found that the pH-responsive activity of the carrier was important, as a structurally analogous non-pH-responsive control carrier elicited significantly fewer lung-resident CD8⁺ T cells. We also demonstrated that dual-delivery of protein antigen and nucleic acid adjuvant on the same NP substantially enhanced the magnitude, functionality, and longevity of the antigen-specific CD8⁺ T_RM response in the lungs. Compared to administration of soluble antigen and adjuvant, the NP also mediated retention of vaccine cargo in pulmonary antigen-presenting cells (APCs), enhanced APC activation, and increased production of T_RM-related cytokines. Overall, these data suggest a promising vaccine platform technology for rapid generation of protective CD8⁺ T_RM cells in the lungs.

Role of Linker Length and Antigen Density in Nanoparticle Peptide Vaccine

Multiple studies have been published emphasizing the significant role of nanoparticle (NP) carriers in antigenic peptide-based subunit vaccines for the induction of potent humoral and cellular responses. Various design parameters of nanoparticle subunit vaccines such as linker chemistry, the proximity of antigenic peptide to NPs, and the density of antigenic peptides on the surface of NPs play an important role in antigen presentation to dendritic cells (DCs) and in subsequent induction of CD8+ T cell response. In this current study, we evaluated the role of peptide antigen proximity and density on DC uptake, antigen cross-presentation, in vitro T cell proliferation, and in vivo induction of CD8+ T cells. To evaluate the role of antigen proximity, CSIINFEKL peptides were systematically conjugated to poly(ethylene glycol) (PEG) hydrogels through N-hydroxysuccinimide-PEG-maleimide linkers of varying molecular weights: 2k, 5k, and 10k. We observed that the peptides conjugated to NPs via the 2k and 5k PEG linkers resulted in higher uptake in bone marrow-derived DCs (BMDCs) and increased p-MHC-I formation on the surface of bone marrow-derived DCs (BMDCs) as compared to the 10k PEG linker formulation. However, no significant differences in vitro T cell proliferation and induction of in vivo CD8+ T cells were found among linker lengths. To study the effect of antigen density, CSIINFEKL peptides were conjugated to PEG hydrogels via 5k PEG linkers at various densities. We found that high antigen density NPs presented the highest p-MHC-I on the surface of BMDCs and induced higher proliferation of T cells, whereas NPs with low peptide density resulted in higher DC cell uptake and elevated frequency of IFN-γ producing CD8+ T cells in mice as compared to the medium- and high-density formulations. Altogether, findings for these experiments highlighted the importance of linker length and peptide antigen density on DC cell uptake, antigen presentation, and induction of in vivo CD8+ T cell response.

A Visible Codelivery Nanovaccine of Antigen and Adjuvant with Self-Carrier for Cancer Immunotherapy

Codelivery nanovaccines of antigens and adjuvants have achieved positive therapy for cancer immunotherapy. The insufficient immunogenicity of these vaccines leads to the difficulty of eliciting robust immune effects for immune clearance due to the inadequate loading efficiency, complex preparation processes, low safety concerns, and weak immune responses. Herein, a visible codelivery nanovaccine of an antigen and adjuvant based on self-cross-linked antigen nanoparticles (ovalbumin nanoparticles (ONPs)) combined with the adjuvant (CpG) for cancer immunotherapy was prepared using antigens themselves as carriers. ONPs not only provide sufficient antigens for continuous simulation of the immune response with high antigen loading efficiency but also serve as natural carriers of CpG. In vitro and in vivo experiments proved that ONPs-CpG can elicit a robust immune response including DC maturity, T cell activation, and IFN-γ production. ONPs-CpG induced strong tumor-specific immunity and exhibited remarkable antitumor immunotherapy effects in vivo using mouse models of lymphoma. Furthermore, to perform the precise vaccine delivery, the dual fluorescent codelivery nanovaccine was monitored in real time in vivo by the visible imaging method. With regard to migration tracking, fluorescence imaging allowed for both high resolution and sensitivity of visible detection based on the fluorescence of ONPs and CpG. The multifunctional nanovaccine could function as a robust platform for cancer immunotherapy and a visible system for antigen-adjuvant tracking.

Spherical Nucleic Acid Nanoparticles: Therapeutic Potential

Spherical nucleic acids (SNAs) are highly oriented, well organized, polyvalent structures of nucleic acids conjugated to hollow or solid core nanoparticles. Because they can transfect many tissue and cell types without toxicity, induce minimum immune response, and penetrate various biological barriers (such as the skin, blood-brain barrier, and blood-tumor barrier), they have become versatile tools for the delivery of nucleic acids, drugs, and proteins for various therapeutic purposes. This article describes the unique structures and properties of SNAs and discusses how these properties enable their application in gene regulation, immunomodulation, and drug and protein delivery. It also summarizes current efforts towards clinical translation of SNAs and provides an expert opinion on remaining challenges to be addressed in the path forward to the clinic.