Erythrocyte-inspired delivery systems

Recent progress in biomimetic nanomedicines based on versatile targeting strategy for atherosclerosis therapy

Atherosclerosis (AS) is considered to be one of the major causes of cardiovascular disease. Its pathological microenvironment is characterised by increased production of reactive oxygen species, lipid oxides, and excessive inflammatory factors, which accumulate at the monolayer endothelial cells in the vascular wall to form AS plaques. Therefore, intervention in the pathological microenvironment would be beneficial in delaying AS. Researchers have designed biomimetic nanomedicines with excellent biocompatibility and the ability to avoid being cleared by the immune system through different therapeutic strategies to achieve better therapeutic effects for the characteristics of AS. Biomimetic nanomedicines can further enhance delivery efficiency and improve treatment efficacy due to their good biocompatibility and ability to evade clearance by the immune system. Biomimetic nanomedicines based on therapeutic strategies such as neutralising inflammatory factors, ROS scavengers, lipid clearance and integration of diagnosis and treatment are versatile approaches for effective treatment of AS. The review firstly summarises the targeting therapeutic strategy of biomimetic nanomedicine for AS in recent 5 years. Biomimetic nanomedicines using cell membranes, proteins, and extracellular vesicles as carriers have been developed for AS.

Invasive metastatic tumor-camouflaged ROS responsive nanosystem for targeting therapeutic brain injury after cardiac arrest

Drug transmission through the blood-brain barrier (BBB) is considered an arduous challenge for brain injury treatment following the return of spontaneous circulation after cardiac arrest (CA-ROSC). Inspired by the propensity of melanoma metastasis to the brain, B16F10 cell membranes are camouflaged on 2-methoxyestradiol (2ME2)-loaded reactive oxygen species (ROS)-triggered "Padlock" nanoparticles that are constructed by phenylboronic acid pinacol esters conjugated D-a-tocopheryl polyethylene glycol succinate (TPGS-PBAP). The biomimetic nanoparticles (BM@TP/2ME2) can be internalized, mainly mediated by the mutual recognition and interaction between CD44v6 expressed on B16F10 cell membranes and hyaluronic acid on cerebral vascular endothelial cells, and they responsively release 2ME2 by the oxidative stress microenvironment. Notably, BM@TP/2ME2 can scavenge excessive ROS to reestablish redox balance, reverse neuroinflammation, and restore autophagic flux in damaged neurons, eventually exerting a remarkable neuroprotective effect after CA-ROSC in vitro and in vivo. This biomimetic drug delivery system is a novel and promising strategy for the treatment of cerebral ischemia-reperfusion injury after CA-ROSC.

Fibrinogen binding to activated platelets and its biomimetic thrombus-targeted thrombolytic strategies

Thrombosis is associated with various fatal arteriovenous syndromes including ischemic stroke, myocardial infarction, and pulmonary embolism. However, current clinical thrombolytic treatment strategies still have many problems in targeting and safety to meet the thrombolytic therapy needs. Understanding the molecular mechanism that underlies thrombosis is critical in developing effective thrombolytic strategies. It is well known that platelets play a central role in thrombosis and the binding of fibrinogen to activated platelets is a common pathway in the process of clot formation. Based on this, a concept of biomimetic thrombus-targeted thrombolytic strategy inspired from fibrinogen binding to activated platelets in thrombosis was proposed, which could selectively bind to activated platelets at a thrombus site, thus enabling targeted delivery and local release of thrombolytic agents for effective thrombolysis. In this review, we first summarized the main characteristics of platelets and fibrinogen, and then introduced the classical molecular mechanisms of thrombosis, including platelet adhesion, platelet activation and platelet aggregation through the interactions of activated platelets with fibrinogen. In addition, we highlighted the recent advances in biomimetic thrombus-targeted thrombolytic strategies which inspired from fibrinogen binding to activated platelets in thrombosis. The possible future directions and perspectives in this emerging area are briefly discussed.

Effect of Polymer and Cell Membrane Coatings on Theranostic Applications of Nanoparticles: A Review

The recent decade has witnessed a remarkable surge in the field of nanoparticles, from their synthesis, characterization, and functionalization to diverse applications. At the nanoscale, these particles exhibit distinct physicochemical properties compared to their bulk counterparts, enabling a multitude of applications spanning energy, catalysis, environmental remediation, biomedicine, and beyond. This review focuses on specific nanoparticle categories, including magnetic, gold, silver, and quantum dots (QDs), as well as hybrid variants, specifically tailored for biomedical applications. A comprehensive review and comparison of prevalent chemical, physical, and biological synthesis methods are presented. To enhance biocompatibility and colloidal stability, and facilitate surface modification and cargo/agent loading, nanoparticle surfaces are coated with different synthetic polymers and very recently, cell membrane coatings. The utilization of polymer- or cell membrane-coated nanoparticles opens a wide variety of biomedical applications such as magnetic resonance imaging (MRI), hyperthermia, photothermia, sample enrichment, bioassays, drug delivery, etc. With this review, the goal is to provide a comprehensive toolbox of insights into polymer or cell membrane-coated nanoparticles and their biomedical applications, while also addressing the challenges involved in translating such nanoparticles from laboratory benchtops to in vitro and in vivo applications. Furthermore, perspectives on future trends and developments in this rapidly evolving domain are provided.

Cell-membrane engineering strategies for clinic-guided design of nanomedicine

Cells are the fundamental units of life. The cell membrane primarily composed of two layers of phospholipids (a bilayer) structurally defines the boundary of a cell, which can protect its interior from external disturbances and also selectively exchange substances and conduct signals from the extracellular environment. The complexity and particularity of transmembrane proteins provide the foundation for versatile cellular functions. Nanomedicine as an emerging therapeutic strategy holds tremendous potential in the healthcare field. However, it is susceptible to recognition and clearance by the immune system. To overcome this bottleneck, the technology of cell membrane coating has been extensively used in nanomedicines for their enhanced therapeutic efficacy, attributed to the favorable fluidity and biocompatibility of cell membranes with various membrane-anchored proteins. Meanwhile, some engineering strategies of cell membranes through various chemical, physical and biological ways have been progressively developed to enable their versatile therapeutic functions against complex diseases. In this review, we summarized the potential clinical applications of four typical cell membranes, elucidated their underlying therapeutic mechanisms, and outlined their current engineering approaches. In addition, we further discussed the limitation of this technology of cell membrane coating in clinical applications, and possible solutions to address these challenges.

Current Progress in the Science of Novel Adjuvant Nano-Vaccine-Induced Protective Immune Responses

Vaccinations are vital as they protect us from various illness-causing agents. Despite all the advancements in vaccine-related research, developing improved and safer vaccines against devastating infectious diseases including Ebola, tuberculosis and acquired immune deficiency syndrome (AIDS) remains a significant challenge. In addition, some of the current human vaccines can cause adverse reactions in some individuals, which limits their use for massive vaccination program. Therefore, it is necessary to design optimal vaccine candidates that can elicit appropriate immune responses but do not induce side effects. Subunit vaccines are relatively safe for the vaccination of humans, but they are unable to trigger an optimal protective immune response without an adjuvant. Although different types of adjuvants have been used for the formulation of vaccines to fight pathogens that have high antigenic diversity, due to the toxicity and safety issues associated with human-specific adjuvants, there are only a few adjuvants that have been approved for the formulation of human vaccines. Recently, nanoparticles (NPs) have gain specific attention and are commonly used as adjuvants for vaccine development as well as for drug delivery due to their excellent immune modulation properties. This review will focus on the current state of adjuvants in vaccine development, the mechanisms of human-compatible adjuvants and future research directions. We hope this review will provide valuable information to discovery novel adjuvants and drug delivery systems for developing novel vaccines and treatments.

