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Most cancer vaccines target peptide antigens, necessitating personalization owing to the vast inter-individual diversity in major histocompatibility complex (MHC) molecules that present peptides to T cells. Furthermore, tumours frequently escape T cell-mediated immunity through mechanisms that interfere with peptide presentation

Lymph nodes (LNs) dynamically expand in response to immunization, but the relationship between LN expansion and the accompanying adaptive immune response is unclear. Here, we first characterized the LN response across time and length scales to vaccines of distinct strengths. High-frequency ultrasound revealed that a bolus ‘weak’ vaccine induced a short-lived, 2-fold volume expansion, while a biomaterial-based ‘strong’ vaccine elicited an ∼7-fold LN expansion, which was maintained several weeks after vaccination. This latter expansion was associated with altered matrix and mechanical properties of the LN microarchitecture. Strong vaccination resulted in massive immune and stromal cell engagement, dependent on antigen presence in the vaccine, and conventional dendritic cells and inflammatory monocytes upregulated genes involved in antigen presentation and LN enlargement. The degree of LN expansion following therapeutic cancer vaccination strongly correlated with vaccine efficacy, even 100 days post-vaccination, and direct manipulation of LN expansion demonstrated a causative role in immunization outcomes.

Adoptive T cell therapy provides the T cell pool needed for immediate tumor debulking, but the infused T cells generally have a narrow repertoire for antigen recognition and limited ability for long-term protection. Here, we present a biomaterial platform that enhances adoptive T cell therapy by synergistically engaging the host immune system via in-situ antigen-free vaccination. T cells alone loaded into these localized cell depots provided significantly better control of subcutaneous B16-F10 tumors than T cells delivered through direct peritumoral injection or intravenous infusion. The anti-tumor response was significantly enhanced when T cell delivery was combined with biomaterial-driven accumulation and activation of host immune cells, as this prolonged the activation state of the delivered T cells, minimized host T cell exhaustion, and enabled long-term tumor control. This integrated approach provides both immediate tumor debulking and long-term protection against solid tumors, including against tumor antigen escape.

Most bacterial vaccines work for a subset of bacterial strains or require the modification of the antigen or isolation of the pathogen before vaccine development. Here we report injectable biomaterial vaccines that trigger potent humoral and T-cell responses to bacterial antigens by recruiting, reprogramming and releasing dendritic cells. The vaccines are assembled from regulatorily approved products and consist of a scaffold with absorbed granulocyte-macrophage colony-stimulating factor and CpG-rich oligonucleotides incorporating superparamagnetic microbeads coated with the broad-spectrum opsonin Fc-mannose-binding lectin for the magnetic capture of pathogen-associated molecular patterns from inactivated bacterial-cell-wall lysates. The vaccines protect mice against skin infection with methicillin-resistant Staphylococcus aureus, mice and pigs against septic shock from a lethal Escherichia coli challenge and, when loaded with pathogen-associated molecular patterns isolated from infected animals, uninfected animals against a challenge with different E. coli serotypes. The strong immunogenicity and low incidence of adverse events, a modular manufacturing process, and the use of components compatible with current good manufacturing practice could make this vaccine technology suitable for responding to bacterial pandemics and biothreats.

Traditional bolus vaccines often fail to sustain robust adaptive immune responses, typically requiring multiple booster shots for optimal efficacy. Additionally, these provide few opportunities to control the resulting subclasses of antibodies produced, which can mediate effector functions relevant to distinct disease settings. Here, it is found that three scaffold-based vaccines, fabricated from poly(lactide-co-glycolide) (PLG), mesoporous silica rods, and alginate cryogels, induce robust, long-term antibody responses to a model peptide antigen gonadotropin-releasing hormone with single-shot immunization. Compared to a bolus vaccine, PLG vaccines prolong germinal center formation and T follicular helper cell responses. Altering the presentation and release of the adjuvant (cytosine-guanosine oligodeoxynucleotide, CpG) tunes the resulting IgG subclasses. Further, PLG vaccines elicit strong humoral responses against disease-associated antigens HER2 peptide and pathogenic E. coli, protecting mice against E. coli challenge more effectively than a bolus vaccine. Scaffold-based vaccines may thus enable potent, durable and versatile humoral immune responses against disease.

