Macrophages as Active Nanocarriers for Targeted Early and Adjuvant Cancer Chemotherapy

Macrophage based drug delivery: Key challenges and strategies

As a natural immune cell and antigen presenting cell, macrophages have been studied and engineered to treat human diseases. Macrophages are well-suited for use as drug carriers because of their biological characteristics, such as excellent biocompatibility, long circulation, intrinsic inflammatory homing and phagocytosis. Meanwhile, macrophages' uniquely high plasticity and easy re-education polarization facilitates their use as part of efficacious therapeutics for the treatment of inflammatory diseases or tumors. Although recent studies have demonstrated promising advances in macrophage-based drug delivery, several challenges currently hinder further improvement of therapeutic effect and clinical application. This article focuses on the main challenges of utilizing macrophage-based drug delivery, from the selection of macrophage sources, drug loading, and maintenance of macrophage phenotypes, to drug migration and release at target sites. In addition, corresponding strategies and insights related to these challenges are described. Finally, we also provide perspective on shortcomings on the road to clinical translation and production.

Macrophage membrane-camouflaged nanoclusters of ultrasmall iron oxide nanoparticles for precision glioma theranostics

Developing effective nanomedicines to cross the blood-brain barrier (BBB) for efficient glioma theranostics is still considered to be a challenging task. Here, we describe the development of macrophage membrane (MM)-coated nanoclusters (NCs) of ultrasmall iron oxide nanoparticles (USIO NPs) with dual pH- and reactive oxygen species (ROS)-responsivenesses for magnetic resonance (MR) imaging and chemotherapy/chemodynamic therapy (CDT) of orthotopic glioma. Surface citrate-stabilized USIO NPs were solvothermally synthesized, sequentially modified with ethylenediamine and phenylboronic acid, and cross-linked with gossypol to form gossypol-USIO NCs (G-USIO NCs), which were further coated with MMs. The prepared MM-coated G-USIO NCs (G-USIO@MM NCs) with a mean size of 99.9 nm display tumor microenvironment (TME)-responsive gossypol and Fe release to promote intracellular ROS production and glutathione consumption. With the MM-mediated BBB crossing and glioma targeting, the G-USIO@MM NCs can specifically inhibit orthotopic glioma in vivo through the gossypol-mediated chemotherapy and Fe-mediated CDT. Meanwhile, USIO NPs can be dissociated from the NCs under the TME, thus allowing for effective T1-weighted glioma MR imaging. The developed G-USIO@MM NCs with simple components and drug as a crosslinker are promising for glioma theranostics, and may be extended to tackle other cancer types.

The clinical regimens and cell membrane camouflaged nanodrug delivery systems in hematologic malignancies treatment

Hematologic malignancies (HMs), also referred to as hematological or blood cancers, pose significant threats to patients as they impact the blood, bone marrow, and lymphatic system. Despite significant clinical strategies using chemotherapy, radiotherapy, stem cell transplantation, targeted molecular therapy, or immunotherapy, the five-year overall survival of patients with HMs is still low. Fortunately, recent studies demonstrate that the nanodrug delivery system holds the potential to address these challenges and foster effective anti-HMs with precise treatment. In particular, cell membrane camouflaged nanodrug offers enhanced drug targeting, reduced toxicity and side effects, and/or improved immune response to HMs. This review firstly introduces the merits and demerits of clinical strategies in HMs treatment, and then summarizes the types, advantages, and disadvantages of current nanocarriers helping drug delivery in HMs treatment. Furthermore, the types, functions, and mechanisms of cell membrane fragments that help nanodrugs specifically targeted to and accumulate in HM lesions are introduced in detail. Finally, suggestions are given about their clinical translation and future designs on the surface of nanodrugs with multiple functions to improve therapeutic efficiency for cancers.

Current advances in modulating tumor hypoxia for enhanced therapeutic efficacy

Hypoxia is a common feature of most solid tumors, which promotes the proliferation, invasion, metastasis, and therapeutic resistance of tumors. Researchers have been developing advanced strategies and nanoplatforms to modulate tumor hypoxia to enhance therapeutic effects. A timely review of this rapidly developing research topic is therefore highly desirable. For this purpose, this review first introduces the impact of hypoxia on tumor development and therapeutic resistance in detail. Current developments in the construction of various nanoplatforms to enhance tumor treatment in response to hypoxia are also systematically summarized, including hypoxia-overcoming, hypoxia-exploiting, and hypoxia-disregarding strategies. We provide a detailed discussion of the rationale and research progress of these strategies. Through a review of current trends, it is hoped that this comprehensive overview can provide new prospects for clinical application in tumor treatment. STATEMENT OF SIGNIFICANCE: As a common feature of most solid tumors, hypoxia significantly promotes tumor progression. Advanced nanoplatforms have been developed to modulate tumor hypoxia to enhanced therapeutic effects. In this review, we first introduce the impact of hypoxia on tumor progression. Current developments in the construction of various nanoplatforms to enhance tumor treatment in response to hypoxia are systematically summarized, including hypoxia-overcoming, hypoxia-exploiting, and hypoxia-disregarding strategies. We discuss the rationale and research progress of the above strategies in detail, and finally introduce future challenges for treatment of hypoxic tumors. By reviewing the current trends, this comprehensive overview can provide new prospects for clinical translatable tumor therapy.

Inflammation-Driven Nanohitchhiker Enhances Postoperative Immunotherapy by Alleviating Prostaglandin E2-Mediated Immunosuppression

Inflammation contributes to the immunosuppressive microenvironment and leads to the recurrence of surgically resected tumors. The COX-2/PGE2 axis is considered a key player in shaping the immunosuppression microenvironment. However, targeted modulation of the postoperative tumor microenvironment is challenging. To specifically curb the inflammation and alleviate immunosuppression, here, we developed a PGE2 inhibitor celecoxib (CXB)-loaded bionic nanoparticle (CP@CM) coated with activated murine vascular endothelial cell (C166 cells) membrane to target postoperative melanoma and inhibit its recurrence. CP@CM adhered to inflammatory white blood cells (WBCs) through the adhesion molecules, including ICAM-1, VCAM-1, E-selectin, and P-selection, expressed on the surface of C166 cells. Leveraging the natural tropism of the WBC to the inflammatory postoperative tumor site, CP@CM efficiently targeted postoperative tumors. In melanoma postoperative recurrence models, CXB significantly reduced PGE2 secretion and the recruitment of immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Treg) by inhibiting the activity of COX-2. This was followed by an increase in the infiltration of CD8+ T cells and CD4+ T cells in tumor tissues. Additionally, the immune responses were further enhanced by combining a PD-L1 monoclonal antibody. Ultimately, this immunotherapeutic strategy reversed the tumor immunosuppressive microenvironment and inhibited tumor recurrence, demonstrating a promising potential for postoperative immunotherapy for melanoma.

