Micro and nanoparticle-based delivery systems for vaccine immunotherapy: an immunological and materials perspective

PLGA particulate delivery systems for subunit vaccines: Linking particle properties to immunogenicity

Among the emerging subunit vaccines are recombinant protein- and synthetic peptide-based vaccine formulations. However, proteins and peptides have a low intrinsic immunogenicity. A common strategy to overcome this is to co-deliver (an) antigen(s) with (an) immune modulator(s) by co-encapsulating them in a particulate delivery system, such as poly(lactic-co-glycolic acid) (PLGA) particles. Particulate PLGA formulations offer many advantages for antigen delivery as they are biocompatible and biodegradable; can protect the antigens from degradation and clearance; allow for co-encapsulation of antigens and immune modulators; can be targeted to antigen presenting cells; and their particulate nature can increase uptake and cross-presentation by mimicking the size and shape of an invading pathogen. In this review we discuss the pros and cons of using PLGA particulate formulations for subunit vaccine delivery and provide an overview of formulation parameters that influence their adjuvanticity and the ensuing immune response.

Cerium dioxide nanoparticles increase immunogenicity of the influenza vaccine

We have demonstrated the influence of cerium dioxide nanoparticles on the immunogenicity of the influenza vaccine on an example of liquid split inactivated Vaxigrip vaccine. Antibody titers were analyzed using the hemagglutination inhibition (HI) assay. Seroprotection, seroconversion, the geometric mean titers (GMTs) and the factor increase (FI) in the GMTs were calculated. The effect of nano-ceria surface stabilizer on the enhancement of immunogenicity was shown. The vaccine modified by citrate-stabilized nano-ceria, in contrast to a non-modified Vaxigrip vaccine, did not provide an adequate level of seroprotection, and seroconversion after vaccination was 66.7% on days 49-63 for virus strain А(H1N1) and 100% on day 49 for virus strain B/Yamagata. For the low immunogenic influenza B virus, the rise in antibody titers (GMT/IF) was 24.38/3.28 after the first injection and 50.40/6.79 on day 49. For the vaccine modified by non-stabilized nano-ceria, for all virus strains under study, on day 63, upon immunization notable levels of seroprotection, seroconversion and GMT/IF were registered (higher than for the non-modified Vaxigrip vaccine). The successful attempt to modify the influenza vaccine demonstrates the possible ways of increasing the specific activity of vaccines using nano-ceria.

Hydrophobic chain modified low molecular weight polyethylenimine for efficient antigen delivery

Developing new therapeutic vaccines to promote antigen cross-presentation in antigen-presenting cells, especially dendritic cells, is regarded as a promising approach to prime antigen-specific T cell responses against tumor cells.

In situ polyethylene sebacate particulate carriers as an alternative to Freund's adjuvant for delivery of a contraceptive peptide vaccine--A feasibility study

The present study evaluates the feasibility of particulate carriers of a biodegradable polymer polyethylene sebacate (PES) as an alternative to Freund's adjuvant in the design of a peptide vaccine formulation. The vaccine formulation comprised of PES and the antigen KLH conjugated 80kDa HSA peptide-1 dissolved in N-methyl-2-pyrrolidone (NMP)/NMP-water as solvent. The antigen revealed good stability and the formulations were readily syringeable. Intradermal injection of the formulations resulted in the formation of PES particulates in situ at the site of injection. The NMP formulations revealed larger particulates which elicited no immunogenic response when injected in rabbits. On the other hand the NMP-water formulation revealed formation of microparticles which were significantly smaller in size, in combination with a small fraction of nanoparticles. It elicited an antibody titer up to 1:3200 in rabbits following intradermal injection. Western blot confirmed generation of antibodies specific to the peptide. Contraceptive efficacy was confirmed by loss of sperm motility and head-to-head agglutination of sperms in the treatment group. Unlike the severe reactions observed with administration of Freund's adjuvant, only mild hypersensitivity reaction was observed with the PES formulations. The mild reaction coupled with the contraceptive efficacy observed suggested PES particulates as a viable alternative to Freund's adjuvant.