Sensitive delivery systems and novel encapsulation technologies for live biotherapeutic products and probiotics

Live biotherapeutic product (LBP), a type of biological product, holds promise for the prevention or treatment of metabolic disease and pathogenic infection. Probiotics are live microorganisms that improve the intestinal microbial balance and beneficially affect the health of the host when ingested in sufficient numbers. These biological products possess the advantages of inhibition of pathogens, degradation of toxins, and modulation of immunity. The application of LBP and probiotic delivery systems has attracted great interest to researchers. The initial used technologies for LBP and probiotic encapsulation are traditional capsules and microcapsules. However, the stability and targeted delivery capability require further improved. The specific sensitive materials can greatly improve the delivery efficiency of LBPs and probiotics. The specific sensitive delivery systems show advantages over traditional ones due to their better properties of biocompatibility, biodegradability, innocuousness, and stability. Moreover, some new technologies, including layer-by-layer encapsulation, polyelectrolyte complexation, and electrohydrodynamic technology, show great potential in LBP and probiotic delivery. In this review, novel delivery systems and new technologies of LBPs and probiotics were presented, and the challenges and prospects were explored in specific sensitive materials for LBP and probiotic delivery.

Recent Progress of Bioinspired Cell Membrane in Cancer Immunotherapy

By modifying immune cells, immunotherapy can activate immune response to establish long-term immune memory and prevent tumor recurrence. However, their effectiveness is largely constricted by the poor immunogenicity, immune escape, and immune tolerance of the tumor. This is related to the characteristics of the tumor itself, such as genome instability and mutation. The combination of various nanocarriers with tumor immunotherapy is beneficial for overcoming the shortcomings of traditional immunotherapy. Nanocarriers coated by cell membranes can extend blood circulation time, improve ability to evade immune clearance, and enhance targeting, thus significantly enhancing the efficacy of immunotherapy and showing great potential in tumor immunotherapy. This article reviews the application research progress of different types of cell membrane-modified nanocarriers in tumor immunotherapy, immunotherapy combination therapy, and tumor vaccines, and provides prospects for future research.

Cell Membrane-Coated Biomimetic Nanoparticles in Cancer Treatment

Nanoparticle-based drug delivery systems hold promise for cancer treatment by enhancing the solubility and stability of anti-tumor drugs. Nonetheless, the challenges of inadequate targeting and limited biocompatibility persist. In recent years, cell membrane nano-biomimetic drug delivery systems have emerged as a focal point of research and development, due to their exceptional traits, including precise targeting, low toxicity, and good biocompatibility. This review outlines the categorization and advantages of cell membrane bionic nano-delivery systems, provides an introduction to preparation methods, and assesses their applications in cancer treatment, including chemotherapy, gene therapy, immunotherapy, photodynamic therapy, photothermal therapy, and combination therapy. Notably, the review delves into the challenges in the application of various cell membrane bionic nano-delivery systems and identifies opportunities for future advancement. Embracing cell membrane-coated biomimetic nanoparticles presents a novel and unparalleled avenue for personalized tumor therapy.

Nanoparticles in tumor microenvironment remodeling and cancer immunotherapy

Cancer immunotherapy and vaccine development have significantly improved the fight against cancers. Despite these advancements, challenges remain, particularly in the clinical delivery of immunomodulatory compounds. The tumor microenvironment (TME), comprising macrophages, fibroblasts, and immune cells, plays a crucial role in immune response modulation. Nanoparticles, engineered to reshape the TME, have shown promising results in enhancing immunotherapy by facilitating targeted delivery and immune modulation. These nanoparticles can suppress fibroblast activation, promote M1 macrophage polarization, aid dendritic cell maturation, and encourage T cell infiltration. Biomimetic nanoparticles further enhance immunotherapy by increasing the internalization of immunomodulatory agents in immune cells such as dendritic cells. Moreover, exosomes, whether naturally secreted by cells in the body or bioengineered, have been explored to regulate the TME and immune-related cells to affect cancer immunotherapy. Stimuli-responsive nanocarriers, activated by pH, redox, and light conditions, exhibit the potential to accelerate immunotherapy. The co-application of nanoparticles with immune checkpoint inhibitors is an emerging strategy to boost anti-tumor immunity. With their ability to induce long-term immunity, nanoarchitectures are promising structures in vaccine development. This review underscores the critical role of nanoparticles in overcoming current challenges and driving the advancement of cancer immunotherapy and TME modification.

Artificial cells for in vivo biomedical applications through red blood cell biomimicry

Recent research in artificial cell production holds promise for the development of delivery agents with therapeutic effects akin to real cells. To succeed in these applications, these systems need to survive the circulatory conditions. In this review we present strategies that, inspired by the endurance of red blood cells, have enhanced the viability of large, cell-like vehicles for in vivo therapeutic use, particularly focusing on giant unilamellar vesicles. Insights from red blood cells can guide modifications that could transform these platforms into advanced drug delivery vehicles, showcasing biomimicry's potential in shaping the future of therapeutic applications.

Erythrocytes Nanoparticle Delivery: A Boon for Targeting Tumor

Although nanoparticles (NPs) have many advantages as drug delivery systems, their poor stability in circulation, premature drug release, and nonspecific uptake in non-target organs have prompted biomimetic approaches to camouflage nano vehicles using natural cell membranes. Among them, which are extensively studied in erythrocytes, are the most abundant circulating blood cells. They are specially used for biomimetic coating on artificial NPs due to their excellent properties of good biocompatibility, biodegradability, non-immunogenicity, and long-term blood circulation. Erythrocyte-mimicking nanoparticles (EM-NPs) are prepared by combining nanoparticle cores with naturally derived erythrocyte (red blood cell or RBC) membranes. Compared with conventional nanosystems, EM-NPs hold the preferable characteristics of prolonged blood circulation time and immune evasion. In this review, the biomimetic platform of erythrocyte membrane-coated NPs is described in various aspects, with particular focus placed on the coating mechanism, preparation methods, characterization method, and recent advances in the biomedical applications of EM-NPs concerning cancer and targeted delivery.

Red blood cell-derived materials for cancer therapy: Construction, distribution, and applications

Cancer has become an increasingly important public health issue owing to its high morbidity and mortality rates. Although traditional treatment methods are relatively effective, they have limitations such as highly toxic side effects, easy drug resistance, and high individual variability. Meanwhile, emerging therapies remain limited, and their actual anti-tumor effects need to be improved. Nanotechnology has received considerable attention for its development and application. In particular, artificial nanocarriers have emerged as a crucial approach for tumor therapy. However, certain deficiencies persist, including immunogenicity, permeability, targeting, and biocompatibility. The application of erythrocyte-derived materials will help overcome the above problems and enhance therapeutic effects. Erythrocyte-derived materials can be acquired via the application of physical and chemical techniques from natural erythrocyte membranes, or through the integration of these membranes with synthetic inner core materials using cell membrane biomimetic technology. Their natural properties such as biocompatibility and long circulation time make them an ideal choice for drug delivery or nanoparticle biocoating. Thus, red blood cell-derived materials are widely used in the field of biomedicine. However, further studies are required to evaluate their efficacy, in vivo metabolism, preparation, design, and clinical translation. Based on the latest research reports, this review summarizes the biology, synthesis, characteristics, and distribution of red blood cell-derived materials. Furthermore, we provide a reference for further research and clinical transformation by comprehensively discussing the applications and technical challenges faced by red blood cell-derived materials in the treatment of malignant tumors.