Reactive oxygen species-responsive polyprodrug micelles deliver cell cycle regulators for chemosensitization

Combination chemotherapy is a common strategy to enhance treatment efficacy and avoid multidrug resistance (MDR) in clinical practice. However, it is difficult to ensure the co-enrichment and reasonable ratio of synergistic drugs in the lesion site after intravenous administration. Integrating synergistic drugs into a nanocarrier can improve drug stability, targeting, drug loading, and importantly, ensure that synergistic drugs work at one destination. This study uses 10-hydroxycamptothecin (HCPT) to construct a polymeric prodrug micelle, and the demethylcantharidin (DMC) is proportionally encapsulated within the micelle. Triggered by reactive oxygen species (ROS), HCPT and DMC were released simultaneously from the co-delivery platform in tumor cells. DMC promotes abnormal cell division by inhibiting the synthesis of the cell cycle checkpoint kinase Protein phosphatase 2A (PP2A), leading to increased cell vulnerability to DNA damage, disordered replication, and death. The co-delivery platform exhibited satisfactory biosafety and antitumor efficacy in vivo. The proposed co-delivery platform may provide a valuable reference for the translation of clinical combination chemotherapy regimens into nano-drug delivery systems.

Macrophage-Based Microrobots for Anticancer Therapy: Recent Progress and Future Perspectives

Macrophages, which are part of the mononuclear phagocytic system, possess sensory receptors that enable them to target cancer cells. In addition, they are able to engulf large amounts of particles through phagocytosis, suggesting a potential "Trojan horse" drug delivery approach to tumors by facilitating the engulfment of drug-hidden particles by macrophages. Recent research has focused on the development of macrophage-based microrobots for anticancer therapy, showing promising results and potential for clinical applications. In this review, we summarize the recent development of macrophage-based microrobot research for anticancer therapy. First, we discuss the types of macrophage cells used in the development of these microrobots, the common payloads they carry, and various targeting strategies utilized to guide the microrobots to cancer sites, such as biological, chemical, acoustic, and magnetic actuations. Subsequently, we analyze the applications of these microrobots in different cancer treatment modalities, including photothermal therapy, chemotherapy, immunotherapy, and various synergistic combination therapies. Finally, we present future outlooks for the development of macrophage-based microrobots.

Bleomycin loaded exosomes enhanced antitumor therapeutic efficacy and reduced toxicity

BACKGROUND

Bleomycin (BLM) is a chemotherapeutic agent with potent antitumor activity against the tumor. However, lung fibrosis is the main drawback that limits BLM use. Tumor targeted, safe, efficient and natural delivery of BLM is important to increase the effectiveness and reduce the toxic side effects. Although tumor derived Exosomes (Exo), provide a potential vehicle for in vivo drug delivery due to their cell tropism. This study primarily focuses on generating a natural delivery platform for Exo loaded with BLM and testing its therapeutic efficacy against cancer.

METHODS

Exosomes were isolated from cancer cells and incubated with BLM. Exo were characterized by transmission electron microscopy, western blot analysis and nanoparticle tracking analysis. We performed in vitro and in vivo analyses to evaluate the effect of Exo-BLM.

RESULTS

Exosomes loaded with BLM are highly cancer targeting and cause the cytotoxicity of tumor cells by ROS. The fluorescence images showed that Exo-BLM accumulated in cancer cells. The results revealed that Exo-BLM induces tumor cell apoptosis by the caspase pathway. In vivo, the treatment of Exo-BLM showed targeted ability and enhanced the antitumor activity.

CONCLUSION

This study provides an avenue for specific BLM therapeutics with minimal side effects.

Macrophages as Promising Carriers for Nanoparticle Delivery in Anticancer Therapy

Macrophages play a critical role in the immune response due to their ability to recognize and remove pathogens, as well as present antigens, which are involved in inflammation, but they are also one of the most abundant immune cell populations present in the tumor microenvironment. In recent years, macrophages have become promising cellular carriers for drug and nanoparticle delivery to the tumor microenvironment, mainly due to their natural properties such as biocompatibility, degradability, lack of immunogenicity, long half-life in circulation, crossing biological barriers, and the possibility of migration and accumulation at a site of inflammation such as a tumor. For the effectiveness of this therapeutic strategy, known as "Trojan horse", it is important that the nanoparticles engulfed by macrophages do not affect their proper functioning. In our review, we discussed how the size, shape, chemical and mechanical properties of nanoparticles influence their internalization by macrophages. In addition, we described the promising research utilizing macrophages, their cell membranes and macrophage-derived exosomes as drug carriers in anticancer therapy. As a prospect of the wider use of this therapeutic strategy, we postulate its future application in boron delivery to the tumor environment in boron neutron capture therapy.

Knowledge Gaps in Generating Cell-Based Drug Delivery Systems and a Possible Meeting with Artificial Intelligence

Cell-based drug delivery systems are new strategies in targeted delivery in which cells or cell-membrane-derived systems are used as carriers and release their cargo in a controlled manner. Recently, great attention has been directed to cells as carrier systems for treating several diseases. There are various challenges in the development of cell-based drug delivery systems. The prediction of the properties of these platforms is a prerequisite step in their development to reduce undesirable effects. Integrating nanotechnology and artificial intelligence leads to more innovative technologies. Artificial intelligence quickly mines data and makes decisions more quickly and accurately. Machine learning as a subset of the broader artificial intelligence has been used in nanomedicine to design safer nanomaterials. Here, how challenges of developing cell-based drug delivery systems can be solved with potential predictive models of artificial intelligence and machine learning is portrayed. The most famous cell-based drug delivery systems and their challenges are described. Last but not least, artificial intelligence and most of its types used in nanomedicine are highlighted. The present Review has shown the challenges of developing cells or their derivatives as carriers and how they can be used with potential predictive models of artificial intelligence and machine learning.

Macrophage membrane-coated nanovesicles for dual-targeted drug delivery to inhibit tumor and induce macrophage polarization

Background

Immunosuppressive M2 macrophages in the tumor microenvironment (TME) can mediate the therapeutic resistance of tumors, and seriously affect the clinical efficacy and prognosis of tumor patients. This study aims to develop a novel drug delivery system for dual-targeting tumor and macrophages to inhibit tumor and induce macrophage polarization.

