Biomaterials as Tools to Decode Immunity

Challenges and Pitfalls of Research Designs Involving Magnesium-Based Biomaterials: An Overview

Magnesium-based biomaterials hold remarkable promise for various clinical applications, offering advantages such as reduced stress-shielding and enhanced bone strengthening and vascular remodeling compared to traditional materials. However, ensuring the quality of preclinical research is crucial for the development of these implants. To achieve implant success, an understanding of the cellular responses post-implantation, proper model selection, and good study design are crucial. There are several challenges to reaching a safe and effective translation of laboratory findings into clinical practice. The utilization of Mg-based biomedical devices eliminates the need for biomaterial removal surgery post-healing and mitigates adverse effects associated with permanent biomaterial implantation. However, the high corrosion rate of Mg-based implants poses challenges such as unexpected degradation, structural failure, hydrogen evolution, alkalization, and cytotoxicity. The biocompatibility and degradability of materials based on magnesium have been studied by many researchers in vitro; however, evaluations addressing the impact of the material in vivo still need to be improved. Several animal models, including rats, rabbits, dogs, and pigs, have been explored to assess the potential of magnesium-based materials. Moreover, strategies such as alloying and coating have been identified to enhance the degradation rate of magnesium-based materials in vivo to transform these challenges into opportunities. This review aims to explore the utilization of Mg implants across various biomedical applications within cellular (in vitro) and animal (in vivo) models.

Preparation of Degradable and Transformable Core-Corona-Type Particles that Control Cellular Uptake by Thermal Shape Change

Particle-cell interactions, such as cellular uptake, vary depending on the particle size, shape, and surface properties. By dynamic control of the physical properties of particles, microparticle-cell interactions can intentionally be altered. Particle degradability is also necessary for their application in the body. In this study, we aimed to prepare degradable core-corona-type particles that are deformed near the body temperature and investigated particle shape-dependent cellular uptake. Degradable and transformable particles consisting of poly(2-methylene-1,3-dioxepane)-co-poly(ethylene glycol) with three-armed poly(ε-caprolactone) (PCL) were prepared. The particle melting point was controlled by the chain length of the three-armed PCL. Particle degradation occurred under both acidic and alkaline conditions via ester group hydrolysis in the polymer backbones. The rod-shaped microparticles prepared by uniaxial stretching at a temperature above the melting point of the core showed less uptake into macrophages than did the spherical microparticles. Therefore, the degradable transformable particles enable macrophage interaction control via stimuli-regulated particle shapes and are expected to be applied as drug delivery carriers that can be decomposed and excreted from the body.

Harnessing 3D in vitro systems to model immune responses to solid tumours: a step towards improving and creating personalized immunotherapies

In vitro 3D models are advanced biological tools that have been established to overcome the shortcomings of oversimplified 2D cultures and mouse models. Various in vitro 3D immuno-oncology models have been developed to mimic and recapitulate the cancer-immunity cycle, evaluate immunotherapy regimens, and explore options for optimizing current immunotherapies, including for individual patient tumours. Here, we review recent developments in this field. We focus, first, on the limitations of existing immunotherapies for solid tumours, secondly, on how in vitro 3D immuno-oncology models are established using various technologies - including scaffolds, organoids, microfluidics and 3D bioprinting - and thirdly, on the applications of these 3D models for comprehending the cancer-immunity cycle as well as for assessing and improving immunotherapies for solid tumours.

Engineering metabolism to modulate immunity

Metabolic programming and reprogramming have emerged as pivotal mechanisms for altering immune cell function. Thus, immunometabolism has become an attractive target area for treatment of immune-mediated disorders. Nonetheless, many hurdles to delivering metabolic cues persist. In this review, we consider how biomaterials are poised to transform manipulation of immune cell metabolism through integrated control of metabolic configurations to affect outcomes in autoimmunity, regeneration, transplant, and cancer. We emphasize the features of nanoparticles and other biomaterials that permit delivery of metabolic cues to the intracellular compartment of immune cells, or strategies for altering signals in the extracellular space. We then provide perspectives on the potential for reciprocal regulation of immunometabolism by the physical properties of materials themselves. Lastly, opportunities for clinical translation are highlighted. This discussion contributes to our understanding of immunometabolism, biomaterials-based strategies for altering metabolic configurations in immune cells, and emerging concepts in this evolving field.

