Tailoring Materials for Modulation of Macrophage Fate

Engineering multifunctional surface topography to regulate multiple biological responses

Surface topography or curvature plays a crucial role in regulating cell behavior, influencing processes such as adhesion, proliferation, and gene expression. Recent advancements in nano- and micro-fabrication techniques have enabled the development of biomimetic systems that mimic native extracellular matrix (ECM) structures, providing new insights into cell-adhesion mechanisms, mechanotransduction, and cell-environment interactions. This review examines the diverse applications of engineered topographies across multiple domains, including antibacterial surfaces, immunomodulatory devices, tissue engineering scaffolds, and cancer therapies. It highlights how nanoscale features like nanopillars and nanospikes exhibit bactericidal properties, while many microscale patterns can direct stem cell differentiation and modulate immune cell responses. Furthermore, we discuss the interdisciplinary use of topography for combined applications, such as the simultaneous regulation of immune and tissue cells in 2D and 3D environments. Despite significant advances, key knowledge gaps remain, particularly regarding the effects of topographical cues on multicellular interactions and dynamic 3D contexts. This review summarizes current fabrication methods, explores specific and interdisciplinary applications, and proposes future research directions to enhance the design and utility of topographically patterned biomaterials in clinical and experimental settings.

The effect of copper content in Ti-Cu alloy with bone regeneration ability on the phenotypic transformation of macrophages

Titanium (Ti) alloys are widely used in bone repair due to their excellent biocompatibility and mechanical properties. However, managing post-implantation inflammatory responses in the defect region and accelerating the healing process remain major challenges in the design of such materials. As a bridge between the innate and adaptive immune systems, macrophages play a pivotal role in bone defect healing through their M2 polarization, which facilitates the secretion of tissue repair-promoting cytokines. Research on the role of copper ions (Cu²⁺) in regulating inflammatory responses at injury sites suggests their potential as active ions for incorporation into alloys as a secondary phase to modulate macrophage polarization. However, the effective concentration and mechanisms in this process remain unclear. Here, we synthesized Ti-xCu (x = 3, 5, 7 wt%) alloys and investigated the effects of copper concentration on macrophage M1/M2 polarization and the underlying mechanisms. In an 8-week rat mandibular bone regeneration experiment, Ti-5Cu demonstrated superior performance compared to pure titanium. At the early stage (2 weeks), Ti-5Cu promoted the dominance of M1 macrophages and upregulated inflammatory cytokines, facilitating the initial inflammatory response. Subsequently, a timely M1-to-M2 phenotype transition was observed, accompanied by elevated expression of the repair-related cytokine IL-10, ultimately leading to improved bone healing. This study provides a theoretical foundation for the development of titanium-copper composite materials with anti-inflammatory and pro-healing properties, paving the way for innovative solutions to promote bone defect repair.

Biocompatible cloaking of bacteria for effective tumor imaging and therapy

Bacteria possess distinctive characteristics, such as tropism, motility, and genetic editability, which make them highly attractive for biomedical applications, such as tumor imaging and therapy. However, the immunogenicity triggered by endotoxins may lead to severe adverse effects and prompt quick elimination in the body, thus restricting their clinical applications. In this study, we described a double-layer coating technique employing tannic acid (TA) and albumin (BSA) for bacteria encapsulation. This compact coating effectively shields endotoxin exposure and inhibits endotoxin leakage from bacteria, exhibiting a favorable safety profile. Moreover, bacteria coated with BSA have superior biocompatibility with their surroundings, which prevents phagocytes from eliminating the bacteria, hence prolonging the reservation in vivo. As bacteria grow, the BSA-TA layer progressively detaches after reaching targeted sites, allowing free bacteria to exploit their own advantages. Importantly, the BSA-TA coating strategy protects bacteria against various environmental assaults without compromising their growth, proliferation, or motility, maintaining their inherent characteristics. In murine tumor models, the BSA-TA-coated bacteria demonstrated enhanced long-term tumor imaging and therapeutic efficacy against tumors. Together, the BSA-TA coating strategy improves the biocompatibility of bacteria and has the capacity to expand the range of bacteria for biomedical applications.

3D bioprinted biomimetic MOF-functionalized hydrogel scaffolds for bone regeneration: Synergistic osteogenesis and osteoimmunomodulation

Critical-size bone defects remain a significant clinical challenge. The lack of endogenous stem cells with osteogenic differentiation potential in the defect area, combined with the inflammatory responses induced by scaffold implantation, highlights the need for biomaterials that can deliver stem cells and possess inflammatory regulation properties. In this study, we developed a 3D bioprinted gelatin methacrylate (GelMA) hydrogel scaffold modified with luteolin-loaded ZIF-8 (LUT@ZIF-8) nanoparticles, designed to deliver bone marrow mesenchymal stem cells (BMSCs) to the defect site and release bioactive components that promote osteogenesis and modulate the immune microenvironment. The LUT@ZIF-8/GelMA hydrogel scaffolds demonstrated excellent physical properties and biocompatibility. The sustained release of luteolin and zinc ions from the LUT@ZIF-8 nanoparticles conferred antibacterial, osteoinductive, and inflammatory regulation effects. The immune microenvironment modulated by LUT@ZIF-8/GelMA hydrogel scaffolds facilitated osteogenic differentiation of BMSCs. Furthermore, in vivo experiments confirmed the osteogenic and inflammatory regulation capabilities of the LUT@ZIF-8/GelMA hydrogel scaffolds. In conclusion, the 3D bioprinted LUT@ZIF-8/GelMA hydrogel scaffolds exhibit osteoimmunomodulatory properties, presenting a promising strategy for the treatment of bone defects.

Machine learning-based label-free macrophage phenotyping in immune-material interactions

The rapid advancement of implantable biomedical materials necessitates a comprehensive understanding of macrophage interactions to optimize implant immunocompatibility. Macrophages, key immune regulators, exhibit phenotypic plasticity by polarizing into pro-inflammatory (M1) or anti-inflammatory (M2) subtypes. Conventional phenotyping techniques, such as flow cytometry and immunostaining, provide insights but have limitations related to fixation and endpoint analysis. This study presents a high-throughput, label-free macrophage phenotyping approach integrating AI-driven image classification with quantitative phase imaging (QPI). THP-1-derived macrophages were differentiated into M0, M1, M2a, and M2c phenotypes, and their morphological and refractive index properties were analyzed using QPI. Although QPI alone could not fully distinguish phenotypes, deep learning models, including GoogLeNet, ShuffleNet, VGG-16, and ResNet-18, were evaluated, with ResNet-18 achieving over 90% accuracy. Additionally, macrophage responses to collagen coatings (types I, III, and IV) were assessed using machine learning-based phenotyping and cytokine profiling. Collagen I induced an M1 response, collagen III supported a balanced M1/M2 profile, and collagen IV promoted a controlled immune environment. These findings demonstrate the potential of AI-driven QPI as a non-invasive tool for macrophage characterization, offering insights into biomaterial immunocompatibility and informing implant design strategies.

Engineered Bacterial Biohybrid-Mediated CD47-SIRPα Blockade and HSP90 Inhibition for Enhanced Immuno-Photothermal Therapy

Macrophage phagocytosis of tumor cells shows significant promise in cancer treatment. However, it faces great challenges due to the upregulation of antiphagocytosis molecules, such as CD47, on the surface of tumor cells. Merely reducing the level of CD47 is insufficient to induce phagocytosis of tumor cells because it lacks enough "eat me" signals. Here, we have developed an engineered bacterial biohybrid system (eVNP@AuNFs) to decrease the expression of CD47 and HSP90 proteins, achieving an enhanced immuno-photothermal combination therapy. The attenuated Salmonella VNP20009, capable of selectively accumulating in hypoxic tumor regions, was intracellularly genetically engineered with CD47 and HSP90 shRNA plasmids and an extracellularly adsorbed flower-like gold nanoparticle (AuNF) photothermal agent, forming an eVNP@AuNF bacterial hybrid. After administration into 4T1 tumor-bearing mice intravenously, the eVNP@AuNF bacterial hybrid could effectively accumulate in tumor tissues and release CD47 and HSP90 shRNA plasmids to reduce the expression of CD47 and HSP90 protein, leading to enhanced macrophage phagocytosis to tumor cells and an improved photothermal effect. Under further NIR-II laser irradiation, extracellular AuNFs of eVNP@AuNFs could photothermally induce immunogenic cell death, including surface calreticulin exposure and high-mobility group box 1 translocation, facilitating the infiltration of the "eat me" signal and multiple immune cells and enhancing tumor immunogenicity. The eVNP@AuNF bacterial hybrid could eradicate the primary tumor and elicit a systemic antitumor immunity response, inhibiting the recurrence of the tumor. This study presents a hybrid system involving bacteria, plasmids, and nanomaterials for tumor therapy, opening an avenue for hierarchical modulation of the tumor immune response.

