Effective and Targeted Human Orthotopic Glioblastoma Xenograft Therapy via a Multifunctional Biomimetic Nanomedicine

Cell-Based Drug Delivery Systems Participate in the Cancer Immunity Cycle for Improved Cancer Immunotherapy

Immunotherapy aims to activate the cancer patient's immune system for cancer therapy. The whole process of the immune system against cancer referred to as the "cancer immunity cycle", gives insight into how drugs can be designed to affect every step of the anticancer immune response. Cancer immunotherapy such as immune checkpoint inhibitor (ICI) therapy, cancer vaccines, as well as small molecule modulators has been applied to fight various cancers. However, the effect of immunotherapy in clinical applications is still unsatisfactory due to the limited response rate and immune-related adverse events. Mounting evidence suggests that cell-based drug delivery systems (DDSs) with low immunogenicity, superior targeting, and prolonged circulation have great potential to improve the efficacy of cancer immunotherapy. Therefore, with the rapid development of cell-based DDSs, understanding their important roles in various stages of the cancer immunity cycle guides the better design of cell-based cancer immunotherapy. Herein, an overview of how cell-based DDSs participate in cancer immunotherapy at various stages is presented and an outlook on possible challenges of clinical translation and application in future development.

Efficiently targeted therapy of glioblastoma xenograft via multifunctional biomimetic nanodrugs

BACKGROUND

Glioblastoma multiforme (GBM) is a fatal malignant primary brain tumor in adults. The therapeutic efficacy of chemotherapeutic drugs is limited due to the blood-brain barrier (BBB), poor drug targeting, and short biological half-lives. Multifunctional biomimetic nanodrugs have great potential to overcome these limitations of chemotherapeutic drugs.

METHODS

We synthesized and characterized a biomimetic nanodrug CMS/PEG-DOX-M. The CMS/PEG-DOX-M effectively and rapidly released DOX in U87 MG cells. Cell proliferation and apoptosis assays were examined by the MTT and TUNEL assays. The penetration of nanodrugs through the BBB and anti-tumor efficacy were investigated in the orthotopic glioblastoma xenograft models.

RESULTS

We showed that CMS/PEG-DOX-M inhibited cell proliferation of U87 MG cells and effectively induced cell apoptosis of U87 MG cells. Intracranial antitumor experiments showed that free DOX hardly penetrated the BBB, but CMS/PEG-DOX-M effectively reached the orthotopic intracranial tumor through the BBB and significantly inhibited tumor growth. Immunofluorescence staining of orthotopic tumor tissue sections confirmed that nanodrugs promoted apoptosis of tumor cells. This study developed a multimodal nanodrug treatment system with the enhanced abilities of tumor-targeting, BBB penetration, and cancer-specific accumulation of chemotherapeutic drugs by combining chemotherapy and photothermal therapy. It can be used as a flexible and effective GBM treatment system and it may also be used for the treatment of other central nervous systems (CNS) tumors and extracranial tumors.

Fabrication and application of cisplatin-loaded mesoporous magnetic nanobiocomposite: a novel approach to smart cervical cancer chemotherapy

There are significant challenges in developing drug carriers for therapeutic perspective. We have investigated a novel nanocarrier system, based on combining functionalized magnetic nanocomposite with Metal–Organic Frameworks (MOFs). Magnetic nanoparticles modified using biocompatible copolymers may be suitable for delivering hydrophobic drugs, such as cisplatin. Furthermore, compared to polymeric nanocarriers, nanocomposite constructed from zeolitic imidazolate framework-8 (ZIF-8) have demonstrated better drug loading capacity, as well as excellent pH-triggered drug release. Cisplatin-encapsulated Fe3O4@SiO2-ZIF-8@N-Chit-FA has been evaluated to determine the antitumor effects of free cisplatin enhancement in cervical cancer cells. In order to increase the stability of the proposed nanocarrier in aqueous solutions, in addition to the density of functional groups, a nano-chitosan layer was coated on top of the magnetic nanocomposite. It was then added with cisplatin onto the surface of Fe3O4@SiO2-ZIF-8@N-Chit-FA to deliver anticancer treatment that could be targeted using a magnetic field. A mouse isograft model of TC1 cells was used to evaluate the in vivo tumor growth inhibition. In tumor-bearing mice, Fe3O4@SiO2-ZIF-8@N-Chit-FA-cisplatin was injected intraperitoneally, and the targeted delivery was amplified by an external magnet (10 mm by 10 mm, surface field strength 0.4 T) fixed over the tumor site. Based on in vivo results, cisplatin-Loaded Mesoporous Magnetic Nanobiocomposite inhibited the growth of cervical tumors (P < 0.001) through the induction of tumor necrosis (P < 0.05) when compared to cisplatin alone. With the application of an external magnetic field, the drug was demonstrated to be able to induce its effects on specific target areas. In summary, Fe3O4 @ SiO2-ZIF-8 @ N-Chit-FA nanocomposites have the potential to be implemented in targeted nanomedicine to deliver bio-functional molecules.

Glioma diagnosis and therapy: Current challenges and nanomaterial-based solutions

Glioma is often referred to as one of the most dreadful central nervous system (CNS)-specific tumors with rapidly-proliferating cancerous glial cells, accounting for nearly half of the brain tumors at an annual incidence rate of 30-80 per a million population. Although glioma treatment remains a significant challenge for researchers and clinicians, the rapid development of nanomedicine provides tremendous opportunities for long-term glioma therapy. However, several obstacles impede the development of novel therapeutics, such as the very tight blood-brain barrier (BBB), undesirable hypoxia, and complex tumor microenvironment (TME). Several efforts have been dedicated to exploring various nanoformulations for improving BBB permeation and precise tumor ablation to address these challenges. Initially, this article briefly introduces glioma classification and various pathogenic factors. Further, currently available therapeutic approaches are illustrated in detail, including traditional chemotherapy, radiotherapy, and surgical practices. Then, different innovative treatment strategies, such as tumor-treating fields, gene therapy, immunotherapy, and phototherapy, are emphasized. In conclusion, we summarize the article with interesting perspectives, providing suggestions for future glioma diagnosis and therapy improvement.