Methods

The anti-tumor effects of methyltransferase like 14 (METTL14) were investigated both in vitro and in vivo. The underlying mechanisms of METTL14 regulating macrophages were also explored in this study. We further constructed the cyclic (Arg-Gly-Asp) (cRGD) peptide modified macrophage membrane-coated nanovesicles to co-deliver METTL14 and the TLR4 agonist.

Results

We found that METTL14 significantly inhibits the growth of tumor in vitro. METTL14 might downregulate TICAM2 and inhibit the Toll-like receptor 4 (TLR4) pathway of macrophages, meanwhile, the combination of METTL14 and the TLR4 agonist could induce M1 polarization of macrophages. Macrophage membrane-coated nanovesicles are characterized by easy modification, drug loading, and dual-targeting tumor and macrophages, and cRGD modification can further enhance its targeting ability. It showed that the nanovesicles could improve the in vivo stability of METTL14, and dual-target tumor and macrophages to inhibit tumor and induce M1 polarization of macrophages.

Conclusions

This study anticipates achieving the dual purposes of tumor inhibition and macrophage polarization, and providing a new therapeutic strategy for tumors.

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Methyltransferase like 14 (METTL14) significantly inhibits the growth of tumor in vitro.

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The combination of METTL14 and TLR4 agonist could induce M1 polarization of macrophages.

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We constructed the cyclic (Arg-Gly-Asp) (cRGD) peptide modified macrophage membrane-coated nanovesicles to co-deliver METTL14 and TLR4 agonist.

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This nanovesicles could dual-target tumor and macrophages to inhibit tumor and induce M1 polarization of macrophages.

Applications and Future Prospects of Micro/Nanorobots Utilizing Diverse Biological Carriers

Targeted drug delivery using micro-nano robots (MNRs) is a rapidly advancing and promising field in biomedical research. MNRs enable precise delivery of drugs, addressing a wide range of healthcare needs. However, the application of MNRs in vivo is limited by power issues and specificity in different scenarios. Additionally, the controllability and biological safety of MNRs must be considered. To overcome these challenges, researchers have developed bio-hybrid micro-nano motors that offer improved accuracy, effectiveness, and safety for targeted therapies. These bio-hybrid micro-nano motors/robots (BMNRs) use a variety of biological carriers, blending the benefits of artificial materials with the unique features of different biological carriers to create tailored functions for specific needs. This review aims to give an overview of the current progress and application of MNRs with various biocarriers, while exploring the characteristics, advantages, and potential hurdles for future development of these bio-carrier MNRs.

Living Cells and Cell-Derived Vesicles: A Trojan Horse Technique for Brain Delivery

Brain diseases remain a significant global healthcare burden. Conventional pharmacological therapy for brain diseases encounters huge challenges because of the blood-brain barrier (BBB) limiting the delivery of therapeutics into the brain parenchyma. To address this issue, researchers have explored various types of drug delivery systems. Cells and cell derivatives have attracted increasing interest as "Trojan horse" delivery systems for brain diseases, owing to their superior biocompatibility, low immunogenicity, and BBB penetration properties. This review provided an overview of recent advancements in cell- and cell-derivative-based delivery systems for the diagnosis and treatment of brain diseases. Additionally, it discussed the challenges and potential solutions for clinical translation.

DNA Nanoclusters Combined with One-Shot Radiotherapy Augment Cancer Immunotherapy Efficiency

Immunotherapy shows immense promise for improving cancer treatment. Combining immunotherapy with radiotherapy provides a conspicuous advantage due to its enhanced abscopal effect. However, established immune tolerance mechanisms in the tumor microenvironment can hamper the generation of a sufficient abscopal effect. Herein, a type of DNA nanocluster (DNAnc) that is self-assembled by a CpG-ODNs-loaded Y-shaped double-stranded DNA vector based on the unique complementary base-pairing rules is designed. The unique structure of DNAnc makes it load more than ≈8125.5 ± 822.5 copies of CpG ODNs within one single nanostructure, which effectively increases resistance to nuclease degradation and elevates the efficiency of repolarizing macrophages to an M1-like phenotype. Mechanistic studies reveal that more DNAncs are endocytosed by macrophages in the cancer tissue and repolarized macrophages to elicit a robust abscopal effect with the accumulation of macrophages induced by radiotherapy, generating potent, long-term, and durable antitumor immunity for the inhibition of tumor metastasis and the prevention of tumor recurrence, which provides a novel strategy to boost cancer immunotherapy.

Cell membrane-coated nanoparticles: a novel multifunctional biomimetic drug delivery system

Recently, nanoparticle-based drug delivery systems have been widely used for the treatment, prevention, and detection of diseases. Improving the targeted delivery ability of nanoparticles has emerged as a critical issue that must be addressed as soon as possible. The bionic cell membrane coating technology has become a novel concept for the design of nanoparticles. The diverse biological roles of cell membrane surface proteins endow nanoparticles with several functions, such as immune escape, long circulation time, and targeted delivery; therefore, these proteins are being extensively studied in the fields of drug delivery, detoxification, and cancer treatment. Furthermore, hybrid cell membrane-coated nanoparticles enhance the beneficial effects of monotypic cell membranes, resulting in multifunctional and efficient delivery carriers. This review focuses on the synthesis, development, and application of the cell membrane coating technology and discusses the function and mechanism of monotypic/hybrid cell membrane-modified nanoparticles in detail. Moreover, it summarizes the applications of cell membranes from different sources and discusses the challenges that may be faced during the clinical application of bionic carriers, including their production, mechanism, and quality control. We hope this review will attract more scholars toward bionic cell membrane carriers and provide certain ideas and directions for solving the existing problems.

Biologically inspired stealth - Camouflaged strategies in nanotechnology for the improved therapies in various diseases

Nanotechnology has received increasing attention in the past decade and it's being used as a model for developing better treatments for a variety of diseases. Despite the fact that nanotechnology-based therapy has greatly improved treatment regimens, it still faces challenges such as inadequate circulation, insufficient accumulation at the target region, and undesired toxicity. In this regard, scientists are working on producing cell-membrane camouflaged nanoparticles as a biomimetic technique for modifying the surface of existing nanoparticles to produce significant therapeutic benefits following imparting myriad of desired functionalities. Membranes originating from erythrocytes, white blood cells, cancer cells, stem cells, platelets, or bacterial cells have been used to coat nanoparticle surfaces and create biologically inspired camouflaged nanoparticles. These biomemitic delivery systems have been proven to have potential applications in diagnosing and treating vaiorus diseases, including drug administration, immunisation, immunological regulation, and detoxification. From its inception to the present, we provide a complete description of this advanced technique for functionalizing nanoparticle surfaces. The method of making these membrane coated nanoparticles as well as their characterisation have been thoroughly discussed. Following that, we focused on the diversity of cell membranes derived from distinct cells in the evolution of nanoparticles, emphasising how these biologically inspired stealth - camouflaged techniques have led to increased therapeutic efficacy in a variety of disease states.