UTX Responds to Nanotopography to Suppress Macrophage Inflammatory Response by Remodeling H3K27me3 Modification

Peri-implantitis is the leading cause of implant failure, primarily due to weak defense at the implant-soft tissue interface, which disrupts the local immune microenvironment. As an integral part of this microenvironment, the implant-tissue interface plays a critical role in shaping immune cell function. Thus, engineering the surface topography of implants has emerged as a novel strategy for sustained immunomodulation following implantation. This study investigated the mechanical regulation of macrophage function by nanopatterned topographies. Titanium nanotubes (TNTs) surfaces reduce the expression of phosphorylated myosin light chain (pMLC) and promote the retention of the UTX histone methyltransferase in the nucleus. This process attenuates the enrichment of the repressive H3K27me3 histone marker at the Abca1 gene locus, increasing Abca1 expression and suppressing inflammation. This study reveals the mechanosensitivity of UTX and provides a new target for the development of therapeutic strategies that integrate mechanical signaling and immune modulation.

An Asymmetric Zn Membrane with Degradability, Antimicrobial, and Bone Immunomodulation for Guided Bone Regeneration

As a biodegradable metal, zinc (Zn) offers a promising material option for barrier membranes in the field of bone regeneration due to its suitable degradation rate and mechanical properties. An ideal barrier membrane not only blocks the growth of epithelial fibers but also promotes bone regeneration. Therefore, we prepared an asymmetric Zn membrane with micrometer-sized pores on one side by laser etching, with the pore side facilitating cell adhesion and proliferation, and the smooth side facilitating the blocking of epithelial cell growth entry. And the antimicrobial peptide GL13K (P1) was loaded onto the smooth surface of Zn by Zn-specific binding peptide (NCS) to resist postoperative bacterial infections, and the small intestinal submucosal hydrogel complex (SIS-P2), which was specifically loaded with Substance P (SP), was placed in the pores on the pore side to modulate the immunity and promote osteogenesis. This innovative asymmetric zinc barrier membrane (Zn-P1-SIS-P2 membrane) exhibited excellent mechanical, antimicrobial, and biocompatibility properties. More importantly, the Zn-P1-SIS-P2 membrane promotes macrophage polarization toward the M2 type, thereby promoting osteogenic differentiation and providing a good immune microenvironment for bone regeneration. In addition, the Zn-P1-SIS-P2 membrane inhibited RANKL-induced osteoclast formation and suppressed bone resorption at the site of bone defects. In conclusion, the Zn-P1-SIS-P2 membrane demonstrated all the desirable qualities of a GBR therapeutic barrier membrane.

Bioprinted M2 macrophage-derived extracellular vesicle mimics attenuate foreign body reaction and enhance vascularized tissue regeneration

Foreign body reaction (FBR) and insufficient vascularization greatly hinder the integration of 3D-bioprinted tissue substitutes with host tissues. Previous studies have shown that these problems are exacerbated by the stiffness of the 3D-bioprinted constructions, which is highly associated with the abnormal polarization of macrophages. Therefore, we developed an engineering strategy using membrane extrusion to prepare macrophage-derived extracellular vesicle mimics (EVMs). The EVMs derived from M1 and M2 macrophages (M1-EVMs and M2-EVMs) were rich in functional proteins. In the 2D environment, M1-EVMs promoted the fibrotic phenotype of fibroblasts, vascularization, and the M1 polarization of macrophages. In contrast, M2-EVMs effectively avoided the fibrotic trend, showed stronger angiogenic capabilities, and prevented excessive M1 polarization, demonstrating their potential to inhibit FBR and promote neovascularization. After bioprinting the EVMs loaded by gelatin-alginate bioink, the basic physical properties of the bioink were not significantly affected, and the biological functions of EVMs remain stable, indicating their potential as bioink additives. In the subcutaneous implantation model, unlike the FBR-aggravating effects of M1-EVMs, 3D-bioprinted M2-EVMs successfully reduced the immune response, prevented fibrous capsule formation, and increased vascular density. When applied to skin wound treatment, 3D-bioprinted M2-EVMs not only inhibited inflammatory levels but also exhibited pleiotropic pro-regenerative effects, effectively promoting vascularization, re-epithelialization, and appendage regeneration. As an innovative additive for bioinks, M2-EVMs present a promising approach to enhance the survival of bioengineered tissues and can further serve as a targeted drug loading system, promoting the development of regenerative medicine and improving clinical outcomes.

Degradation of WE43 Magnesium Alloy in Vivo and Its Degradation Products on Macrophages

Due to their biocompatibility, biodegradability, and suitable mechanical properties, magnesium-based biodegradable implants are emerging as a promising alternative to traditional metal implants. The Mg-4Y-3RE (WE43) biodegradable alloy is among the most extensively studied and widely utilized magnesium alloys in clinical applications. As an absorbable and degradable metallic material, magnesium alloys undergo gradual degradation, wear, and fracture within the body. These alloys reduce the long-term risks associated with permanent implants but generate insoluble byproducts that accumulate in surrounding tissues. Following the implantation of magnesium alloys, granulation tissue and fibrous encapsulation typically form around the material. However, limited research has addressed the interaction between insoluble byproducts of magnesium alloys and macrophages. This study focused on the biological effects of macrophages during the second stage of the host inflammatory response in the degradation process of magnesium alloy. Using subcutaneous implantation of WE43 magnesium alloy sheets, observations were made regarding the degradation components, morphological changes in surrounding tissues, and the biological effects of macrophages upon phagocytosis of insoluble byproducts. The primary degradation products of WE43 in vivo were identified as Ca3 (PO4)2, Mg3(PO4)2, Na3PO4, NaCa (PO4), MgSO4, MgCO3, NaCl, Mg24Y5, and Mg12YNd. Postimplantation, levels of IL-1β and IL-18 in adjacent tissues significantly increased (p < 0.05). By 8 weeks, compared to nitinol alloy, significant thickening of the fibrous capsule (p < 0.05) was observed, accompanied by substantial inflammatory cell infiltration, vascularization, and the presence of macrophages and multinucleated giant cells. Macrophages were observed extending pseudopodia to enclose and phagocytose particles, forming phagosomes and creating a relatively isolated microenvironment around the engulfed substances, where further particle degradation occurred. Following the phagocytosis of degradation products, macrophages exhibited increased lysosome numbers, mitochondrial swelling and damage, phagolysosome formation, and autophagosome development. Furthermore, the degradation products were observed to induce elevated reactive oxygen species (ROS) production in macrophages, activation of P2X7 receptors, enhanced IL-6 secretion, endoplasmic reticulum stress, autophagy, and activation of the NLRP3 inflammasome pathway. This study provides novel insights and contributes a theoretical foundation for a more comprehensive understanding of magnesium alloy degradation in vivo.

Spatiotemporally Programming Microenvironment to Recapitulate Endochondral Ossification via Greenhouse-Inspired Bionic Niche

Various biomaterials have been developed to address challenging critical-sized bone defects. However, most of them focus on intramembranous ossification (IMO) rather than endochondral ossification (ECO), often resulting in suboptimal therapeutic outcomes. Drawing inspiration from the functionality of the greenhouse ecosystem, herein a bionic niche is innovatively crafted to recapitulate the ECO process. This niche consists of three hierarchical components: an embedded microchannel network that facilitates cell infiltration and matter exchange, a polydopamine surface modification layer with immunomodulatory functions, and an ECO-targeted delivery system based on mesoporous silica nanoparticles. Through spatiotemporally programming of the microenvironment, the bionic niche effectively recapitulates the key stages of ECO. Notably, even in the rat calvaria, a region well-known for IMO, the bionic niche is capable of initiating ECO, evident by cartilage template formation, leading to efficient bone regeneration. Taken together, this study introduces prospective concepts for designing next-generation ECO-driven biomaterials for bone tissue engineering.

Understanding the Dual Role of Macrophages in Tumor Growth and Therapy: A Mechanistic Review

Macrophages are heterogeneous cells that are the mediators of tissue homeostasis. These immune cells originated from monocytes and are classified into two basic categories, M1 and M2 macrophages. M1 macrophages exhibit anti-tumorous inflammatory reactions due to the behavior of phagocytosis. M2 macrophages or tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment (TME) and have a basic role in tumor progression by interacting with other immune cells in TME. By the expression of various cytokines, chemokines, and growth factors, TAMs lead to strengthening tumor cell proliferation, angiogenesis, and suppression of the immune system which further support invasion and metastasis. This review discusses recent and updated mechanisms regarding tumor progression by M2 macrophages. Moreover, the current therapeutic approaches targeting TAMs, their advantages, and limitations are also summarized, and further treatment approaches are outlined along with an elaboration of the tumor regression role of macrophages. This comprehensive review article possibly helps to understand the mechanisms underlying the tumor progression and regression role of macrophages in a comparative way from a basic level to the advanced one.