Mechanical stimulation (mechanotherapy) can promote skeletal muscle repair, but a lack of reproducible protocols and mechanistic understanding of the relation between mechanical cues and tissue regeneration limit progress in this field. To address these gaps, we developed a robotic device equipped with real-time force control and compatible with ultrasound imaging for tissue strain analysis. We investigated the hypothesis that specific mechanical loading improves tissue repair by modulating inflammatory responses that regulate skeletal muscle regeneration. We report that cyclic compressive loading within a specific range of forces substantially improves functional recovery of severely injured muscle in mice. This improvement is attributable in part to rapid clearance of neutrophil populations and neutrophil-mediated factors, which otherwise may impede myogenesis. Insights from this work will help advance therapeutic strategies for tissue regeneration broadly.

The coronavirus disease 2019 (COVID‐19) pandemic demonstrates the importance of generating safe and efficacious vaccines that can be rapidly deployed against emerging pathogens. Subunit vaccines are considered among the safest, but proteins used in these typically lack strong immunogenicity, leading to poor immune responses. Here, a biomaterial COVID‐19 vaccine based on a mesoporous silica rods (MSRs) platform is described. MSRs loaded with granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), the toll‐like receptor 4 (TLR‐4) agonist monophosphoryl lipid A (MPLA), and SARS‐CoV‐2 viral protein antigens slowly release their cargo and form subcutaneous scaffolds that locally recruit and activate antigen‐presenting cells (APCs) for the generation of adaptive immunity. MSR‐based vaccines generate robust and durable cellular and humoral responses against SARS‐CoV‐2 antigens, including the poorly immunogenic receptor binding domain (RBD) of the spike (S) protein. Persistent antibodies over the course of 8 months are found in all vaccine configurations tested and robust in vitro viral neutralization is observed both in a prime‐boost and a single‐dose regimen. These vaccines can be fully formulated ahead of time or stored lyophilized and reconstituted with an antigen mixture moments before injection, which can facilitate its rapid deployment against emerging SARS‐CoV‐2 variants or new pathogens. Together, the data show a promising COVID‐19 vaccine candidate and a generally adaptable vaccine platform against infectious pathogens., Mesoporous silica rods (MSRs) scaffolds are used as a platform to induce adaptive immunity against SARS‐CoV‐2 antigens. Sustained delivery of GM‐CSF, MPLA, and a variety of SARS‐CoV‐2 subunit immunogens from the MSR vaccine recruite immune cells into the scaffolds and consistently induce antigen‐specific long‐lasting antibodies, cytotoxic T lymphocyte responses (CTL), and viral neutralization in vitro.

Disruption of the tumor extracellular matrix (ECM) may alter immune cell infiltration into the tumor and antitumor T cell priming in the tumor-draining lymph nodes (tdLNs). Here, we explore how intratumoral enzyme treatment (ET) of B16 melanoma tumors with ECM-depleting enzyme hyaluronidase alters adaptive and innate immune populations, including T cells, DCs, and macrophages, in the tumors and tdLNs. ET increased CD103

The immune system plays key roles in tissue homeostatic and disease processes, and manipulation of innate and adaptive immune responses is of great promise for a wide array of human afflictions, including tissue repair and regeneration, cancer, autoimmune syndromes and chronic infections. Systemic approaches to immunomodulation can correct both hypoactive and hyperactive immunity; however, they typically interfere with the homeostatic role of the immune system at nontarget sites, are associated with lifelong comorbidities and potentially fatal side effects. To overcome these issues, macroscale delivery devices can be placed at sites of interest in the body and engineered to locally control the pharmacokinetics of immunomodulatory agents, including small molecules, macromolecules and cells. In this Review, we outline important cellular targets of immunotherapies in tissue repair and cancer and discuss how macroscale delivery devices can be designed to modulate the release of molecular factors to impact immune cell behaviour, control the fate of delivered therapeutic cells or directly recruit, house and modulate host cells for immunotherapy applications. Macroscale delivery devices can be used to manipulate innate and adaptive immune responses. In this Review, the authors highlight important cellular targets of immunotherapies in tissue repair and cancer and discuss macroscale biomaterials strategies for therapeutic immunomodulation.