Macrophage cell membrane-based nanoparticles: a new promising biomimetic platform for targeted delivery and treatment

Synthetic nanoparticles with surface bioconjugation are promising platforms for targeted therapy, but their simple biological functionalization is still a challenging task against the complex intercellular environment. Once synthetic nanoparticles enter the body, they are phagocytosed by immune cells by the immune system. Recently, the cell membrane camouflage strategy has emerged as a novel therapeutic tactic to overcome these issues by utilizing the fundamental properties of natural cells. Macrophage, a type of immune system cells, plays critical roles in various diseases, including cancer, atherosclerosis, rheumatoid arthritis, infection and inflammation, due to the recognition and engulfment function of removing substances and pathogens. Macrophage membranes inherit the surface protein profiles and biointerfacing properties of source cells. Therefore, the macrophage membrane cloaking can protect synthetic nanoparticles from phagocytosis by the immune cells. Meanwhile, the macrophage membrane can make use of the natural correspondence to accurately recognize antigens and target inflamed tissue or tumor sites. In this review, we have summarized the advances in the fabrication, characterization and homing capacity of macrophage membrane cloaking nanoparticles in various diseases, including cancers, immune diseases, cardiovascular diseases, central nervous system diseases, and microbial infections. Although macrophage membrane-camouflaged nanoparticles are currently in the fetal stage of development, there is huge potential and challenge to explore the conversion mode in the clinic.

Effects of the media conditioned by various macrophage subtypes derived from THP-1 cells on tunneling nanotube formation in pancreatic cancer cells

Background

Tunneling nanotubes (TNTs) are special membrane structures for intercellular communications. Vital cargoes (such as mitochondria) could be delivered from healthy cells to rescue damaged ones through TNTs. The TNTs could be utilized for the purpose of systematic delivery of therapeutic agents between cells. However, there are insufficient studies on the controlled enhancement of TNT formations. The purpose of this study is to understand how macrophages influence the TNT formation in cancer cells.

Results

Here we compared the capabilities of inducing TNTs in human pancreatic cancer cells (PANC-1) of the media conditioned by M0, M1 and M2 macrophages derived from THP-1 cells. The M0 and M1 macrophage conditioned media promoted TNT formation. Using a focused ion beam to cut through a TNT, we observed tunnel-like structures inside dense cytoskeletons with scanning electron microscopy. The TNT formation correlated with raised motility, invasion, and epithelial–mesenchymal transition in the PANC-1 cells. Mitochondria and lysosomes were also found to be transported in the TNTs.

Conclusions

These results suggest that TNT formation could be one of the responses to the immune stress in pancreatic cancer cells caused by M0 and M1 macrophages. This finding is valuable for the development of macrophage-targeting cancer therapy.

Nanozyme-laden intelligent macrophage EXPRESS amplifying cancer photothermal-starvation therapy by responsive stimulation

Precise delivery and responsive activation of therapeutic agents are critical for tumor precise therapy. Herein, inspired by intelligent express, a nanozyme-laden intelligent macrophage express was fabricated based on IR 820-macrophage loaded with GOx nanozymes for tumor-targeted photothermal-amplified starvation therapy with fluorescence imaging guidance. The nanozyme-laden intelligent macrophage express exerted precise delivery through cargo loading, conveying and unloading. For efficient cargo loading, H₂O₂-sensitive GOx nanozymes with blocked enzymatic activity were packaged on macrophage expresses with excellent phagocytic ability. Due to the inherent tumor tropism, the therapeutic agents-laden macrophage expresses naturally accumulated at tumor site with fluorescence navigation to track the conveying process. The spatiotemporal unpacking of the laden therapeutic agents at tumor site was triggered by the external laser for the macrophage express photothermal property. The released special tumor-microenvironment responsive GOx nanozymes were activated by H₂O₂ in tumor to start starvation therapy. Photothermal therapy generated mild hyperthermia and starvation therapy produced H₂O₂ further increased the nanozymes enzymatic activity, enhancing GOx-mediated starvation therapy. The nanozyme-laden intelligent macrophage express integrated laser-induce drug release and activation, tumor microenvironment-responsiveness, and circular amplification property, achieving the synergistic effects of PTT and starvation therapy in vitro and in vivo.

Multi-Modal Imaging Monitored M2 Macrophage Targeting Sono-Responsive Nanoparticles to Combat MRSA Deep Infections

Background

MRSA with high morbidity and mortality is prone to cause serious infection, SDT has become a new antibiotic-free modality for bacterial infection treatment. Switching from proinflammatory M1 macrophages to anti-inflammatory M2 macrophages dominant could activate the immune system to generate an anti-infection immune response.

Methods

Herein, we developed M2 macrophages derived cell membranes coated PLGA nanoparticles with IR780 encapsulation (M2/IR780@PLGA) for antibacterial SDT and subsequent M2 macrophage polarization to enhance the therapeutic efficacy of MRSA myositis. For in situ visualization of antibacterial SDT, both diagnostic high-frequency US and magnetic resonance imaging (MRI) were introduced to monitor the sono-therapeutic progression of M2/IR780@PLGA nanoparticles in mice with bacterial myositis.

Results

Our developed M2/IR780@PLGA nanoparticles exhibited excellent antibacterial effects due to the IR780 under low-frequency US irradiation in vitro. In an MRSA-infected mice model, a great deal of M2/IR780@PLGA nanoparticles accumulated at the site of inflammation due to M2 macrophage coating. The infected legs in the M2/IR780@PLGA nanoparticles-based SDT group were significantly smaller, fewer blood flow signals, a slight muscular edema without obvious intermuscular abscesses under high-frequency US and MR images guidance. Histopathology proved the infected legs in the M2/IR780@PLGA nanoparticles-mediated SDT group had less clumped bacteria infiltration, more M2 macrophage expression and less M1 macrophage expression. The percentage of mature dendritic cells in spleens was much higher in the group of mice with M2/IR780@PLGA nanoparticles-based SDT.