Silicon Enhances Functional Mitochondrial Transfer to Improve Neurovascularization in Diabetic Bone Regeneration

Diabetes mellitus is a metabolic disorder associated with an increased risk of fractures and delayed fracture healing, leading to a higher prevalence of bone defects. Recent advancements in strategies aim at regulating immune responses and enhancing neurovascularization have not met expectations. This study demonstrates that a silicon-based strategy significantly enhances vascularization and innervation, thereby optimizing the repair of diabetic bone defects. Silicon improves mitochondrial function and modulates mitochondrial fission dynamics in macrophages via the Drp1-Mff signaling pathway. Subsequently, functional mitochondria are transferred from macrophages to endothelial and neuronal cells through microvesicles, providing a protective mechanism for blood vessels and peripheral nerves during early wound healing. On this basis, an optimized strategy combining a silicified collagen scaffold with a Drp1-Fis1 interaction inhibitor is used to further regulate mitochondrial fission in macrophages and enhance the trafficking of functional mitochondria into stressed receptor cells. In diabetic mice with critical-sized calvarial defects, the silicon-based treatment significantly promotes vessel formation, nerve growth, and mineralized tissue development. These findings provide therapeutic insights into the role of silicon in promoting diabetic bone regeneration and highlight the importance of intercellular communication in diabetic conditions.

Construction of anti-calcification small-diameter vascular grafts using decellularized extracellular matrix/poly (L-lactide-co-ε-caprolactone) and baicalin-cathepsin S inhibitor

The long-term transplantation of small-diameter vascular grafts (SDVGs) is associated with a risk of calcification, which is a key factor limiting the clinical translation of SDVG. Hence, there is an urgency attached to the development of new SDVGs with anti-calcification properties. Here, we used decellularized extracellular matrix (dECM) and poly (L-lactide-co-ε-caprolactone) (PLCL) as base materials and combined these with baicalin, cathepsin S (Cat S) inhibitor to prepare PBC-SDVGs by electrospinning. Baicalin contains carboxyl and hydroxyl groups that can interact with chemical groups in dECM powder, potentially blocking calcium nucleation sites. Cat S inhibitor prevents elastin degradation and further reduces the risk of calcification. PBC-SDVGs were biocompatible and when implanted in rat abdominal aorta, accelerated endothelialization, enhanced vascular tissue regeneration, inhibited elastin degradation, and promoted macrophage polarization M2 phenotype to regulate inflammation. After 3 months of implantation, the results of Doppler ultrasound, MicroCT, and histological staining revealed a significant reduction in calcification. In summary, the developed anti-calcification SDVGs offer a promising strategy for long-term implantation with significant clinical application potential. STATEMENT OF SIGNIFICANCE: The dECM and PLCL were used as base materials, connected with baicalin, and loaded with Cat S inhibitor to prepare PBC-SDVGs. The baicalin and dECM powder formed hydrogen bonds to crosslink together reducing the calcium deposition. In vitro, the vascular graft downregulated the expression level of osteogenic genes and promoted macrophage polarization toward an anti-inflammatory M2 phenotype, thereby reducing calcification. The PBC-SDVGs implanted in rat abdominal aorta can accelerate endothelialization, enhance vascular tissue regeneration, inhibit elastin degradation, reduce inflammation response and calcification.

Emerging nanomedicines for macrophage-mediated cancer therapy

Tumor-associated macrophages (TAMs) contribute to tumor progression by promoting angiogenesis, remodeling the tumor extracellular matrix, inducing tumor invasion and metastasis, as well as immune evasion. Due to the high plasticity of TAMs, they can polarize into different phenotypes with distinct functions, which are primarily categorized as the pro-inflammatory, anti-tumor M1 type, and the anti-inflammatory, pro-tumor M2 type. Notably, anti-tumor macrophages not only directly phagocytize tumor cells, but also present tumor-specific antigens and activate adaptive immunity. Therefore, targeted regulation of TAMs to unleash their potential anti-tumor capabilities is crucial for improving the efficacy of cancer immunotherapy. Nanomedicine serves as a promising vehicle and can inherently interact with TAMs, hence, emerging as a new paradigm in cancer immunotherapy. Due to their controllable structures and properties, nanomedicines offer a plethora of advantages over conventional drugs, thus enhancing the balance between efficacy and toxicity. In this review, we provide an overview of the hallmarks of TAMs and discuss nanomedicines for targeting TAMs with a focus on inhibiting recruitment, depleting and reprogramming TAMs, enhancing phagocytosis, engineering macrophages, as well as targeting TAMs for tumor imaging. We also discuss the challenges and clinical potentials of nanomedicines for targeting TAMs, aiming to advance the exploitation of nanomedicine for cancer immunotherapy.

Decoding biomaterial-associated molecular patterns (BAMPs): influential players in bone graft-related foreign body reactions

Bone grafts frequently induce immune-mediated foreign body reactions (FBR), which hinder their clinical performance and result in failure. Understanding biomaterial-associated molecular patterns (BAMPs), including physicochemical properties of biomaterial, adsorbed serum proteins, and danger signals, is crucial for improving bone graft outcomes. Recent studies have investigated the role of BAMPs in the induction and maintenance of FBR, thereby advancing the understanding of FBR kinetics, triggers, stages, and key contributors. This review outlines the stages of FBR, the components of BAMPs, and their roles in immune activation. It also discusses various bone grafting biomaterials, their physicochemical properties influencing protein adsorption and macrophage modulation, and the key mechanisms of protein adsorption on biomaterial surfaces. Recent advancements in surface modifications and immunomodulatory strategies to mitigate FBR are also discussed. Furthermore, the authors look forward to future studies that will focus on a comprehensive proteomic analysis of adsorbed serum proteins, a crucial component of BAMPs, to identify proteins that promote or limit inflammation. This understanding could facilitate the design of biomaterials that selectively adsorb beneficial proteins, thereby reducing the risk of FBR and enhancing bone regeneration.

Inhalable Ce Nanozyme-Backpacked Phage Aims at Ischemic Cerebral Injury by M1-Microglia Hitchhiking

There is a desperate need for precise nanomedications to treat ischemic cerebral injury. Yet, the drawbacks of poor delivery efficiency and off-target toxicity in pathologic parenchyma for traditional antioxidants against ischemic stroke result in inadequate brain accumulation. M13 bacteriophages are highly phagocytosed by M1-polarized microglia and can be carried toward the neuroinflammatory sites. Here, a bio-active, inhalable, Ce0.9Zr0.1O2-backpacked-M13 phage (abbreviated as CZM) is developed and demonstrates how M13 bacteriophages are taken up by different phenotypes' microglia. With the M1 microglia's proliferating and migrating, CZM can be extensively and specifically delivered to the site of the ischemic core and penumbra, where the surviving nerve cells need to be shielded from secondary oxidative stress and inflammatory cascade initiated by reactive oxygen species (ROS). With non-invasive administration, CZM effectively alleviates oxidative damage and apoptosis of neurons by eliminating ROS generated by hyperactive M1-polarized microglia. Here, a secure and effective strategy for the targeted therapy of neuroinflammatory maladies is offered by this research.

Photoresponsive Blood-Derived Protein Hydrogels Packed with Bioactive Carbon Dots Modulate Mitochondrial Homeostasis and Reprogram Metabolism for Chronic Wound Healing in Diabetes

Autologous platelet concentrates (APC) represent a class of personalized regenerative materials for vascularized tissue regeneration. However, shortcomings including poor controllability of gel formation, lack of reactive oxygen species (ROS) scavenging ability, and deficient anti-inflammatory capacity restrict the tissue healing outcomes of APC. This study proposes an APC-based synergistic platform (CurCDs@iPRF-MA) for the treatment of chronic wounds in diabetes. Such a platform is composed of injectable platelet-rich fibrin (iPRF), gelatin methacryloyl (GelMA), and a carbogenic nanodrug from curcumin (CurCDs) that is injectable before the light-induced gel formation process, greatly facilitating the clinical applications of APC. Significantly, CurCDs@iPRF-MA can modulate the mitochondrial homeostasis under inflammatory conditions, activate the oxidative phosphorylation (OXPHOS) program, and regulate the diabetic microenvironment through metabolic reprogramming to achieve macrophage phenotype regulation and ROS elimination, as well as promote vascularization by releasing autologous growth factors, dramatically improving the healing efficacy of the chronic wounds in diabetes. This study offers a practical and effective approach to developing spatiotemporally controllable and multifunctional APC-based hydrogels for highly effective tissue regeneration.