Micro-Nanocarriers Based Drug Delivery Technology for Blood-Brain Barrier Crossing and Brain Tumor Targeting Therapy

The greatest obstacle to using drugs to treat brain tumors is the blood-brain barrier (BBB), making it difficult for conventional drug molecules to enter the brain. Therefore, how to safely and effectively penetrate the BBB to achieve targeted drug delivery to brain tumors has been a challenging research problem. With the intensive research in micro- and nanotechnology in recent years, nano drug-targeted delivery technologies have shown great potential to overcome this challenge, such as inorganic nanocarriers, organic polymer-carriers, liposomes, and biobased carriers, which can be designed in different sizes, shapes, and surface functional groups to enhance their ability to penetrate the BBB and targeted drug delivery for brain tumors. In this review, the composition and overcoming patterns of the BBB are detailed, and then the hot research topics of drug delivery carriers for brain tumors in recent years are summarized, and their mechanisms of action on the BBB and the factors affecting drug delivery are described in detail, and the effectiveness of targeted therapy for brain tumors is evaluated. Finally, the challenges and dilemmas in developing brain tumor drug delivery systems are discussed, which will be promising in the future for targeted drug delivery to brain tumors based on micro-nanocarriers technology.

A Closed-Loop Autologous Erythrocyte-Mediated Delivery Platform for Diabetic Nephropathy Therapy

Failure to control blood glucose level (BGL) may aggravate oxidative stress and contribute to the development of diabetic nephropathy (DN). Using erythrocytes (ERs) as the carriers, a smart self-regulatory insulin (INS) release system was constructed to release INS according to changes in BGLs to improve patients' compliance and health. To overcome the limited sources of ERs and decrease the risk of transmitting infections, we developed an in vitro, closed-loop autologous ER-mediated delivery (CAER) platform, based on a commercial hemodialysis instrument modified with a glucose-responsive ER-based INS delivery system (GOx-INS@ER). After the blood was drained via a jugular vein cannula, some of the blood was pumped into the CAER platform. The INS was packed inside the autologous ERs in the INS reactor, and then their surface was modified with glucose oxidase (GOx), which acts as a glucose-activated switch. In vivo, the CAER platform showed that the BGL responsively controlled INS release in order to control hyperglycemia and maintain the BGL in the normal range for up to 3 days; plus, there was good glycemic control without the added burden of hemodialysis in DN rabbits. These results demonstrate that this closed-loop extracorporeal hemodialysis platform provides a practical approach for improving diabetes management in DN patients.

Advances in Preclinical/Clinical Glioblastoma Treatment: Can Nanoparticles Be of Help?

Glioblastoma multiforme (GB) is the most aggressive and frequent primary malignant tumor in the central nervous system (CNS), with unsatisfactory and challenging treatment nowadays. Current standard of care includes surgical resection followed by chemotherapy and radiotherapy. However, these treatments do not much improve the overall survival of GB patients, which is still below two years (the 5-year survival rate is below 7%). Despite various approaches having been followed to increase the release of anticancer drugs into the brain, few of them demonstrated a significant success, as the blood brain barrier (BBB) still restricts its uptake, thus limiting the therapeutic options. Therefore, enormous efforts are being devoted to the development of novel nanomedicines with the ability to cross the BBB and specifically target the cancer cells. In this context, the use of nanoparticles represents a promising non-invasive route, allowing to evade BBB and reducing systemic concentration of drugs and, hence, side effects. In this review, we revise with a critical view the different families of nanoparticles and approaches followed so far with this aim.

Inflammation-targeted nanomedicine against brain cancer: From design strategies to future developments

Brain cancer is an aggressive type of cancer with poor prognosis. While the immune system protects against cancer in the early stages, the tumor exploits the healing arm of inflammatory reactions to accelerate its growth and spread. Various immune cells penetrate the developing tumor region, establishing a pro-inflammatory tumor milieu. Additionally, tumor cells may release chemokines and cytokines to attract immune cells and promote cancer growth. Inflammation and its associated mechanisms in the progression of cancer have been extensively studied in the majority of solid tumors, especially brain tumors. However, treatment of the malignant brain cancer is hindered by several obstacles, such as the blood-brain barrier, transportation inside the brain interstitium, inflammatory mediators that promote tumor growth and invasiveness, complications in administering therapies to tumor cells specifically, the highly invasive nature of gliomas, and the resistance to drugs. To resolve these obstacles, nanomedicine could be a potential strategy that has facilitated advancements in diagnosing and treating brain cancer. Due to the numerous benefits provided by their small size and other features, nanoparticles have been a prominent focus of research in the drug-delivery field. The purpose of this article is to discuss the role of inflammatory mediators and signaling pathways in brain cancer as well as the recent advances in understanding the nano-carrier approaches for enhancing drug delivery to the brain in the treatment of brain cancer.

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.

Erythrocyte Membrane-Enveloped Salvianolic Acid B Nanoparticles Attenuate Cerebral Ischemia-Reperfusion Injury

Purpose

Ischemic stroke is the second leading cause of death and the third leading cause of disability worldwide. Salvianolic acid B (SAB), a water-soluble phenolic acid derived from the traditional Chinese medicine Salvia miltiorrhiza, exerted protective effects on cerebral ischemia-reperfusion injury. However, the efficacy of SAB is seriously hindered by poor blood brain barrier (BBB) permeability and short biological half-life in plasma. Brain targeted biomimetic nanoparticle delivery systems offer much promise in overcoming these limitations.