Conclusion

This study provides a promising nanoparticles-based SDT anti-bacterial strategy, which could effectively enhance the antibacterial SDT and subsequent promote M2 macrophage polarization to boost the therapeutic efficacy of MRSA myositis.

Myocardium-Targeted Micelle Nanomedicine That Salvages the Heart from Ischemia/Reperfusion Injury

Cardioprotective medication is the common treatment to relieve myocardial ischemia/reperfusion (I/R) injury. However, limited by the low bioavailability of therapeutic drugs, the therapeutic outcome is barely satisfactory. Because the I/R injury can enhance the permeability of the vasculature and allow the extravasation of nanoparticles into the surrounding tissue, herein we formulate the cardiotonic drug olprinone (Olp) in cross-linked micelles as the nanomedicine to achieve myocardium-targeted delivery after systematic administration. As a result, the local concentration of Olp in the injured myocardium is raised by orders of magnitude with prolonged drug duration time. The treatment successfully preserves the pumping efficiency of the heart, alleviates ventricular remodeling, and thus stops the positive feedback loop for the deteriorated cardiac function. Consequently, the myocardium-targeted nanomedicine significantly salvages the heart from I/R injury before irreversible pathological changes take place.

Cell-based drug delivery systems and their in vivo fate

Cell-based drug delivery systems (DDSs) have received attention recently because of their unique biological properties and self-powered functions, such as excellent biocompatibility, low immunogenicity, long circulation time, tissue-homingcharacteristics, and ability to cross biological barriers. A variety of cells, including erythrocytes, stem cells, and lymphocytes, have been explored as functional vectors for the loading and delivery of various therapeutic payloads (e.g., small-molecule and nucleic acid drugs) for subsequent disease treatment. These cell-based DDSs have their own unique in vivo fates, which are attributed to various factors, including their biological properties and functions, the loaded drugs and loading process, physiological and pathological circumstances, and the body's response to these carrier cells, which result in differences in drug delivery efficiency and therapeutic effect. In this review, we summarize the main cell-based DDSs and their biological properties and functions, applications in drug delivery and disease treatment, and in vivo fate and influencing factors. We envision that the unique biological properties, combined with continuing research, will enable development of cell-based DDSs as friendly drug vectors for the safe, effective, and even personalized treatment of diseases.

Harnessing anti-tumor and tumor-tropism functions of macrophages via nanotechnology for tumor immunotherapy

Reprogramming the immunosuppressive tumor microenvironment by modulating macrophages holds great promise in tumor immunotherapy. As a class of professional phagocytes and antigen-presenting cells in the innate immune system, macrophages can not only directly engulf and clear tumor cells, but also play roles in presenting tumor-specific antigen to initiate adaptive immunity. However, the tumor-associated macrophages (TAMs) usually display tumor-supportive M2 phenotype rather than anti-tumor M1 phenotype. They can support tumor cells to escape immunological surveillance, aggravate tumor progression, and impede tumor-specific T cell immunity. Although many TAMs-modulating agents have shown great success in therapy of multiple tumors, they face enormous challenges including poor tumor accumulation and off-target side effects. An alternative solution is the use of advanced nanostructures, which not only can deliver TAMs-modulating agents to augment therapeutic efficacy, but also can directly serve as modulators of TAMs. Another important strategy is the exploitation of macrophages and macrophage-derived components as tumor-targeting delivery vehicles. Herein, we summarize the recent advances in targeting and engineering macrophages for tumor immunotherapy, including (1) direct and indirect effects of macrophages on the augmentation of immunotherapy and (2) strategies for engineering macrophage-based drug carriers. The existing perspectives and challenges of macrophage-based tumor immunotherapies are also highlighted.

A neutrophil-mediated carrier regulates tumor stemness by inhibiting autophagy to prevent postoperative triple-negative breast cancer recurrence and metastasis

Recurrence and metastasis after resection are still the main challenges in clinical treatment of breast cancer. Residual tumor and cancer stem-like cells are the primary culprits of recurrence and metastasis. Recent research studies indicate that autophagy is a cytoprotective mechanism of tumors, which maintains the stemness of cancer cells and promotes tumor proliferation and metastasis. Here, we constructed a "Trojan horse" using neutrophils as the carrier (PH-RL@NEs) to prevent the recurrence and metastasis of postoperative breast cancer. Neutrophils, as a "Trojan horse," can quickly respond to postoperative inflammation and accurately deliver drugs to the residual tumor site. The inflammation-triggered "Trojan horse" was then opened to release the liposomes containing the chemotherapeutic drug paclitaxel (PTX) and the autophagy inhibitor hydroxychloroquine (HCQ). We found that HCQ could effectively inhibit tumor cell autophagy, interfere with tumor epithelial-mesenchymal transition, and reduce the tumor stem cell-like population. In the orthotopic 4T1 postoperative recurrence models, PTX and HCQ synergistically killed tumors and regulated the stemness of tumor cells, thereby significantly inhibiting tumor recurrence and metastasis. Our work proved that the inhibition of autophagy to reduce tumor stemness is feasible and effective, which opens up a new prospect for postoperative tumor treatment. STATEMENT OF SIGNIFICANCE: The present study aimed to solve the issues of postoperative recurrence and metastasis of breast cancer and low efficiency of drug administration after surgery. For this purpose, we constructed neutrophils containing hydroxychloroquine (HCQ) and paclitaxel (PTX) co-loaded liposomes (PH-RL@NEs), which for the first time regulated the stemness of tumor cells by inhibiting autophagy, thereby inhibiting postoperative recurrence and metastasis of breast cancer cells. The results showed that PH-RL@NEs enhanced the targeted drug delivery efficiency, with the help of postoperative inflammation chemotaxis of neutrophils. HCQ effectively inhibited autophagy of tumor cells and reduced tumor stem cell-like cells, thus improving the therapeutic effect in the 4T1 in situ postoperative recurrence model.

Nanocarriers surface engineered with cell membranes for cancer targeted chemotherapy

Background

Inspired by nature, the biomimetic approach has been incorporated into drug nanocarriers for cancer targeted chemotherapy. The nanocarriers are cloaked in cell membranes, which enables them to incorporate the functions of natural cells.

Key scientific concepts of review

Nanocarriers surface engineered with cell membranes have emerged as a fascinating source of materials for cancer targeted chemotherapy. A distinctive characteristic of cell membrane-coated nanocarriers (CMCNs) is that they include carbohydrates, proteins, and lipids, in addition to being biocompatible. CMCNs are capable of interacting with the complicated biological milieu of the tumor because they contain the signaling networks and intrinsic functions of their parent cells. Numerous cell membranes have been investigated for the purpose of masking nanocarriers with membranes, and various tumor-targeting methods have been devised to improve cancer targeted chemotherapy. Moreover, the diverse structure of the membrane from different cell sources broadens the spectrum of CMCNs and offers an entirely new class of drug-delivery systems.

