An Artificial Antigen-Presenting Cell Delivering 11 Immune Molecules Expands Tumor Antigen–Specific CTLs in Ex Vivo and In Vivo Murine Melanoma Models

Rapid Generation of Therapeutic Nanoparticles Using Cell-Free Expression Systems

The surface modification of membrane-based nanoparticles, such as liposomes, polymersomes, and lipid nanoparticles, with targeting molecules, such as binding proteins, is an important step in the design of therapeutic materials. However, this modification can be costly and time-consuming, requiring cellular hosts for protein expression and lengthy purification and conjugation steps to attach proteins to the surface of nanocarriers, which ultimately limits the development of effective protein-conjugated nanocarriers. Here, the use of cell-free protein synthesis systems to rapidly create protein-conjugated membrane-based nanocarriers is demonstrated. Using this approach, multiple types of functional binding proteins, including affibodies, computationally designed proteins, and scFvs, can be cell-free expressed and conjugated to liposomes in one-pot. The technique can be expanded further to other nanoparticles, including polymersomes and lipid nanoparticles, and is amenable to multiple conjugation strategies, including surface attachment to and integration into nanoparticle membranes. Leveraging these methods, rapid design of bispecific artificial antigen presenting cells and enhanced delivery of lipid nanoparticle cargo in vitro is demonstrated. It is envisioned that this workflow will enable the rapid generation of membrane-based delivery systems and bolster our ability to create cell-mimetic therapeutics.

Cell-Sized Lipid Vesicles as Artificial Antigen-Presenting Cells for Antigen-Specific T Cell Activation

In this study, efficient T cell activation is demonstrated using cell-sized artificial antigen-presenting cells (aAPCs) with protein-conjugated bilayer lipid membranes that mimic biological cell membranes. The highly uniform aAPCs are generated by a facile method based on standard droplet microfluidic devices. These aAPCs are able to activate the T cells in peripheral blood mononuclear cells, showing a 28-fold increase in interferon gamma (IFNγ) secretion, a 233-fold increase in antigen-specific CD8 T cells expansion, and a 16-fold increase of CD4 T cell expansion. The aAPCs do not require repetitive boosting or additional stimulants and can function at a relatively low aAPC-to-T cell ratio (1:17). The research presents strong evidence that the surface fluidity and size of the aAPCs are critical to the effective formation of immune synapses essential for T cell activation. The findings demonstrate that the microfluidic-generated aAPCs can be instrumental in investigating the physiological conditions and mechanisms for T cell activation. Finally, this method demonstrates the feasibility of customizable aAPCs for a cost-effective off-the-shelf approach to immunotherapy.

DNA-based artificial dendritic cells for in situ cytotoxic T cell stimulation and immunotherapy

In immunotherapy, ex vivo stimulation of T cells requires significant resources and effort. Here, we report artificial dendritic cell-mimicking DNA microflowers (DM) for programming T cell stimulation in situ. To mimic dendritic cells, DNA-based artificial dendritic microflowers were constructed, surface-coated with polydopamine, and further modified with anti-CD3 and anti-CD28 antibodies to yield antibody-modified DM (DM-A). The porous structure of DM-A allowed entrapment of the T cell-stimulating cytokine, ineterleukin-2, yielding interleukin-2-loaded DM-A (DM-AI). For comparison, polystyrene microparticles coated with polydopamine and modified with anti-CD3 and anti-CD28 antibodies (PS-A) were used. Compared to PS-A, DM-AI showed significantly greater contact with T cell surfaces. DM-AI provided the highest ex vivo expansion of cytotoxic T cells. Local injection of DM-AI to tumor tissues induced the recruitment of T cells and expansion of cytotoxic T cells in tumor microenvironments. Unlike the other groups, model animals injected with DM-AI did not exhibit growth of primary tumors. Treatment of mice with DM-AI also protected against growth of a rechallenged distant tumor, and thus prevented tumor recurrence in this model. DM-AI has great potential for programmed stimulation of CD8⁺ T cells. This concept could be broadly extended for the programming of specific T cell stimulation profiles.