Exploiting Unique Features of Microneedles to Modulate Immunity

Microneedle arrays (MNAs) are small patches containing hundreds of short projections that deliver signals directly to dermal layers without causing pain. These technologies are of special interest for immunotherapy and vaccine delivery because they directly target immune cells concentrated in the skin. The targeting abilities of MNAs result in efficient immune responses-often more protective or therapeutic-compared to conventional needle delivery. MNAs also offer logistical benefits, such as self-administration and transportation without refrigeration. Thus, numerous preclinical and clinical studies are exploring these technologies. Here the unique advantages of MNA, as well as critical challenges-such as manufacturing and sterility issues-the field faces to enable widespread deployment are discussed. How MNA design parameters can be exploited for controlled release of vaccines and immunotherapies, and the application to preclinical models of infection, cancer, autoimmunity, and allergies are explained. Specific strategies are also discussed to reduce off-target effects compared to conventional vaccine delivery routes, and novel chemical and manufacturing controls that enable cargo stability in MNAs across flexible intervals and temperatures. Clinical research using MNAs is then examined. Drawbacks of MNAs and the implications, and emerging opportunities to exploit MNAs for immune engineering and clinical use are concluded.

Supramolecular Biomaterials for Cancer Immunotherapy

Cancer immunotherapy has achieved tremendous successful clinical results and obtained historic victories in tumor treatments. However, great limitations associated with feeble immune responses and serious adverse effects still cannot be neglected due to the complicated multifactorial etiology and pathologic microenvironment in tumors. The rapid development of nanomedical science and material science has facilitated the advanced progress of engineering biomaterials to tackle critical issues. The supramolecular biomaterials with flexible and modular structures have exhibited unparalleled advantages of high cargo-loading efficiency, excellent biocompatibility, and diversiform immunomodulatory activity, thereby providing a powerful weapon for cancer immunotherapy. In past decades, supramolecular biomaterials were extensively explored as versatile delivery platforms for immunotherapeutic agents or designed to interact with the key moleculars in immune system in a precise and controllable manner. In this review, we focused on the crucial role of supramolecular biomaterials in the modulation of pivotal steps during tumor immunotherapy, including antigen delivery and presentation, T lymphocyte activation, tumor-associated macrophage elimination and repolarization, and myeloid-derived suppressor cell depletion. Based on extensive research, we explored the current limitations and development prospects of supramolecular biomaterials in cancer immunotherapy.

Interactions of Cells and Biomaterials for Nerve Tissue Engineering: Polymers and Fabrication

Neural injuries affect millions globally, significantly impacting their quality of life. The inability of these injuries to heal, limited ability to regenerate, and the lack of available treatments make regenerative medicine and tissue engineering a promising field of research for developing methods for nerve repair. This review evaluates the use of natural and synthetic polymers, and the fabrication methods applied that influence a cell's behavior. Methods include cross-linking hydrogels, incorporation of nanoparticles, and 3D printing with and without live cells. The endogenous cells within the injured area and any exogenous cells seeded on the polymer construct play a vital role in regulating healthy neural activity. This review evaluates the body's local and systemic reactions to the implanted materials. Although numerous variables are involved, many of these materials and methods have exhibited the potential to provide a biomaterial environment that promotes biocompatibility and the regeneration of a physical and functional nerve. Future studies may evaluate advanced methods for modifying material properties and characterizing the tissue-biomaterial interface for clinical applications.

Biomaterial-based delivery platforms for transdermal immunotherapy

Nowadays, immunotherapy is one of the most essential treatments for various diseases and a broad spectrum of disorders are assumed to be treated by altering the function of the immune system. For this reason, immunotherapy has attracted a great deal of attention and numerous studies on different approaches for immunotherapies have been investigated, using multiple biomaterials and carriers, from nanoparticles (NPs) to microneedles (MNs). In this review, the immunotherapy strategies, biomaterials, devices, and diseases supposed to be treated by immunotherapeutic strategies are reviewed. Several transdermal therapeutic methods, including semisolids, skin patches, chemical, and physical skin penetration enhancers, are discussed. MNs are the most frequent devices implemented in transdermal immunotherapy of cancers (e.g., melanoma, squamous cell carcinoma, cervical, and breast cancer), infectious (e.g., COVID-19), allergic and autoimmune disorders (e.g., Duchenne's muscular dystrophy and Pollinosis). The biomaterials used in transdermal immunotherapy vary in shape, size, and sensitivity to external stimuli (e.g., magnetic field, photo, redox, pH, thermal, and even multi-stimuli-responsive) were reported. Correspondingly, vesicle-based NPs, including niosomes, transferosomes, ethosomes, microemulsions, transfersomes, and exosomes, are also discussed. In addition, transdermal immunotherapy using vaccines has been reviewed for Ebola, Neisseria gonorrhoeae, Hepatitis B virus, Influenza virus, respiratory syncytial virus, Hand-foot-and-mouth disease, and Tetanus.