In situ 3D bioprinted GDMA/Prussian blue nanozyme hydrogel with wet adhesion promotes macrophage phenotype modulation and intestinal defect repair

Developing hydrogels with wet-adhesion, immunomodulation and regenerative repair capabilities in intestinal repair remains a formidable challenge. In the present study, the development of an anti-inflammatory, wet-adhesive, decellularized extracellular matrix hydrogel produced using three-dimensional (3D) -printing technology is presented. This hydrogel, which integrates gelatin and dopamine, was demonstrated to display excellent wet-adhesion properties, fully harnessing the outstanding regenerative potential of the decellularized small-intestine matrix. Furthermore, the integration of Prussian Blue nanozymes imparted significant anti-inflammatory and antioxidant properties. Through modulating macrophage polarization, the hydrogel was not only found to enhance tissue repair, but also to substantially mitigate inflammation. In vivo experiments (namely, histopathological analyses using a rat model) demonstrated that this hydrogel was able to effectively enhance tissue regeneration and healing in models of intestinal damage. In conclusion, through the utilization of 3D-printing technology, the present study has shown that the precise manufacturing and customization of the hydrogel to various shapes and sizes of intestinal defects may be executed, thereby providing an innovative strategy for intestinal repair. This advanced hydrogel has therefore been shown to hold significant promise as a bioadhesive for both emergency repair and regenerative therapy.

Macrophage-related inflammatory responses to degradation products of biodegradable molybdenum implants

Metallic molybdenum (Mo) has been increasingly recognized as a potential biodegradable metal for biomedical implants. However, the macrophage-mediated inflammatory responses to Mo-based implants remain underexplored. This study examined the in vitro inflammatory reactions of macrophages to the degradation products of biodegradable Mo implants. The short-term and long-term biodegradation behavior and the subsequent impact on cytotoxicity, metabolism, and macrophage polarization were assessed. Both Mo and its degradation products were shown to be non-toxic within macrophage tolerance limits. Nevertheless, morphological changes and pro-inflammatory polarization were observed in cells around Mo-based specimen. Notably, matrix metalloproteinase 9 (Mmp9) was identified as a key gene influencing macrophage polarization in proximity to Mo. Additionally, pre-treating the Mo specimens in culture medium for 24 h significantly mitigated its stimulatory effects on cells. These results demonstrated the significance of optimizing Mo pre-treatment methods to prevent localized inflammation associated with its degradation. Specifically, pre-treatment of Mo can effectively mitigate the adverse impacts of its early degradation on macrophages and the surrounding immune environment. Our research into these early degradation phases introduces new avenues for studying molybdenum's immunomodulatory properties, potentially through precise control of its release and the targeted expression of pivotal genes.

Microenvironment-responsive nanoparticles functionalized titanium implants mediate redox balance and immunomodulation for enhanced osseointegration

Various pathological conditions (e.g., diabetes, osteoporosis) are accompanied by persistent oxidative stress, which compromises the immune microenvironment and poses substantial challenges for osseointegration. Reactive oxygen species (ROS) play a "double-edged sword" role in bone tissue. Therefore, developing responsive biomaterials to maintain redox balance dynamically is crucial for enhanced osseointegration. Herein, the microenvironment-responsive coordination nanoparticles (C-Ca-SalB NPs) composed of salvianolic acid B (SalB), catechol-conjugated chitosan (CS-C), and Ca2+ are constructed and further covalently immobilized onto titanium implant surfaces. The resulting implants achieve on-demand antioxidant and immunomodulatory effects in a microenvironment-responsive manner, thus facilitating bone regeneration under both normal and oxidative conditions. Under physiological conditions, the functionalized implants display modest immunomodulatory properties without affecting oxidative balance, while C-Ca-SalB NPs remain relatively stable. However, the modified implants enable rapid decomposition of C-Ca-SalB NPs under acidic oxidative conditions, displaying robust ROS-scavenging, anti-inflammatory, and osteoinductive capacities, ultimately remodeling the pathological microenvironment into a regenerative one. Overall, smart implants with controlled bioactive agent release in this study present a comprehensive solution for enhancing bone-implant integration, particularly in the challenging context of oxidative stress.

Application of 4D-Printed Magnetoresponsive FOGS Hydrogel Scaffolds in Auricular Cartilage Regeneration

3D-printed hydrogel scaffolds are widely utilized in auricular cartilage tissue engineering. However, issues such as graft-related inflammation, poor mechanical properties, and the lack of external modulation of 3D-printed scaffolds in vivo have raised significant concerns. To address these challenges, a "fried egg" structure is designed, consisting of chitosan-coated ferroferric oxide magnetic nanoparticles (Fe3O4@CS MNPs), which are uniformly incorporated into hydrogel. Through 4D printing technology, magnetoresponsive hydrogel scaffolds are constructed to overcome the aforementioned limitations. The results demonstrated that, compared to 3D printing, 4D-printed magnetic hydrogel scaffolds significantly enhanced cartilage tissue regeneration in both in vitro and in vivo environments when subjected to an external magnetic field (MF). Furthermore, the mechanical strength of regenerated cartilage approached to that of natural cartilage. The chitosan coating on the surface of MNPs exhibited anti-inflammatory and antibacterial properties, promoting M2 polarization of macrophages and suppressing graft-related inflammation and bacteria. Transcriptomic analysis confirmed that MNPs modulate macrophage immunity by activating JAK2/STAT3 signaling pathway. Taken together, a magnetoresponsive multifunctional scaffold is designed that can be externally controlled by magnetic fields to promote ear cartilage tissue regeneration. The regenerated cartilage exhibits excellent biocompatibility, anti-inflammatory, antibacterial properties, and mechanical performance, providing new insights for auricular cartilage tissue engineering.

Enhanced Immune Modulation and Bone Tissue Regeneration through an Intelligent Magnetic Scaffold Targeting Macrophage Mitochondria

During the bone tissue repair process, the highly dynamic interactions between the host and materials hinder precise, stable, and sustained immune modulation. Regulating the immune response based on potential mechanisms of macrophage phenotypic changes may represent an effective strategy for promoting bone healing. This study successfully constructs a co-dispersed pFe₃O₄-MXene nanosystem by loading positively charged magnetite (pFe₃O₄) nanoparticles onto MXene nanosheets using electrostatic self-assembly. Subsequently, this work fabricates a biomimetic porous bone scaffold (PFM) via selective laser sintering, which exhibit superior magnetic properties, mechanical performance, hydrophilicity, and biocompatibility. Further investigations demonstrate that the PFM scaffold could precisely and remotely modulate macrophage polarization toward the M2 phenotype under a static magnetic field, significantly enhancing osteogenesis and angiogenesis. Proteomic analysis reveal that the scaffold upregulates Arg2 expression, enhancing mitochondrial function and accelerating oxidative phosphorylation, thereby inducing the M2 transition. In vivo experiments validated the scaffold's immune regulatory capacity in subcutaneous and cranial defect repairs in rats, effectively promoting new bone formation. Overall, this strategy of immune modulation targeting macrophage metabolism and mitochondrial function offers novel insights for material design in tissue engineering and regenerative medicine.

CaMKK2 Regulates Macrophage Polarization Induced by Matrix Stiffness: Implications for Shaping the Immune Response in Stiffened Tissues

Macrophages are essential for immune responses and maintaining tissue homeostasis, exhibiting a wide range of phenotypes depending on their microenvironment. The extracellular matrix (ECM) is a vital component that provides structural support and organization to tissues, with matrix stiffness acting as a key regulator of macrophage behavior. Using physiologically relevant 3D stiffening hydrogel models, it is found that increased matrix stiffness alone promoted macrophage polarization toward a pro-regenerative phenotype, mimicking the effect of interleukin-4(IL-4) in softer matrices. Blocking Calcium/calmodulin-dependent kinase kinase 2 (CaMKK2) selectively inhibited stiffness-induced macrophage polarization without affecting IL-4-driven pro-regenerative pathways. In functional studies, CaMKK2 deletion prevented M2-like/pro-tumoral polarization caused by matrix stiffening, which in turn hindered tumor growth. In a murine wound healing model, loss of CaMKK2 impaired matrix stiffness-mediated macrophage accumulation, ultimately disrupting vascularization. These findings highlight the critical role of CaMKK2 in the macrophage mechanosensitive fate determination and gene expression program, positioning this kinase as a promising therapeutic target to selectively modulate macrophage responses in pathologically stiff tissues.