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Artificial dendritic cells were constructed by coating DNA microflowers with antibodies.

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DNA-based artificial dendritic cells activated T cell stronger than polymeric particles with smooth surfaces.

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Locally injected DNA-based artificial dendritic cells expanded cytotoxic T cells, modulating tumor immune microenvironments.

Assessing the Efficacy of a Tumor Nanovaccine and Artificial Antigen Presenting Cell-Based System as a Combination Therapy in a Mouse Model of Melanoma

Tumor cell lysate (TCL)-based vaccines contain a large number of tumor-specific and related antigens, albeit at low levels, that require active transfer and presentation by antigen-presenting cells (APCs) in vivo, which stimulate a weak immune response. The artificial APC (aAPC) system presented herein is a cell-based therapeutic system that can significantly enhance the immune response compared to TCL-based vaccines. This study combines these two treatment strategies to assess their in vitro and in vivo effects. We successfully prepared TCL-poly(lactic-co-glycolic acid)-PEI (TPP) and demonstrated that it was phagocytosed by the APCs and enhanced the maturation of DCs in vitro. The use of TPP in combination with the aAPCs resulted in better antitumor effects compared to the individual therapies. The combination therapy induced a higher proportion of CD4+ T, CD8+ T, and TRP2180–188-specific CD8+ T cells in comparison with the individual therapies. Additionally, the combination therapy enhanced the in vitro proliferation activity; greater inhibited regulatory T cells; and promoted inflammatory cytokine secretion, while reduced the production of inhibitory cytokines. In conclusion, the combination therapy consisting of the TPP tumor nanovaccine and the aAPC system enabled a broader immune response and achieve better antitumor effects compared to treatment with the individual therapies.

In vivo mRNA delivery to virus-specific T cells by light-induced ligand exchange of MHC class I antigen-presenting nanoparticles

Simultaneous delivery of mRNA to multiple populations of antigen (Ag)-specific CD8+ T cells is challenging given the diversity of peptide epitopes and polymorphism of class I major histocompatibility complexes (MHCI). We developed Ag-presenting nanoparticles (APNs) for mRNA delivery using pMHCI molecules that were refolded with photocleavable peptides to allow rapid ligand exchange by UV light and site-specifically conjugated with a lipid tail for postinsertion into preformed mRNA lipid nanoparticles. Across different TCR transgenic mouse models (P14, OT-1, and Pmel), UV-exchanged APNs bound and transfected their cognate Ag-specific CD8+ T cells equivalent to APNs produced using conventionally refolded pMHCI molecules. In mice infected with PR8 influenza, multiplexed delivery of UV-exchanged APNs against three immunodominant epitopes led to ~50% transfection of a VHH mRNA reporter in cognate Ag-specific CD8+ T cells. Our data show that UV-mediated peptide exchange can be used to rapidly produce APNs for mRNA delivery to multiple populations of Ag-specific T cells in vivo.

Lighting the way to personalized mRNA immune cell therapies

Nanoparticles, mRNA, and ultraviolet light combine to reprogram specific immune cells directly in the body.

Leveraging biomaterials for enhancing T cell immunotherapy

The dynamic roles of T cells in the immune system to recognize and destroy the infected or mutated cells render T cell therapy a prospective treatment for a variety of diseases including cancer, autoimmune diseases, and allograft rejection. However, the clinical applications of T cell therapy remain unsatisfactory due to the tedious manufacturing process, off-target cytotoxicity, poor cell persistence, and associated adverse effects. To this end, various biomaterials have been introduced to enhance T cell therapy by facilitating proliferation, enhancing local enrichment, prolonging retention, and alleviating side effects. This review highlights the design strategies of biomaterials developed for T cell expansion, enrichment, and delivery as well as their corresponding therapeutic effects. The prospects of biomaterials for enhancing T cell immunotherapy are also discussed in this review.

