Artificial Nanoscale Erythrocytes from Clinically Relevant Compounds for Enhancing Cancer Immunotherapy

Artificial Macrophage with Hierarchical Nanostructure for Biomimetic Reconstruction of Antitumor Immunity

Artificial cells are constructed from synthetic materials to imitate the biological functions of natural cells. By virtue of nanoengineering techniques, artificial cells with designed biomimetic functions provide alternatives to natural cells, showing vast potential for biomedical applications. Especially in cancer treatment, the deficiency of immunoactive macrophages results in tumor progression and immune resistance. To overcome the limitation, a BaSO4@ZIF-8/transferrin (TRF) nanomacrophage (NMΦ) is herein constructed as an alternative to immunoactive macrophages. Alike to natural immunoactive macrophages, NMΦ is stably retained in tumors through the specific affinity of TRF to tumor cells. Zn2+ as an "artificial cytokine" is then released from the ZIF-8 layer of NMΦ under tumor microenvironment. Similar as proinflammatory cytokines, Zn2+ can trigger cell anoikis to expose tumor antigens, which are selectively captured by the BaSO4 cavities. Therefore, the hierarchical nanostructure of NMΦs allows them to mediate immunogenic death of tumor cells and subsequent antigen capture for T cell activation to fabricate long-term antitumor immunity. As a proof-of-concept, the NMΦ mimics the biological functions of macrophage, including tumor residence, cytokine release, antigen capture and immune activation, which is hopeful to provide a paradigm for the design and biomedical applications of artificial cells.

Emerging Trends in Nano-Driven Immunotherapy for Treatment of Cancer

Despite advancements in the development of anticancer medications and therapies, cancer still has the greatest fatality rate due to a dismal prognosis. Traditional cancer therapies include chemotherapy, radiotherapy, and targeted therapy. The conventional treatments have a number of shortcomings, such as a lack of selectivity, non-specific cytotoxicity, suboptimal drug delivery to tumour locations, and multi-drug resistance, which results in a less potent/ineffective therapeutic outcome. Cancer immunotherapy is an emerging and promising strategy to elicit a pronounced immune response against cancer. Immunotherapy stimulates the immune system with cancer-specific antigens or immune checkpoint inhibitors to overcome the immune suppressive tumour microenvironment and kill the cancer cells. However, delivery of the antigen or immune checkpoint inhibitors and activation of the immune response need to circumvent the issues pertaining to short lifetimes and effect times, as well as adverse effects associated with off-targeting, suboptimal, or hyperactivation of the immune system. Additional challenges posed by the tumour suppressive microenvironment are less tumour immunogenicity and the inhibition of effector T cells. The evolution of nanotechnology in recent years has paved the way for improving treatment efficacy by facilitating site-specific and sustained delivery of the therapeutic moiety to elicit a robust immune response. The amenability of nanoparticles towards surface functionalization and tuneable physicochemical properties, size, shape, and surfaces charge have been successfully harnessed for immunotherapy, as well as combination therapy, against cancer. In this review, we have summarized the recent advancements made in choosing different nanomaterial combinations and their modifications made to enable their interaction with different molecular and cellular targets for efficient immunotherapy. This review also highlights recent trends in immunotherapy strategies to be used independently, as well as in combination, for the destruction of cancer cells, as well as prevent metastasis and recurrence.

Modified Aerotaxy for the Plug-in Manufacture of Cell-Penetrating Fenton Nanoagents for Reinforcing Chemodynamic Cancer Therapy