Translational Challenges and Prospective Solutions in the Implementation of Biomimetic Delivery Systems

Biomimetic delivery systems (BDSs), inspired by the intricate designs of biological systems, have emerged as a groundbreaking paradigm in nanomedicine, offering unparalleled advantages in therapeutic delivery. These systems, encompassing platforms such as liposomes, protein-based nanoparticles, extracellular vesicles, and polysaccharides, are lauded for their targeted delivery, minimized side effects, and enhanced therapeutic outcomes. However, the translation of BDSs from research settings to clinical applications is fraught with challenges, including reproducibility concerns, physiological stability, and rigorous efficacy and safety evaluations. Furthermore, the innovative nature of BDSs demands the reevaluation and evolution of existing regulatory and ethical frameworks. This review provides an overview of BDSs and delves into the multifaceted translational challenges and present emerging solutions, underscored by real-world case studies. Emphasizing the potential of BDSs to redefine healthcare, we advocate for sustained interdisciplinary collaboration and research. As our understanding of biological systems deepens, the future of BDSs in clinical translation appears promising, with a focus on personalized medicine and refined patient-specific delivery systems.

Targeted therapy of breast tumor by PLGA-based nanostructures: The versatile function in doxorubicin delivery

Breast carcinoma is a molecularly diverse illness, and it is among the most prominent and often reported malignancies in female across the globe. Surgical intervention, chemotherapy, immunotherapy, gene therapy, and endocrine treatment are among the currently viable treatment options for the carcinoma of breast. Chemotherapy is among the most prevalent cancer management strategy. Doxorubicin (DOX) widely employed as a cytostatic medication for the treatment of a variety of malignancies. Despite its widespread acceptance and excellent efficacy against an extensive line up of neoplasia, it has a variety of shortcomings that limit its therapeutic potential in the previously mentioned indications. Employment of nanoparticulate systems has come up as a unique chemo medication delivery strategy and are being considerably explored for the amelioration of breast carcinoma. Polylactic-co-glycolic acid (PLGA)-based nano systems are being utilized in a number of areas within the medical research and medication delivery constitutes one of the primary functions for PLGA given their inherent physiochemical attributes, including their aqueous solubility, biocompatibility, biodegradability, versatility in formulation, and limited toxicity. Herein along with the different application of PLGA-based nano formulations in cancer therapy, the present review intends to describe the various research investigations that have been conducted to enumerate the effectiveness of DOX-encapsulated PLGA nanoparticles (DOX-PLGA NPs) as a feasible treatment option for breast cancer.

Surface Functionalization of Gold Nanoparticles for Targeting the Tumor Microenvironment to Improve Antitumor Efficiency

Gold nanoparticles (AuNPs) have undergone significant research for their use in the treatment of cancer. Numerous researchers have established their potent antitumor properties, which have greatly impacted the treatment of cancer. AuNPs have been used in four primary anticancer treatment modalities, namely radiation, photothermal therapy, photodynamic therapy, and chemotherapy. However, the ability of AuNPs to destroy cancer is lacking and can even harm healthy cells without the right direction to transport them to the tumor microenvironment. Consequently, a suitable targeting technique is needed. Based on the distinct features of the human tumor microenvironment, this review discusses four different targeting strategies that target the four key features of the tumor microenvironment, including abnormal vasculature, overexpression of specific receptors, an acidic microenvironment, and a hypoxic microenvironment, to direct surface-functionalized AuNPs to the tumor microenvironment and increase antitumor efficacies. In addition, some current completed or ongoing clinical trials of AuNPs will also be discussed below to further reinforce the concept of using AuNPs in anticancer therapy.

Thermal-controlled cellular uptake of "hot" nanoparticles

Nanoparticles (NPs) have shown immense potential in the field of biomedical applications, particularly in NP-based photothermal therapy, which offers a remote-controlled approach to achieve precise temperature control for site-specific heating and sub-cellular tumor treatment. However, the molecular mechanisms underlying related cellular activities, such as the cellular uptake behavior of irradiated NPs in photothermal effects, remain elusive. In this study, we conducted a thorough investigation of the interaction between an irradiated NP with elevated temperature (ranging from 270 to 360 K) and a model bilayer membrane composed of DPPC or DOPC using nonequilibrium coarse-grained molecular dynamics simulations with the implicit-solvent Dry Martini force field. We observe that the interaction between a "hot" NP and a membrane is thermally regulated. In addition, the wrapping of membranes around NPs exhibits a strong dependence on the temperature of the irradiated NP, demonstrating a step-like change in behavior. This membrane wrapping effect is attributed to the heat conduction between NPs and membrane lipids, which occurs almost simultaneously with the membrane deformation and wrapping of NPs during the NP-membrane interaction process. Especially, during the process of heat conduction, a gel-to-fluid phase transition of the membrane may occur, which plays a crucial role in determining the deformation behavior of the membrane. Moreover, it is found that the membrane lipids in the two leaflets exhibit obvious and asymmetric molecular-level responses to heat flux, characterized by significant changes in packing states (e.g., the order parameter of lipid tails and area per lipid) and possible interdigitation between lipids. Furthermore, the thermal-controlled wrapping effect is tightly linked to the properties of NPs (e.g., size, NP-lipid affinity) and lipid species. Our findings are valuable for comprehending the thermal-regulated cellular internalization of NPs and offer insights into devising strategies to precisely modulate NP endocytosis by exploiting the interplay between heating and NP properties.

"Bioinspired" Membrane-Coated Nanosystems in Cancer Theranostics: A Comprehensive Review

Achieving precise cancer theranostics necessitates the rational design of smart nanosystems that ensure high biological safety and minimize non-specific interactions with normal tissues. In this regard, "bioinspired" membrane-coated nanosystems have emerged as a promising approach, providing a versatile platform for the development of next-generation smart nanosystems. This review article presents an in-depth investigation into the potential of these nanosystems for targeted cancer theranostics, encompassing key aspects such as cell membrane sources, isolation techniques, nanoparticle core selection, approaches for coating nanoparticle cores with the cell membrane, and characterization methods. Moreover, this review underscores strategies employed to enhance the multi-functionality of these nanosystems, including lipid insertion, membrane hybridization, metabolic engineering, and genetic modification. Additionally, the applications of these bioinspired nanosystems in cancer diagnosis and therapeutics are discussed, along with the recent advances in this field. Through a comprehensive exploration of membrane-coated nanosystems, this review provides valuable insights into their potential for precise cancer theranostics.