Virus-Based Nanoparticles as Versatile Nanomachines

Nanoscale engineering is revolutionizing the way we prevent, detect, and treat diseases. Viruses have played a special role in these developments because they can function as prefabricated nanoscaffolds that have unique properties and are easily modified. The interiors of virus particles can encapsulate and protect sensitive compounds, while the exteriors can be altered to display large and small molecules in precisely defined arrays. These properties of viruses, along with their innate biocompatibility, have led to their development as actively targeted drug delivery systems that expand on and improve current pharmaceutical options. Viruses are naturally immunogenic, and antigens displayed on their surface have been used to create vaccines against pathogens and to break self-tolerance to initiate an immune response to dysfunctional proteins. Densely and specifically aligned imaging agents on viruses have allowed for high-resolution and noninvasive visualization tools to detect and treat diseases earlier than previously possible. These and future applications of viruses have created an exciting new field within the disciplines of both nanotechnology and medicine.

Engineering immunity: Modulating dendritic cell subsets and lymph node response to direct immune-polarization and vaccine efficacy

While successful vaccines have been developed against many pathogens, there are still many diseases and pathogenic infections that are highly evasive to current vaccination strategies. Thus, more sophisticated approaches to control the type and quality of vaccine-induced immune response must be developed. Dendritic cells (DCs) are the sentinels of the body and play a critical role in immune response generation and direction by bridging innate and adaptive immunity. It is now well recognized that DCs can be separated into many subgroups, each of which has a unique function. Better understanding of how various DC subsets, in lymphoid organs and in the periphery, can be targeted through controlled delivery; and how these subsets modulate and control the resulting immune response could greatly enhance our ability to develop new, effective vaccines against complex diseases. In this review, we provide an overview of DC subset biology and discuss current immunotherapeutic strategies that utilize DC targeting to modulate and control immune responses.

Particle-based platforms for malaria vaccines

Recombinant subunit vaccines in general are poor immunogens likely due to the small size of peptides and proteins, combined with the lack or reduced presentation of repetitive motifs and missing complementary signal(s) for optimal triggering of the immune response. Therefore, recombinant subunit vaccines require enhancement by vaccine delivery vehicles in order to attain adequate protective immunity. Particle-based delivery platforms, including particulate antigens and particulate adjuvants, are promising delivery vehicles for modifying the way in which immunogens are presented to both the innate and adaptive immune systems. These particle delivery platforms can also co-deliver non-specific immunostimodulators as additional adjuvants. This paper reviews efforts and advances of the Particle-based delivery platforms in development of vaccines against malaria, a disease that claims over 600,000 lives per year, most of them are children under 5 years of age in sub-Sahara Africa.

Diaminosulfide based polymer microparticles as cancer vaccine delivery systems

The aim of the research presented here was to determine the characteristics and immunostimulatory capacity, in vivo, of antigen and adjuvant co-loaded into microparticles made from a novel diaminosulfide polymer, poly(4,4'-trimethylenedipiperdyl sulfide) (PNSN), and to assess their potential as cancer vaccine vectors. PNSN microparticles co-loaded with the antigen, ovalbumin (OVA), and adjuvant, CpG 1826, (PNSN(OVA + CpG)) were fabricated and characterized for size (1.64 μm diameter; PDI=0.62), charge (-23.1 ± 0.3), and loading efficiencies of antigen (7.32 μg/mg particles) and adjuvant (0.95 μg/mg particles). The ability of PNSN(OVA + CpG) to stimulate cellular and humoral immune responses in vivo was compared with other PNSN microparticle formulations as well as with poly(lactic-co-glycolic acid)(PLGA)-based microparticles, co-loaded with OVA and CpG (PLGA(OVA + CpG)), an adenovirus encoding OVA (Ad5-OVA), and OVA delivered with incomplete Freund's adjuvant (IFA(OVA)). In vivo OVA-specific IgG1 responses, after subcutaneous prime/boosts in mice, were similar when PNSN(OVA + CpG) and PLGA(OVA + CpG) were compared and the presence of CpG 1826 within the PNSN microparticles demonstrated significantly improved responses when compared to PNSN microparticles loaded with OVA alone (PNSN(OVA)), plus or minus soluble CpG 1826. Cellular immune responses to all particle-based vaccine formulations ranged from being negligible to modest with PNSN(OVA + CpG) generating the greatest responses, displaying significantly increased levels of OVA-specific CD8+ T lymphocytes compared to controls and IFA(OVA) treated mice. Finally, it was shown that of all vaccination formulations tested PNSN(OVA + CpG) was the most protective against subsequent challenge with an OVA-expressing tumor cell line, E.G7. Thus, microparticles made from poly(diaminosulfide)-based macromolecules possess promising potential as vaccine vectors and, as demonstrated here, may have impact as cancer vaccines in particular.

