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Cell therapies are emerging as a promising new therapeutic modality in medicine, generating effective treatments for previously incurable diseases. Clinical success of cell therapies has energized the field of cellular engineering, spurring further exploration of novel approaches to improve their therapeutic performance. Engineering of cell surfaces using natural and synthetic materials has emerged as a valuable tool in this endeavor. This review summarizes recent advances in the development of technologies for decorating cell surfaces with various materials including nanoparticles, microparticles, and polymeric coatings, focusing on the ways in which surface decorations enhance carrier cells and therapeutic effects. Key benefits of surface-modified cells include protecting the carrier cell, reducing particle clearance, enhancing cell trafficking, masking cell-surface antigens, modulating inflammatory phenotype of carrier cells, and delivering therapeutic agents to target tissues. While most of these technologies are still in the proof-of-concept stage, the promising therapeutic efficacy of these constructs from in vitro and in vivo preclinical studies has laid a strong foundation for eventual clinical translation. Cell surface engineering with materials can imbue a diverse range of advantages for cell therapy, creating opportunities for innovative functionalities, for improved therapeutic efficacy, and transforming the fundamental and translational landscape of cell therapies., (© 2023 Wiley‐VCH GmbH.)

Messenger ribonucleic acid (mRNA) has long been touted as a next-generation therapeutic modality for infectious disease, cancer, and genetic disorders. Lipid nanoparticles (LNPs) provide an elegant delivery strategy for mRNA cargo to help realize this potential for vaccination. However, systemic exposure seen with traditional LNP formulations can have significant implications on efficacy and safety. Efforts to mitigate this have largely been focused on laborious lipid or LNP redesign. Here, the use of a deep eutectic-lipid nanocomposite delivery system for the tuning of mRNA expression for intramuscular injections in vivo is reported. One deep eutectic, cholinium malonate, allows for the linear control of percent expression at the muscular injection site based solely on its concentration in the formulation. The same deep eutectic solvent (DES) can increase local muscle expression by 68% and significantly decrease off-target liver expression by 72%. Physico-chemical studies suggest that the DES incorporates into or onto the pre-formed LNPs thus impacting endosomal escape and in situ interactions. These nanocomposites provide new possibilities for previously approved LNP formulations and without the need for lipid redesign to induce localized expression., (© 2024 Wiley‐VCH GmbH.)

B cells, despite their several unique functionalities, remain largely untapped for use as an adoptive cell therapy and are limited to in vitro use for antibody production. B cells can be easily sourced, they possess excellent lymphoid-homing capabilities, and they can act as antigen-presenting cells (APCs), offering an alternative to dendritic cells (DCs), which have shown limited efficacy in the clinical setting. Soluble factors such as IL-4 and anti-CD40 antibody can enhance the activation, survival, and antigen-presenting capabilities of B cells; however, it is difficult to attain sufficiently high concentrations of these biologics to stimulate B cells in vivo . Micropatches as Cell Engagers (MACE) are polymeric microparticles, surface functionalized with anti-CD40 and anti-IgM, which can attach to B cells and simultaneously engage multiple B-cell receptors (BCR) and CD40 receptors. Stimulation of these receptors through MACE, unlike free antibodies, enhanced the display of costimulatory molecules on the B-cell surface, increased B-cell viability, and improved antigen presentation by B cells to T cells in vitro . B-cell activation by MACE further synergized with soluble IL-4 and anti-CD40. MACE also elicited T-cell chemokine secretion by B cells. Upon intravenous adoptive transfer, MACE-bound B cells homed to the spleen and lymph nodes, key sites for antigen presentation to T cells. Adoptive transfer of MACE-B cells pulsed with the CD4+ and CD8+ epitopes of ovalbumin significantly delayed tumor progression in a murine subcutaneous EG7-OVA tumor model, demonstrating the functional benefit conferred to B cells by MACE.