Methods

A brain targeted biomimetic nanomedicine (RR@SABNPs) was developed, which comprised of SAB loaded bovine serum albumin nanoparticles and functionalized red blood cell membrane (RBCM) with Arg-Gly-Asp (RGD). The characterization parameters, including particle size, zeta potential, morphology, Encapsulation Efficiency (EE), Drug Loading (DL), release behavior, stability, and biocompatibility, were investigated. Moreover, the middle cerebral artery occlusion/reperfusion (MCAO/R) mouse model was used to assess the therapeutic efficacy of RR@SABNPs on ischemic stroke. Finally, the reactive oxygen species (ROS) levels and mitochondrial membrane potential (MMP) were detected by DHE and JC‑1 staining in oxygen-glucose deprivation/reperfusion (OGD/R) and H₂O₂ injured PC12 cells.

Results

RR@SABNPs exhibited spheric morphology with core-shell structures and good stability and biocompatibility. Meanwhile, RR@SABNPs can significantly prolong SAB circulation time by overcoming the reticuloendothelial system (RES) and actively targeting ischemic BBB. Moreover, RR@SABNPs had comprehensive protective effects on MCAO/R model mice, manifested as a reduced infarct volume and improved neurological and sensorimotor functions, and significantly scavenged excess ROS and maintained MMP.

Conclusion

The designed brain targeted biomimetic nanomedicine RR@SABNPs can significantly prolong the half-time of SAB, deliver SAB into the ischemic brain and exhibit good therapeutic effects on MCAO/R model mice.

A tumor microenvironment-responsive micelle co-delivered radiosensitizer Dbait and doxorubicin for the collaborative chemo-radiotherapy of glioblastoma

Glioblastoma is rather recalcitrant to existing therapies and effective interventions are needed. Here we report a novel microenvironment-responsive micellar system (ch-K5(s-s)R8-An) for the co-delivery of the radiosensitizer Dbait and the chemotherapeutic doxorubicin (DOX) to glioblastoma. Accordingly, the ch-K5(s-s)R8-An/(Dbait-DOX) micelles plus radiotherapy (RT) treatment resulted in a high degree of apoptosis and DNA damage, which significantly reduced cell viability and proliferation capacity of U251 cells to 64.0% and 16.3%, respectively. The angiopep-2-modified micelles exhibited substantial accumulation in brain-localized U251 glioblastoma xenografts in mice compared to angiopep-2-lacking micelles. The ch-K5(s-s)R8-An/(Dbait-DOX) + RT treatment group exhibited the smallest tumor size and most profound tumor tissue injury in orthotopic U251 tumors, leading to an increase in median survival time of U251 tumor-bearing mice from 26 days to 56 days. The ch-K5(s-s)R8-An/(Dbait-DOX) micelles can be targeted to brain-localized U251 tumor xenografts and sensitize the tumor to chemotherapy and radiotherapy, thereby overcoming the inherent therapeutic challenges associated with malignant glioblastoma.

Recent advances in erythrocyte membrane-camouflaged nanoparticles for the delivery of anti-cancer therapeutics

INTRODUCTION

Red blood cell (or erythrocyte) membrane-camouflaged nanoparticles (RBC-NPs) not only have a superior circulation life and do not induce accelerated blood clearance, but also possess special functions, which offers great potential in cancer therapy.

AREAS COVERED

This review focuses on the recent advances of RBC-NPs for delivering various agents to treat cancers in light of their vital role in improving drug delivery. Meanwhile, the construction and in vivo behavior of RBC-NPs are discussed to provide an in-depth understanding of the basis of RBC-NPs for improved cancer drug delivery.

EXPERT OPINION

Although RBC-NPs are quite prospective in delivering anti-cancer therapeutics, they are still in their infancy stage and many challenges need to be overcome for successful translation into the clinic. The preparation and modification of RBC membranes, the optimization of coating methods, the scale-up production and the quality control of RBC-NPs, and the drug loading and release should be carefully considered in the clinical translation of RBC-NPs for cancer therapy.

Targeted liposomes for combined delivery of artesunate and temozolomide to resistant glioblastoma

The effective treatment of glioblastoma (GBM) is a great challenge because of the blood-brain barrier (BBB) and the growing resistance to single-agent therapeutics. Targeted combined co-delivery of drugs could circumvent these challenges; however, the absence of more effective combination drug delivery strategies presents a potent barrier. Here, a unique combination ApoE-functionalized liposomal nanoplatform based on artesunate-phosphatidylcholine (ARTPC) encapsulated with temozolomide (ApoE-ARTPC@TMZ) was presented that can successfully co-deliver dual therapeutic agents to TMZ-resistant U251-TR GBM in vivo. Examination in vitro showed ART-mediated inhibition of DNA repair through the Wnt/β-catenin signaling cascade, which also improved GBM sensitivity to TMZ, resulting in enhanced synergistic DNA damage and induction of apoptosis. In assessing BBB permeation, the targeted liposomes were able to effectively traverse the BBB through low-density lipoprotein family receptors (LDLRs)-mediated transcytosis and achieved deep intracranial tumor penetration. More importantly, the targeted combination liposomes resulted in a significant decrease of U251-TR glioma burden in vivo that, in concert, substantially improved the survival of mice. Additionally, by lowering the effective dosage of TMZ, the combination liposomes reduced systemic TMZ-induced toxicity, highlighting the preclinical potential of this novel integrative strategy to deliver combination therapies to brain tumors.