Nanoparticle Drug Delivery Systems Designed to Improve Cancer Vaccines and Immunotherapy

Recent studies have demonstrated great therapeutic potential of educating and unleashing our own immune system for cancer treatment. However, there are still major challenges in cancer immunotherapy, including poor immunogenicity of cancer vaccines, off-target side effects of immunotherapeutics, as well as suboptimal outcomes of adoptive T cell transfer-based therapies. Nanomaterials with defined physico-biochemical properties are versatile drug delivery platforms that may address these key technical challenges facing cancer vaccines and immunotherapy. Nanoparticle systems have been shown to improve targeted delivery of tumor antigens and therapeutics against immune checkpoint molecules, amplify immune activation via the use of new stimuli-responsive or immunostimulatory materials, and augment the efficacy of adoptive cell therapies. Here, we review the current state-of-the-art in nanoparticle-based strategies designed to potentiate cancer immunotherapies, including cancer vaccines with subunit antigens (e.g., oncoproteins, mutated neo-antigens, DNA and mRNA antigens) and whole-cell tumor antigens, dendritic cell-based vaccines, artificial antigen-presenting cells, and immunotherapeutics based on immunogenic cell death, immune checkpoint blockade, and adoptive T-cell therapy.

Poly(lactic acid) and poly(lactic-co-glycolic acid) particles as versatile carrier platforms for vaccine delivery

The development of safe and effective vaccines for cancer and infectious diseases remains a major goal in public health. Over the last two decades, controlled release of vaccine antigens and immunostimulant molecules has been achieved using nanometer or micron-sized delivery vehicles synthesized using biodegradable polymers. In addition to achieving a depot effect, enhanced vaccine efficacy using such delivery vehicles has been attributed to efficient targeting of antigen presenting cells such as dendritic cells. Biodegradable and biocompatible poly(lactic acid) and poly(lactic-co-glycolic acid) polymers belong to one such family of polymers that have been a popular choice of material used in the design of these delivery vehicles. This review summarizes research findings from ourselves and others highlighting the promise of poly(lactic acid)- and poly(lactic-co-glycolic acid)-based vaccine carriers in enhancing immune responses.

Engineered PRINT(®) nanoparticles for controlled delivery of antigens and immunostimulants

Particle replication in non-wetting templates (PRINT) is a novel nanoparticle platform that provides compositional flexibility with the ability to specify size and shape in formulating vaccines. The PRINT platform also offers manufacturing and cost advantages over traditional particle technologies. Across multiple antigen and adjuvant formulations, robust antibody and cellular responses have been achieved using PRINT particles in mouse models. Preclinical studies applying PRINT technology in the disease areas of influenza, malaria, and pneumonia are described in this commentary. The proof of principle studies pave the way toward significant cost-effective solutions to global vaccine supply needs.

Supramolecular peptide vaccines: tuning adaptive immunity

Successful immunotherapies must be designed to elicit targeted immune responses having a specifiable phenotype across many dimensions, including the phenotypes of T cells, B cells, antigen-presenting cells, and others. For synthetic or subunit vaccines, stimulation of strong enough immune responses usually requires adjuvants, which can cause local inflammation and complicate the targeting of such phenotypes. Supramolecular materials provide routes for reducing or eliminating supplemental adjuvants. Owing to their compositional controllability, supramolecular assemblies show promise for fine-tuning immune responses by adjusting combinations of material attributes including epitope content, multivalency, size, dose, and small quantities of specific adjuvants. Here we focus on supramolecular vaccines incorporating multiple epitopes in precise ratios, with an emphasis on peptides that form high-aspect ratio (i.e. fibrillar) structures.

pH-Responsive Poly(D,L-lactic-co-glycolic acid) Nanoparticles with Rapid Antigen Release Behavior Promote Immune Response