Tumour-associated neutrophils can exert antitumour effects but can also assume a pro-tumoural phenotype in the immunosuppressive tumour microenvironment. Here we show that neutrophils can be polarized towards the antitumour phenotype by discoidal polymer micrometric 'patches' that adhere to the neutrophils' surfaces without being internalized. Intravenously administered micropatch-loaded neutrophils accumulated in the spleen and in tumour-draining lymph nodes, and activated splenic natural killer cells and T cells, increasing the accumulation of dendritic cells and natural killer cells. In mice bearing subcutaneous B16F10 tumours or orthotopic 4T1 tumours, intravenous injection of the micropatch-loaded neutrophils led to robust systemic immune responses, a reduction in tumour burden and improvements in survival rates. Micropatch-activated neutrophils combined with the checkpoint inhibitor anti-cytotoxic T-lymphocyte-associated protein 4 resulted in strong inhibition of the growth of B16F10 tumours, and in complete tumour regression in one-third of the treated mice. Micropatch-loaded neutrophils could provide a potent, scalable and drug-free approach for neutrophil-based cancer immunotherapy., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Adoptive cell therapies are dramatically altering the treatment landscape of cancer. However, treatment of solid tumors remains a major unmet need, in part due to limited adoptive cell infiltration into the tumor and in part due to the immunosuppressive tumor microenvironment. The heterogeneity of tumors and presence of nonresponders also call for development of antigen-independent therapeutic approaches. Myeloid cells offer such an opportunity, given their large presence in the immunosuppressive tumor microenvironment, such as in triple negative breast cancer. However, their therapeutic utility is hindered by their phenotypic plasticity. Here, the impressive trafficking ability of adoptively transferred monocytes is leveraged into the immunosuppressive 4T1 tumor to develop an antitumor therapy. To control monocyte differentiation in the tumor microenvironment, surface-adherent "backpacks" stably modified with interferon gamma (IFNγ) are developed to stimulate macrophage plasticity into a pro-inflammatory, antitumor phenotype, a strategy as referred to as Ornate Polymer backpacks on Tissue Infiltrating Monocytes (OPTIMs). Treatment with OPTIMs substantially reduces tumor burden in a mouse 4T1 model and significantly increases survival. Cytokine and immune cell profiling reveal that OPTIMs remodeled the tumor microenvironment into a pro-inflammatory state., (© 2024 Wiley‐VCH GmbH.)

Mechanistic understanding of phase transformation dynamics during battery charging and discharging is crucial toward rationally improving intercalation electrodes. Most studies focus on constant-current conditions. However, in real battery operation, such as in electric vehicles during discharge, the current is rarely constant. In this work we study current pulsing in Li X FePO 4 (LFP), a model and technologically important phase-transforming electrode. A current-pulse activation effect has been observed in LFP, which decreases the overpotential by up to ∼70% after a short, high-rate pulse. This effect persists for hours or even days. Using scanning transmission X-ray microscopy and operando X-ray diffraction, we link this long-lived activation effect to a pulse-induced electrode homogenization on both the intra- and interparticle length scales, i.e., within and between particles. Many-particle phase-field simulations explain how such pulse-induced homogeneity contributes to the decreased electrode overpotential. Specifically, we correlate the extent and duration of this activation to lithium surface diffusivity and the magnitude of the current pulse. This work directly links the transient electrode-level electrochemistry to the underlying phase transformation and explains the critical effect of current pulses on phase separation, with significant implication on both battery round-trip efficiency and cycle life. More broadly, the mechanisms revealed here likely extend to other phase-separating electrodes, such as graphite.

The choroid plexus (ChP) of the brain plays a central role in orchestrating the recruitment of peripheral leukocytes into the central nervous system (CNS) through the blood-cerebrospinal fluid (BCSF) barrier in pathological conditions, thus offering a unique niche to diagnose CNS disorders. We explored whether magnetic resonance imaging of the ChP could be optimized for mild traumatic brain injury (mTBI). mTBI induces subtle, yet influential, changes in the brain and is currently severely underdiagnosed. We hypothesized that mTBI induces sufficient alterations in the ChP to cause infiltration of circulating leukocytes through the BCSF barrier and developed macrophage-adhering gadolinium [Gd(III)]-loaded anisotropic micropatches (GLAMs), specifically designed to image infiltrating immune cells. GLAMs are hydrogel-based discoidal microparticles that adhere to macrophages without phagocytosis. We present a fabrication process to prepare GLAMs at scale and demonstrate their loading with Gd(III) at high relaxivities, a key indicator of their effectiveness in enhancing image contrast and clarity in medical imaging. In vitro experiments with primary murine and porcine macrophages demonstrated that GLAMs adhere to macrophages also under shear stress and did not affect macrophage viability or functions. Studies in a porcine mTBI model confirmed that intravenously administered macrophage-adhering GLAMs provide a differential signal in the ChP and lateral ventricles at Gd(III) doses 500- to 1000-fold lower than those used in the current clinical standard Gadavist. Under the same mTBI conditions, Gadavist did not offer a differential signal at clinically used doses. Our results suggest that macrophage-adhering GLAMs could facilitate mTBI diagnosis.