Brain Co-Delivery of Temozolomide and Cisplatin for Combinatorial Glioblastoma Chemotherapy

Glioblastoma (GBM) is an intractable malignancy with high recurrence and mortality. Combinatorial therapy based on temozolomide (TMZ) and cisplatin (CDDP) shows promising potential for GBM therapy in clinical trials. However, significant challenges include limited blood-brain-barrier (BBB) penetration, poor targeting of GBM tissue/cells, and systemic side effects, which hinder its efficacy in GBM therapy. To surmount these challenges, new GBM-cell membrane camouflaged and pH-sensitive biomimetic nanoparticles (MNPs) inspired by the fact that cancer cells readily pass the BBB and localize with homologous cells, are developed. This study's results show that MNPs can efficiently co-load TMZ and CDDP, transport these across the BBB to specifically target GBM. Incorporation of pH-sensitive polymer then allows for controlled release of drug cargos at GBM sites for combination drug therapy. Mice bearing orthotopic U87MG or drug-resistant U251^R GBM tumor and treated with MNPs@TMZ+CDDP show a potent anti-GBM effect, greatly extending the survival time relative to mice receiving single-drug loaded nanoparticles. No obvious side effects are apparent in histological analyses or blood routine studies. Considering these results, the study's new nanoparticle formulation overcomes multiple challenges currently limiting the efficacy of combined TMZ and CDDP GBM drug therapy and appears to be a promising strategy for future GBM combinatorial chemotherapy.

Brain co-delivery of first-line chemotherapy drug and epigenetic bromodomain inhibitor for multidimensional enhanced synergistic glioblastoma therapy

Glioblastoma (GBM) is a central nervous system tumor with poor prognosis due to the rapid development of resistance to mono chemotherapy and poor brain targeted delivery. Chemoimmunotherapy (CIT) combines chemotherapy drugs with activators of innate immunity that hold great promise for GBM synergistic therapy. Herein, we chose temozolomide, TMZ, and the epigenetic bromodomain inhibitor, OTX015, and further co-encapsulated them within our well-established erythrocyte membrane camouflaged nanoparticle to yield ApoE peptide decorated biomimetic nanomedicine (ABNM@TMZ/OTX). Our nanoplatform successfully addressed the limitations in brain-targeted drug co-delivery, and simultaneously achieved multidimensional enhanced GBM synergistic CIT. In mice bearing orthotopic GL261 GBM, treatment with ABNM@TMZ/OTX resulted in marked tumor inhibition and greatly extended survival time with little side effects. The pronounced GBM treatment efficacy can be ascribed to three key factors: (i) improved nanoparticle-mediated GBM targeting delivery of therapeutic agents by greatly enhanced blood circulation time and blood-brain barrier penetration; (ii) inhibited cellular DNA repair and enhanced TMZ sensitivity to tumor cells; (iii) enhanced anti-tumor immune responses by inducing immunogenic cell death and inhibiting PD-1/PD-L1 conjugation leading to enhanced expression of CD4+ and CD8+ T cells. The study validated a biomimetic nanomedicine to yield a potential new treatment for GBM.

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.

An update on dual targeting strategy for cancer treatment

The key issue in the treatment of solid tumors is the lack of efficient strategies for the targeted delivery and accumulation of therapeutic cargoes in the tumor microenvironment (TME). Targeting approaches are designed for more efficient delivery of therapeutic agents to cancer cells while minimizing drug toxicity to normal cells and off-targeting effects, while maximizing the eradication of cancer cells. The highly complicated interrelationship between the physicochemical properties of nanoparticles, and the physiological and pathological barriers that are required to cross, dictates the need for the success of targeting strategies. Dual targeting is an approach that uses both purely biological strategies and physicochemical responsive smart delivery strategies to increase the accumulation of nanoparticles within the TME and improve targeting efficiency towards cancer cells. In both approaches, either one single ligand is used for targeting a single receptor on different cells, or two different ligands for targeting two different receptors on the same or different cells. Smart delivery strategies are able to respond to triggers that are typical of specific disease sites, such as pH, certain specific enzymes, or redox conditions. These strategies are expected to lead to more precise targeting and better accumulation of nano-therapeutics. This review describes the classification and principles of dual targeting approaches and critically reviews the efficiency of dual targeting strategies, and the rationale behind the choice of ligands. We focus on new approaches for smart drug delivery in which synthetic and/or biological moieties are attached to nanoparticles by TME-specific responsive linkers and advanced camouflaged nanoparticles.

Synchronous Disintegration of Ferroptosis Defense Axis via Engineered Exosome-Conjugated Magnetic Nanoparticles for Glioblastoma Therapy

Glioblastoma (GBM) is one of the most fatal central nervous system tumors and lacks effective or sufficient therapies. Ferroptosis is a newly discovered method of programmed cell death and opens a new direction for GBM treatment. However, poor blood-brain barrier (BBB) penetration, reduced tumor targeting ability, and potential compensatory mechanisms hinder the effectiveness of ferroptosis agents during GBM treatment. Here, a novel composite therapeutic platform combining the magnetic targeting features and drug delivery properties of magnetic nanoparticles with the BBB penetration abilities and siRNA encapsulation properties of engineered exosomes for GBM therapy is presented. This platform can be enriched in the brain under local magnetic localization and angiopep-2 peptide-modified engineered exosomes can trigger transcytosis, allowing the particles to cross the BBB and target GBM cells by recognizing the LRP-1 receptor. Synergistic ferroptosis therapy of GBM is achieved by the combined triple actions of the disintegration of dihydroorotate dehydrogenase and the glutathione peroxidase 4 ferroptosis defense axis with Fe3 O4 nanoparticle-mediated Fe2+ release. Thus, the present findings show that this system can serve as a promising platform for the treatment of glioblastoma.

Engineering a HEK-293T exosome-based delivery platform for efficient tumor-targeting chemotherapy/internal irradiation combination therapy

Exosomes are nanoscale monolayer membrane vesicles that are actively endogenously secreted by mammalian cells. Currently, multifunctional exosomes with tumor-targeted imaging and therapeutic potential have aroused widespread interest in cancer research. Herein, we developed a multifunctional HEK-293T exosome-based targeted delivery platform by engineering HEK-293T cells to express a well-characterized exosomal membrane protein (Lamp2b) fused to the αv integrin-specific iRGD peptide and tyrosine fragments. This platform was loaded with doxorubicin (Dox) and labeled with radioiodine-131 (131I) using the chloramine-T method. iRGD exosomes showed highly efficient targeting and Dox delivery to integrin αvβ3-positive anaplastic thyroid carcinoma (ATC) cells as demonstrated by confocal imaging and flow cytometry in vitro and an excellent tumor-targeting capacity confirmed by single-photon emission computed tomography-computed tomography after labeling with 131I in vivo. In addition, intravenous injection of this vehicle delivered Dox and 131I specifically to tumor tissues, leading to significant tumor growth inhibition in an 8505C xenograft mouse model, while showing biosafety and no side effects. These as-developed multifunctional exosomes (denoted as Dox@iRGD-Exos-131I) provide novel insight into the current treatment of ATC and hold great potential for improving therapeutic efficacy against a wide range of integrin αvβ3-overexpressing tumors.