In the quest to treat intracellular infectious diseases and virus infection, nanoparticles (NPs) have been considered to be efficient tools for inducing potent immune responses, specifically cellular immunity. Antigen processing and presenting by antigen presenting cells (APCs) could influence immune response, especially the priming of T-cell-mediated cellular immunity. Here, we fabricated pH-responsive poly(D,L-lactic-co-glycolic acid) (PLGA) NPs with rapid antigen intracellular release behavior in APCs. The NPs, which had thin shells and large inner space, contain ammonium bicarbonate (NH4HCO3), which could regulate release in endosomes and lysosomes, acting as an antigen release promoter in dendritic cells (DCs), and were coencapsulated with antigen (ovalbumin, OVA). Hydrogen ions (H(+)) in DC endosomes and lysosomes (pH ∼5.0 and 6.5) could react with NH4HCO3 to generate NH3 and CO2, which broke NPs and released antigens. After uptake by DCs, antigens encapsulated in pH-responsive PLGA NPs could escape from lysosomes into the cytoplasm and be cross-presented. Moreover, the NPs induced up-regulation of co-stimulatory molecules and stimulated cytokine production. Mouse immunization with pH-responsive PLGA NPs induced greater lymphocyte activation, more antigen-specific CD8(+) T cells, stronger cytotoxic capacity (IFN-γ and granzyme B), enhanced antigen-specific IgG antibodies, and higher serum IgG2a/IgG1, indicating cellular immunity. The NPs also improved generation of memory T cells to protect against reinfection. Thus, pH-responsive PLGA NPs, which induced strong cellular immune responses and offered antibody protection, could be potentially useful as effective vaccine delivery and adjuvant systems for the therapy of intracellular infectious diseases and virus infection.

Guiding principles in the design of molecular bioconjugates for vaccine applications

Antigen- and adjuvant-based bioconjugates that can stimulate the immune system play an important role in vaccine applications. Bioconjugates have demonstrated unique physicochemical and biological properties, enabling vaccines to be delivered to key immune cells, to target specific intracellular pathways, or to mimic immunogenic properties of natural pathogens. In this Review we highlight recent advances in such molecular immunomodulators, with an emphasis on the structure-function relationships that provide the foundation for rational design of safe and effective vaccines and immunotherapies.

New surface radiolabeling schemes of super paramagnetic iron oxide nanoparticles (SPIONs) for biodistribution studies

Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 ± 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90-110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with (14)C, with a final activity of 0.097 nCi mg(-1) of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and detection techniques. The radiolabeling approach described here is applicable to the synthesis of a large class of nanomaterials with multiple core and surface functionalities. This work combined with the biodistribution data suggests that the radiolabeling schemes carried out in this study have broad implications for use in pharmacokinetic studies for a variety of nanomaterials.

Physicochemical and immunological assessment of engineered pure protein particles with different redox states

The development of subunit antigen delivery formulations has become an important research endeavor, especially in cases where a whole cell vaccine approach has significant biosafety issues. Particle-based systems have shown particular efficacy due to their inherent immunogenicity. In some cases, fabrication techniques can lead to changes in the redox states of encapsulated protein antigens. By employing a uniform, well-characterized, single-protein system, it is possible to elucidate how the molecular details of particle-based protein antigens affect their induced immune responses. Using mesoporous silica-templated, amide bond-stabilized ovalbumin particles, three types of particles were fabricated from native, reduced, and oxidized ovalbumin, resulting in particles with different physicochemical properties and immunogenicity. Phagocytosis, transcription factor activation, and cytokine secretion by a mouse macrophage cell line did not reveal significant differences between the three types of particles. Oxidation of the ovalbumin, however, was shown to inhibit the intracellular degradation of the particles compared with native and reduced ovalbumin particles. Slow intracellular degradation of the oxidized particles was correlated with inefficient antigen presentation and insignificant levels of T cell priming and antibody production in vivo. In contrast, particles fabricated from native and reduced ovalbumin were rapidly degraded after internalization by macrophages in vitro and resulted in significant T cell and B cell immune responses in vivo. Taken together, the current study demonstrates how the redox state of a protein antigen significantly impacts the immunogenicity of the particulate vaccine formulations.