Chemically Engineered Immune Cell-Derived Microrobots and Biomimetic Nanoparticles: Emerging Biodiagnostic and Therapeutic Tools

Over the past decades, considerable attention has been dedicated to the exploitation of diverse immune cells as therapeutic and/or diagnostic cell-based microrobots for hard-to-treat disorders. To date, a plethora of therapeutics based on alive immune cells, surface-engineered immune cells, immunocytes' cell membranes, leukocyte-derived extracellular vesicles or exosomes, and artificial immune cells have been investigated and a few have been introduced into the market. These systems take advantage of the unique characteristics and functions of immune cells, including their presence in circulating blood and various tissues, complex crosstalk properties, high affinity to different self and foreign markers, unique potential of their on-demand navigation and activity, production of a variety of chemokines/cytokines, as well as being cytotoxic in particular conditions. Here, the latest progress in the development of engineered therapeutics and diagnostics inspired by immune cells to ameliorate cancer, inflammatory conditions, autoimmune diseases, neurodegenerative disorders, cardiovascular complications, and infectious diseases is reviewed, and finally, the perspective for their clinical application is delineated.

Biomaterials to enhance antigen-specific T cell expansion for cancer immunotherapy

T cells are often referred to as the 'guided missiles' of our immune system because of their capacity to traffic to and accumulate at sites of infection or disease, destroy infected or mutated cells with high specificity and sensitivity, initiate systemic immune responses, sterilize infections, and produce long-lasting memory. As a result, they are a common target for a range of cancer immunotherapies. However, the myriad of challenges of expanding large numbers of T cells specific to each patient's unique tumor antigens has led researchers to develop alternative, more scalable approaches. Biomaterial platforms for expansion of antigen-specific T cells offer a path forward towards broadscale translation of personalized immunotherapies by providing "off-the-shelf", yet modular approaches to customize the phenotype, function, and specificity of T cell responses. In this review, we discuss design considerations and progress made in the development of ex vivo and in vivo technologies for activating antigen-specific T cells, including artificial antigen presenting cells, T cell stimulating scaffolds, biomaterials-based vaccines, and artificial lymphoid organs. Ultimate translation of these platforms as a part of cancer immunotherapy regimens hinges on an in-depth understanding of T cell biology and cell-material interactions.

CCR7 as a therapeutic target in Cancer

The CCR7 chemokine axis is comprised of chemokine ligand 21 (CCL21) and chemokine ligand 19 (CCL19) acting on chemokine receptor 7 (CCR7). This axis plays two important but apparently opposing roles in cancer. On the one hand, this axis is significantly engaged in the trafficking of a number of effecter cells involved in mounting an immune response to a growing tumour. This suggests therapeutic strategies which involve potentiation of this axis can be used to combat the spread of cancer. On the other hand, the CCR7 axis plays a significant role in controlling the migration of tumour cells towards the lymphatic system and metastasis and can thus contribute to the expansion of cancer. This implies that therapeutic strategies which involve decreasing signaling through the CCR7 axis would have a beneficial effect in preventing dissemination of cancer. This dichotomy has partly been the reason why this axis has not yet been exploited, as other chemokine axes have, as a therapeutic target in cancer. Recent report of a crystal structure for CCR7 provides opportunities to exploit this axis in developing new cancer therapies. However, it remains unclear which of these two strategies, potentiation or antagonism of the CCR7 axis, is more appropriate for cancer therapy. This review brings together the evidence supporting both roles of the CCR7 axis in cancer and examines the future potential of each of the two different therapeutic approaches involving the CCR7 axis in cancer.