Lipid Nanoparticles as Platforms for Theranostic Purposes: Recent Advances in the Field

Lipid nanoparticles (LNPs) are the first approved nanomedicines and the most well-studied class of nanocarriers for drug delivery. Currently, they are in the frontline of the pandemic fight as vaccine formulations and therapeutic products. However, even though they are so well-studied, new materials and new modifications arise every day that can improve their properties. Their dynamic nature, especially the liquid crystal state of membranes, is under constant investigation and it is that which many times leads to their complex biological behavior. In addition, newly discovered biomaterials and nanoparticles that possess promising effects and functionalities, but also toxicity and/or poor pharmacokinetics, can be combined with LNPs to ameliorate their properties. As a result, many promising theranostic applications have emerged during the past decade, proving the huge potential of LNPs in the field. In the present review, we summarize some of the most prominent classes of LNPs for nanotheranostic purposes, and present state-of-the-art research examples, with emphasis on the utilized biomaterials and the functionality that they confer to the resultant supramolecular nanosystems, in relation to diagnostic and therapeutic modalities. Although there has been unprecedented progress in theranostics, the translational gap between the bench and the clinic is undeniable. This issue must be addressed by experts in a coordinated way, in order to fully exploit these nanomedicines for the benefit of the society.

Latest Advances in Biomimetic Cell Membrane-Coated and Membrane-Derived Nanovectors for Biomedical Applications

In the last decades, many nanovectors were developed for different diagnostic or therapeutic purposes. However, most nanosystems have been designed using a “bottom-up” approach, in which the basic components of the nanovector become assembled to achieve complex and specific behaviors. Despite the fine control of formulative conditions, the complexity of these systems often results cumbersome and difficult to scale-up. Recently, biomimetic materials emerged as a complementary or alternative design approach through a “top-down strategy”, using cell-derived materials as building blocks to formulate innovative nanovectors. The use of cell membranes as nanoparticle coatings endows nanomaterials with the biological identity and some of the functions of the cells they are derived from. In this review, we discuss some of the latest examples of membrane coated and membrane-derived biomimetic nanomaterials and underline the common general functions offered by the biomaterials used. From these examples, we suggest a systematic classification of these biomimetic materials based on their biological sources and formulation techniques, with their respective advantages and disadvantages, and summarize the current technologies used for membranes isolation and integration on nanovectors. We also discuss some current technical limitations and hint to future direction of the improvement for biomimetics.

Biomimetic Lipopolysaccharide-Free Bacterial Outer Membrane-Functionalized Nanoparticles for Brain-Targeted Drug Delivery

The blood-brain barrier (BBB) severely blocks the intracranial accumulation of most systemic drugs. Inspired by the contribution of the bacterial outer membrane to Escherichia coli K1 (EC-K1) binding to and invasion of BBB endothelial cells in bacterial meningitis, utilization of the BBB invasion ability of the EC-K1 outer membrane for brain-targeted drug delivery and construction of a biomimetic self-assembled nanoparticle with a surface featuring a lipopolysaccharide-free EC-K1 outer membrane are proposed. BBB penetration of biomimetic nanoparticles is demonstrated to occur through the transcellular vesicle transport pathway, which is at least partially dependent on internalization, endosomal escape, and transcytosis mediated by the interactions between outer membrane protein A and gp96 on BBB endothelial cells. This biomimetic nanoengineering strategy endows the loaded drugs with prolonged circulation, intracranial interstitial distribution, and extremely high biocompatibility. Based on the critical roles of gp96 in cancer biology, this strategy reveals enormous potential for delivering therapeutics to treat gp96-overexpressing intracranial malignancies.

Brain-Targeted Codelivery of Bcl-2/Bcl-xl and Mcl-1 Inhibitors by Biomimetic Nanoparticles for Orthotopic Glioblastoma Therapy

Glioblastoma (GBM) is among the most treatment-resistant solid tumors and often recurrs after resection. One of the mechanisms through which GBM escapes various treatment modalities is the overexpression of anti-apoptotic Bcl-2 family proteins (e.g., Bcl-2, Bcl-xl, and Mcl-1) in tumor cells. Small-molecule inhibitors such as ABT-263 (ABT), which can promote mitochondrial-mediated cell apoptosis by selectively inhibiting the function of Bcl-2 and Bcl-xl, have been proven to be promising anticancer agents in clinical trials. However, the therapeutic prospects of ABT for GBM treatment are hampered by its limited blood-brain barrier (BBB) penetration, dose-dependent thrombocytopenia, and the drug resistance driven by Mcl-1, which is overexpressed in GBM cells and further upregulated upon treatment with ABT. Herein, we reported that the Mcl-1-specific inhibitor A-1210477 (A12) can act synergistically with ABT to induce potent cell apoptosis in U87 MG cells, drug-resistant U251 cells, and patient-derived GBM cancer stem cells. We further designed a biomimetic nanomedicine, based on the apolipoprotein E (ApoE) peptide-decorated red blood cell membrane and pH-sensitive dextran nanoparticles, for the brain-targeted delivery of ABT and A12. The synergistic anti-GBM effect was retained after encapsulation in the nanomedicine. Additionally, the obtained nanomedicine possessed good biocompatibility, exhibited efficient BBB penetration, and could effectively suppress tumor growth and prolong the survival time of mice bearing orthotopic GBM xenografts without inducing detectable adverse effects.