Modulating antibacterial immunity via bacterial membrane-coated nanoparticles

Synthetic nanoparticles coated with cellular membranes have been increasingly explored to harness natural cell functions toward the development of novel therapeutic strategies. Herein, we report on a unique bacterial membrane-coated nanoparticle system as a new and exciting antibacterial vaccine. Using Escherichia coli as a model pathogen, we collect bacterial outer membrane vesicles (OMVs) and successfully coat them onto small gold nanoparticles (AuNPs) with a diameter of 30 nm. The resulting bacterial membrane-coated AuNPs (BM-AuNPs) show markedly enhanced stability in biological buffer solutions. When injected subcutaneously, the BM-AuNPs induce rapid activation and maturation of dendritic cells in the lymph nodes of the vaccinated mice. In addition, vaccination with BM-AuNPs generates antibody responses that are durable and of higher avidity than those elicited by OMVs only. The BM-AuNPs also induce an elevated production of interferon gamma (INFγ) and interleukin-17 (IL-17), but not interleukin-4 (IL-4), indicating its capability of generating strong Th1 and Th17 biased cell responses against the source bacteria. These observed results demonstrate that using natural bacterial membranes to coat synthetic nanoparticles holds great promise for designing effective antibacterial vaccines.

Nanoparticle-based immunotherapy for cancer

The design of nanovaccines capable of triggering effective antitumor immunity requires an understanding of how the immune system senses and responds to threats, including pathogens and tumors. Equally important is an understanding of the mechanisms employed by tumor cells to evade immunity and an appreciation of the deleterious effects that antitumor immune responses can have on tumor growth, such as by skewing tumor cell composition toward immunologically silent tumor cell variants. The immune system and tumors engage in a tug-of-war driven by competition where promoting antitumor immunity or tumor cell death alone may be therapeutically insufficient. Nanotechnology affords a unique opportunity to develop therapeutic compounds than can simultaneously tackle both aspects, favoring tumor eradication. Here, we review the current status of nanoparticle-based immunotherapeutic strategies for the treatment of cancer, ranging from antigen/adjuvant delivery vehicles (to professional antigen-presenting cell types of the immune system) to direct tumor antigen-specific T-lymphocyte-targeting compounds and their combinations thereof.

Development of stabilized glucomannosylated chitosan nanoparticles using tandem crosslinking method for oral vaccine delivery

Aim: The aim of this study was to develop a novel platform technology, comprising of stable glucomannosylated chitosan nanoparticles, for oral immunization. Materials & methods: Chitosan nanoparticles were stabilized by tandem crosslinking using tripolyphosphate followed by glutaraldehyde. Process and formulation variables were optimized using a ‘Box–Behnken’ design. The in vitro and in vivo performances were established in RAW 264.7 and BALB/c mice, respectively. Results: The lyophilized formulation was exceptionally stable in simulated biological media and the enclosed antigen was conformationally stable. The mechanistic understanding of glucomannosylated chitosan nanoparticles in RAW 264.7 revealed transcellular uptake via both mannose and glucose transporter-mediated endocytosis. Glucomannan modification resulted in significantly higher systemic (serum IgG titer), mucosal (secretory IgA) and cell-mediated (IL-2 and IFN-γ) immune responses in comparison with nonmodified chitosan nanoparticles. Conclusion: The present strategy is expected to contribute some novel tools for the oral delivery of numerous biomacromolecules.

Original submitted 8 August 2013; Revised submitted 15 December 2013

Bovine serum albumin adsorbed PGA-co-PDL nanocarriers for vaccine delivery via dry powder inhalation

PURPOSE

Dry powder vaccine delivery via the pulmonary route has gained significant attention as an alternate route to parenteral delivery. In this study, we investigated bovine serum albumin (BSA) adsorbed poly(glycerol adipate-co-ω-pentadecalactone), PGA-co-PDL polymeric nanoparticles (NPs) within L-leucine (L-leu) microcarriers for dry powder inhalation.

METHODS

NPs were prepared by oil-in-water single emulsion-solvent evaporation and particle size optimised using Taguchi's design of experiment. BSA was adsorbed onto NPs at different ratios at room temperature. The NPs were spray-dried in aqueous suspension of L-leu (1:1.5) using a Büchi-290 mini-spray dryer. The resultant nanocomposite microparticles (NCMPs) were characterised for toxicity (MTT assay), aerosolization (Next Generation Impactor), in vitro release study and BSA was characterized using SDS-PAGE and CD respectively.