Biomimetic and bioinspired nano-platforms for cancer vaccine development

The advent of immunotherapy has revolutionized the treating modalities of cancer. Cancer vaccine, aiming to harness the host immune system to induce a tumor-specific killing effect, holds great promises for its broad patient coverage, high safety, and combination potentials. Despite promising, the clinical translation of cancer vaccines faces obstacles including the lack of potency, limited options of tumor antigens and adjuvants, and immunosuppressive tumor microenvironment. Biomimetic and bioinspired nanotechnology provides new impetus for the designing concepts of cancer vaccines. Through mimicking the stealth coating, pathogen recognition pattern, tissue tropism of pathogen, and other irreplaceable properties from nature, biomimetic and bioinspired cancer vaccines could gain functions such as longstanding, targeting, self-adjuvanting, and on-demand cargo release. The specific behavior and endogenous molecules of each type of living entity (cell or microorganism) offer unique features to cancer vaccines to address specific needs for immunotherapy. In this review, the strategies inspired by eukaryotic cells, bacteria, and viruses will be overviewed for advancing cancer vaccine development. Our insights into the future cancer vaccine development will be shared at the end for expediting the clinical translation.

Cell membrane-coated nanomaterials for cancer therapy

With the development of nanotechnology, nanoparticles have emerged as a delivery carrier for tumor drug therapy, which can improve the therapeutic effect by increasing the stability and solubility and prolonging the half-life of drugs. However, nanoparticles are foreign substances for humans, are easily cleared by the immune system, are less targeted to tumors, and may even be toxic to the body. As a natural biological material, cell membranes have unique biological properties, such as good biocompatibility, strong targeting ability, the ability to evade immune surveillance, and high drug-carrying capacity. In this article, we review cell membrane-coated nanoparticles (CMNPs) and their applications to tumor therapy. First, we briefly describe CMNP characteristics and applications. Second, we present the characteristics and advantages of different cell membranes as well as nanoparticles, provide a brief description of the process of CMNPs, discuss the current status of their application to tumor therapy, summarize their shortcomings for use in cancer therapy, and propose future research directions. This review summarizes the research progress on CMNPs in cancer therapy in recent years and assesses remaining problems, providing scholars with new ideas for future research on CMNPs in tumor therapy.

Stealth and pseudo-stealth nanocarriers

The stealth effect plays a central role on capacitating nanomaterials for drug delivery applications through improving the pharmacokinetics such as blood circulation, biodistribution, and tissue targeting. Here based on a practical analysis of stealth efficiency and a theoretical discussion of relevant factors, we provide an integrated material and biological perspective in terms of engineering stealth nanomaterials. The analysis surprisingly shows that more than 85% of the reported stealth nanomaterials encounter a rapid drop of blood concentration to half of the administered dose within 1 h post administration although a relatively long β-phase is observed. A term, pseudo-stealth effect, is used to delineate this common pharmacokinetics behavior of nanomaterials, that is, dose-dependent nonlinear pharmacokinetics because of saturating or depressing bio-clearance of RES. We further propose structural holism can be a watershed to improve the stealth effect; that is, the whole surface structure and geometry play important roles, rather than solely relying on a single factor such as maximizing repulsion force through polymer-based steric stabilization (e.g., PEGylation) or inhibiting immune attack through a bio-inspired component. Consequently, engineering delicate structural hierarchies to minimize attractive binding sites, that is, minimal charges/dipole and hydrophobic domain, becomes crucial. In parallel, the pragmatic implementation of the pseudo-stealth effect and dynamic modulation of the stealth effect are discussed for future development.

Genetically engineered cellular nanoparticles for biomedical applications

In recent years, nanoparticles derived from cellular membranes have been increasingly explored for the prevention and treatment of human disease. With their flexible design and ability to interface effectively with the surrounding environment, these biomimetic nanoparticles can outperform their traditional synthetic counterparts. As their popularity has increased, researchers have developed novel ways to modify the nanoparticle surface to introduce new or enhanced capabilities. Moving beyond naturally occurring materials derived from wild-type cells, genetic manipulation has proven to be a robust and flexible method by which nanoformulations with augmented functionalities can be generated. In this review, an overview of genetic engineering approaches to express novel surface proteins is provided, followed by a discussion on the various biomedical applications of genetically modified cellular nanoparticles.

Nanomedicine-mediated therapeutic approaches for pulmonary arterial hypertension

Nanomedicine has emerged as a field in which there are opportunities to improve the diagnosis, treatment and prevention of incurable diseases. Pulmonary arterial hypertension (PAH) is known as a severe and fatal disease affecting children and adults. Conventional treatments have not produced optimal effectiveness in treating this condition. Several reasons for this include drug instability, poor solubility of the drug and a shortened duration of pharmacological action. The present review focuses on new approaches for delivering anti-PAH drugs using nanotechnology with the aim of overcoming these shortcomings and increasing their efficacy. Solid-lipid nanoparticles, liposomes, metal-organic frameworks and polymeric nanoparticles have demonstrated advantages for the potential treatment of PAH, including increased drug bioavailability, drug solubility and accumulation in the lungs.

Red blood cell membrane-camouflaged poly(lactic-co-glycolic acid) microparticles as a potential controlled release drug delivery system for local stellate ganglion microinjection

The stellate ganglion (SG) is a part of the sympathetic nervous system that has important regulatory effects on several human tissues and organs in the upper body. SG block and intervention have been clinically and preclinically implemented to manage chronic pain in the upper extremities, neck, head, and upper chest as well as chronic heart failure. However, there has been very limited effort to develop and investigate polymer-based drug delivery systems for local delivery to the SG. In this study, we fabricated red blood cell (RBC) membrane-camouflaged poly(lactic-co-glycolic acid) (PLGA) (PLGAM) microparticles for use as a potential long-term controlled release system for local drug delivery. The structure, size, and surface zeta potential results indicated that the spherical PLGAM microparticles were successfully fabricated. Both PLGA and PLGAM microparticles exhibited biocompatibility with human adipose mesenchymal stem cells (ADMSC) and satellite glial cells and showed hemocompatibility. In addition, both PLGA and PLGAM displayed no significant effects on the secretion of proinflammatory cytokines by human monocyte derived macrophages in vitro. We microinjected microparticles into rat SGs and evaluated the retention time of microparticles and the effects of the microparticles on inflammation in vivo over 21 days. Subsequently, we fabricated drug-loaded PLGAM microparticles by using GW2580, a colony stimulating factor-1 receptor inhibitor, as a model drug and assessed its encapsulation efficiency, drug release profiles, biocompatibility, and anti-inflammatory effects in vitro. Our results demonstrated the potential of PLGAM microparticles for long-term controlled local drug release in the SG. STATEMENT OF SIGNIFICANCE: SG block by locally injecting therapeutics to inhibit the activity of the sympathetic nerves provides a valuable benefit to manage chronic pain and chronic heart failure. We describe the fabrication of RBC membrane-camouflaged PLGA microparticles with cytocompatibility, hemocompatibility, and low immunogenicity, and demonstrate that they can be successfully and safely microinjected into rat SGs. The microparticle retention time within SG is over 21 days without eliciting detectable inflammation. Furthermore, we incorporate a CSF-1R inhibitor as a model drug and demonstrate the capacities of long-term drug release and regulation of macrophage functions. The strategies demonstrate the feasibility to locally microinject therapeutics loaded microparticles into SGs and pave the way for further efficacy and disease treatment evaluation.