Anti-Parkinsonian Therapy: Strategies for Crossing the Blood-Brain Barrier and Nano-Biological Effects of Nanomaterials

Parkinson's disease (PD), a neurodegenerative disease that shows a high incidence in older individuals, is becoming increasingly prevalent. Unfortunately, there is no clinical cure for PD, and novel anti-PD drugs are therefore urgently required. However, the selective permeability of the blood-brain barrier (BBB) poses a huge challenge in the development of such drugs. Fortunately, through strategies based on the physiological characteristics of the BBB and other modifications, including enhancement of BBB permeability, nanotechnology can offer a solution to this problem and facilitate drug delivery across the BBB. Although nanomaterials are often used as carriers for PD treatment, their biological activity is ignored. Several studies in recent years have shown that nanomaterials can improve PD symptoms via their own nano-bio effects. In this review, we first summarize the physiological features of the BBB and then discuss the design of appropriate brain-targeted delivery nanoplatforms for PD treatment. Subsequently, we highlight the emerging strategies for crossing the BBB and the development of novel nanomaterials with anti-PD nano-biological effects. Finally, we discuss the current challenges in nanomaterial-based PD treatment and the future trends in this field. Our review emphasizes the clinical value of nanotechnology in PD treatment based on recent patents and could guide researchers working in this area in the future.

Red blood cell biomimetic nanoparticle with anti-inflammatory, anti-oxidative and hypolipidemia effect ameliorated atherosclerosis therapy

A main pathogenic factor of atherosclerosis is the local oxidative stress microenvironment. Probucol (PU) has anti-inflammatory, antioxidative and hypolipidemic effects, showing great potential to treat atherosclerosis. However, its low bioavailability limits its development. Herein, PU was encapsulated to form RP-PU with star-shaped polymers and red blood cell membranes. Star-shaped polymers show lower solution viscosity, a smaller hydrodynamic radius and a higher drug loading content than linear polymers. RP-PU had a good sustained-release effect and excellent biocompatibility. RP-PU can be efficiently internalized by cells to improve biodistribution. ApoE^-/- mice were treated with RP-PU, and the contents of lipids and related metabolic enzymes were effectively reduced. The collagen fibers in the aortic root sections were reduced by RP-PU compared with control and PU. Moreover, RP-PU inhibited foam cell formation, decreased ICAM-1 and MCP-1 expression and delayed lesion formation. Consequently, RP-PU biomimetic nanoparticles can be developed as an anti-atherosclerotic nanotherapeutic.

Heme Oxygenase-1 targeting exosomes for temozolomide resistant glioblastoma synergistic therapy

Glioblastoma (GBM) is a highly fatal and recurrent brain cancer without a complete prevailing remedy. Although the synthetic nanotechnology-based approaches exhibit excellent therapeutic potential, the associated cytotoxic effects and organ clearance failure rest major obstacles from bench to clinics. Here, we explored allogeneic bone marrow mesenchymal stem cells isolated exosomes (BMSC_Exo) decorated with heme oxygenase-1 (HMOX1) specific short peptide (HSSP) as temozolomide (TMZ) and small interfering RNA (siRNA) nanocarrier for TMZ resistant glioblastoma therapy. The BMSC_Exo had excellent TMZ and siRNA loading ability and could traverse the blood-brain barrier (BBB) by leveraging its intrinsic brain accumulation property. Notably, with HSSP decoration, the TMZ or siRNA encapsulated BMSC_Exo exhibited excellent TMZ resistant GBM targeting ability both in vitro and in vivo due to the overexpression of HMOX1 in TMZ resistant GBM cells. Further, the HSSP decorated BMSC_Exo delivered the STAT3 targeted siRNA to the TMZ resistant glioma and restore the TMZ sensitivity, consequently achieved the synergistically drug resistant GBM treatment with TMZ. Our results showed this biomimetic nanoplatform can serve as a flexible, robust and inert system for GBM treatment, especially emphasizing the drug resistant challenge.

Iron promotes neurological function recovery in mice with ischemic stroke through endogenous repair mechanisms

The endogenous repair mechanisms play an important role in the recovery of nerve function after stroke, such as gliosis, synaptic plasticity, remyelination and nerve regeneration. Iron is the most abundant trace metal element in the brain and plays a crucial role in the maintenance of normal cerebral function. It is an important coenzyme factor in the process of cell metabolism, DNA synthesis, purine catabolism and neurotransmitter synthesis and decomposition. However, it is unclear what role iron plays in the long-term recovery of neurological function after stroke. In this study, we first observed that changes in iron metabolism occurred during neurological function recovery in the mice with distal middle cerebral artery occlusion (dMCAO). Our data showed that plasticity changes due to endogenous repair mechanisms resulted in improvements in cerebral cortex function. These changes involved gliosis, synaptic function reconstruction, remyelination, and activation of neural stem cells. In order to examine the potential role of iron, we synthesized liposomal-encapsulated deferoxamine (DFO) nanoparticles to further explore the effect and the mechanism of iron on the recovery of neurological function in dMCAO mice. Our results showed that liposome-DFO decreased iron deposition and reversed plasticity changes in cerebral cortex function after stroke, which delayed neurological function recovery. This experiment shows that the increasing iron level promotes endogenous repair in ischemic stroke. Our finding reveals the change regularity of iron and emphasizes the beneficial role of iron in the recovery process of neurological function, which provides an important basis for the prevention and/or treatment of ischemia-reperfusion and recovery after stroke.