Research progress of metal-CpG composite nanoadjuvants in tumor immunotherapy

The practical benefits and therapeutic potential of tumor vaccines in immunotherapy have drawn significant attention in the field of cancer treatment. Among the available vaccines, nanovaccines that utilize nanoparticles as carriers or adjuvants have demonstrated considerable effectiveness in combating cancer. Cytosine-phosphate-guanine oligodeoxynucleotide (CpG ODN), a common adjuvant in tumor nanovaccines, activates both humoral and cellular immunity by recognizing toll-like receptor 9 (TLR9), thereby aiding in the prevention and treatment of cancer. Metal nanoparticles hold great promise in tumor immunotherapy due to their adjustable size, surface functionalization, ability to regulate innate immunity, and capacity for controlled delivery of antigens or immunomodulators. Consequently, composite nanoadjuvants, formed by combining metal nanoparticles with CpG ODNs, can be customized to meet the specific performance requirements of different application scenarios, effectively overcoming the limitations of conventional immunotherapy approaches. This review provides a comprehensive analysis of the critical role of metal-CpG composite nanoadjuvants in advancing vaccine adjuvants for cancer therapy and prevention, highlighting their efficacy in preclinical settings.

Exosome-mediated effects of BRCA1 on cardiovascular artery disease

The progression of coronary artery disease atherosclerosis (CAD) is closely associated with cardiomyocyte apoptosis and inflammatory responses. This study focused on investigating the impact of BRCA1 in exosomes (Exo) derived from M1 macrophages on CAD. Through the analysis of single-cell RNA-seq datasets, significant communication between macrophages and cardiomyocytes in CAD patients was observed. BRCA1, identified as a significant apoptosis-related gene, was pinpointed through the assessment of differential gene expression and weighted gene co-expression network analysis (WGCNA). Experimental procedures involved BRCA1 lentivirus transfection of M1 macrophages, isolation of Exo for application to cardiomyocytes and smooth muscle cells, cell viability assessments, and characterization of Exo. The results showed that BRCA1-Exo from M1 macrophages induced cardiomyocyte apoptosis and affected smooth muscle cell behavior. In vivo studies further supported the exacerbating effects of BRCA1-Exo on CAD progression. Overall, the involvement of Exo carrying BRCA1 from M1 macrophages is evident in the induction of cardiomyocyte apoptosis and the regulation of smooth muscle cell behaviors, thereby contributing to CAD atherosclerosis progression. These findings unveil novel molecular targets that could have potential implications for CAD treatment strategies.

Recent Progress in Radiosensitive Nanomaterials for Radiotherapy-Triggered Drug Release

Benefiting from the unique properties of ionizing radiation, such as high tissue penetration, spatiotemporal resolution, and clinical relevance compared with other external stimuli, radiotherapy-induced drug release strategies are showing great promise in developing effective and personalized cancer treatments. However, the requirement of high doses of X-ray irradiation to break chemical bonds for drug release limits the application of radiotherapy-induced prodrug activation in clinics. Recent advances in nanomaterials offer a promising approach for radiotherapy sensitization as well as integrating multiple modalities for improved therapy outcomes. In particular, the catalytic radiosensitization that utilizes electrons and energy generated by nanomaterials upon X-ray irradiation has demonstrated excellent potential for enhanced radiotherapy. In this Review, we summarize the design principles of X-ray-responsive chemical bonds for controlled drug release, strategies for catalytic radiosensitization, and recent progress of X-ray-responsive nanoradiosensitizers for enhanced radiotherapy by integration with chemotherapy, chemodynamic therapy, photodynamic therapy, photothermal therapy, gas therapy, and immunotherapy. Finally, we discuss the challenges of X-ray-responsive nanoradiosensitizers heading toward possible clinical translation. We expect that emerging strategies based on radiotherapy-triggered drug release will facilitate a frontier in accurate and effective cancer therapy in the near future.

Controlled Release of Cold Atmospheric Plasma by Gelatin Scaffold Enhances Wound Healing via Macrophage Modulation

Cold atmospheric plasma (CAP) has emerged as a promising therapeutic tool for wound healing and tissue regeneration. However, the clinical application of CAP faces challenges, particularly the need for repeated treatments to maintain therapeutic efficacy and the difficulty in controlling the release of reactive oxygen and nitrogen species (ROS/RNS), which can cause tissue damage at high concentrations. In this study, we developed a controlled-release system by integrating CAP with a skin bionics gelatin scaffold (CAP-GS), enabling the sustained, localized release of CAP without the need for repeated applications. Our results demonstrate that CAP-GS significantly accelerates skin wound healing by modulating the immune microenvironment and reducing inflammation. The gelatin scaffold effectively regulates the release of ROS/RNS, maintaining levels conducive to M2 macrophage polarization and minimizing oxidative damage. Furthermore, CAP-GS enhances macrophage metabolism, including oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO), metabolic pathways characteristic of M2 polarization. The increased secretion of growth factors by CAP-GS-treated macrophages contributes to cell proliferation, migration, and tissue regeneration. These findings highlight CAP-GS as a promising, clinically applicable system for wound healing and tissue repair, overcoming the limitations of traditional CAP treatments and offering an approach to regenerative medicine.

Metal-Phenolic Modified Coaxial Electrospun Biomembrane Combined with the Photothermal Effect Enhances Bone Regeneration by Ameliorating Oxidative Stress and Mitochondrial Dysfunction via the PI3K/Akt Signaling Pathway

Critical-sized bone defect regeneration remains a significant clinical challenge due to the complex cascade of biological processes involved. To address this, we developed a sophisticated hierarchical biomembrane (PCS@MPN10) designed to modulate the osteogenic microenvironment. Using coaxial electrospinning, we fabricated a core-shell structure with polylactic acid (PLA) as the membrane base, incorporating simvastatin in the core and chitosan in the shell. The membrane surface was further modified with a tannic acid-iron metal-polyphenol network coating. Our results demonstrated that the biomembrane exhibits excellent biocompatibility, photothermal properties, and significant antibacterial activity. Additionally, the membrane regulates the microenvironment by promoting M1-to-M2 macrophage polarization, showing strong osteogenic potential both in vitro and in vivo. Furthermore, PCS@MPN10+NIR modulates mitochondrial function through the PI3K-AKT pathway, clears mitochondrial reactive oxygen species (ROS), and alleviates cellular oxidative stress, thereby enhancing bone regeneration. Overall, these findings suggest that this biomembrane holds great promise as a strategy for improving bone regeneration in critical-sized defects.

Regulation of immune microenvironments by polyetheretherketone surface topography for improving osseointegration

Optimizing the immune microenvironment is essential for successful implant osseointegration. In this study, four different nano/microstructures were fabricated on polyetheretherketone (PEEK) substrates by varying the agitation speed during sulfonation to influence osteoimmunomodulation and implant integration. The results indicate that nano/microstructures with minimal dimensions (SP450) inhibit actin polymerization by reducing calcium influx through PIEZO1, activating the anti-inflammatory M2 macrophage phenotype. Among the tested specimens, SP450 exhibited the lowest expression levels of tumor necrosis factor-α and interleukin-1β while releasing the highest levels of anti-inflammatory factors, including interleukin-4 and interleukin-10. This optimized immune environment promotes the osteogenesis of MC3T3-E1 pre-osteoblasts and enhances the osseointegration of PEEK implants. Transcriptomic analysis and validation experiment further revealed that SP450 inhibits osteoclastic differentiation by down-regulating transforming growth factor-β2 and suppressing the NF-κB signaling pathway. These findings suggest that manipulating the surface topography of PEEK implants is an effective strategy for enhancing osseointegration with promising clinical applications.

Chirality Regulates Bone Regeneration through Mechanoresponse and Immunoregulation

As an omnipresent occurrence in the natural world, chirality plays a crucial role in numerous biological and physiological processes. Therefore, incorporation of chirality into biointerface materials has been emerging as a research hotspot in the development of regenerative biomaterials. Nevertheless, how chiral biointerface materials interact with biological organisms remains poorly understood. In the current study, a bioinspired chiral self-assembled nanohydroxyapatite material is developed for bone regeneration using a distraction osteogenesis model. We found that the left-handed chirality, rather than the right-handed chirality, possessed the greatest heightened ability for bone regeneration. Molecular mechanism research reveals that the left-handed chirality can activate mechanosensitive pathways to promote Ca2+ influx, subsequently enhancing macrophage type-2 polarization through phosphorylation of signal transducer and activator of transcription (STAT6), which eventually stimulates bone regeneration by harnessing the synergistic effects of angiogenesis and osteogenesis. These findings provide additional insights into the underlying mechanism of chiral recognition between biological systems and biointerface materials, offering alternative pathways for the development of biomaterials.