Targeted immunomodulation of dendritic cells (DCs) in vivo will enable manipulation of T-cell priming and amplification of anticancer immune responses, but a general strategy has been lacking. Here we show that DCs concentrated by a biomaterial can be metabolically labelled with azido groups in situ, which allows for their subsequent tracking and targeted modulation over time. Azido-labelled DCs were detected in lymph nodes for weeks, and could covalently capture dibenzocyclooctyne (DBCO)-bearing antigens and adjuvants via efficient Click chemistry for improved antigen-specific CD8+ T-cell responses and antitumour efficacy. We also show that azido labelling of DCs allowed for in vitro and in vivo conjugation of DBCO-modified cytokines, including DBCO–IL-15/IL-15Rα, to improve priming of antigen-specific CD8+ T cells. This DC labelling and targeted modulation technology provides an unprecedented strategy for manipulating DCs and regulating DC–T-cell interactions in vivo. Dendritic cells concentrated in vivo within a hydrogel have been metabolically tagged with azido groups to enable tracking as well as delivery of antigens, adjuvants and cytokines, thereby facilitating targeted immunomodulation.

Most bacterial vaccines work for a subset of bacterial strains or require the modification of the antigen or isolation of the pathogen before vaccine development. Here we report injectable biomaterial vaccines that trigger potent humoral and T-cell responses to bacterial antigens by recruiting, reprogramming and releasing dendritic cells. The vaccines are assembled from regulatorily approved products and consist of a scaffold with absorbed granulocyte-macrophage colony-stimulating factor and CpG-rich oligonucleotides incorporating superparamagnetic microbeads coated with the broad-spectrum opsonin Fc-mannose-binding lectin for the magnetic capture of pathogen-associated molecular patterns from inactivated bacterial-cell-wall lysates. The vaccines protect mice against skin infection with methicillin-resistant Staphylococcus aureus, mice and pigs against septic shock from a lethal Escherichia coli challenge and, when loaded with pathogen-associated molecular patterns isolated from infected animals, uninfected animals against a challenge with different E. coli serotypes. The strong immunogenicity and low incidence of adverse events, a modular manufacturing process, and the use of components compatible with current good manufacturing practice could make this vaccine technology suitable for responding to bacterial pandemics and biothreats.

Vaccines have shown significant promise in eliciting protective and therapeutic responses. However, most effective vaccines require several booster shots, and it is challenging to generate potent responses against small molecules and synthetic peptide antigens often used to increase target specificity and improve vaccine stability. As continuous antigen uptake and processing by APCs and persistent toll-like receptor (TLR) priming have been shown to amplify antigen specific humoral immunity, we explored whether a single injection of a mesoporous silica micro-rod (MSR) vaccine containing synthetic molecules and peptides can effectively generate potent and durable antigen-specific humoral immunity. A single injection of the MSR vaccine against a gonadotropin-releasing hormone (GnRH) decapeptide elicited highly potent anti-GnRH response that lasted for over 12 months. The MSR vaccine generated higher titers than bolus or alhydrogel alum vaccine formulations. Moreover, a MSR vaccine directed against a Her2/neu peptide within the Trastuzumab binding domain showed immunoreactivity to native Her2 protein on tumor cell surface and, when directed against nicotine, generated long-term anti-nicotine antibodies. Mechanistically, we found that the MSR vaccine induced persistent germinal center (GC) B-cell activity for more than 3 weeks after a single injection, generation of memory B cells, and that at least 7 days of immunostimulation by the vaccine was required to generate an effective humoral response. Together, these data suggest that the MSR vaccine represents a promising technology for synthetic antigen vaccines to bypass the need for multiple immunizations and enhance long-term production of antibodies against endogenous antigens in the context of reproductive biology, cancer, and chronic addiction.

Broad spectrum vaccines could provide a solution to the emergence of antibiotic resistant microbes, pandemics and engineered biothreat agents. Here, we describe a modular vaccine (composite infection vaccine technology (ciVAX)) which can be rapidly assembled and in which 4 of the 5 components are already approved for human use. ciVAX consists of an injectable biomaterial scaffold with factors to recruit and activate dendritic cells (DC) in vivo and microbeads conjugated with the broad-spectrum opsonin Fc-Mannose-binding Lectin (FcMBL) that is pre-bound to polysaccharide-rich cell wall antigens, such as the pathogen-associated molecular patterns (PAMPs) fractions, captured from whole inactivated bacteria. Vaccination of mice and rabbits with ciVAX generates potent humoral and T cell responses to PAMPs isolated from native antibiotic-resistant E. coli and S. aureus, and ciVAX protects mice and pigs against lethal E coli challenge in sepsis and septic shock models. In addition to the efficacy of ciVAX against homologous challenge, PAMPS isolated from an infected animal protects other animals against infection by heterologous challenge using different E. coli serotypes – demonstrating the potential for use of ciVAX in controlling pandemics. The advantage of the ciVAX technology is the strong immunogenicity with limited reactogenicity, the use of inactivated pathogens, and the modular manufacture using cGMP approved products which can be stockpiled ready for the next pandemic.One Sentence SummaryBiomaterial vaccine induces strong immunogenicity, weak reactogenicity, and protects from E. coli sepsis in rodents and pigs, and MRSA skin abscess.