RESULTS

NPs of size 128.50 ± 6.57 nm, PDI 0.07 ± 0.03 suitable for targeting lung dendritic cells were produced. BSA adsorption for 1 h resulted in 10.23 ± 1.87 μg of protein per mg of NPs. Spray-drying with L-leu resulted in NCMPs with 42.35 ± 3.17% yield. In vitro release study at 37°C showed an initial burst release of 30.15 ± 2.33% with 95.15 ± 1.08% over 48 h. Aerosolization studies indicated fine particle fraction (FPF%) dae < 4.46 μm as 76.95 ± 5.61% and mass median aerodynamic diameter (MMAD) of 1.21 ± 0.67 μm. The cell viability was 87.01 ± 14.11% (A549 cell line) and 106.04 ± 21.14% (16HBE14o- cell line) with L-leu based NCMPs at 1.25 mg/ml concentration after 24 h treatment. The SDS-PAGE and CD confirmed the primary and secondary structure of the released BSA.

CONCLUSIONS

The results suggest that PGA-co-PDL/L-leu NCMPs may be a promising carrier for pulmonary vaccine delivery due to excellent BSA adsorption and aerosolization behaviour.

Overcoming the challenges in administering biopharmaceuticals: formulation and delivery strategies

The formulation and delivery of biopharmaceutical drugs, such as monoclonal antibodies and recombinant proteins, poses substantial challenges owing to their large size and susceptibility to degradation. In this Review we highlight recent advances in formulation and delivery strategies--such as the use of microsphere-based controlled-release technologies, protein modification methods that make use of polyethylene glycol and other polymers, and genetic manipulation of biopharmaceutical drugs--and discuss their advantages and limitations. We also highlight current and emerging delivery routes that provide an alternative to injection, including transdermal, oral and pulmonary delivery routes. In addition, the potential of targeted and intracellular protein delivery is discussed.

Enhanced in vivo targeting of murine nonparenchymal liver cells with monophosphoryl lipid A functionalized microcapsules

A broad spectrum of infectious liver diseases emphasizes the need of microparticles for targeted delivery of immunomodulatory substances to the liver. Microcapsules (MCs) are particularly attractive for innovative drug and vaccine formulations, enabling the combination of antigen, drugs, and adjuvants. The present study aimed to develop microcapsules characterized by an enhanced liver deposition and accelerated uptake by nonparenchymal liver cells (NPCs). Initially, two formulations of biodegradable microcapsules were synthesized from either hydroxyethyl starch (HES) or mannose. Notably, HES-MCs accumulated primarily in the liver, while mannose particles displayed a lung preference. Functionalization of HES-MCs with anti-CD40, anti-DEC205, and/or monophosphoryl lipid A (MPLA) enhanced uptake of MCs by nonparenchymal liver cells in vitro. In contrast, only MPLA-coated HES-MCs promoted significantly the in vivo uptake by NPCs. Finally, HES-MCs equipped with MPLA, anti-CD40, and anti-DEC205 induced the secretion of TNF-α, IL-6 by Kupffer cells (KCs), and IFN-γ and IL-12p70 by liver dendritic cells (DCs). The enhanced uptake and activation of KCs by MPLA-HES-MCs is a promising approach to prevent or treat infection, since KCs are exploited as an entry gate in various infectious diseases, such as malaria. In parallel, loading and activating liver DCs, usually prone to tolerance, bears the potential to induce antigen specific, intrahepatic immune responses necessary to prevent and treat infections affecting the liver.