Gather wisdom to overcome barriers: Well-designed nano-drug delivery systems for treating gliomas

Due to the special physiological and pathological characteristics of gliomas, most therapeutic drugs are prevented from entering the brain. To improve the poor prognosis of existing therapies, researchers have been continuously developing non-invasive methods to overcome barriers to gliomas therapy. Although these strategies can be used clinically to overcome the blood‒brain barrier (BBB), the accurate delivery of drugs to the glioma lesions cannot be ensured. Nano-drug delivery systems (NDDS) have been widely used for precise drug delivery. In recent years, researchers have gathered their wisdom to overcome barriers, so many well-designed NDDS have performed prominently in preclinical studies. These meticulous designs mainly include cascade passing through BBB and targeting to glioma lesions, drug release in response to the glioma microenvironment, biomimetic delivery systems based on endogenous cells/extracellular vesicles/protein, and carriers created according to the active ingredients of traditional Chinese medicines. We reviewed these well-designed NDDS in detail. Furthermore, we discussed the current ongoing and completed clinical trials of NDDS for gliomas therapy, and analyzed the challenges and trends faced by clinical translation of these well-designed NDDS.

Engineered Cell Membrane-Derived Nanocarriers: The Enhanced Delivery System for Therapeutic Applications

There has been a rapid development of biomimetic platforms using cell membranes as nanocarriers to camouflage nanoparticles for enhancing bio-interfacial capabilities. Various sources of cell membranes have been explored for natural functions such as circulation and targeting effect. Biomedical applications of cell membranes-based delivery systems are expanding from cancer to multiple diseases. However, the natural properties of cell membranes are still far from achieving desired functions and effects as a nanocarrier platform for various diseases. To obtain multi-functionality and multitasking in complex biological systems, various functionalized modifications of cell membranes are being developed based on physical, chemical, and biological methods. Notably, many research opportunities have been initiated at the interface of multi-technologies and cell membranes, opening a promising frontier in therapeutic applications. Herein, the current exploration of natural cell membrane functionality, the design principles for engineered cell membrane-based delivery systems, and the disease applications are reviewed, with a special focus on the emerging strategies in engineering approaches.

Cell Membrane-Cloaked Nanotherapeutics for Targeted Drug Delivery

Cell membrane cloaking technique is bioinspired nanotechnology that takes advantage of naturally derived design cues for surface modification of nanoparticles. Unlike modification with synthetic materials, cell membranes can replicate complex physicochemical properties and biomimetic functions of the parent cell source. This technique indeed has the potential to greatly augment existing nanotherapeutic platforms. Here, we provide a comprehensive overview of engineered cell membrane-based nanotherapeutics for targeted drug delivery and biomedical applications and discuss the challenges and opportunities of cell membrane cloaking techniques for clinical translation.

Angiopep-2-Modified Nanoparticles for Brain-Directed Delivery of Therapeutics: A Review

Nanotechnology has opened up a world of possibilities for the treatment of brain disorders. Nanosystems can be designed to encapsulate, carry, and deliver a variety of therapeutic agents, including drugs and nucleic acids. Nanoparticles may also be formulated to contain photosensitizers or, on their own, serve as photothermal conversion agents for phototherapy. Furthermore, nano-delivery agents can enhance the efficacy of contrast agents for improved brain imaging and diagnostics. However, effective nano-delivery to the brain is seriously hampered by the formidable blood-brain barrier (BBB). Advances in understanding natural transport routes across the BBB have led to receptor-mediated transcytosis being exploited as a possible means of nanoparticle uptake. In this regard, the oligopeptide Angiopep-2, which has high BBB transcytosis capacity, has been utilized as a targeting ligand. Various organic and inorganic nanostructures have been functionalized with Angiopep-2 to direct therapeutic and diagnostic agents to the brain. Not only have these shown great promise in the treatment and diagnosis of brain cancer but they have also been investigated for the treatment of brain injury, stroke, epilepsy, Parkinson's disease, and Alzheimer's disease. This review focuses on studies conducted from 2010 to 2021 with Angiopep-2-modified nanoparticles aimed at the treatment and diagnosis of brain disorders.

Membrane-Decorated Exosomes for Combination Drug Delivery and Improved Glioma Therapy

Glioblastoma multiforme (GBM) is the most aggressive tumor of the central nervous system in adults. The standard therapy of GBM fails to eradicate it due to the drug resistance of glioblastoma stem cells (GSCs) and the presence of the blood-brain-barrier (BBB). Temozolomide (TMZ) is the first-line anti-GBM drug after surgery. However, the high activity of O⁶-alkylguanine-DNA alkyltransferase (AGT) limits the therapeutic effect of TMZ. Herein, we reported dual-receptor-specific exosomes as vehicles loaded with TMZ and O⁶-benzylguanine (BG) for eradicating TMZ-resistant GBM. Exosomes pose great promise as nanocarriers due to their intrinsic low immunogenicity, strong cargo-protective capacity, ideal size range, and natural penetration ability of the blood-brain-barrier (BBB). The target ligands angiopep-2 and CD133 RNA aptamers were conjugated on exosomes via an amphiphilic molecule bridge, which was induced to express on donor cells. The resulting nanocarriers exhibited efficient uptake by U87MG and GSCs, excellent BBB penetration ability, and perfect GBM accumulation due to An2 and CD133 aptamer functionalization. Such superior properties of the two dual-receptor-specific exosomes resulted in excellent in vitro proliferation inhibition of U87MG and GSCs and extension of the median survival time of U87MG-bearing mice, without causing adverse effects. The formed exosome nanocomposites can serve as powerful nanomedicine for GBM therapy and provide a promising avenue for targeted therapy against other diseases of the central nervous system.

Dcf1 induces glioblastoma cells apoptosis by blocking autophagy

BACKGROUND

Dcf1 has been demonstrated to play vital roles in many CNS diseases, it also has a destructive role on cell mitochondria in glioma cells and promotes the autophagy. Hitherto, it is unclear whether the viability of glioblastoma cells is affected by Dcf1, in particular Dcf1 possesses broad localization on different organelles, and the organelles interaction frequently implicated in cancer cells survival.