Traumatic brain injury (TBI) is a debilitating disease with no current therapies outside of acute clinical management. While acute, controlled inflammation is important for debris clearance and regeneration after injury, chronic, rampant inflammation plays a significant adverse role in the pathophysiology of secondary brain injury. Immune cell therapies hold unique therapeutic potential for inflammation modulation, due to their active sensing and migration abilities. Macrophages are particularly suited for this task, given the role of macrophages and microglia in the dysregulated inflammatory response after TBI. However, maintaining adoptively transferred macrophages in an anti-inflammatory, wound-healing phenotype against the proinflammatory TBI milieu is essential. To achieve this, we developed discoidal microparticles, termed backpacks, encapsulating anti-inflammatory interleukin-4, and dexamethasone for ex vivo macrophage attachment. Backpacks durably adhered to the surface of macrophages without internalization and maintained an anti-inflammatory phenotype of the carrier macrophage through 7 days in vitro. Backpack-macrophage therapy was scaled up and safely infused into piglets in a cortical impact TBI model. Backpack-macrophages migrated to the brain lesion site and reduced proinflammatory activation of microglia in the lesion penumbra of the rostral gyrus of the cortex and decreased serum concentrations of proinflammatory biomarkers. These immunomodulatory effects elicited a 56% decrease in lesion volume. The results reported here demonstrate, to the best of our knowledge, a potential use of a cell therapy intervention for a large animal model of TBI and highlight the potential of macrophage-based therapy. Further investigation is required to elucidate the neuroprotection mechanisms associated with anti-inflammatory macrophage therapy., (© The Author(s) 2023. Published by Oxford University Press on behalf of National Academy of Sciences.)

Natural killer (NK) cell therapies have emerged as a potential therapeutic approach to various cancers. Their efficacy, however, is limited by their low persistence and anergy. Current approaches to sustain NK cell persistence in vivo include genetic modification, activation via pretreatment, or coadministration of supporting cytokines or antibodies. Such supporting therapies exhibit limited efficacy in vivo , in part due to the reversal of their effect within the immunosuppressive tumor microenvironment and off-target toxicity. Here, we report a material-based approach to address this challenge. Specifically, we describe the use of polymeric micropatches as a platform for sustained, targeted activation of NK cells, an approach referred to as microparticles as cell engagers (MACE). Poly(lactide- co -glycolic) acid (PLGA) micropatches, 4-8 μm in diameter and surface-modified with NK cell receptor targeting antibodies, exhibited strong adhesion to NK cells and induced their activation without the need of coadministered cytokines. The activation induced by MACE was greater than that induced by nanoparticles, attesting to the crucial role of MACE geometry in the activation of NK cells. MACE-bound NK cells remained viable and exhibited trans-endothelial migration and antitumor activity in vitro . MACE-bound NK cells activated T cells, macrophages, and dendritic cells in vitro . Adoptive transfer of NK-MACE also demonstrated superior antitumor efficacy in a mouse melanoma lung metastasis model compared to unmodified NK cells. Overall, MACE offers a simple, scalable, and effective way of activating NK cells and represents an attractive platform to improve the efficacy of NK cell therapy.

Multiple sclerosis (MS) is an incurable autoimmune disease and is currently treated by systemic immunosuppressants with off-target side effects. Although aberrant myeloid function is often observed in MS plaques in the central nervous system (CNS), the role of myeloid cells in therapeutic intervention is currently overlooked. Here, we developed a myeloid cell-based strategy to reduce the disease burden in experimental autoimmune encephalomyelitis (EAE), a mouse model of progressive MS. We developed monocyte-adhered microparticles ("backpacks") for activating myeloid cell phenotype to an anti-inflammatory state through localized interleukin-4 and dexamethasone signals. We demonstrate that backpack-laden monocytes infiltrated into the inflamed CNS and modulated both the local and systemic immune responses. Within the CNS, backpack-carrying monocytes regulated both the infiltrating and tissue-resident myeloid cell compartments in the spinal cord for functions related to antigen presentation and reactive species production. Treatment with backpack-monocytes also decreased the level of systemic pro-inflammatory cytokines. Additionally, backpack-laden monocytes induced modulatory effects on T H 1 and T H 17 populations in the spinal cord and blood, demonstrating cross talk between the myeloid and lymphoid arms of disease. Backpack-carrying monocytes conferred therapeutic benefit in EAE mice, as quantified by improved motor function. The use of backpack-laden monocytes offers an antigen-free, biomaterial-based approach to precisely tune cell phenotype in vivo, demonstrating the utility of myeloid cells as a therapeutic modality and target.