Tuning innate immune function using microneedles containing multiple classes of toll-like receptor agonists

Microneedle arrays (MNAs) are patches displaying hundreds of micron-scale needles that can penetrate skin. As a result, these arrays efficiently and painlessly access this immune cell-rich niche, motivating significant clinical interest in MNA-based vaccines. Our lab has developed immune polyelectrolyte multilayers (iPEMs), nanostructures built entirely from immune signals employing electrostatic self-assembly. iPEMs consist of positively charged peptide antigen and negatively charged toll-like receptor agonists (TLRas) to assemble these components at ultra-high density since no carrier is needed. Here we used this technology to deliver MNAs with antigen and defined ratios of multiple classes of TLRa. Notably, this approach resulted in facile assembly and corresponding signal transduction through each respective TLR pathway. This control ultimately activated primary antigen presenting cells and drove proliferation of antigen-specific T cells. In related in vivo vaccine studies, application of MNAs resulted in distinct T cells response depending on the number of TLRa classes delivered with MNAs. These MNAs technologies create an opportunity to deliver nanostructured vaccine components at high density, and to probe integration of multiple TLRas in skin to tune immunity.

New tools for immunologists: models of lymph node function from cells to tissues

The lymph node is a highly structured organ that mediates the body's adaptive immune response to antigens and other foreign particles. Central to its function is the distinct spatial assortment of lymphocytes and stromal cells, as well as chemokines that drive the signaling cascades which underpin immune responses. Investigations of lymph node biology were historically explored in vivo in animal models, using technologies that were breakthroughs in their time such as immunofluorescence with monoclonal antibodies, genetic reporters, in vivo two-photon imaging, and, more recently spatial biology techniques. However, new approaches are needed to enable tests of cell behavior and spatiotemporal dynamics under well controlled experimental perturbation, particularly for human immunity. This review presents a suite of technologies, comprising in vitro, ex vivo and in silico models, developed to study the lymph node or its components. We discuss the use of these tools to model cell behaviors in increasing order of complexity, from cell motility, to cell-cell interactions, to organ-level functions such as vaccination. Next, we identify current challenges regarding cell sourcing and culture, real time measurements of lymph node behavior in vivo and tool development for analysis and control of engineered cultures. Finally, we propose new research directions and offer our perspective on the future of this rapidly growing field. We anticipate that this review will be especially beneficial to immunologists looking to expand their toolkit for probing lymph node structure and function.

Transforming bioengineering with unbiased teams and tools

Scientific bias originates from both researchers and techniques. Evidence-based strategies to mitigate this bias include the assembly of diverse teams, development of rigorous experimental designs, and use of unbiased analytical techniques. Here, we highlight potential starting points to decrease bias in bioengineering research.

Delivery route considerations for designing antigen-specific biomaterial strategies to combat autoimmunity

Disease modifying drugs and biologics used to treat autoimmune diseases, although promising, are non-curative. As the field moves towards development of new approaches to treat autoimmune disease, antigen-specific therapies immunotherapies (ASITs) have emerged. Despite clinical approval of ASITs for allergies, clinical trials using soluble ASITs for autoimmunity have been largely unsuccessful. A major effort to address this shortcoming is the use of biomaterials to harness the features unique to specific delivery routes. This review focuses on biomaterials being developed for delivery route-specific strategies to induce antigen-specific responses in autoimmune diseases such as multiple sclerosis, type 1 diabetes, rheumatoid arthritis, and celiac disease. We first discuss the delivery strategies used in ongoing and completed clinical trials in autoimmune ASITs. Next, we highlight pre-clinical biomaterial approaches from the most recent 3 years in the context of these same delivery route considerations. Lastly, we provide discussion on the gaps remaining in biomaterials development and comment on the need to consider delivery routes in the process of designing biomaterials for ASITs.

TPGS Decorated Liposomes as Multifunctional Nano-Delivery Systems

Liposomes are sphere-shaped vesicles that can capture therapeutics either in the outer phospholipid bilayer or inner aqueous core. Liposomes, especially when surface-modified with functional materials, have been used to achieve many benefits in drug delivery, including improving drug solubility, oral bioavailability, pharmacokinetics, and delivery to disease target sites such as cancers. Among the functional materials used to modify the surface of liposomes, the FDA-approved non-ionic surfactant D-alpha-tocopheryl polyethylene glycol succinate (TPGS) is increasingly being applied due to its biocompatibility, lack of toxicity, applicability to various administration routes and ability to enhance solubilization, stability, penetration and overall pharmacokinetics. TPGS decorated liposomes are emerging as a promising drug delivery system for various diseases and are expected to enter the market in the coming years. In this review article, we focus on the multifunctional properties of TPGS-coated liposomes and their beneficial therapeutic applications, including for oral drug delivery, vaccine delivery, ocular administration, and the treatment of various cancers. We also suggest future directions to optimise the manufacture and performance of TPGS liposomes and, thus, the delivery and effect of encapsulated diagnostics and therapeutics.