Therapeutic Vaccine Strategies against Human Papillomavirus

High-risk types of human papillomavirus (HPV) cause over 500,000 cervical, anogenital and oropharyngeal cancer cases per year. The transforming potential of HPVs is mediated by viral oncoproteins. These are essential for the induction and maintenance of the malignant phenotype. Thus, HPV-mediated malignancies pose the unique opportunity in cancer vaccination to target immunologically foreign epitopes. Therapeutic HPV vaccination is therefore an ideal scenario for proof-of-concept studies of cancer immunotherapy. This is reflected by the fact that a multitude of approaches has been utilized in therapeutic HPV vaccination design: protein and peptide vaccination, DNA vaccination, nanoparticle- and cell-based vaccines, and live viral and bacterial vectors. This review provides a comprehensive overview of completed and ongoing clinical trials in therapeutic HPV vaccination (summarized in tables), and also highlights selected promising preclinical studies. Special emphasis is given to adjuvant science and the potential impact of novel developments in vaccinology research, such as combination therapies to overcome tumor immune suppression, the use of novel materials and mouse models, as well as systems vaccinology and immunogenetics approaches.

Engaging adaptive immunity with biomaterials

Adaptive immune responses, characterized by T cells and B cells engaging and responding to specific antigens, can be raised by biomaterials containing proteins, peptides, and other biomolecules. How does one avoid, control, or exploit such responses? This review will discuss major properties and processes that influence biomaterials-directed adaptive immunity, including the physical dimensions of a material, its epitope content, and its multivalency. Selected strategies involving novel biomaterials designs will be discussed to illustrate these points of control. Specific immunological processes that biomaterials are being developed to direct will be highlighted, including minimally inflammatory scaffolds for tissue repair and immunotherapies eliciting desired B cell (antibody) responses, T cell responses, or tolerance. The continuing development of a knowledge base for specifying the strength and phenotype of biomaterials-mediated adaptive immune responses is important, not only for the engineering of better vaccines and immunotherapies, but also for managing immune responses against newer generations of increasingly biological and biomolecular materials in contexts such as tissue repair, tissue engineering, or cell delivery.

An emerging interface between life science and nanotechnology: present status and prospects of reproductive healthcare aided by nano-biotechnology

Among the various applications of nano-biotechnology, healthcare is considered one of the most significant domains. For that possibility to synthesize various kind of nanoparticles (NPs) and the ever-increasing ability to control their size as well as structure, to improve surface characteristics and binding NPs with other desired curing agents has played an important role. In this paper, a brief sketch of various kinds of nanomaterials and their biomedical applications is given. Despite claims of bio-nanotechnology about to touch all areas of medical science, information pertaining to the role of nanotechnology for the betterment of reproductive healthcare is indeed limited. Therefore, the various achievements of nano-biotechnology for healthcare in general have been illustrated while giving special insight into the role of nano-biotechnology for the future of reproductive healthcare betterment as well as current achievements of nanoscience and nanotechnology in this arena.

Materials that harness and modulate the immune system

Recently, biomaterial scientists have married materials engineering and immunobiology to conceptualize new immunomodulatory materials. This special class of biomaterials can modulate and harness the innate properties of immune functionality for enhanced therapeutic efficacy. Generally, two fundamental strategies are followed in the design of immunomodulatory biomaterials: (1) immuno-evasive (immuno-mimetic, immuno-suppressing, or immuno-inert) biomaterials and (2) immuno-activating or immuno-enhancing biomaterials. This article highlights the development and application of a number of immunomodulatory materials, categorized by these two general approaches.

Intradermal powder immunization with protein-containing vaccines

The central importance for global public health policy of delivering life-saving vaccines for all children makes the development of efficacious and safe needle-free alternatives to hypodermic needles, preferably in a thermostable form, a matter of pressing urgency. This paper comprehensively reviews past in vivo studies on intradermal powder immunization with vaccine formulations that do not require refrigeration. Particular emphasis is given to the immune response in relation to antigen adjuvantation. While needle-free intradermal delivery of vaccines induces a predominantly Th2-type immune response, adjuvants powerfully enhance and modulate the magnitude and nature of the elicited immune response at various effector sites.

Carbon nanotubes as vaccine scaffolds

Carbon nanotubes display characteristics that are potentially useful in their development as scaffolds for vaccine compositions. These features include stability in vivo, lack of intrinsic immunogenicity, low toxicity, and the ability to be appended with multiple copies of antigens. In addition, the particulate nature of carbon nanotubes and their unusual properties of rapid entry into antigen-presenting cells, such as dendritic cells, make them especially useful as carriers of antigens. Early attempts demonstrating carbon nanotube-based vaccines can be used in both infectious disease settings and cancer are promising.