Biomimetic nanoparticles for DC vaccination: a versatile approach to boost cancer immunotherapy

Cancer immunotherapy, which harnesses the immune system to fight cancer, has begun to make a breakthrough in clinical applications. Dendritic cells (DCs) are the bridge linking innate and adaptive immunity and the trigger of tumor immune response. Considering the cumbersome process and poor efficacy of classic DC vaccines, there has been interest in transferring the field of in vitro-generated DC vaccines to nanovaccines. Conventional nanoparticles have insufficient targeting ability and are easily cleared by the reticuloendothelial system. Biological components have evolved very specific functions, which are difficult to fully reproduce with synthetic materials, making people interested in using the further understanding of biological systems to prepare nanoparticles with new and enhanced functions. Biomimetic nanoparticles are semi-biological or nature-derived delivery systems comprising one or more natural materials, which have a long circulation time in vivo and excellent performance of targeting DCs, and can mimic the antigen-presenting behavior of DCs. In this review, we introduce the classification, design, preparation, and challenges of different biomimetic nanoparticles, and discuss their application in activating DCs in vivo and stimulating T cell antitumor immunity. Incorporating biomimetic nanoparticles into cancer immunotherapy has shown outstanding advantages in precisely coaxing the immune system against cancer.

Cell Membrane Biomimetic Nanoparticles with Potential in Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is to blame for about 60% of dementia cases worldwide. The blood-brain barrier (BBB) prevents many medications for AD from having clinical therapeutic effects that can be used to treat the affected area. Many researchers have turned their attention to cell membrane biomimetic nanoparticles (NPs) to solve this situation. Among them, NPs can extend the half-life of drugs in the body as the "core" of the wrapped drug, and the cell membrane acts as the "shell" of the wrapped NPs to functionalize the NPs, which can further improve the delivery efficiency of nano-drug delivery systems. Researchers are learning that cell membrane biomimetic NPs can circumvent the BBB's restriction, prevent harm to the body's immune system, extend the period that NPs spend in circulation, and have good biocompatibility and cytotoxicity, which increases efficacy of drug release. This review summarized the detailed production process and features of core NPs and further introduced the extraction methods of cell membrane and fusion methods of cell membrane biomimetic NPs. In addition, the targeting peptides for modifying biomimetic NPs to target the BBB to demonstrate the broad prospects of cell membrane biomimetic NPs drug delivery systems were summarized.

Biomimetic cell membrane-coated poly(lactic-co-glycolic acid) nanoparticles for biomedical applications

Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) are commonly used for drug delivery because of their favored biocompatibility and suitability for sustained and controlled drug release. To prolong NP circulation time, enable target-specific drug delivery and overcome physiological barriers, NPs camouflaged in cell membranes have been developed and evaluated to improve drug delivery. Here, we discuss recent advances in cell membrane-coated PLGA NPs, their preparation methods, and their application to cancer therapy, management of inflammation, treatment of cardiovascular disease and control of infection. We address the current challenges and highlight future research directions needed for effective use of cell membrane-camouflaged NPs.

Nucleus-Targeting Manganese Dioxide Nanoparticles Coated with the Human Umbilical Cord Mesenchymal Stem Cell Membrane for Cancer Cell Therapy

Recently, development of drug delivery systems for accurate delivery of antitumor drugs to tumor sites to improve their antitumor efficacy has attracted great interest in the area of cancer immunotherapy. In this report, an intelligent biodegradable hollow manganese dioxide (HMnO₂) nanoparticle (NP) with a human umbilical cord mesenchymal stem cell (hUC-MSC) membrane coating was designed to exert efficient chemo-immunotherapy for cancer treatment. A TAT peptide-modified membrane structure was constructed for nuclear targeting. Our findings showed that this new nanoreactor inherited the active targeting capability of MSCs and exhibited tumoritropic accumulation significantly at the cancerous parts. Compared with other formulations, intravenous injection of the NPs markedly inhibited tumor growth, relapse, and metastasis. Moreover, we found that the NPs effectively boosted dendritic cell maturation and recruited effector T cells into tumors. Overall, this work demonstrates the great potential of applying MSC membrane-coated manganese dioxide NPs as nucleus-targeting nanocarriers in cancer chemo-immunotherapy.

Generation of Red Blood Cell Nanovesicles as a Delivery Tool

Extracellular vesicles (EVs) are natural membranous vesicles with immense potential as drug delivery tools. However, their large-scale production remains a huge technical challenge, is time consuming, and expensive. Thus, EV mimetics (nanovesicles) generated from easily sourced red blood cells (RBCs) have gained vested interest as an effective and scalable drug delivery system. Their surface proteins (e.g., CD47) inherited from parental RBCs also improve their biocompatibility and bioavailability. Here, we outline a step-by-step guide for large-scale production of RBC nanovesicles using one-step extrusion method coupled to rapid density-cushion centrifugation. We also outline protocol for their extensive biophysical characterization (size and morphology using single particle analysis and cryogenic electron microscopy), and in-depth mass spectrometry-based proteome characterization. Finally, we outline two strategies (active loading during extrusion vs. passive loading via diffusion) to incorporate pharmacological compound(s) into nanovesicles and detect their loading using spectrophotometry.

Biomimetic cell membrane-coated nanocarriers for targeted siRNA delivery in cancer therapy

Small interfering RNA (siRNA) therapeutics for cancer are a focus of increasing research interest. However, the major obstacle to their clinical application is the targeted delivery of siRNA to cancer cells at desirable levels. Cell membrane-coated nanocarriers have the advantage of combining the properties of both cell membranes and nanoparticles (NPs). In this review, we highlight the most common RNAi therapeutics and the extracellular and intracellular barriers to siRNA delivery. Moreover, we discuss clinical applications of different cell membrane-coated nanocarriers for targeted siRNA delivery, including cancer cell membranes (CCMs), platelet membranes, erythrocyte membranes, stem cell membranes, exosome membranes, and hybrid membranes. Taken together, biomimetic cell membrane-coated nanotechnology is a promising strategy for targeted siRNA delivery for cancer treatment.

Erythrocyte-Inspired Functional Materials for Biomedical Applications

Erythrocytes are the most abundant cells in the blood. As the results of long-term natural selection, their specific biconcave discoid morphology and cellular composition are responsible for gaining excellent biological performance. Inspired by the intrinsic features of erythrocytes, various artificial biomaterials emerge and find broad prospects in biomedical applications such as therapeutic delivery, bioimaging, and tissue engineering. Here, a comprehensive review from the fabrication to the applications of erythrocyte-inspired functional materials is given. After summarizing the biomaterials mimicking the biological functions of erythrocytes, the synthesis strategies of particles with erythrocyte-inspired morphologies are presented. The emphasis is on practical biomedical applications of these bioinspired functional materials. The perspectives for the future possibilities of the advanced erythrocyte-inspired biomaterials are also discussed. It is hoped that the summary of existing studies can inspire researchers to develop novel biomaterials; thus, accelerating the progress of these biomaterials toward clinical biomedical applications.