Strategies for promoting neurovascularization in bone regeneration

Bone tissue relies on the intricate interplay between blood vessels and nerve fibers, both are essential for many physiological and pathological processes of the skeletal system. Blood vessels provide the necessary oxygen and nutrients to nerve and bone tissues, and remove metabolic waste. Concomitantly, nerve fibers precede blood vessels during growth, promote vascularization, and influence bone cells by secreting neurotransmitters to stimulate osteogenesis. Despite the critical roles of both components, current biomaterials generally focus on enhancing intraosseous blood vessel repair, while often neglecting the contribution of nerves. Understanding the distribution and main functions of blood vessels and nerve fibers in bone is crucial for developing effective biomaterials for bone tissue engineering. This review first explores the anatomy of intraosseous blood vessels and nerve fibers, highlighting their vital roles in bone embryonic development, metabolism, and repair. It covers innovative bone regeneration strategies directed at accelerating the intrabony neurovascular system over the past 10 years. The issues covered included material properties (stiffness, surface topography, pore structures, conductivity, and piezoelectricity) and acellular biological factors [neurotrophins, peptides, ribonucleic acids (RNAs), inorganic ions, and exosomes]. Major challenges encountered by neurovascularized materials during their clinical translation have also been highlighted. Furthermore, the review discusses future research directions and potential developments aimed at producing bone repair materials that more accurately mimic the natural healing processes of bone tissue. This review will serve as a valuable reference for researchers and clinicians in developing novel neurovascularized biomaterials and accelerating their translation into clinical practice. By bridging the gap between experimental research and practical application, these advancements have the potential to transform the treatment of bone defects and significantly improve the quality of life for patients with bone-related conditions.

Whole-Component Antigen Nanovaccines Combined With aTIGIT for Enhanced Innate and Adaptive Anti-tumor Immunity

Using entire tumor cells or tissues that display both common and patient-specific antigens can potentially trigger a comprehensive and long-lasting anti-tumor immune response. However, the limited immunogenicity, low uptake efficiency, and susceptibility to degradation of whole-component antigens present significant challenges. In this study, we employed tumor lysates (TLs) as whole-component antigens, in conjunction with MgAl-layered double hydroxide (MA) as nanoadjuvants and Mn2+ as immunostimulants, to create personalized MMAT (Mn2+-MA-TLs) nanovaccines. After subcutaneous injection of MMAT nanovaccines, the high local concentrations of TLs and Mn2+ facilitated the recruitment and activation of antigen-presenting cells (APCs), thereby inducing a robust adaptive immune response. Remarkably, MMAT nanovaccines enabled lysosomal escape, enhanced antigen cross-presentation, and activated the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway in APCs. Furthermore, MMAT nanovaccines, when combined with the anti-TIGIT monoclonal antibody (aTIGIT), an immune checkpoint inhibitor, not only stimulated T-cell-based adaptive anti-tumor immune responses but also activated the NK-cell-based innate anti-tumor immunity, effectively suppressing tumor growth, recurrence, and metastasis. Thus, the ternary MMAT nanovaccines developed here introduced a pioneered paradigm for the rapid preparation of whole-component tumor antigens with nanoadjuvants and immunostimulants into nanovaccines, offering new prospects for clinical immunotherapies.

Accelerating repair of infected bone defects through post-reinforced injectable hydrogel mediated antibacterial/immunoregulatory microenvironment at bone-hydrogel interface

Functional injectable hydrogel (IH) is promising for infected bone defects (IBDs) repair, but how to endow it with desired antibacterial/immunoregulatory functions as well as avoid mechanical failures during its manipulation has posed as main challenges. Herein, rosmarinic acid (RosA), a natural product with antibacterial/immunoregulatory activities, was utilized to develop a FCR IH through forming phenylboronic acid ester bonds with 4-formylphenyl phenylboronic acid (4-FPBA) grafted chitosan (CS) (FC). After being applied to the IBD site, the FCR IH was then injected with tobramycin (Tob) solution, another alkaline antibacterial drug, to induce in situ crystallization of the FC, endowing the resultant FCRT hydrogel with adaptively enhanced mechanical strength and structural stability. Owing to the specific structural composition, the FCRT hydrogel could sustainedly release Tob and RosA molecules at the IBD interface, effectively eliminating in situ bacterial infection. In addition, the released RosA molecules also induced the M2 polarization of in situ macrophages (Mφ), which was identified to be related to the NF-κB and PI3K-AKT pathways, therefore promoting the osteogenic differentiation of in situ bone marrow stromal cells (BMSCs). Due to the simultaneous antibacterial/osteo-immunoregulatory microenvironment at the IBD interface, the repair of IBDs was proved to be greatly accelerated by the FCRT hydrogel.

Biomaterial Surface-Mediated Macrophages Exert Immunomodulatory Roles by Exosomal CCL2-Induced Membrane Integrin β1 Trafficking in Recipient Cells

The interaction between biomaterials and immune system is a critical area of research, especially in tissue engineering and regenerative medicine. A fascinating and less explored aspect involves the immunomodulatory behaviors of macrophage (MΦ)-derived exosomes induced by biomaterial surfaces. Herein, untreated surface, nanostructured surface, and type I collagen (Col-I)-decorated nanostructured surface of titanium implants are chosen to culture MΦs, followed by extraction of MΦ-derived exosomes and investigation of their immunomodulatory functions and mechanisms. The results show that the exosomes in the untreated group carried plenty of inflammatory cytokines, predominantly C─C motif chemokine ligand 2 (CCL2). After targeting recipient cells, the CCL2 on the exosomes can specifically bind to its receptor C─C motif chemokine receptor 2, triggering downstream signaling pathways to induce internalization of membrane integrin β1 and targeted lysosomal degradation, consequently suppressing the functions of recipient cells. In contrast, the exosomes in the nanostructured group, especially Col-I-decorated nanostructured group carried few CCL2, moderating their inhibition on the functions of recipient cells. These findings not only clearly show that CCL2 is a key constituent of exosomes involved in the interaction between biomaterials and host immune system, but also potentially a key target for designing advanced biomaterials to promote tissue repair and regeneration.

Recent progress in cancer vaccines and nanovaccines

Vaccine science, nanotechnology, and immunotherapy are at the forefront of cancer treatment strategies, each offering significant potential for enhancing tumor-specific immunity and establishing long-lasting immune memory to prevent tumor recurrence. Despite the promise of these personalized and precision-based anti-cancer approaches, challenges such as immunosuppression, suboptimal immune activation, and T-cell exhaustion continue to hinder their effectiveness. The limited clinical success of cancer vaccines often stems from difficulties in identifying effective antigens, efficiently targeting immune cells, lymphoid organs, and the tumor microenvironment, overcoming immune evasion, enhancing immunogenicity, and avoiding lysosomal degradation. However, numerous studies have demonstrated that integrating nanotechnology with immunotherapeutic strategies in vaccine development can overcome these challenges, leading to potent antitumor immune responses and significant progress in the field. This review highlights the critical components of cancer vaccine and nanovaccine strategies for immunomodulatory antitumor therapy. It covers general vaccine strategies, types of vaccines, antigen forms, nanovaccine platforms, challenges faced, potential solutions, and key findings from preclinical and clinical studies, along with future perspectives. To fully unlock the potential of cancer vaccines and nanovaccines, precise immunological monitoring during early-phase trials is essential. This approach will help identify and address obstacles, ultimately expanding the available options for patients who are resistant to conventional cancer immunotherapies.

Ligand Inter-Relation Analysis Via Graph Theory Predicts Macrophage Response

Graph theory has been widely used to quantitatively analyze complex networks of molecules, materials, and cells. Analyzing the dynamic complex structure of extracellular matrix can predict cell-material interactions but has not yet been demonstrated. In this study, graph theory-based mathematical modeling of RGD ligand graph inter-relation is demonstrated by differentially cutting off RGD-to-RGD interlinkages with flexibly conjugated magnetic nanobars (MNBs) with tunable aspect ratio. The RGD-to-RGD interlinkages are less effectively cut off by MNBs with a lower aspect ratio, which decreases the shortest path while increasing the number of instances thereof, thereby augmenting RGD nano inter-relation. This facilitates integrin recruitment of macrophages and thus actin fiber assembly and vinculin expression, which mediates pro-regenerative polarization, involving myosin II, actin polymerization, and rho-associated protein kinase. Unidirectional pre-aligning or reversibly lifting highly elongated MNBs both increase RGD nano inter-relation, which promotes host macrophage adhesion and switches their polarization from pro-inflammatory to pro-regenerative phenotype. The latter approach produces nano-spaces through which macrophages can penetrate and establish RGD links thereunder. Using graph theory, this study presents the example of mathematically modeling the functionality of extracellular-matrix-mimetic materials, which can help elucidate complex dynamics of the interactions occurring between host cells and materials via versatile geometrical nano-engineering.