Nanoparticle conjugation of CpG enhances adjuvancy for cellular immunity and memory recall at low dose

In subunit vaccines, strong CD8(+) T-cell responses are desired, yet they are elusive at reasonable adjuvant doses. We show that targeting adjuvant to the lymph node (LN) via ultrasmall polymeric nanoparticles (NPs), which rapidly drain to the LN after intradermal injection, greatly enhances adjuvant efficacy at low doses. Coupling CpG-B or CpG-C oligonucleotides to NPs led to better dual-targeting of adjuvant and antigen (codelivered on separate NPs) in cross-presenting dendritic cells compared with free adjuvant. This led to enhanced dendritic cell maturation and T helper 1 (Th1)-cytokine secretion, in turn driving stronger effector CD8(+) T-cell activation with enhanced cytolytic profiles and, importantly, more powerful memory recall. With only 4 μg CpG, NP-CpG-B could substantially protect mice from syngeneic tumor challenge, even after 4 mo of vaccination, compared with free CpG-B. Together, these results show that nanocarriers can enhance vaccine efficacy at a low adjuvant dose for inducing potent and long-lived cellular immunity.

VLPs and particle strategies for cancer vaccines

Effective delivery of tumor antigens to APCs is one of the key steps for eliciting a strong and durable immune response to tumors. Several cancer vaccines have been evaluated in clinical trials, based on soluble peptides, but results have not been fully satisfactory. To improve immunogenicity particles provide a valid strategy to display and/or incorporate epitopes which can be efficiently targeted to APCs for effective induction of adaptive immunity. In the present review, we report some leading technologies for developing particulate vaccines employed in cancer immunotherapy, highlighting the key parameters for a rational design to elicit both humoral and cellular responses.

The use of nanolipoprotein particles to enhance the immunostimulatory properties of innate immune agonists against lethal influenza challenge

Recent studies have demonstrated that therapies targeting the innate immune system have the potential to provide transient, non-specific protection from a variety of infectious organisms; however, the potential of enhancing the efficacy of such treatments using nano-scale delivery platforms requires more in depth evaluation. As such, we employed a nanolipoprotein (NLP) platform to enhance the efficacy of innate immune agonists. Here, we demonstrate that the synthetic Toll-like receptor (TLR) agonists monophosphoryl lipid A (MPLA) and CpG oligodeoxynucleotides (CpG) can be readily incorporated into NLPs. Conjugation of MPLA and CpG to NLPs (MPLA:NLP and CpG:NLP, respectively) significantly enhanced their immunostimulatory profiles both in vitro and in vivo compared to administration of agonists alone, as evidenced by significant increases in cytokine production, cell surface expression of activation markers, and upregulation of immunoregulatory genes. Importantly, enhancement of cytokine production by agonist conjugation to NLPs was also observed in primary human dendritic cells. Furthermore, BALB/c mice pretreated with CpG:NLP constructs survived a lethal influenza challenge whereas pretreatment with CpG alone had no effect on survival.

Water-soluble polymers coupled with glycopeptide antigens and T-cell epitopes as potential antitumor vaccines

Highly decorated: Tumor-associated MUC1 glycopeptide and tetanus toxoid T-cell epitope P2 can be attached to water-soluble poly(N-(2-hydroxypropyl)methacrylamide) carriers by orthogonal ligation techniques. Fully synthetic vaccine A with additional nanostructure-promoting domains induced antibodies that exhibit high affinity to tumor cells.

Multifunctional nanoparticles for drug delivery and molecular imaging

Recent advances in nanotechnology and growing needs in biomedical applications have driven the development of multifunctional nanoparticles. These nanoparticles, through nanocrystalline synthesis, advanced polymer processing, and coating and functionalization strategies, have the potential to integrate various functionalities, simultaneously providing (a) contrast for different imaging modalities, (b) targeted delivery of drug/gene, and (c) thermal therapies. Although still in its infancy, the field of multifunctional nanoparticles has shown great promise in emerging medical fields such as multimodal imaging, theranostics, and image-guided therapies. In this review, we summarize the techniques used in the synthesis of complex nanostructures, review the major forms of multifunctional nanoparticles that have emerged over the past few years, and provide a perceptual vision of this important field of nanomedicine.