Spatial delivery of immune cues to lymph nodes to define therapeutic outcomes in cancer vaccination

Recently approved cancer immunotherapies - including CAR-T cells and cancer vaccination, - show great promise. However, these technologies are hindered by the complexity and cost of isolating and engineering patient cells ex vivo. Lymph nodes (LNs) are key tissues that integrate immune signals to coordinate adaptive immunity. Directly controlling the signals and local environment in LNs could enable potent and safe immunotherapies without cell isolation, engineering, and reinfusion. Here we employ intra-LN (i.LN.) injection of immune signal-loaded biomaterial depots to directly control cancer vaccine deposition, revealing how the combination and geographic distribution of signals in and between LNs impact anti-tumor response. We show in healthy and diseased mice that relative proximity of antigen and adjuvant in LNs - and to tumors - defines unique local and systemic characteristics of innate and adaptive response. These factors ultimately control survival in mouse models of lymphoma and melanoma. Of note, with appropriate geographic signal distributions, a single i.LN. vaccine treatment confers near-complete survival to tumor challenge and re-challenge 100 days later, without additional treatments. These data inform design criteria for immunotherapies that leverage biomaterials for loco-regional LN therapy to generate responses that are systemic and specific, without systemically exposing patients to potent or immunotoxic drugs.

Emerging vaccine nanotechnology: From defense against infection to sniping cancer

Looking retrospectively at the development of humanity, vaccination is an unprecedented medical landmark that saves lives by harnessing the human immune system. During the ongoing coronavirus disease 2019 (COVID-19) pandemic, vaccination is still the most effective defense modality. The successful clinical application of the lipid nanoparticle-based Pfizer/BioNTech and Moderna mRNA COVID-19 vaccines highlights promising future of nanotechnology in vaccine development. Compared with conventional vaccines, nanovaccines are supposed to have advantages in lymph node accumulation, antigen assembly, and antigen presentation; they also have, unique pathogen biomimicry properties because of well-organized combination of multiple immune factors. Beyond infectious diseases, vaccine nanotechnology also exhibits considerable potential for cancer treatment. The ultimate goal of cancer vaccines is to fully mobilize the potency of the immune system as a living therapeutic to recognize tumor antigens and eliminate tumor cells, and nanotechnologies have the requisite properties to realize this goal. In this review, we summarize the recent advances in vaccine nanotechnology from infectious disease prevention to cancer immunotherapy and highlight the different types of materials, mechanisms, administration methods, as well as future perspectives.

Mapping the Mechanical and Immunological Profiles of Polymeric Microneedles to Enable Vaccine and Immunotherapy Applications

Biomaterials hold great promise for vaccines and immunotherapy. One emerging biomaterials technology is microneedle (MNs) delivery. MNs are arrays of micrometer-sized needles that are painless and efficiently deliver cargo to the specialized immunological niche of the skin. MNs typically do not require cold storage and eliminate medical sharps. Nearly all materials exhibit intrinsic properties that can bias immune responses toward either pro-immune or inhibitory effects. Thus, because MNs are fabricated from degradable polymers to enable cargo loading and release, understanding the immunological profiles of these matrices is essential to enable new MN vaccines and immunotherapies. Additionally, understanding the mechanical properties is important because MNs must penetrate the skin and conform to a variety of skin or tissue geometries. Here we fabricated MNs from important polymer classes – including extracellular matrix biopolymers, naturally-derived polymers, and synthetic polymers – with both high- and low-molecular-weights (MW). We then characterized the mechanical properties and intrinsic immunological properties of these designs. The library of polymer MNs exhibited diverse mechanical properties, while causing only modest changes in innate signaling and antigen-specific T cell proliferation. These data help inform the selection of MN substrates based on the mechanical and immunological requirements needed for a specific vaccine or immunotherapy application.

Supramolecular biomaterials for enhanced cancer immunotherapy

Cancer immunotherapy has achieved promising clinical results. However, many limitations associated with current cancer immunotherapy still exist, including low response rates and severe adverse effects in patients. Engineering biomaterials for...