Eu-Doped TiO2 Coatings via One-Step In Situ Preparation Enhance Macrophage Polarization and Osseointegration of Implants

The controllable regulation of immune and osteogenic processes plays a critical role in the modification of biocompatible materials for tissue regeneration. In this study, titanium dioxide-europium coatings (MAO/Eu) were prepared on the surface of a titanium alloy (Ti-6Al-4V) via a one-step process combining microarc oxidation (MAO) and in situ doping. The incorporation of Eu significantly improved the hydrophilic and mechanical properties of the TiO2 coatings without altering their morphology. The presence of Eu effectively stimulated calcium influx in macrophages and activated β-catenin through the wnt/β-catenin signaling pathway. Consequently, macrophage M2 polarization was accelerated through the overexpression of prostaglandin E2 (PGE2). Additionally, Ca2+ promoted the osteogenic differentiation of MC3T3-E1 cells through the synergistic upregulation of transcription factors (e.g., AP-1, BMP-2). In vivo studies demonstrated that MAO/Eu coatings significantly enhanced osseointegration compared with the titanium alloy group. Therefore, MAO/Eu shows promising potential as an ideal coating for implants that offers effective immunomodulatory strategies and improves bone integration.

Functional Nanosheet Immunoswitches Reprogramming Innate Macrophages for Immunotherapy of Colorectal Cancer and Sepsis

Macrophages are involved in the immunopathogenesis of cancer and inflammatory diseases and are a primary target for immunotherapy to reprogram the M1 and M2 phenotypes in tumor and inflammatory microenvironments. Herein, functional nanosheet immunoswitches that can bidirectionally polarize macrophages in tumor and inflammatory microenvironments are designed for effective immunotherapy of colorectal cancer and sepsis. WSe2 nanosheets are functionalized with palmitic acid to obtain an M1 immunoswitch (PA-WSe2) that promotes the polarization of macrophages toward the M1 phenotype in the tumor microenvironment by activating the STAT1 signaling pathway. WS2 nanosheets bearing linoleic acid are synthesized as an M2 immunoswitch (LA-WS2) that effectively polarizes macrophages to the M2 phenotype in the septic microenvironment by activating the STAT3 signaling pathway. The PA-WSe2 M1 immunoswitch upregulates the secretion of pro-inflammatory cytokines and reactive oxygen and nitrogen species (ROS and RNS) via M1 polarization, leading to the effective immunotherapy for colorectal cancer in vivo. In contrast, the LA-WS2 M2 immunoswitch induces the elevated production of anti-inflammatory cytokines and scavenging of ROS and RNS through M2 polarization, resulting in superior immunotherapy for severe sepsis in mice. These nanosheet immunoswitches can provide a route to immunotherapy for various cancers and inflammatory diseases.

Cytokine mRNA Delivery and Local Immunomodulation in the Placenta using Lipid Nanoparticles

During pregnancy, the maternal immune system adapts to balance tolerance of the semi-allogenic fetus while protecting the fetus from pathogens. Dysregulated immune activity at the maternal-fetal interface contributes to pregnancy complications, such as recurrent pregnancy loss and preeclampsia. Compared to healthy placentas, preeclamptic placentas exhibit increased pro-inflammatory signaling, including a predominance of inflammatory macrophages, leading to impaired tissue remodeling and restricted blood flow. However, the precise mechanisms driving this immune imbalance remain poorly understood, in part due to the lack of tools to probe individual pathways. Here, we use lipid nanoparticles (LNPs) to deliver cytokine-encoded mRNA to placental cells, called trophoblasts, enabling local immunomodulation. LNP-mediated delivery of IL-4 and IL-13 mRNA induced cytokine secretion by trophoblasts, leading to polarization of primary human monocytes toward anti-inflammatory phenotypes. Notably, lowering the mRNA dose increased expression of alternatively-activated macrophage markers, revealing an inverse relationship between dose and polarization status. Intravenous injection of LNPs in pregnant mice achieved placental secretion of IL-4 and IL-13 with minimal changes to pro-inflammatory cytokines in the serum. These findings establish LNPs as a tool for local immunomodulation in the placenta, offering a strategy to study and treat immune dysfunction in pregnancy and in other inflammatory conditions.

Effect of 3D-Printed Polycaprolactone Scaffold With Powdery/Smooth Micromorphology on Local Immune Environments

Selective laser sintering (SLS) has become a viable approach for producing biodegradable medical implants in various clinical applications. The resulting scaffolds typically exhibit a powdery microstructure, which may potentially impact the behavior of immune cells and immune responses in surrounding tissues. However, limited research has been conducted to understand the effect of surface morphology in SLS-fabricated scaffolds on local immune environments. This study aims to compare the effect of SLS-fabricated polycaprolactone (PCL) scaffolds with powdery and smooth surface morphologies on immune-related biological responses. Compared with those on the powdery micromorphology, RAW264.7 macrophages displayed greater dispersion and adopted a spread and elongated morphology on the scaffolds with smooth surface. The expression levels of arginase-1 and CD206 were found to be upregulated in macrophages adhering to the PCL scaffolds with smooth surface, accompanied by an augmented secretion of anti-inflammatory cytokines TGF-β and IL-10. Conversely, there was a decrease in the secretion of pro-inflammatory cytokines TNF-α and IL-12. When implanted in vivo, the SLS-derived scaffolds were completely covered by host tissues, Withing increased collagen deposition, indicating good histocompatibility. At 1-week post-implantation, there was a significantly higher presence of M2-type macrophages surrounding the scaffold compared to M1 macrophages in both groups. By 3 weeks post-implantation, the overall level of macrophages had decreased in both groups. However, a significant higher level of M1 macrophages were observed in the powdery scaffold group. At the same time, the number of neutrophils around the powder scaffold increased significantly, demonstrating long-term local inflammatory responses. The results suggested that post-treated scaffolds with smooth surfaces can effectively reduce local inflammation, making them more suitable for clinical implantation.

Noninvasive in vivo imaging of macrophages: understanding tumor microenvironments and delivery of therapeutics

Macrophages are pivotal in the body's defense and response to inflammation. They are present in significant numbers and are widely implicated in various diseases, including cancer. While molecular and histological techniques have advanced our understanding of macrophage biology, their precise function within the cancerous microenvironments remains underexplored. Enhancing our knowledge of macrophages and the dynamics of their extracellular vesicles (EVs) in cancer development can potentially improve therapeutic management. Notably, macrophages have also been harnessed to deliver drugs. Noninvasive in vivo molecular imaging of macrophages is crucial for investigating intricate cellular processes, comprehending the underlying mechanisms of diseases, tracking cells and EVs' migration, and devising macrophage-dependent drug-delivery systems in living organisms. Thus, in vivo imaging of macrophages has become an indispensable tool in biomedical research. The integration of multimodal imaging approaches and the continued development of novel contrast agents hold promise for overcoming current limitations and expanding the applications of macrophage imaging. This study comprehensively reviews several methods for labeling macrophages and various imaging modalities, assessing the merits and drawbacks of each approach. The review concludes by offering insights into the applicability of molecular imaging techniques for real time monitoring of macrophages in preclinical and clinical scenarios.

Chitosan immunomodulation: insights into mechanisms of action on immune cells and signaling pathways

Chitosan, a biodegradable and biocompatible natural polymer composed of β-(1-4)-linked N-acetyl glucosamine (GlcNAc) and d-glucosamine (GlcN) and derived from crustacean shells, has been widely studied for various biomedical applications, including drug delivery, cartilage repair, wound healing, and tissue engineering, because of its unique physicochemical properties. One of the most promising areas of research is the investigation of the immunomodulatory properties of chitosan, since the biopolymer has been shown to modulate the maturation, activation, cytokine production, and polarization of dendritic cells and macrophages, two key immune cells involved in the initiation and regulation of innate and adaptive immune responses, leading to enhanced immune responses. Several signaling pathways, including the cGAS-STING, STAT-1, and NLRP3 inflammasomes, are involved in chitosan-induced immunomodulation. This review provides a comprehensive overview of the current understanding of the in vitro immunomodulatory effects of chitosan. This information may facilitate the development of chitosan-based therapies and vaccine adjuvants for various immune-related diseases.

Spatial distribution-based progression of spinal cord injury pathology: a key role for neuroimmune cells

An external trauma, illness, or other pathological cause can harm the structure and function of the spinal cord, resulting in a significant neurological disorder known as spinal cord injury (SCI). In addition to impairing movement and sensory functions, spinal cord injury (SCI) triggers complex pathophysiological responses, with the spatial dynamics of immune cells playing a key role. The inflammatory response and subsequent healing processes following SCI are profoundly influenced by the spatial distribution and movement of immune cells. Despite significant advances in both scientific and clinical research, SCI therapy still faces several challenges. These challenges primarily stem from our limited understanding of the spatial dynamics of immune cell distribution and the processes that regulate their interactions within the microenvironment following injury. Therefore, a comprehensive investigation into the spatial dynamics of immune cells following SCI is essential to uncover their mechanisms in neuroinflammation and repair, and to develop novel therapeutic strategies.