"Hook&Loop" multivalent interactions based on disk-shaped nanoparticles strengthen active targeting

How to enhance active targeting efficiency remains a challenge. Multivalent interactions play a crucial role in improving the binding ability between ligands and receptors. It is hypothesized that nanoparticles bearing a flat conformation attain simultaneous formation of multiple ligand-receptor bindings, which could be vividly metaphorized by the "Hook&Loop" rationale. In this study, spherical, rod-shaped and disk-shaped folic acid-modified red blood cell membrane-coated biomimetic mesoporous silica nanoparticles (FRMSNs) were prepared to verify the shape-based multivalent interactions. The fundamental concepts of multivalent interactions have been proved by a series of both in vitro and in vivo evaluations. Physical characterization confirmed the morphology, shape and surface features of FRMSNs. Strengthened binding and internalization of disk-shaped FRMSNs by K562 cells stresses the merits of multivalent interactions. Whereas Bio-TEM visually demonstrates the proposed "plane" contact of disk-shaped particles with cells, quantification further confirmed strengthened "plane" binding affinity with folate binding proteins owing to multivalent interactions. In K562 xenograft mice, doxorubicin-loaded disk-shaped FRMSNs effectively slowed down chronic myeloid leukemia progression. It is concluded that disks favor multivalent interactions which leads to enhanced active targeting efficiency.

Cell-Based Drug Delivery Systems with Innate Homing Capability as a Novel Nanocarrier Platform

Nanoparticle-based drug delivery systems have been designed to treat various diseases. However, many problems remain, such as inadequate tumor targeting and poor therapeutic outcomes. To overcome these obstacles, cell-based drug delivery systems have been developed. Candidates for cell-mediated drug delivery include blood cells, immune cells, and stem cells with innate tumor tropism and low immunogenicity; they act as a disguise to deliver the therapeutic payload. In drug delivery systems, therapeutic agents are encapsulated intracellularly or attached to the surface of the plasma membrane and transported to the desired site. Here, we review the pros and cons of cell-based therapies and discuss their homing mechanisms in the tumor microenvironment. In addition, different strategies to load therapeutic agents inside or on the surface of circulating cells and the current applications for a wide range of disease treatments are summarized.

Red blood cell-based vaccines for ameliorating cancer chemoimmunotherapy

Immune checkpoint blockade (ICB) therapy has shown promising antitumor effects, but its immune response rate remains unsatisfactory. In recent years, chemotherapy has been proven to have synergistic effects with ICB therapy because some chemotherapeutic agents can enhance the immunogenicity of tumor cells by inducing immunogenic cell death (ICD). However, it cannot be ignored that chemotherapy often shows limited therapeutic efficacy due to high cytotoxicity, drug resistance, and some other side effects. Herein, we report a strategy to improve cancer immunotherapy by utilizing red blood cell-based vaccines (RBC-vaccines) where chemotherapy-induced tumor antigens (cAgs) are anchored onto red blood cells (RBCs) via the EDC/NHS-mediated amine coupling reaction. In this work, RBC-vaccines administered subcutaneously are primarily devoured by dendritic cells (DCs) and significantly improve the efficacy of αPD-1 (anti-programmed cell death 1) treatment by increasing the infiltration of intratumoral CD8⁺ and CD4⁺ T cells and elevating the intratumoral ratio of CD8⁺ T cells to regulatory T cells in the CT-26 colon cancer model. Finally, based on the rejection of tumor rechallenge in cured mice, the combination therapy of RBC-vaccines and αPD-1 can induce the expansion of memory T cells and thereby establish a long-term antitumor immune response. Taken together, the proposed RBC-vaccines have great potential to improve chemoimmunotherapy. STATEMENT OF SIGNIFICANCE: Immunotherapy, especially immune checkpoint blockade therapy, has made great contributions to the treatment of some advanced cancers. Unfortunately, the great majority of patients with cancer do not benefit from immunotherapy. To enhance the response rate of immunotherapy, we developed red blood cell-based vaccines (RBC-vaccines) against cancers where antigens were harvested from chemotherapy-treated cancer cells and then attached to erythrocytes via covalent surface modification. Such RBC-vaccines could provide a wide variety of tumor antigens and damage-associated molecular patterns without the use of any extra ingredients to trigger a stronger antitumor immune response. More importantly, the combination of RBC-vaccines with PD-1 blockade could significantly improve the efficacy of cancer immunotherapy and induce durable antitumor immunity.

Synergistic chemotherapy and phototherapy based on red blood cell biomimetic nanomaterials

Novel drug delivery systems (DDSs) have become the mainstay of research in targeted cancer therapy. By combining different therapeutic strategies, potential DDSs and synergistic treatment approaches are needed to effectively deal with evolving drug resistance and the adverse effects of cancer. Nowadays, developing and optimizing human cell-based DDSs has become a new research strategy. Among them, red blood cells can be used as DDSs as they significantly enhance the pharmacokinetics of the transported drug cargo. Phototherapy, as a novel adjuvant in cancer treatment, can be divided into photodynamic therapy and photothermal therapy. Phototherapy using erythropoietic nanocarriers to mimic the unique properties of erythrocytes and overcome the limitations of existing DDSs shows excellent prospects in clinical settings. This review provides an overview of the development of photosensitizers and research on bio-nano-delivery systems based on erythrocytes and erythrocyte membranes that are used in achieving synergistic outcomes during phototherapy/chemotherapy.

Hemolytic Activity of Nanoparticles as a Marker of Their Hemocompatibility

The potential use of nanomaterials in medicine offers opportunities for novel therapeutic approaches to treating complex disorders. For that reason, a new branch of science, named nanotoxicology, which aims to study the dangerous effects of nanomaterials on human health and on the environment, has recently emerged. However, the toxicity and risk associated with nanomaterials are unclear or not completely understood. The development of an adequate experimental strategy for assessing the toxicity of nanomaterials may include a rapid/express method that will reliably, quickly, and cheaply make an initial assessment. One possibility is the characterization of the hemocompatibility of nanomaterials, which includes their hemolytic activity as a marker. In this review, we consider various factors affecting the hemolytic activity of nanomaterials and draw the reader's attention to the fact that the formation of a protein corona around a nanoparticle can significantly change its interaction with the red cell. This leads us to suggest that the nanomaterial hemolytic activity in the buffer does not reflect the situation in the blood plasma. As a recommendation, we propose studying the hemocompatibility of nanomaterials under more physiologically relevant conditions, in the presence of plasma proteins in the medium and under mechanical stress.