Aim of review

This review will describe the manufacturing processes for CMCNs and the therapeutic uses for different kinds of cell membrane-coated nanocarrier-based drug delivery systems, as well as addressing obstacles and future prospects.

Graphical Abstract

Recent progress of macrophage vesicle-based drug delivery systems

Nanoparticle drug delivery systems (NDDSs) are promising platforms for efficient delivery of drugs. In the past decades, many nanomedicines have received clinical approval and completed translation. With the rapid advance of nanobiotechnology, natural vectors are emerging as novel strategies to carry and delivery nanoparticles and drugs for biomedical applications. Among diverse types of cells, macrophage is of great interest for their essential roles in inflammatory and immune responses. Macrophage-derived vesicles (MVs), including exosomes, microvesicles, and those from reconstructed membranes, may inherit the chemotactic migration ability and high biocompatibility. The unique properties of MVs make them competing candidates as novel drug delivery systems for precision nanomedicine. In this review, the advantages and disadvantages of existing NDDSs and MV-based drug delivery systems (MVDDSs) were compared. Then, we summarized the potential applications of MVDDSs and discuss future perspectives. The development of MVDDS may provide avenues for the treatment of diseases involving an inflammatory process.

Nanomedicine Strategies to Circumvent Intratumor Extracellular Matrix Barriers for Cancer Therapy

The dense and heterogeneous physical network of the extracellular matrix (ECM) in tumors represents a formidable barrier that limits intratumor drug delivery and the therapeutic efficacy of many anticancer therapies. Here, the two major nanomedicine strategies to circumvent intratumor ECM barriers: regulating the physiochemical properties of nanomedicines and remodeling the components and structure of the ECM are summarized. Nanomedicines can be rationally regulated by optimizing physiochemical properties or designed with biomimetic features to promote ECM permeation capability. Meanwhile, they can also be designed to remodel the ECM by modulating signaling pathways or destroying the components and architecture of the ECM via chemical, biological, or physical treatments. These efforts produce profound improvements in intratumor drug delivery and anticancer efficacy. Moreover, to aid in their anticancer efficacy, feasible approaches for improving ECM-circumventing nanomedicines are proposed.

Cell Membrane-Coated Mimics: A Methodological Approach for Fabrication, Characterization for Therapeutic Applications, and Challenges for Clinical Translation

Cell membrane-coated (CMC) mimics are micro/nanosystems that combine an isolated cell membrane and a template of choice to mimic the functions of a cell. The design exploits its physicochemical and biological properties for therapeutic applications. The mimics demonstrate excellent biological compatibility, enhanced biointerfacing capabilities, physical, chemical, and biological tunability, ability to retain cellular properties, immune escape, prolonged circulation time, and protect the encapsulated drug from degradation and active targeting. These properties and the ease of adapting them for personalized clinical medicine have generated a significant research interest over the past decade. This review presents a detailed overview of the recent advances in the development of cell membrane-coated (CMC) mimics. The primary focus is to collate and discuss components, fabrication methodologies, and the significance of physiochemical and biological characterization techniques for validating a CMC mimic. We present a critical analysis of the two main components of CMC mimics: the template and the cell membrane and mapped their use in therapeutic scenarios. In addition, we have emphasized on the challenges associated with CMC mimics in their clinical translation. Overall, this review is an up to date toolbox that researchers can benefit from while designing and characterizing CMC mimics.

Nanomaterials targeting tumor associated macrophages for cancer immunotherapy

Tumor-associated macrophages (TAMs) play an important role in regulating tumor growth, invasion and metastasis, and constitute approximately 50% of tumor mass. TAMs can exist in two different subtypes, M1-polarized phenotype (pro-inflammatory and immunostimulatory) and M2-polarized phenotype (immunosuppressive myeloid cells). M2 macrophages can suppress CD8⁺ T cells to support tumor survival. A number of biological strategies aimed at engineering macrophages to modulate the tumor immune microenvironment remain at the forefront of cancer research. Here, we review the different therapeutic strategies that have been developed based on nanotechnology to modulate macrophage functions, such as inhibition of macrophage recruitment to tumor, depletion of M2-polarized macrophages, reprograming of M2-polarized macrophages to M1-polarized macrophages, and blocking of the CD47-signal-regulatory protein alpha (CD47-SIRPα) pathway. Furthermore, we also discuss how to image TAMs with nanoparticles to unravel novel treatment options and observe their responses to the various therapies. Overall, macrophage-mediated immune modulation based on nanotechnology can be further investigated to be effectively developed as an immunoadjuvant therapy against different cancers.

Nano-engineered immune cells as "guided missiles" for cancer therapy

Immune cells can actively regulate tumors or inflammatory sites and have good biocompatibility and safety. Currently, they are one of the most promising candidates for drug delivery systems. Moreover, immune cells can significantly extend the circulation time of nanoparticles and have broad-spectrum tumor-targeting properties. This article first introduces the immune cell types most commonly used in recent years, analyzes their advantages and disadvantages, and elucidates their application in anti-tumor therapy. Next, the various ways of loading nanoparticles on immune cells that have been used in recent years are summarized and simply divided into two categories: backpacks and Trojan horses. Finally, the two "mountains" that stand in front of us when using immune cells as cell carriers, off-target problems and effective release strategies, are discussed.

Multistage targeted "Photoactive neutrophil" for enhancing synergistic photo-chemotherapy

Cell-based drug delivery system holds a great promise in anticancer treatment, due to its potential of maximizing therapeutic efficacy while minimizing adverse effects. However, current cell system can only deliver drugs in tumor lesions, but lack an ability to target subcellular locus of therapeutic actions, thereby compromising anticancer efficacy. Herein, we bioengineered living neutrophils as a novel type of "Photoactive neutrophil" (PAN) with capabilities of self-amplified multistage targeting and inflammation response for enhancing mitochondria-specific photo-chemotherapy. PAN encapsulated multifunctional nanocomplex (RA/Ce6) of RGD-apoptotic peptide conjugate (RA) decorated liposomal photosensitizer Ce6, and could overcome tumor barriers to selectively release RA/Ce6 within tumor. Consequently, RA/Ce6 actively entered cancer cells and accumulated in mitochondria to trigger combined photodynamic therapy (PDT) and RA-induced mitochondrial membrane disruption, resulting in enhanced therapeutic effects. Importantly, PAN exhibited inflammation amplified tumor targeting after PDT, and initiated combined photo-chemotherapy to suppress tumor growth without adverse effects, leading to prolonged mice survival. Therefore, PAN represents the first multistage targeted cell therapy, and brings new insights into cancer treatment.