Immune Cell-Derived Extracellular Vesicles – New Strategies in Cancer Immunotherapy

Immune cell-derived extracellular vesicles (EVs) have increasingly become the focus of research due to their unique characteristics and bioinspired applications. They are lipid bilayer membrane nanosized vesicles harboring a range of immune cell-derived surface receptors and effector molecules from parental cells. Immune cell-derived EVs are important mediators of intercellular communication that regulate specific mechanisms of adaptive and innate immune responses. However, the mechanisms underlying the antitumor effects of EVs are still being explored. Importantly, immune cell-derived EVs have some unique features, including accessibility, storage, ability to pass through blood-brain and blood-tumor barriers, and loading of various effector molecules. Immune cell-derived EVs have been directly applied or engineered as potent antitumor vaccines or for the diagnosis of clinical diseases. More research applications involving genetic engineering, membrane engineering, and cargo delivery strategies have improved the treatment efficacy of EVs. Immune cell-derived EV-based therapies are expected to become a separate technique or to complement immunotherapy, radiotherapy, chemotherapy and other therapeutic modalities. This review aims to provide a comprehensive overview of the characteristics and functions of immune cell-derived EVs derived from adaptive (CD4⁺ T, CD8⁺ T and B cells) and innate immune cells (macrophages, NK cells, DCs, and neutrophils) and discuss emerging therapeutic opportunities and prospects in cancer treatment.

Biomaterial-enabled induction of pancreatic-specific regulatory T cells through distinct signal transduction pathways

Autoimmune diseases-where the immune system mistakenly targets self-tissue-remain hindered by non-specific therapies. For example, even molecularly specific monoclonal antibodies fail to distinguish between healthy cells and self-reactive cells. An experimental therapeutic approach involves delivery of self-molecules targeted by autoimmunity, along with immune modulatory signals to produce regulatory T cells (TREG) that selectively stop attack of host tissue. Much has been done to increase the efficiency of signal delivery using biomaterials, including encapsulation in polymer microparticles (MPs) to allow for co-delivery and cargo protection. However, less research has compared particles encapsulating drugs that target different TREG inducing pathways. In this paper, we use poly (lactic-co-glycolide) (PLGA) to co-encapsulate type 1 diabetes (T1D)-relevant antigen and 3 distinct TREG-inducing molecules - rapamycin (Rapa), all-trans retinoic acid (atRA), and butyrate (Buty) - that target the mechanistic target of Rapa (mTOR), the retinoid pathway, and histone deacetylase (HDAC) inhibition, respectively. We show all formulations are effectively taken up by antigen presenting cells (APCs) and that antigen-containing formulations are able to induce proliferation in antigen-specific T cells. Further, atRA and Rapa MP formulations co-loaded with antigen decrease APC activation levels, induce TREG differentiation, and reduce inflammatory cytokines in pancreatic-reactive T cells.

Nanotechnology-enhanced immunotherapy for metastatic cancer

A vast majority of cancer deaths occur as a result of metastasis. Unfortunately, effective treatments for metastases are currently lacking due to the difficulty of selectively targeting these small, delocalized tumors distributed across a variety of organs. However, nanotechnology holds tremendous promise for improving immunotherapeutic outcomes in patients with metastatic cancer. In contrast to conventional cancer immunotherapies, rationally designed nanomaterials can trigger specific tumoricidal effects, thereby improving immune cell access to major sites of metastasis such as bone, lungs, and lymph nodes, optimizing antigen presentation, and inducing a persistent immune response. This paper reviews the cutting-edge trends in nano-immunoengineering for metastatic cancers with an emphasis on different nano-immunotherapeutic strategies. Specifically, it discusses directly reversing the immunological status of the primary tumor, harnessing the potential of peripheral immune cells, preventing the formation of a pre-metastatic niche, and inhibiting the tumor recurrence through postoperative immunotherapy. Finally, we describe the challenges facing the integration of nanoscale immunomodulators and provide a forward-looking perspective on the innovative nanotechnology-based tools that may ultimately prove effective at eradicating metastatic diseases.

Tetrahedral Framework Nucleic Acids Reverse New-Onset Type 1 Diabetes

Type 1 diabetes (T1D) is caused by breakdowns of central and peripheral immune tolerance and destructions of insulin-producing β-cells. Conventional insulin injection cannot cure the disease. Regulatory immune cells, including regulatory T-cells (Tregs) and regulatory B-cells (Bregs), play critical roles in immune tolerance. Inducing regulatory immune cells to halt the progress of T1D and restore immune tolerance is the promising approach in T1D immunotherapy. Here, tetrahedral framework nucleic acids (tFNAs) were utilized to treat T1D in non-obese diabetic (NOD) mice. 250 nM tFNA treatment was adopted in the experiment to reverse hyperglycemia and protect insulin-secreting β-cells in diabetic NOD mice. In addition, 250 nM tFNA treatment could induce Tregs and Bregs and suppress helper T (Th)-cells in the pancreas. In the pancreas, cytokines, as a significant signal during CD4⁺ T-cell differentiation, directly direct the differentiation programs. Apart from cytokines directing the differentiation of T-cells, the signal transducer and activator of transcription (STAT) signal is strongly associated with T-cell differentiation and T1D progression. We demonstrated tFNA treatment inducing regulatory immune cells probably by increasing TGF-β levels and the STAT signal. To sum up, 250 nM tFNA treatment could protect the diabetic NOD mice from hyperglycemia and preserve the functions of β-cells by restoring peripheral immune tolerance. The possible mechanism of inducing immune tolerance was related to the STAT signal and cytokine changes in the pancreas. Moreover, immunoregulation capabilities of tFNAs were demonstrated in the experiment, which set the foundation of tFNAs participating in further antigen-specific immunotherapies.