Biomimetic Dp44mT-nanoparticles selectively induce apoptosis in Cu-loaded glioblastoma resulting in potent growth inhibition

Selective targeting of elevated copper (Cu) in cancer cells by chelators to induce tumor-toxic reactive oxygen species (ROS) may be a promising approach in the treatment of glioblastoma multiforme (GBM). Previously, the Cu chelator di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT) attracted much interest due to its potent anti-tumor activity mediated by the formation of a highly redox-active Cu-Dp44mT complex. However, its translational potential was limited by the development of toxicity in murine models of cancer reflecting poor selectivity. Here, we overcame the limitations of Dp44mT by incorporating it in new biomimetic nanoparticles (NPs) optimized for GBM therapy. Biomimetic design elements enhancing selectivity included angiopeptide-2 functionalized red blood cell membrane (Ang-M) camouflaging of the NPs carrier. Co-loading Dp44mT with regadenoson (Reg), that transiently opens the blood-brain-barrier (BBB), yielded biomimetic Ang-MNPs@(Dp44mT/Reg) NPs that actively targeted and traversed the BBB delivering Dp44mT specifically to GBM cells. To further improve selectivity, we innovatively pre-loaded GBM tumors with Cu. Oral dosing of U87MG-Luc tumor bearing mice with diacetyl-bis(4-methylthiosemicarbazonato)-copperII (Cu(II)-ATSM), significantly enhanced Cu-level in GBM tumor. Subsequent treatment of mice bearing Cu-enriched orthotopic U87MG-Luc GBM with Ang-MNPs@(Dp44mT/Reg) substantially prevented orthotopic GBM growth and led to maximal increases in median survival time. These results highlighted the importance of both angiopeptide-2 functionalization and tumor Cu-loading required for greater selective cytotoxicity. Targeting Ang-MNPs@(Dp44mT/Reg) NPs also down-regulated antiapoptotic Bcl-2, but up-regulated pro-apoptotic Bax and cleaved-caspase-3, demonstrating the involvement of the apoptotic pathway in GBM suppression. Notably, Ang-MNPs@(Dp44mT/Reg) showed negligible systemic drug toxicity in mice, further indicating therapeutic potential that could be adapted for other central nervous system disorders.

Aptamer-Modified Erythrocyte Membrane-Coated pH-Sensitive Nanoparticles for c-Met-Targeted Therapy of Glioblastoma Multiforme

Biomimetic drug delivery systems, especially red blood cell (RBC) membrane-based nanoparticle drug delivery systems (RNP), have been extensively utilized in tumor drug delivery because of their excellent biocompatibility and prolonged circulation. In this study, we developed an active targeting pH-sensitive RNP loaded with DOX by decorating an aptamer SL1 on RBC membranes (SL1-RNP-DOX) for c-Met-targeted therapy of glioblastoma multiforme (GBM). SL1 could specifically bind to c-Met, which is highly expressed in GBM U87MG cells and facilitate DOX delivery to GBM cells. In vitro studies demonstrated that U87MG cells had a higher uptake of SL1-RNP-DOX (3.25 folds) and a stronger pro-apoptosis effect than unmodified RNP-DOX. In vivo fluorescence imaging and tissue distribution further demonstrated the higher tumor distribution of SL1-RNP-DOX (2.17 folds) compared with RNP-DOX. As a result, SL1-RNP-DOX presented the best anti-GBM effect with a prolonged median survival time (23 days vs. 15.5 days) and the strongest tumor cell apoptosis in vivo among all groups. In conclusion, SL1-RNP-DOX exhibited a promising targeting delivery strategy for GBM therapy.

Novel nano-encapsulated probiotic agents: Encapsulate materials, delivery, and encapsulation systems

Gut microbes are closely associated with most human health. When ingested orally, probiotics can effectively regulate the composition and quantity of human intestinal microorganisms, which is beneficial to human health. However, probiotics will be affected by the harsh environment of the digestive tract during the in vivo transportation process, and ensuring the viability of probiotics is a great challenge. Probiotic encapsulating technology provides an effective solution to this problem. The introduction of extreme temperatures, large probiotic microcapsule sizes and the difficulty in controlling probiotic microcapsule particle sizes mean that traditional microcapsule encapsulation methods have some limitations. From traditional microcapsule technology to the bulk encapsulation of probiotics with nanofibers and nanoparticles to the recent ability to wear nano "armor" for a single probiotic through biofilm, biological membrane and nanocoating. Emerging probiotic nanoagents provides a new conceptual and development direction for the field of probiotic encapsulation. In this review, we presented the characteristics of encapsulated probiotic carrier materials and digestive tract transport systems, we focused on the encapsulation systems of probiotic nanoagents, we analyzed the shortcomings and advantages of the current agent encapsulation systems, and we stated the developmental direction and challenges for these agents for the future.

Red Blood Cell Inspired Strategies for Drug Delivery: Emerging Concepts and New Advances

In the past five decades, red blood cells (RBCs) have been extensively explored as drug delivery systems due to their distinguishing potential in modulating the pharmacokinetic, pharmacodynamics, and biological activity of carried payloads. The extensive interests in RBC-mediated drug delivery technologies are in part derived from RBCs' unique biological features such as long circulation time, wide access to many tissues in the body, and low immunogenicity. Owing to these outstanding properties, a large body of efforts have led to the development of various RBC-inspired strategies to enable precise drug delivery with enhanced therapeutic efficacy and reduced off-target toxicity. In this review, we discuss emerging concepts and new advances in such RBC-inspired strategies, including native RBCs, ghost RBCs, RBC-mimetic nanoparticles, and RBC-derived extracellular vesicles, for drug delivery.

Cell membrane-based biomimetic nanosystems for advanced drug delivery in cancer therapy: A comprehensive review

Natural types of cells display distinct characteristics with homotypic targeting and extended circulation in the blood, which are worthy of being explored as promising drug delivery systems (DDSs) for cancer therapy. To enhance their delivery efficiency, these cells can be combined with therapeutic agents and artificial nanocarriers to construct the next generation of DDSs in the form of biomimetic nanomedicines. In this review, we present the recent advances in cell membrane-based DDSs (CDDSs) and their applications for efficient cancer therapy. Different sources of cell membranes are discussed, mainly including red blood cells (RBC), leukocytes, cancer cells, stem cells and hybrid cells. Moreover, the extraction methods used for obtaining such cells and the mechanism contributing to the functional action of these biomimetic CDDSs are explained. Finally, a future perspective is proposed to highlight the limitations of CDDSs and the possible resolutions toward clinical transformation of currently developed biomimetic chemotherapies.

Cell membrane-camouflaged inorganic nanoparticles for cancer therapy

Inorganic nanoparticles (INPs) have been paid great attention in the field of oncology in recent past years since they have enormous potential in drug delivery, gene delivery, photodynamic therapy (PDT), photothermal therapy (PTT), bio-imaging, driven motion, etc. To overcome the innate limitations of the conventional INPs, such as fast elimination by the immune system, low accumulation in tumor sites, and severe toxicity to the organism, great efforts have recently been made to modify naked INPs, facilitating their clinical application. Taking inspiration from nature, considerable researchers have exploited cell membrane-camouflaged INPs (CMCINPs) by coating various cell membranes onto INPs. CMCINPs naturally inherit the surface adhesive molecules, receptors, and functional proteins from the original cell membrane, making them versatile as the natural cells. In order to give a timely and representative review on this rapidly developing research subject, we highlighted recent advances in CMCINPs with superior unique merits of various INPs and natural cell membranes for cancer therapy applications. The opportunity and obstacles of CMCINPs for clinical translation were also discussed. The review is expected to assist researchers in better eliciting the effect of CMCINPs for the management of tumors and may catalyze breakthroughs in this area.