Adeno-associated virus (AAV)-mediated gene therapy is a promising therapeutic modality for curing many diseases including monogenic diseases. However, limited tissue-targeting and restricted re-administration due to the vector immunogenicity largely restrict its therapeutic potential. Here, using a red blood cell (RBC) as the carrier vehicle for AAV is demonstrated to improve its tissue-targeted transduction and enable its re-administration. Anchoring AAV to the RBC surface minimally affected its infectability toward endothelial cells. Meanwhile, AAV anchored onto RBCs is predominantly delivered to and shows efficient transduction in the lungs by virtue of the biophysical features of RBCs. RBC-anchored AAVs lead to a four- to five-fold enhancement in target gene expression in the lungsas compared to free AAVs following a single- or dual-dosing regimen. While RBC anchoring does not prevent the induction of adaptive immune responses against AAV, it results in successful transgene expression upon re-administration following prior AAV exposure. The ability to re-administer is partially attributed to the delayed and reduced AAV neutralization by neutralizing antibodies, resulting from the combination of limited exposure of physically confined AAVs and the short time required to reach the lungs. This study's findings suggest that the RBC-mediated approach is a promising strategy for repetitive, targeted AAV gene therapy., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Shape of particulate drug carries has been identified as a key parameter in determining their biological outcome. In this review, we analyze the field of particle shape as it shifts from fundamental investigations to contemporary applications for disease treatment, while highlighting outstanding remaining questions. We summarize fabrication and characterization methods and discuss in depth how particle shape influences biological interactions with cells, transport in the vasculature, targeting in the body, and modulation of the immune response. As the field moves from discoveries to applications, further attention needs to be paid to factors such as characterization and quality control, selection of model organisms, and disease models. Taken together, these aspects will provide a conceptual foundation for designing future non-spherical drug carriers to overcome biological barriers and improve therapeutic efficacy., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Cell therapies have emerged as a promising therapeutic modality with the potential to treat and even cure a diverse array of diseases. Cell therapies offer unique clinical and therapeutic advantages over conventional small molecules and the growing number of biologics. Particularly, living cells can simultaneously and dynamically perform complex biological functions in ways that conventional drugs cannot; cell therapies have expanded the spectrum of available therapeutic options to include key cellular functions and processes. As such, cell therapies are currently one of the most investigated therapeutic modalities in both preclinical and clinical settings, with many products having been approved and many more under active clinical investigation. Here, we highlight the diversity and key advantages of cell therapies and discuss their current clinical advances. In particular, we review 28 globally approved cell therapy products and their clinical use. We also analyze >1700 current active clinical trials of cell therapies, with an emphasis on discussing their therapeutic applications. Finally, we critically discuss the major biological, manufacturing, and regulatory challenges associated with the clinical translation of cell therapies., (© 2021 The Authors. Bioengineering & Translational Medicine published by Wiley Periodicals LLC on behalf of American Institute of Chemical Engineers.)

Liposome-based drug delivery systems have allowed for better drug tolerability and longer circulation times but are often optimized for a single agent due to the inherent difficulty of co-encapsulating two drugs with differing chemical profiles. Here, we design and test a prodrug based on a ribosylated nucleoside form of 5-fluorouracil, 5-fluorouridine (5FUR), with the final purpose of co-encapsulation with doxorubicin (DOX) in liposomes. To improve the loading of 5FUR, we developed two 5FUR prodrugs that involved the conjugation of either one or three moieties of tryptophan (W) known respectively as, 5FUR-W and 5FUR-W 3 . 5FUR-W demonstrated greater chemical stability than 5FUR-W3 and allowed for improved loading with fewer possible byproducts from tryptophan hydrolysis. Varied drug ratios of 5FUR-W: DOX were encapsulated for in vivo testing in the highly aggressive 4T1 murine breast cancer model. A liposomal molar ratio of 2.5 5FUR-W: DOX achieved a 62.6% reduction in tumor size compared to the untreated control group and a 33% reduction compared to clinical doxorubicin liposomes in a proof-of-concept study to demonstrate the viability of the co-encapsulated liposomes. We believe that the new prodrug 5FUR-W demonstrates a prodrug design with clinical translatability by reducing the number of byproducts produced by the hydrolysis of tryptophan, while also allowing for loading flexibility.