Peptide-based supramolecular vaccine systems

Currently approved replication-competent and inactivated vaccines are limited by excessive reactogenicity and poor safety profiles, while subunit vaccines are often insufficiently immunogenic without co-administering exogenous adjuvants. Self-assembling peptide-, peptidomimetic-, and protein-based biomaterials offer a means to overcome these challenges through their inherent modularity, multivalency, and biocompatibility. As these scaffolds are biologically derived and present antigenic arrays reminiscent of natural viruses, they are prone to immune recognition and are uniquely capable of functioning as self-adjuvanting vaccine delivery vehicles that improve humoral and cellular responses. Beyond this intrinsic immunological advantage, the wide range of available amino acids allows for facile de novo design or straightforward modifications to existing sequences. This has permitted the development of vaccines and immunotherapies tailored to specific disease models, as well as generalizable platforms that have been successfully applied to prevent or treat numerous infectious and non-infectious diseases. In this review, we briefly introduce the immune system, discuss the structural determinants of coiled coils, β-sheets, peptide amphiphiles, and protein subunit nanoparticles, and highlight the utility of these materials using notable examples of their innate and adaptive immunomodulatory capacity.

Tetrahedral Framework Nucleic Acids Reestablish Immune Tolerance and Restore Saliva Secretion in a Sjögren's Syndrome Mouse Model

As one of the most frequent autoimmune diseases, Sjogren's syndrome (SS) is characterized by overactive lymphocytic infiltration in the exocrine glands, with ensuing dry mouth and dry eyes. Unfortunately, so far, there are no appropriate therapies without causing overall immunosuppression. Tetrahedral framework nucleic acids (tFNAs) were regarded as promising nanoscale materials whose immunomodulatory capabilities have already been verified. Herein, we reveal, for the first time, that tFNAs were utilized to treat SS in female nonobese diabetic (NOD) mice, the animal model used for SS. We proved a 250 nM tFNA treatment was successful in suppressing inflammation and stimulating saliva secretion in NOD mice. Specialised proteins for the secretory function and structure of acinar cells in submandibular glands (SMGs) were restored. It has been the permanent goal for SS treatment to establish immune tolerance and stop disease development. Surprisingly, tFNA treatment guided T cells toward regulatory T cells (Tregs), while suppressing T helper (Th) cell responses. Th cells include Th1, Th17, and follicular helper T (Tfh) cells. Tregs are highly significant in immune tolerance. Inducing Tregs is a promising approach to reestablish immune tolerance. Comparable results were also observed in B cell responses. Reductions in the percentage of germinal center (GC) B cells and plasma cells were detected, and a marked increase in the percentage of regulatory B cells (Bregs) was also noticed. The mechanisms of inducing Tregs may associated with cytokine changes. Changes of T cell subsets, especially changes of Tfh, may influence the differentiation of B cells accordingly. Collectively, our results demonstrated the immunomodulatory capacities of tFNAs once again, which may provide a novel, safe, and effective option for the treatment of SS and other autoimmune diseases.

Design of Dissolvable Microneedles for Delivery of a Pfs47-Based Malaria Transmission-Blocking Vaccine

The development of effective malaria vaccines remains a global health priority. In addition to an effective vaccine, there is urgent demand for effective delivery technologies that can be easily deployed. The need for effective vaccine delivery tools is particularly pertinent in resource-poor settings where access to healthcare is limited. Microneedles are micron-scale structures that offer distinct advantages for vaccine delivery by efficiently targeting skin-resident immune cells, eliminating injection-associated pain, and improving patient compliance. Here, we developed and characterized a candidate malaria vaccine loaded and deployed using dissolvable microneedle arrays. Of note, a newly indicated human-relevant antigen was employed, Plasmodium falciparum surface protein P47. P47 and a potent toll-like receptor (TLR9) agonist vaccine adjuvant, CpG, were fabricated into microneedles using a gelatin polymer. Protein binding, ELISA, and fluorescence analysis confirmed the molecular structure, and the function of the P47 antigen and CpG was maintained after fabrication, storage, and release from microneedles. In cell culture, the cargo released from the microneedle arrays triggered TLR9 signaling and activated primary dendritic cells at levels similar to native, unincorporated vaccine components. Together, these studies demonstrate the potential of microneedles as an easily deployable strategy for a P47-based malaria vaccine.