Targeted Delivery of Drugs and Genes Using Polymer Nanocarriers for Cancer Therapy

Cancer is one of the primary causes of worldwide human deaths. Most cancer patients receive chemotherapy and radiotherapy, but these treatments are usually only partially efficacious and lead to a variety of serious side effects. Therefore, it is necessary to develop new therapeutic strategies. The emergence of nanotechnology has had a profound impact on general clinical treatment. The application of nanotechnology has facilitated the development of nano-drug delivery systems (NDDSs) that are highly tumor selective and allow for the slow release of active anticancer drugs. In recent years, vehicles such as liposomes, dendrimers and polymer nanomaterials have been considered promising carriers for tumor-specific drug delivery, reducing toxicity and improving biocompatibility. Among them, polymer nanoparticles (NPs) are one of the most innovative methods of non-invasive drug delivery. Here, we review the application of polymer NPs in drug delivery, gene therapy, and early diagnostics for cancer therapy.

Biomimetic Drug Delivery Systems Oriented by Biological Function in Tumor Targeting

The emergence of nanoscale drug delivery systems provides new opportunities for targeting the delivery of chemotherapeutic drugs and has achieved excellent results. In recent years, with the rise in the concept of intelligent drug delivery systems, the design and preparation of carriers have become more and more complicated, which is not conducive to clinical transformation. Researchers are gradually focused on biomimetic nanoscale drug delivery systems, trying to combine the physicochemical properties of nanoscale carriers with the natural biological functions of endogenous substances, so as to boost tumor targeting delivery. In this article, we first classify and introduce biomimetic nanoscale drug delivery systems, and then emphasize their unique biological functions. The biomimetic nanoscale drug delivery systems have the advantages of simple preparation, powerful functions, and low immunogenicity, having a good application prospect.

Novel Therapeutic Platform of Micelles and Nanogels from Dopa-Functionalized Triblock Copolymers

Multi-drug delivery systems constructed from a basic polymeric scaffold, and which have the ability to target a variety of biomedical applications, can streamline the development of nanomedicine to provide both environmental and economical relief. Herein, amphiphilic ABA-triblock copolymers are synthesized and assembled sequentially into micelles and nanogels as drug delivery systems following a thorough evaluation on advanced in vitro models to explore their potential for the treatment of cancer and bacterial infections. Short blocks of 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one (MAC) are oligomerized from PEG6k and thereafter functionalized with dihydroxyphenylalanine (dopa)-functional thiols using thiol-ene coupling (TEC) click chemistry. The copolymers self-assemble into well-defined micelles in aqueous solution and are further formulated into nanogels via UV-induced TEC. The resulting spherical micelles and nanogels are stable nanoparticles, with sizes ranging between 100 and 200 nm. The nanogels are found to be non-toxic to a panel of cell lines and mask the toxicity of the potent drugs until their release. The nanogels would be superior to micelles for the elimination of cancer cells supported by both 2D cell culture and a 3D spheroid model. The opposite conclusion could be drawn for bacteria inhibition.

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

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

In situ poly I:C released from living cell drug nanocarriers for macrophage-mediated antitumor immunotherapy

Immunotherapy is one of the most promising approaches to inhibit tumor growth and metastasis by activating host immune functions. However, the arising problems such as low immune response caused by complex tumor microenvironment and extremely systemic immune storm still limit the clinical applications of immunotherapy. Here, we construct Poly I: C-encapsulated poly (lactic-co-glycolic acid) nanoparticles (PLP NPs) with a slow release profile. A biomimetic system (MPLP), which loads PLP NPs on the surface of bone marrow-derived macrophage (BMDM) via the maleimide-thiol conjugation, is synthesized to effectively deliver PLP, control drug release and activate the tumor-specific immune response in situ. The results show that PLP NPs loading does not affect the activity and function of BMDM. Then, BMDM acts as a living cell drug vehicle and promotes the accumulation of PLP NPs in tumors, where Poly I: C is released from PLP NPs and reprograms BMDM into tumoricidal M1 macrophage. Furthermore, MPLP triggers potent antitumor immune responses in vivo and effectively inhibits local and metastatic tumors without causing adverse pathological immune reactions. This study offers an inspiration to facilitate clinical translation through the delivery of drugs by living immune cells for future anticancer therapy.

Tumor-associated macrophage-targeted therapeutics in ovarian cancer

Ovarian cancer is one of the most common gynecological malignancies. The tumor microenvironment plays an important role in regulating the progression of ovarian cancer. Macrophages, which are important immune cells in the tumor microenvironment, participate in the regulation of various biological behaviors and influence the prognosis of ovarian cancer. A large number of studies have targeted macrophages for the treatment of ovarian cancer. In addition, macrophages also play a regulatory role by interacting with other immune cells, including T cells and mesothelial cells, in the ovarian cancer microenvironment. In this review, we discuss the progress made in macrophage-targeted therapy for ovarian cancer. Although there are still several challenges in using this treatment, targeted macrophage therapy is still a promising treatment for ovarian cancer.

A Smart Nanoparticle-Laden and Remote-Controlled Self-Destructive Macrophage for Enhanced Chemo/Chemodynamic Synergistic Therapy

Macrophages are known to penetrate tumor central hypoxic areas and hold great potential in cancer drug delivery. However, it remains a big challenge for current macrophage-based drug delivery systems (MDDSs) to prevent premature drug leakage and sufficiently release the therapeutics in tumor sites. Moreover, these MDDSs would encounter drug resistance and a hypoxic microenvironment in solid tumors, which further compromised their therapeutic efficacy. Herein, by internalizing a smart nanoparticle (doxorubicin (DOX)-loaded mesoporous carbon nanosphere wrapped with MnO₂ shell) into macrophages, a macrophage vehicle (MMDM) is developed for enhanced chemo/chemodynamic synergistic therapy. The resulting MMDM could avoid premature drug leakage-induced cell dysfunction and maximally maintain cell viability. After accumulating in tumor tissues, the MMDM could be destroyed under a near-infrared laser to sufficiently release the nanoparticle out of the carrier macrophages. The released nanoparticle could then decompose H₂O₂ to generate O₂ in the tumor microenvironment to relieve tumor hypoxia. Meanwhile, the MnO₂ shell of the nanoparticle is reduced to Mn²⁺ by intracellular glutathione, triggering the release of DOX and subsequently resulting in an enhanced Mn²⁺-mediated Fenton-like reaction. This study provides an intriguing strategy to macrophage-based delivery systems for enhanced chemo/chemodynamic synergistic therapy.