Immunogenic Cell Death Activates the Tumor Immune Microenvironment to Boost the Immunotherapy Efficiency

Tumor immunotherapy is only effective in a fraction of patients due to a low response rate and severe side effects, and these challenges of immunotherapy in clinics can be addressed through induction of immunogenic cell death (ICD). ICD is elicited from many antitumor therapies to release danger associated molecular patterns (DAMPs) and tumor‐associated antigens to facilitate maturation of dendritic cells (DCs) and infiltration of cytotoxic T lymphocytes (CTLs). The process can reverse the tumor immunosuppressive microenvironment to improve the sensitivity of immunotherapy. Nanostructure‐based drug delivery systems (NDDSs) are explored to induce ICD by incorporating therapeutic molecules for chemotherapy, photosensitizers (PSs) for photodynamic therapy (PDT), photothermal conversion agents for photothermal therapy (PTT), and radiosensitizers for radiotherapy (RT). These NDDSs can release loaded agents at a right dose in the right place at the right time, resulting in greater effectiveness and lower toxicity. Immunotherapeutic agents can also be combined with these NDDSs to achieve the synergic antitumor effect in a multi‐modality therapeutic approach. In this review, NDDSs are harnessed to load multiple agents to induce ICD by chemotherapy, PDT, PTT, and RT in combination of immunotherapy to promote the therapeutic effect and reduce side effects associated with cancer treatment.

Morphological Characteristics, Hemoglobin Content, and Membrane Mechanical Properties of Red Blood Cell Delivery Systems

Red blood cell (RBC)-based systems are under extensive development as platforms for the delivery of various biomedical agents. While the importance of the membrane biochemical characteristics in relation to circulation kinetics of RBC delivery systems has been recognized, the membrane mechanical properties of such carriers have not been extensively studied. Using optical methods in conjunction with image analysis and mechanical modeling, we have quantified the morphological and membrane mechanical characteristics of RBC-derived microparticles containing the near-infrared cargo indocyanine green (ICG). We find that these particles have a significantly lower surface area, volume, and deformability as compared to normal RBCs. The residual hemoglobin has a spatially distorted distribution in the particles. The membrane bending modulus of the particles is about twofold higher as compared to normal RBCs and exhibits greater resistance to flow. The induced increase in the viscous characteristics of the membrane is dominant over the elastic and entropic effects of ICG. Our results suggest that changes to the membrane mechanical properties are a result of impaired membrane-cytoskeleton attachment in these particles. We provide a mechanistic explanation to suggest that the compromised membrane-cytoskeleton attachment and altered membrane compositional and structural asymmetry induce curvature changes to the membrane, resulting in mechanical remodeling of the membrane. These findings highlight the importance of membrane mechanical properties as an important criterion in the design and engineering of future generations of RBC-based delivery systems to achieve prolonged circulation.

Recent Progress in Red Blood Cells-Derived Particles as Novel Bioinspired Drug Delivery Systems: Challenges and Strategies for Clinical Translation

Red Blood Cells (RBCs)-derived particles are an emerging group of novel drug delivery systems. The natural attributes of RBCs make them potential candidates for use as a drug carrier or nanoparticle camouflaging material as they are innately biocompatible. RBCs have been studied for multiple decades in drug delivery applications but their evolution in the clinical arena are considerably slower. They have been garnering attention for the unique capability of conserving their membrane proteins post fabrication that help them to stay non-immunogenic in the biological environment prolonging their circulation time and improving therapeutic efficiency. In this review, we discuss about the synthesis, significance, and various biomedical applications of the above-mentioned classes of engineered RBCs. This article is focused on the current state of clinical translation and the analysis of the hindrances associated with the transition from lab to clinic applications.

Cell-derived membrane biomimetic nanocarriers for targeted therapy of pulmonary disease

Pulmonary diseases are currently one of the major threats of human health, especially considering the recent COVID-19 pandemic. However, the current treatments are facing the challenges like insufficient local drug concentrations, the fast lung clearance and risks to induce unexpected inflammation. Cell-derived membrane biomimetic nanocarriers are recently emerged delivery strategy, showing advantages of long circulation time, excellent biocompatibility and immune escape ability. In this review, applications of using cell-derived membrane biomimetic nanocarriers from diverse cell sources for the targeted therapy of pulmonary disease were summarized. In addition, improvements of the cell-derived membrane biomimetic nanocarriers for augmented therapeutic ability against different kinds of pulmonary diseases were introduced. This review is expected to provide a general guideline for the potential applications of cell-derived membrane biomimetic nanocarriers to treat pulmonary diseases.

Cyclic arginine-glycine-aspartic acid-modified red blood cells for drug delivery: Synthesis and in vitro evaluation

Red blood cells (RBCs) are an excellent choice for cell preparation research because of their biocompatibility, high drug loading, and long half-life. In this study, doxorubicin (DOX) was encapsulated with RBCs as the carrier. The biotin-avidin system binding principle was used to modify biotinylated cyclic arginine-glycine-aspartic acid (cRGD) onto RBC surfaces for accurate targeting, high drug loading, and sustained drug release. The RBC drug delivery system (DDS) was characterized, and the concentration of surface sulfur in the energy spectrum was 6.330%. The physical and chemical properties of RBC DDS were as follows: drug content, 0.857 mg/mL; particle size, 3339 nm; potential value, -12.5 mV; and cumulative release rate, 81.35%. There was no significant change in RBC morphology for up to seven days. The results of the targeting and cytotoxicity studies of RBC DDS showed that many RBCs covered the surfaces of U251 cells, and the fluorescence intensity was higher than that of MCF-7 cells. The IC50 value of unmodified drug-loaded RBCs was 2.5 times higher than that of targeted modified drug-loaded RBCs, indicating that the targeting of cancer cells produced satisfactory inhibition. This study confirms that the RBC DDS has the characteristics of accurate targeting, high drug loading, and slow drug release, which increases its likelihood of becoming a clinical cancer treatment in the future.

Delivery strategies in treatments of leukemia

Leukemia is a hematological malignancy associated with the uncontrolled proliferation of mutant progenitors, suppressing the production of normal blood cells. Current treatments, including chemotherapy, radiotherapy, and immunotherapy, still lead to unsatisfactory results with a 5 year survival rate of only 30-50%. The poor prognosis is related to both disease relapse and treatment-associated toxicity. Delivery strategies can improve the in vivo pharmacokinetics of drugs, navigating the therapeutics to target cells or the tumor microenvironment and reversing drug resistance, which maximizes tumor elimination and alleviates systematic adverse effects. This review discusses available FDA-approved anti-leukemia drugs and therapies with a focus on the advances in the development of anti-leukemia drug delivery systems. Additionally, challenges in clinical translation of the delivery strategies and future research opportunities in leukemia treatment are also included.

Nanoparticle protein corona evolution: from biological impact to biomarker discovery

Nanoparticles exposed to biological fluids such as blood, quickly interact with their surrounding milieu resulting in a biological coating that results in large part as a function of the physicochemical properties of the nanomaterial. The large nanoparticle surface area-to-volume ratio further augments binding of biological molecules and the resulting biomolecular or protein corona, once thought of as problematic biofouling, is now viewed as a rich source of biological information that can guide the development of nanomedicines. This review gives an overview of the utility of the protein corona in proteomic profiling and discusses how a better understanding of nano-bio interactions can accelerate the clinical translation of nanomedicines and facilitate the identification of disease-specific biomarkers. With the FDA requirement of the protein corona analysis of nanoparticles in place, it is envisaged that analyzing the protein corona of nanoparticles on a case-by-case basis can provide highly valuable nano-bio interface information that can aid and improve their clinical translation.