Titanium nanotubes modulate immunophenotyping and cytokine secretion of T cells via IL-17A: a bioinformatic analysis and experimental validation

Object

We aim to explore the immunomodulatory properties of T cells on different titanium nanotubes and the key immunological factors involved in this process.

Methods

Transcriptome data from GEO database of healthy people and healthy implants were used to analyze cell infiltration and factor distribution of adaptive immune using bioinformatics tools. T cells from activated rat were cultured on titanium nanotubes that were prepared by anodization with different diameters (P-0, NT15-30 nm, NT40-100 nm, NT70-200 nm). The proliferation and expressions of the main transcription factors and cytokines of T-cells were detected. Magnetic bead sorting of CD3+ T cells and transcriptome sequencing were performed to explore the signaling pathways and key immune factors that may influence the related immune responses.

Results

Bioinformatics analysis showed that healthy peri-implant tissues were enriched by the most of T-cell subtypes. T-cell-mediated adaptive immunological responses involved IL-17A. On the third day, the NT15 and NT40 groups showed significantly higher pro-proliferative effects than the NT70 group (P<0.05). Notably, the NT40 group exhibited the lowest T-bet expression (P<0.05) along with the highest levels of Rorγt, Gata3, and Foxp3(P<0.05), followed by the NT15 group. Additionally, the NT40 group demonstrated reduced RANKL, TNF-α, and IL-6 (P<0.05) and increased OPG and IL-10 (P<0.05). Meanwhile, the NT15 group had lower IFN-γ expression(P>0.05) but higher IL-4, and TGF-β1 expressions(P<0.05). Differential expressed genes (DGEs) of T-cell related to the morphologies of titanium nanotubes were mostly enriched in the IL-17 signaling pathway mediated by IL-17A/F. Gene and protein expressions indicated that the NT40 group had the highest secretion in IL-17A of T cells.

Conclusion

Titanium nanotube morphologies in medium (100 nm) and small (30 nm) sizes significantly influence T cell differentiation and immune factor secretion, with T-cell-derived IL-17A likely playing a key regulatory role.

Nanosystems for modulation of immune responses in periodontal therapy: a mini-review

Periodontitis is one of the most common oral diseases. It is generally treated by non-surgical and/or surgical therapy with adjunctive approaches for prevention and control. The current understanding of the pathogenesis of periodontitis has unraveled the importance of the inflammatory and immune reactions to combat periodontitis whose etiology is an overlap of microbial, genetic, and environmental factors in a susceptible host. Based on this premise, many therapeutic modalities have been investigated or attempted to resolve this inflammatory disease. Amongst these, nanomedicine has been shown to have therapeutic applications in periodontitis, especially focused on immunomodulation because periodontitis is characterized by over-reactive immune response. This mini-review explores the potential of nanosystems in treating periodontitis by providing an overview of the research efforts in this field of therapeutics. The unique physicochemical and targeting properties of nanosystems seem to be potentially effective platforms for treating periodontitis.

Remodel Heterogeneous Electrical Microenvironment at Nano-Scale Interface Optimizes Osteogenesis by Coupling of Immunomodulation and Angiogenesis

Immunomodulation is essential for implants to regulate tissue regeneration, while bioelectricity plays a fundamental role in regulating immune activities. Under natural preferences, the bone matrix electrical microenvironment is heterogeneous in the nanoscale, which provides fundamental electrical cues to regulate bone immunity and regenerative repair. However, remodeling bone nanoscale heterogeneous electrical microenvironment remains a challenge, and the underlying immune modulation mechanism remains to be explored. In this research, in situ discretely distributed nano-heterojunctions are constructed on titanium oxide nanofibers to mimic the heterogeneous electrical microenvironment exhibited by bone collagen fibers. The material is identified to directly regulate calcium ion channeling for anti-inflammatory polarization of macrophages. Surprisingly, the highly biomimetic heterogeneous electrical microenvironment can induce a pro-angiogenic phenotypic transformation of macrophages, leading to enhanced neo-vascularization at the early stage of osteogenesis. Mechanistic exploration identifies that PI3K signaling pathway-mediated FGF2 secretion may partially explain for strengthened coupling of immunomodulation and angiogenesis, which optimizes subsequent bone regeneration. These findings highlight the significance of biomimetic heterogeneous electrical cues on immune-modulation and provide a design principle for future electroactive implant materials.

Granular Nanofiber-Hydrogel Composite-Programmed Regenerative Inflammation and Adipose Tissue Formation

The interplay between biomaterials and host immune responses critically determines outcomes in tissue restoration. Recent studies suggest that physicochemical properties of materials can dictate pro-regenerative versus pro-fibrotic responses and have begun to define the key immune cell types and signals governing these divergent effects. This emerging understanding enables the engineering of regenerative biomaterials capable of functional restoration in situ. An injectable nanofiber-hydrogel composite (NHC) microparticles are designed and constructed from cross-linked electrospun collagen nanofiber fragments surface-bonded to the hyaluronic acid hydrogel network via covalent conjugation during the cross-linking process. The collagen nanofiber fragments, acting as the structural reinforcement component, increased the overall storage modulus of the NHC to a level comparable to native soft tissues while maintaining a sufficiently high degree of porosity of the hydrogel phase to allow host cell infiltration following subcutaneous injection of the NHC microparticles. More importantly, the NHC promoted macrophage/monocyte infiltration, migration, and spreading, sustained cell recruitment over time, and enhanced the proangiogenic effect and recruitment of PDGFRα+ perivascular progenitor cells, leading to extensive adipose tissue remodeling. This study demonstrates the regenerative potential of the injectable NHC microgels as an off-the-shelf solution for devastating soft tissue losses.

Biomolecule and Ion Releasing Mesoporous Nanoparticles: Nonconvergent Osteogenic and Osteo-immunogenic Performance

Immune-involved cell communications have recently been introduced as key role players in the fate of mesenchymal stem cells in making bone tissue. In this study, a drug delivery system for bone (re)generation based on copper-doped mesoporous bioactive glass nanoparticles (BGNPs) was developed to codeliver copper as a biologically active ion and icariin as an anti-inflammatory agent. This design was based on temporal inflammation fluctuations from proinflammatory to anti-inflammatory during bone generation. Three in vitro models were performed with human mesenchymal stem cells (hMSCs) to verify the osteo-immunomodulatory effects of released copper ions and icariin: nonstimulated, co-conditioned with macrophage medium and co-cultured with macrophages. Both icariin and copper showed increased levels of alkaline phosphatase activation, indicating a direct osteogenic effect. Copper-doped BGNPs showed the highest increase of osteo-immunogenic properties in a mineralization assay and also induced short-term inflammation. However, the mineralization dropped in copper doped BGNPs after loading with icariin due to copper-icariin chelate formation and inhibition of the early inflammatory phase in the immune-stimulated in vitro models. In the absence of copper, the direct osteogenic properties of icariin overtook its osteo-immunogenic inhibition and increased calcification. Overall, BGNPs doped with 5 mol % copper and no icariin showed the highest bone-forming capacity.

Harnessing Nanotechnology for Gout Therapy: Colchicine-Loaded Nanoparticles Regulate Macrophage Polarization and Reduce Inflammation

Gout is a disease caused by hyperuricemia, characterized by inflammation reactions triggered by macrophage polarization. Colchicine is a commonly used drug for gout treatment, but its mechanism of action remains unclear. The aim of this study was to investigate the regulatory effect of colchicine on macrophage polarization to enhance the therapeutic effectiveness against gout inflammation. To accomplish this, a mouse model was established, and peripheral blood mononuclear cell samples were collected. Single-cell RNA sequencing was employed to reveal cellular heterogeneity and identify key genes. Molecular docking and experimental validation were performed to confirm the binding between the key genes and colchicine. Lentiviral intervention and biochemical indicator detection were conducted to assess the impact of key genes on gout mice. Additionally, the therapeutic effect of colchicine incorporated into neutrophil membrane-coated nanoparticles was investigated. The study found that macrophage polarization plays a critical role in gout, and AHNAK was identified as the key gene through which colchicine affects macrophage polarization. Lentiviral intervention to decrease AHNAK expression was shown to alleviate joint swelling in gout mice and regulate macrophage polarization. Colchicine encapsulated in R4F peptide-modified neutrophil membrane-coated Pluronic F127 nanoparticle (R4F-NM@F127) nanocarriers inhibited M1 macrophage polarization, induced M2 macrophage polarization, alleviated gout, and minimized toxicity to normal tissues. Colchicine suppressed M1 macrophage polarization and induced M2 macrophage polarization by binding to AHNAK protein, thereby alleviating gout. Colchicine incorporated into R4F-NM@F127 nanocarriers can serve as a targeted therapeutic drug to regulate macrophage polarization, alleviate gout, and reduce toxicity to normal tissues.