The assemblies of anisotropic nanomaterials have attracted considerable interest in advanced tumor therapeutics because of the extended surfaces for loading of active molecules and the extraordinary responses to external stimuli for combinatorial therapies. These nanomaterials were usually constructed through templated or seed-mediated hydrothermal reactions, but the lack of uniformity in size and morphology, as well as the process complexities from multiple separation and purification steps, impede their practical use in cancer nanotherapy. Gas-phase epitaxy, also called aerotaxy (AT), has been introduced as an innovative method for the continuous assembly of anisotropic nanomaterials with a uniform distribution. This process does not require expensive crystal substrates and high vacuum conditions. Nevertheless, AT has been used limitedly to build high-aspect-ratio semiconductor nanomaterials. With these considerations, a modified AT was designed for the continuous in-flight assembly of the cell-penetrating Fenton nanoagents (Mn-Fe CaCO₃ (AT) and Mn-Fe SiO₂ (AT)) in a single-pass gas flow because cellular internalization activity is essential for cancer nanotherapeutics. The modified AT of Mn-Fe CaCO₃ and Mn-Fe SiO₂ to generate surface nanoroughness significantly enhanced the cellular internalization capability because of the preferential contact mode with the cancer cell membrane for Fenton reaction-induced apoptosis. In addition, it was even workable for doxorubicin (DOX)-resistant cancer cells after DOX loading on the nanoagents. After combining with immune-checkpoint blockers (antiprogrammed death-ligand 1 antibodies), the antitumor effect was improved further with no systemic toxicity as chemo-immuno-chemodynamic combination therapeutics despite the absence of targeting ligands and external stimuli.

Combination chemotherapeutic and immune-therapeutic anticancer approach via anti-PD-L1 antibody conjugated albumin nanoparticles

Anticancer regimens have been substantially enriched through monoclonal antibodies targeting immune checkpoints, programmed cell death-1/programmed cell death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte antigen-4. Inconsistent clinical efficacy after solo immunotherapy may be compensated by nanotechnology-driven combination therapy. We loaded human serum albumin (HSA) nanoparticles with paclitaxel (PTX) via nanoparticle albumin-bound technology and pooled them with anti-PD-L1 monoclonal antibody through a pH-sensitive linker for targeting and immune response activation. Our tests demonstrated satisfactory preparation of paclitaxel-loaded, PD-L1-targeted albumin nanoparticles (PD-L1/PTX@HSA). They had small particle size (~200 nm) and polydispersity index (~0.12) and successfully incorporated each constituent. Relative to normal physiological pH, the formulation exhibited higher drug-release profiles favoring cancer cell-targeted release at low pH. Modifying nanoparticles with programmed cell death-ligand 1 increased cancer cell internalization in vitro and tumor accumulation in vivo in comparison with non-PD-L1-modified nanoparticles. PD-L1/PTX@HSA constructed by nanoparticle albumin-bound technology displayed successful tumor inhibition efficacy both in vitro and in vivo. There was successful effector T-cell infiltration, immunosuppressive programmed cell death-ligand 1, and regulatory T-cell suppression because of cytotoxic T-lymphocyte antigen-4 synergy. Moreover, PD-L1/PTX@HSA had low organ toxicity. Hence, the anti-tumor immune responses of PD-L1/PTX@HSA combined with chemotherapy and cytotoxic T-lymphocyte antigen-4 is a potential anti-tumor strategy for improving quantitative and qualitative clinical efficacy.

The Fate of Nanoparticles In Vivo and the Strategy of Designing Stealth Nanoparticle for Drug Delivery

Nano-drug delivery systems (Nano-DDS) offer powerful advantages in drug delivery and targeted therapy for diseases. Compared to the traditional drug formulations, Nano-DDS can increase solubility, biocompatibility, and reduce off-targeted side effects of free drugs. However, they still have some disadvantages that pose a limitation in reaching their full potential in clinical use. Protein adsorption in blood, activation of the complement system, and subsequent sequestration by the mononuclear phagocyte system (MPS) consequently result in nanoparticles (NPs) to be rapidly cleared from circulation. Therefore, NPs have low drug delivery efficiency. So, it is important to develop stealth NPs for reducing bio-nano interaction. In this review, we first conclude the interaction between NPs and biological environments, such as blood proteins and MPS, and factors influencing each other. Next, we will summarize the new strategies to reduce NPs protein adsorption and uptake by the MPS based on current knowledge of the bio-nano interaction. Further directions will also be highlighted for the development of biomimetic stealth nano-delivery systems by combining targeted strategies for a better therapeutic effect.