Tetrahedral Framework Nucleic Acids Induce Immune Tolerance and Prevent the Onset of Type 1 Diabetes

A failure in immune tolerance leads to autoimmune destruction of insulin-producing β-cells, leading to type 1 diabetes (T1D). Inhibiting autoreactive T cells and inducing regulatory T cells (Tregs) to re-establish immune tolerance are promising approaches to prevent the onset of T1D. Here, we investigated the ability of tetrahedral framework nucleic acids (tFNAs) to induce immune tolerance and prevent T1D in nonobese diabetic (NOD) mice. In prediabetic NOD mice, tFNAs treatment led to maintenance of normoglycemia and reduced incidence of diabetes. Moreover, the tFNAs (250 nM) treatment preserved the mass and function of β-cells, increased the frequency of Tregs, and suppressed autoreactive T cells, leading to immune tolerance. Collectively, our results demonstrate that tFNAs treatment aids glycemic control, provides β-cell protection, and prevents the onset of T1D in NOD mice by immunomodulation. These results highlight the potential of tFNAs for the prevention of autoimmune T1D.

Tetrahedral Framework Nucleic Acid-Based Delivery of Resveratrol Alleviates Insulin Resistance: From Innate to Adaptive Immunity

Tetrahedral framework nucleic acid (tFNA)-based delivery of resveratrol (RSV) ameliorates the performance of RSV.

tFNAs-RSV improve insulin sensitivity in high-fat diet-fed mice by promoting Treg and Th2 and suppressing Th1 and Th17, and switching macrophage from M1 to M2 phenotype both in vitro and in vivo.

Obesity-induced insulin resistance is the hallmark of metabolic syndrome, and chronic, low-grade tissue inflammation links obesity to insulin resistance through the activation of tissue-infiltrating immune cells. Current therapeutic approaches lack efficacy and immunomodulatory capacity. Thus, a new therapeutic approach is needed to prevent chronic inflammation and alleviate insulin resistance. Here, we synthesized a tetrahedral framework nucleic acid (tFNA) nanoparticle that carried resveratrol (RSV) to inhibit tissue inflammation and improve insulin sensitivity in obese mice. The prepared nanoparticles, namely tFNAs-RSV, possessed the characteristics of simple synthesis, stable properties, good water solubility, and superior biocompatibility. The tFNA-based delivery ameliorated the lability of RSV and enhanced its therapeutic efficacy. In high-fat diet (HFD)-fed mice, the administration of tFNAs-RSV ameliorated insulin resistance by alleviating inflammation status. tFNAs-RSV could reverse M1 phenotype macrophages in tissues to M2 phenotype macrophages. As for adaptive immunity, the prepared nanoparticles could repress the activation of Th1 and Th17 and promote Th2 and Treg, leading to the alleviation of insulin resistance. Furthermore, this study is the first to demonstrate that tFNAs, a nucleic acid material, possess immunomodulatory capacity. Collectively, our findings demonstrate that tFNAs-RSV alleviate insulin resistance and ameliorate inflammation in HFD mice, suggesting that nucleic acid materials or nucleic acid-based delivery systems may be a potential agent for the treatment of insulin resistance and obesity-related metabolic diseases.