A tumor-sensitive biological metal-organic complex for drug delivery and cancer therapy

Metal-organic complexes (MOCs) or metal-organic frameworks (MOFs) have attracted increasing interest for constructing nanoscale drug delivery systems for cancer therapy. However, conventional MOC/MOF materials usually contain toxic metals or low-biocompatible organic ligands. Also, current approaches for creating tumor-sensitive nanocarriers are always based on the instability of coordination bonds under acidic conditions, or through post-synthetic modification with sensitive molecules. As a matter of fact, it is more facile to fabricate tumor-sensitive MOCs/MOFs based on the stimuli-responsiveness of organic ligands. In this study, a novel tumor-sensitive biological MOC (bioMOC-Zn(Cys)) was created through the assembly of endogenous Zn2+ ions and the small biological molecule (l-cystine, Cys). The disulfide bond in l-cystine is cleavable by the overexpressed GSH in tumor cells, thus achieving rapid release of drugs from nanocarriers. By encapsulating doxorubicin (DOX) in bioMOC-Zn(Cys), DOX@bioMOC-Zn(Cys) displayed higher cellular uptake and cytotoxicity in cancer cells than free DOX. In vivo investigations indicated that DOX@bioMOC-Zn(Cys) largely inhibited tumor growth and reduced side effects. Remarkably, since both metal ions and organic ligands were obtained from biological sources, bioMOC-Zn(Cys) exhibited superior biocompatibility. This study presents a new method for fabricating MOC-based nanodrugs with high tumor-sensitivity and low toxicity.

Tumor microenvironment responsive drug delivery systems

Conventional tumor-targeted drug delivery systems (DDSs) face challenges, such as unsatisfied systemic circulation, low targeting efficiency, poor tumoral penetration, and uncontrolled drug release. Recently, tumor cellular molecules-triggered DDSs have aroused great interests in addressing such dilemmas. With the introduction of several additional functionalities, the properties of these smart DDSs including size, surface charge and ligand exposure can response to different tumor microenvironments for a more efficient tumor targeting, and eventually achieve desired drug release for an optimized therapeutic efficiency. This review highlights the recent research progresses on smart tumor environment responsive drug delivery systems for targeted drug delivery. Dynamic targeting strategies and functional moieties sensitive to a variety of tumor cellular stimuli, including pH, glutathione, adenosine-triphosphate, reactive oxygen species, enzyme and inflammatory factors are summarized. Special emphasis of this review is placed on their responsive mechanisms, drug loading models, drawbacks and merits. Several typical multi-stimuli responsive DDSs are listed. And the main challenges and potential future development are discussed.

Advances in living cell-based anticancer therapeutics

This review summarizes recent advances in the applications of living cells as drug carriers or active drugs for anticancer drug delivery and cancer therapy.

Novel β-1,3-d-glucan porous microcapsule enveloped folate-functionalized liposomes as a Trojan horse for facilitated oral tumor-targeted co-delivery of chemotherapeutic drugs and quantum dots

In this study, novel β-1,3-d-glucan porous microcapsule enveloped folate-functionalized liposomes were developed for the potential co-delivery of chemotherapeutic drugs and quantum dots with facilitated drug absorption and antitumor efficacy.

Exploiting Current Understanding of Hypoxia Mediated Tumour Progression for Nanotherapeutic Development

Hypoxia is one of the most common phenotypes of malignant tumours. Hypoxia leads to the increased activity of hypoxia-inducible factors (HIFs), which regulate the expression of genes controlling a raft of pro-tumour phenotypes. These include maintenance of the cancer stem cell compartment, epithelial-mesenchymal transition (EMT), angiogenesis, immunosuppression, and metabolic reprogramming. Hypoxia can also contribute to the tumour progression in a HIF-independent manner via the activation of a complex signalling network pathway, including JAK-STAT, RhoA/ROCK, NF-κB and PI3/AKT. Recent studies suggest that nanotherapeutics offer a unique opportunity to target the hypoxic microenvironment, enhancing the therapeutic window of conventional therapeutics. In this review, we summarise recent advances in understanding the impact of hypoxia on tumour progression, while outlining possible nanotherapeutic approaches for overcoming hypoxia-mediated resistance.

Harnessing tumor-associated macrophages as aids for cancer immunotherapy

Cancer immunotherapies that engage immune cells to fight against tumors are proving to be powerful weapons in combating cancer and are becoming increasingly utilized in the clinics. However, for the majority of patients with solid tumors, little or no progress has been seen, presumably due to lack of adequate approaches that can reprogram the local immunosuppressive tumor milieu and thus reinvigorate antitumor immunity. Tumor-associated macrophages (TAMs), which abundantly infiltrate most solid tumors, could contribute to tumor progression by stimulating proliferation, angiogenesis, metastasis, and by providing a barrier against antitumor immunity. Initial TAMs-targeting strategies have shown efficacy across therapeutic modalities and tumor types in both preclinical and clinical studies. TAMs-targeted therapeutic approaches can be roughly divided into those that deplete TAMs and those that modulate TAMs activities. We here reviewed the mechanisms by which macrophages become immunosuppressive and compromise antitumor immunity. TAMs-focused therapeutic strategies are also summarized.

Cell Membrane Coating Technology: A Promising Strategy for Biomedical Applications

Cell membrane coating technology is an approach to the biomimetic replication of cell membrane properties, and is an active area of ongoing research readily applicable to nanoscale biomedicine. Nanoparticles (NPs) coated with cell membranes offer an opportunity to unite natural cell membrane properties with those of the artificial inner core material. The coated NPs not only increase their biocompatibility but also achieve effective and extended circulation in vivo, allowing for the execution of targeted functions. Although cell membrane-coated NPs offer clear advantages, much work remains before they can be applied in clinical practice. In this review, we first provide a comprehensive overview of the theory of cell membrane coating technology, followed by a summary of the existing preparation and characterization techniques. Next, we focus on the functions and applications of various cell membrane types. In addition, we collate model drugs used in cell membrane coating technology, and review the patent applications related to this technology from the past 10 years. Finally, we survey future challenges and trends pertaining to this technology in an effort to provide a comprehensive overview of the future development of cell membrane coating technology.