Existing strategies to enhance peptide immunogenicity for cancer vaccination generally require direct peptide alteration, which, beyond practical issues, may impact peptide presentation and result in vaccine variability. Here, we report a simple adsorption approach using polyethyleneimine (PEI) in a mesoporous silica microrod (MSR) vaccine to enhance antigen immunogenicity. The MSR–PEI vaccine significantly enhanced host dendritic cell activation and T-cell response over the existing MSR vaccine and bolus vaccine formulations. Impressively, a single injection of the MSR–PEI vaccine using an E7 peptide completely eradicated large, established TC-1 tumours in about 80% of mice and generated immunological memory. When immunized with a pool of B16F10 or CT26 neoantigens, the MSR–PEI vaccine eradicated established lung metastases, controlled tumour growth and synergized with anti-CTLA4 therapy. Our findings from three independent tumour models suggest that the MSR-PEI vaccine approach may serve as a facile and powerful multi-antigen platform to enable robust personalized cancer vaccination. A strategy to enhance antigen immunogenicity is shown using polyethyleneimine adsorbed on mesoporous silica microrod vaccine as a platform for neoantigens, supporting potent humoral immune response and inhibition of tumour growth following vaccination.

Short peptides are the minimal modality of antigen recognized by cellular immunity and are therefore considered a safe and highly specific source of antigen for vaccination. Nevertheless, successful peptide immunotherapy is limited by the short half-life of peptide antigens in vivo as well as their weak immunogenicity. We recently reported a vaccine strategy based on dendritic cell-recruiting Mesoporous Silica Rod (MSR) scaffolds to enhance T-cell responses against subunit antigen. In this study, we investigated the effect of covalently conjugating peptide antigens to MSRs to increase their retention in the scaffolds. Using both stable thioether and reducible disulfide linkages, peptide conjugation greatly increased peptide loading compared to passive adsorption. In vitro, Bone Marrow derived Dendritic Cells (BMDCs) could present Ovalbumin (OVA)-derived peptides conjugated to MSRs and induce antigen-specific T-cell proliferation. Stable conjugation decreased presentation in vitro while reducible conjugation maintained levels of presentation as high as soluble peptide. Compared to soluble peptide, in vitro, expansion of OT-II T-cells was not affected by adsorption or stable conjugation to MSRs but was enhanced with reversible conjugation to MSRs. Both conjugation schemes increased peptide residence time in MSR scaffolds in vivo compared to standard bolus injections or a simple adsorption method. When MSR scaffolds loaded with GM-CSF and CpG-ODN were injected subcutaneously, recruited dendritic cells could present antigen in situ with the stable conjugation increasing presentation capacity. Overall, this simple conjugation approach could serve as a versatile platform to efficiently incorporate peptide antigens in MSR vaccines and potentiate cellular responses.

Vaccines have shown significant promise in eliciting protective and therapeutic responses. However, most effective vaccines require several booster shots, and it is challenging to generate potent responses against small molecules and synthetic peptide antigens often used to increase target specificity and improve vaccine stability. As continuous antigen uptake and processing by APCs and persistent toll-like receptor (TLR) priming have been shown to amplify antigen specific humoral immunity, we explored whether a single injection of a mesoporous silica micro-rod (MSR) vaccine containing synthetic molecules and peptides can effectively generate potent and durable antigen-specific humoral immunity. A single injection of the MSR vaccine against a gonadotropin-releasing hormone (GnRH) decapeptide elicited highly potent anti-GnRH response that lasted for over 12 months. The MSR vaccine generated higher titers than bolus or alhydrogel alum vaccine formulations. Moreover, a MSR vaccine directed against a Her2/neu peptide within the Trastuzumab binding domain showed immunoreactivity to native Her2 protein on tumor cell surface and, when directed against nicotine, generated long-term anti-nicotine antibodies. Mechanistically, we found that the MSR vaccine induced persistent germinal center (GC) B-cell activity for more than 3 weeks after a single injection, generation of memory B cells, and that at least 7 days of immunostimulation by the vaccine was required to generate an effective humoral response. Together, these data suggest that the MSR vaccine represents a promising technology for synthetic antigen vaccines to bypass the need for multiple immunizations and enhance long-term production of antibodies against endogenous antigens in the context of reproductive biology, cancer, and chronic addiction.