Approaches to safely and effectively augment cellular functions without compromising the inherent biological properties of the cells, especially through the integration of biologically labile domains, remain of great interest. Here, a versatile strategy to assemble biologically active nanocomplexes, including proteins, DNA, mRNA, and even viral carriers, on cellular surfaces to generate a cell-based hybrid system referred to as "Cellnex" is established. This strategy can be used to engineer a wide range of cell types used in adoptive cell transfers, including erythrocytes, macrophages, NK cells, T cells, etc. Erythrocyte nex can enhance the delivery of cargo proteins to the lungs in vivo by 11-fold as compared to the free cargo counterpart. Biomimetic microfluidic experiments and modeling provided detailed insights into the targeting mechanism. In addition, Macrophage nex is capable of enhancing the therapeutic efficiency of anti-PD-L1 checkpoint inhibitors in vivo. This simple and adaptable approach may offer a platform for the rapid generation of complex cellular systems., (© 2020 Wiley-VCH GmbH.)

Cancer therapy is increasingly shifting toward targeting the tumor immune microenvironment and influencing populations of tumor infiltrating lymphocytes. Breast cancer presents a unique challenge as tumors of the triple-negative breast cancer subtype employ a multitude of immunosilencing mechanisms that promote immune evasion and rapid growth. Treatment of breast cancer with chemotherapeutics has been shown to induce underlying immunostimulatory responses that can be further amplified with the addition of immune-modulating agents. Here, we investigate the effects of combining doxorubicin (DOX) and gemcitabine (GEM), two commonly used chemotherapeutics, with monophosphoryl lipid A (MPLA), a clinically used TLR4 adjuvant derived from liposaccharides. MPLA was incorporated into the lipid bilayer of liposomes loaded with a 1:1 molar ratio of DOX and GEM to create an intravenously administered treatment. In vivo studies indicated excellent efficacy of both GEM-DOX liposomes and GEM-DOX-MPLA liposomes against 4T1 tumors. In vitro and in vivo results showed increased dendritic cell expression of CD86 in the presence of liposomes containing chemotherapeutics and MPLA. Despite this, a tumor rechallenge study indicated little effect on tumor growth upon rechallenge, indicating the lack of a long-term immune response. GEM/DOX/MPLA-L displayed remarkable control of the primary tumor growth and can be further explored for the treatment of triple-negative breast cancer with other forms of immunotherapy., (© 2020 The Authors. Bioengineering & Translational Medicine published by Wiley Periodicals LLC on behalf of American Institute of Chemical Engineers.)

Macrophages play a key role in defending against foreign pathogens, healing wounds, and regulating tissue homeostasis. Driving this versatility is their phenotypic plasticity, which enables macrophages to respond to subtle cues in tightly coordinated ways. However, when this coordination is disrupted, macrophages can aid the progression of numerous diseases, including cancer, cardiovascular disease, and autoimmune disease. The central link between these disorders is aberrant macrophage polarization, which misguides their functional programs, secretory products, and regulation of the surrounding tissue microenvironment. As a result of their important and deterministic roles in both health and disease, macrophages have gained considerable attention as targets for drug delivery. Here, we discuss the role of macrophages in the initiation and progression of various inflammatory diseases, summarize the leading drugs used to regulate macrophages, and review drug delivery systems designed to target macrophages. We emphasize strategies that are approved for clinical use or are poised for clinical investigation. Finally, we provide a prospectus of the future of macrophage-targeted drug delivery systems., Competing Interests: Declaration of Competing Interest S.M. is a shareholder of, consultant to, and recipient of research grants from several drug delivery, pharmaceutical and biotechnology companies, including those active in the general area of research discussed in this article. S.M. is the inventor on several patents in the field of drug delivery and formulations that are owned by their current or former employers. The views presented here should not be considered as endorsements of any specific product or company., (Copyright © 2019 Elsevier B.V. All rights reserved.)