Nano-Enhanced Cancer Immunotherapy: Immunology Encounters Nanotechnology

Cancer immunotherapy utilizes the immune system to fight cancer and has already moved from the laboratory to clinical application. However, and despite excellent therapeutic outcomes in some hematological and solid cancers, the regular clinical use of cancer immunotherapies reveals major limitations. These include the lack of effective immune therapy options for some cancer types, unresponsiveness to treatment by many patients, evolving therapy resistance, the inaccessible and immunosuppressive nature of the tumor microenvironment (TME), and the risk of potentially life-threatening immune toxicities. Given the potential of nanotechnology to deliver, enhance, and fine-tune cancer immunotherapeutic agents, the combination of cancer immunotherapy with nanotechnology can overcome some of these limitations. In this review, we summarize innovative reports and novel strategies that successfully combine nanotechnology and cancer immunotherapy. We also provide insight into how nanoparticular combination therapies can be used to improve therapy responsiveness, to reduce unwanted toxicity, and to overcome adverse effects of the TME.

Chemical Strategies to Boost Cancer Vaccines

Personalized cancer vaccines (PCVs) are reinvigorating vaccine strategies in cancer immunotherapy. In contrast to adoptive T-cell therapy and checkpoint blockade, the PCV strategy modulates the innate and adaptive immune systems with broader activation to redeploy antitumor immunity with individualized tumor-specific antigens (neoantigens). Following a sequential scheme of tumor biopsy, mutation analysis, and epitope prediction, the administration of neoantigens with synthetic long peptide (SLP) or mRNA formulations dramatically improves the population and activity of antigen-specific CD4+ and CD8+ T cells. Despite the promising prospect of PCVs, there is still great potential for optimizing prevaccination procedures and vaccine potency. In particular, the arduous development of tumor-associated antigen (TAA)-based vaccines provides valuable experience and rational principles for augmenting vaccine potency which is expected to advance PCV through the design of adjuvants, delivery systems, and immunosuppressive tumor microenvironment (TME) reversion since current personalized vaccination simply admixes antigens with adjuvants. Considering the broader application of TAA-based vaccine design, these two strategies complement each other and can lead to both personalized and universal therapeutic methods. Chemical strategies provide vast opportunities for (1) exploring novel adjuvants, including synthetic molecules and materials with optimizable activity, (2) constructing efficient and precise delivery systems to avoid systemic diffusion, improve biosafety, target secondary lymphoid organs, and enhance antigen presentation, and (3) combining bioengineering methods to innovate improvements in conventional vaccination, "smartly" re-educate the TME, and modulate antitumor immunity. As chemical strategies have proven versatility, reliability, and universality in the design of T cell- and B cell-based antitumor vaccines, the union of such numerous chemical methods in vaccine construction is expected to provide new vigor and vitality in cancer treatment.

Indocyanine Green-Nexturastat A-PLGA Nanoparticles Combine Photothermal and Epigenetic Therapy for Melanoma

In this study, we describe poly (lactic-co-glycolic) acid (PLGA)-based nanoparticles that combine photothermal therapy (PTT) with epigenetic therapy for melanoma. Specifically, we co-encapsulated indocyanine green (ICG), a PTT agent, and Nexturastat A (NextA), an epigenetic drug within PLGA nanoparticles (ICG-NextA-PLGA; INAPs). We hypothesized that combining PTT with epigenetic therapy elicits favorable cytotoxic and immunomodulatory responses that result in improved survival in melanoma-bearing mice. We utilized a nanoemulsion synthesis scheme to co-encapsulate ICG and NextA within stable and monodispersed INAPs. The INAPs exhibited concentration-dependent and near-infrared (NIR) laser power-dependent photothermal heating characteristics, and functioned as effective single-use agents for PTT of melanoma cells in vitro. The INAPs functioned as effective epigenetic therapy agents by inhibiting the expression of pan-histone deacetylase (HDAC) and HDAC6-specific activity in melanoma cells in vitro. When used for both PTT and epigenetic therapy in vitro, the INAPs increased the expression of co-stimulatory molecules and major histocompatibility complex (MHC) Class I in melanoma cells relative to controls. These advantages persisted in vivo in a syngeneic murine model of melanoma, where the combination therapy slowed tumor progression and improved median survival. These findings demonstrate the potential of INAPs as agents of PTT and epigenetic therapy for melanoma.