Implantable and Injectable Biomaterial Scaffolds for Cancer Immunotherapy

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

Self-Assembly as a Molecular Strategy to Improve Immunotherapy

Immunotherapies harness an individual's immune system to battle diseases such as cancer and autoimmunity. During cancer, the immune system often fails to detect and destroy cancerous cells, whereas during autoimmune disease, the immune system mistakenly attacks self-tissue. Immunotherapies can help guide more effective responses in these settings, as evidenced by recent advances with monoclonal antibodies and adoptive cell therapies. However, despite the transformative gains of immunotherapies for patients, many therapies are not curative, work only for a small subset of patients, and lack specificity in distinguishing between healthy and diseased cells, which can cause severe side effects. From this perspective, self-assembled biomaterials are promising technologies that could help address some of the limitations facing immunotherapies. For example, self-assembly allows precision control over the combination and relative concentration of immune cues and directed cargo display densities. These capabilities support selectivity and potency that could decrease off-target effects and enable modular or personalized immunotherapies. The underlying forces driving self-assembly of most systems in aqueous solution result from hydrophobic interactions or charge polarity. In this Account, we highlight how these forces are being used to self-assemble immunotherapies for cancer and autoimmune disease.Hydrophobic interactions can create a range of intricate structures, including peptide nanofibers, nanogels, micelle-like particles, and in vivo assemblies with protein carriers. Certain nanofibers with hydrophobic domains uniquely benefit from the ability to elicit immune responses without additional stimulatory signals. This feature can reduce nonspecific inflammation but may also limit the nanofiber's application because of their inherent stimulatory properties. Micelle-like particles have been developed with the ability to incorporate a range of tumor-specific antigens for immunotherapies in mouse models of cancer. Key observations have revealed that both the total dose of antigen and display density of antigen per particle can impact immune response and efficacy of immunotherapies. These developments are promising benchmarks that could reveal design principles for engineering more specific and personalized immunotherapies.There has also been extensive work to develop platforms using electrostatic interactions to drive assembly of oppositely charged immune signals. These strategies benefit from the ability to tune biophysical interactions between components by altering the ratio of cationic to anionic charge during formulation, or the density of charge. Using a layer-by-layer assembly method, our lab developed hollow capsules composed entirely of immune signals for therapies in cancer and autoimmune disease models. This platform allowed for 100% of the immunotherapy to be composed of immune signals and completely prevents the onset of disease in a mouse model of multiple sclerosis. Layer-by-layer assembly has also been used to coat microneedle patches to target signals to immune cells in the dermal layer. As an alternative to layer-by-layer assembly, one step assembly can be achieved by mixing cationic and anionic components in solution. Additional approaches have created molecular structures that leverage hydrogen bonding for self-assembly. The creativity of engineered self-assembly has led to key insights that could benefit future immunotherapies and revealed aspects that require further study. The challenge now remains to utilize these insights to push development of new immunotherapeutics into clinical settings.

Co-delivery of Peptide Neoantigens and Stimulator of Interferon Genes Agonists Enhances Response to Cancer Vaccines

Cancer vaccines targeting patient-specific neoantigens have emerged as a promising strategy for improving responses to immune checkpoint blockade. However, neoantigenic peptides are poorly immunogenic and inept at stimulating CD8⁺ T cell responses, motivating a need for new vaccine technologies that enhance their immunogenicity. The stimulator of interferon genes (STING) pathway is an endogenous mechanism by which the innate immune system generates an immunological context for priming and mobilizing neoantigen-specific T cells. Owing to this critical role in tumor immune surveillance, a synthetic cancer nanovaccine platform (nanoSTING-vax) was developed that mimics immunogenic cancer cells in its capacity to efficiently promote co-delivery of peptide antigens and the STING agonist, cGAMP. The co-loading of cGAMP and peptides into pH-responsive, endosomolytic polymersomes promoted the coordinated delivery of both cGAMP and peptide antigens to the cytosol, thereby eliciting inflammatory cytokine production, co-stimulatory marker expression, and antigen cross-presentation. Consequently, nanoSTING-vax significantly enhanced CD8⁺ T cell responses to a range of peptide antigens. Therapeutic immunization with nanoSTING-vax, in combination with immune checkpoint blockade, inhibited tumor growth in multiple murine tumor models, even leading to complete tumor rejection and generation of durable antitumor immune memory. Collectively, this work establishes nanoSTING-vax as a versatile platform for enhancing immune responses to neoantigen-targeted cancer vaccines.

Emerging Adjuvants for Cancer Immunotherapy

Cancer is a life-threatening disease, and immunotherapies have been developed as a novel, potent treatment for cancer. Adjuvants, used alone or in combination with other agents, play crucial roles in immune activation. This is necessary for cancer immunotherapy, particularly in the construction of therapeutic cancer vaccines. Adjuvants activate antigen-presenting cells and promote the presentation of antigen epitopes on major histocompatibility complex molecules, further enhancing adaptive immune responses, including cytotoxic T lymphocytes, to elicit cancer-cell death. However, the applications of adjuvants are limited by their poor efficacy or insufficient safety. In recent studies, researchers attempted to develop safe, efficacious adjuvants for cancer immunotherapy, and many compounds (including inorganic compounds, organic molecules, polymers, and colloids) have been identified and optimized as agonists of various pathways. In this review, we focus on the discovery and structural design of emerging adjuvants and discuss how these findings benefit healthcare.

Engineered biomaterials for cancer immunotherapy

Although cancer immunotherapy is showing tremendous promise and has progressed to the clinic, it has only achieved sporadic efficacy, with only a fraction of patients benefitting from the therapy and with undesirable side effects due to poor selectivity and high doses. Localized delivery of immunomodulators to activate anticancer immunity in situ avoids overactivation of the systemic immune system and reduces side effects. Engineered biomaterials-implantable, injectable, or transdermal-fabricated into drug delivery devices are critical components for the development of localized cancer immunotherapies. In this review, we briefly summarize progress in the application of engineered biomaterials to the localized delivery of cancer immunotherapy.