Orchestration of biomimetic membrane coating and nanotherapeutics in personalized anticancer therapy

Nanoparticle-based therapeutic and detectable modalities can augment anticancer efficiency, holding potential in capable target and suppressive metastases post administration. However, the individual discrepancies of the current "one-size-fits-all" strategies for anticancer nanotherapeutics have heralded the need for "personalized therapy". Benefiting from the special inherency of various cells, diverse cell membrane-coated nanoparticles (CMCNs) were established on a patient-by-patient basis, which would facilitate the personalized treatment of individual cancer patients. CMCNs in a complex microenvironment can evade the immune system and target homologous tumors with a suppressed immune response, as well as a prolonged circulation time, consequently increasing the drug accumulation at the tumor site and anticancer therapeutic efficacy. This review focuses on the emerging strategies and advances of CMCNs to synergistically integrate the merit of source cells with nanoparticulate delivery systems for the orchestration of personalized anticancer nanotherapeutics, thus discussing their rationalities in facilitating chemotherapy, imaging, immunotherapy, phototherapy, radiotherapy, sonodynamic, magnetocaloric, chemodynamic and gene therapy. Furthermore, the mechanism, challenges and opportunities of CMCNs in personalized anticancer therapy were highlighted to further boost cooperation from different fields, including materials science, chemistry, medicine, pharmacy and biology for the lab-to-clinic translation of CMCNs combined with the individual advantages of source cells and nanotherapeutics.

Emerging nanotaxanes for cancer therapy

The clinical application of taxane (including paclitaxel, docetaxel, and cabazitaxel)-based formulations is significantly impeded by their off-target distribution, unsatisfactory release, and acquired resistance/metastasis. Recent decades have witnessed a dramatic progress in the development of high-efficiency, low-toxicity nanotaxanes via the use of novel biomaterials and nanoparticulate drug delivery systems (nano-DDSs). Thus, in this review, the achievements of nanotaxanes-targeted delivery and stimuli-responsive nano-DDSs-in preclinical or clinical trials have been outlined. Then, emerging nanotherapeutics against tumor resistance and metastasis have been overviewed, with a particular emphasis on synergistic therapy strategies (e.g., combination with surgery, chemotherapy, radiotherapy, biotherapy, immunotherapy, gas therapy, phototherapy, and multitherapy). Finally, the latest oral nanotaxanes have been briefly discussed.

Detection of Viruses and Virus-Neutralizing Antibodies Using Synthetic Erythrocytes: Toward a Tuneable Tool for Virus Surveillance

The hemagglutination inhibition assay (HAI) is a classical method used worldwide in many analytical applications, including pathogen identification, vaccine production monitoring, and detection and characterization of pathogen-neutralizing antibodies (n-Ab). This is also a World Health Organization (WHO) reference method for the global surveillance of influenza viruses, which provides the information needed for the annual reformulation of the flu vaccine. HAI is a simple and inexpensive method that is performed without sophisticated equipment. However, it has to be carried out with fresh red blood cells (RBCs), a highly variable, unstable, and hard to mass-produce reagent, which impairs assay reproducibility. Here, we used the tests employed for influenza surveillance as a model to develop synthrocytes^©, a synthetic reagent that could substitute animal erythrocytes in HAI. Contrary to previous examples exploiting sophisticated production paths to generate therapeutic synthetic RBCs, we founded production on the identification of microparticles able to generate different sedimentation patterns when agglutinated or not, which is the main requirement for HAI testing. Upon incorporation of influenza-binding receptors and optimization of production and assay conditions, synthrocytes succeeded in binding influenza A(H1N1) and B viruses as erythrocytes do, but were faster and more stable. Synthrocytes were finally employed in an HAI-like assay to detect the WHO reference reagents for influenza surveillance. Our results show that it is possible to substitute erythrocytes in classical HAI by a highly tuneable and potentially mass-produced synthetic reagent, which should facilitate worldwide HAI standardization with minimal equipment or training requirements.