Mechanical properties of the extracellular microenvironment are known to alter cellular behavior, such as spreading, proliferation or differentiation. Previous studies have primarily focused on studying the effect of matrix stiffness on cells using hydrogel substrates that exhibit purely elastic behavior. However, these studies have neglected a key property exhibited by the extracellular matrix (ECM) and various tissues; viscoelasticity and subsequent stress-relaxation. As muscle exhibits viscoelasticity, stress-relaxation could regulate myoblast behavior such as spreading and proliferation, but this has not been previously studied. In order to test the impact of stress relaxation on myoblasts, we created a set of two-dimensional RGD-modified alginate hydrogel substrates with varying initial elastic moduli and rates of relaxation. The spreading of myoblasts cultured on soft stress-relaxing substrates was found to be greater than cells on purely elastic substrates of the same initial elastic modulus. Additionally, the proliferation of myoblasts was greater on hydrogels that exhibited stress-relaxation, as compared to cells on elastic hydrogels of the same modulus. These findings highlight stress-relaxation as an important mechanical property in the design of a biomaterial system for the culture of myoblasts. STATEMENT OF SIGNIFICANCE: This article investigates the effect of matrix stress-relaxation on spreading and proliferation of myoblasts by using tunable elastic and stress-relaxing alginate hydrogels substrates with different initial elastic moduli. Many past studies investigating the effect of mechanical properties on cell fate have neglected the viscoelastic behavior of extracellular matrices and various tissues and used hydrogels exhibiting purely elastic behavior. Muscle tissue is viscoelastic and exhibits stress-relaxation. Therefore, stress-relaxation could regulate myoblast behavior if it were to be incorporated into the design of hydrogel substrates. Altogether, we showed that stress-relaxation impacts myoblasts spreading and proliferation. These findings enable a better understanding of myoblast behavior on viscoelastic substrates and could lead to the design of more suitable substrates for myoblast expansion in vitro.

Biomaterials have shown substantial potential to integrate synergistically with current cancer vaccine strategies and enhance their effectiveness. We recently developed an injectable biomaterial vaccine via spontaneous assembly of mesoporous silica (MPS) microparticles into a 3D scaffold in vivo. When formulated with GM-CSF and the TLR-9 agonist CpG, the MPS vaccine modulates host dendritic cell (DC) activation and trafficking. Here we demonstrate that a single injection of the MPS vaccine induced persistent germinal center B cell activity for over 30 days. Consequently, when immunized with a small linear Her2/neu peptide within the Trastuzumab binding domain, the MPS vaccine elicited over 2 orders of magnitude higher IgG1 and IgG2a antibody titer compared to a traditional bolus vaccine, and the antibody exhibited immunoreactivity on the native Her2 structure on breast cancer cells. To further enhance CTL responses against tumor antigens, we co-presented the antigen with polyethylenimine (PEI) in the MPS vaccine. PEI increased antigen cross-presentation in murine DCs, and TNF-a and IL-6 production in both murine and human DCs in vitro. Compared to the MPS vaccine, the MPS-PEI vaccine enhanced activated and antigen+ DCs in the vaccine and the vaccine draining lymph node by ~2 fold. Systemically, using both OVA and a HPV-E7 peptide as antigens, the MPS-PEI vaccine induced ~2.5 fold higher IFN-y producing antigen specific circulating CD8+ T-cells compared to the MPS vaccine. Impressively, using a HPV-E7 expressing tumor model, we demonstrated that a single injection of the MPS-PEI vaccine completely eradicated large established tumors in over 80% of mice. Finally, when immunized with a pool of recently sequenced B16 melanoma neoantigen peptides, the MPS-PEI vaccine induced potent therapeutic tumor growth control and synergy with anti-CTLA4 checkpoint blockade therapy. These findings suggest that the MPS vaccine may serve as a facile multifunctional and multi-epitope platform to modulate host immune cell function and augment personalized antitumor immunity. Citation Format: Aileen W. Li, Maxence O. Dellacherie, Miguel Sobral, Omr O. Ali, Jaeyun Kim, David J. Mooney. DC-recruiting biomaterial vaccine to enhance antitumor immunity [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B119.