METHODS

Surgically excised WHO grade IV human glioblastoma tissues were collected and cells isolated for culturing. RT-PCR and DNA sequencing assay to estimate the abundance and mutation of Dcf1. iTRAQ sequencing and bioinformatic analysis were performed. Subsequently, immunoprecipitation assay to evaluate the degradation of HistoneH2A isomers by UBA52 ubiquitylation. Transmission electron microscopy (TEM) was applied to observe the structure change of mitochondria and autophagosome. Organelle isolated assay to determine the distribution of protein. Cell cycle and apoptosis were evaluated by flow cytometric assays.

RESULTS

Dcf1 was downregulated in WHO grade IV tumor without mutation, and overexpression of Dcf1 was found to significantly regulate glioblastoma cells. One hundred and seventy-six differentially expressed proteins were identified by iTRAQ sequencing. Furthermore, we confirmed that overexpression of Dcf1 destabilized the structure of the nucleosome via UBA52 ubiquitination to downregulate HistoneH2A.X but not macroH2A or HistoneH2A.Z, decreased the mitochondrial DNA copy number and inhibited the mitochondrial biogenesis, thus causing mitochondrial destruction and dysfunction in order to supply cellular energy and induce mitophagy preferentially but not apoptosis. Dcf1 also has disrupted the integrity of lysosomes to block autolysosome degradation and autophagy and to increase the release of Cathepsin B and D from lysosomes into cytosol. These proteins cleaved and activated BID to induce glioblastoma cells apoptosis.

CONCLUSIONS

In this study, we demonstrated that unmutated Dcf1 expression is negatively related to the malignancy of glioblastoma, Dcf1 overexpression causes nucleosomes destabilization, mitochondria destruction and dysfunction to induce mitophagy preferentially, and block autophagy by impairing lysosomes to induce apoptosis in glioblastoma.

Delivery of siRNA based on engineered exosomes for glioblastoma therapy by targeting STAT3

Small interfering RNA (siRNA) has been considered as a promising strategy for treatment of glioblastoma (GBM), which is an aggressive brain disease with the poor prognosis. However, siRNA therapy for...

Surface functionalized biomimetic bioreactors enable the targeted starvation-chemotherapy to glioma

Altering the glucose supply and the metabolic pathways would be an intriguing strategy in starvation therapy toward cancers. Nevertheless, starvation therapy alone could be inadequate to eliminate tumor cells completely. Herein, a multifunctional bioreactor was fabricated for synergistic starvation-chemotherapy through embedding glucose oxidase (GOx) and doxorubicin (DOX) in the tumor targeting ligands (RGD) modified red blood cell membrane camouflaged metal-organic framework (MOF) nanoparticle (denoted as RGD-mGZD). Owing to the remarkable biointerfacing property, the designed RGD-mGZD could not only possess enhanced blood retention time inherited from red blood cells, but also preferentially target the tumor site after the modification with RGD peptide. Once the bioreactor reached the desired region, GOx promptly consumed the intratumoral glucose and oxygen to starve cancer cells for robust starvation therapy. More importantly, the aggravated acidic microenvironment at the tumor region was found to induce the decomposition of the MOF structure, thus triggering the release of DOX for reinforced chemotherapy. This bioreactor would further prompt the development of synergistic patterns toward cancer treatment in a spatiotemporally controlled manner.

Engineered Cell Membrane-Derived Nanoparticles in Immune Modulation

Immune modulation is one of the most effective approaches in the therapy of complex diseases, including public health emergency. However, most immune therapeutics such as drugs, vaccines, and cellular therapy suffer from the limitations of poor efficacy and adverse side effects. Fortunately, cell membrane-derived nanoparticles (CMDNs) have superior compatibility with other therapeutics and offer new opportunities to push the limits of current treatments in immune modulation. As the interface between cells and outer surroundings, cell membrane contains components which instruct intercellular communication and the plasticity of cytomembrane has significantly potentiated CMDNs to leverage our immune system. Therefore, cell membranes employed in immunomodulatory CMDNs have gradually shifted from natural to engineered. In this review, unique properties of immunomodulatory CMDNs and engineering strategies of emerging CMDNs for immune modulation, with an emphasis on the design logic are summarized. Further, this review points out some pressing problems to be solved during clinical translation and put forward some suggestions on the prospect of immunoregulatory CMDNs. It is anticipated that this review can provide new insights on the design of immunoregulatory CMDNs and expand their potentiation in the precise control of the dysregulated immune system.

Engineering of stimuli-responsive self-assembled biomimetic nanoparticles

Nanoparticle-based therapeutics have the potential to change the paradigm of how we approach the diagnosis and treatment of human disease. Employing naturally derived cell membranes as a surface coating has created a powerful new approach by which nanoparticles can be functionalized towards a wide range of biomedical applications. By using membranes derived from different cell sources, the resulting nanoparticles inherit properties that can make them well-suited for a variety of tasks. In recent years, stimuli-responsive platforms with the ability to release payloads on demand have received increasing attention due to their improved delivery, reduced side effects, and precision targeting. Nanoformulations have been developed to respond to external stimuli such as magnetic fields, ultrasound, and radiation, as well as local stimuli such as pH gradients, redox potentials, and other chemical conditions. Here, an overview of the novel cell membrane coating platform is provided, followed by a discussion of stimuli-responsive platforms that leverage this technology.

Modulation of the Blood-Brain Barrier for Drug Delivery to Brain

The blood-brain barrier (BBB) precisely controls brain microenvironment and neural activity by regulating substance transport into and out of the brain. However, it severely hinders drug entry into the brain, and the efficiency of various systemic therapies against brain diseases. Modulation of the BBB via opening tight junctions, inhibiting active efflux and/or enhancing transcytosis, possesses the potential to increase BBB permeability and improve intracranial drug concentrations and systemic therapeutic efficiency. Various strategies of BBB modulation have been reported and investigated preclinically and/or clinically. This review describes conventional and emerging BBB modulation strategies and related mechanisms, and safety issues according to BBB structures and functions, to try to give more promising directions for designing more reasonable preclinical and clinical studies.

Effective Triple-Negative Breast Cancer Targeted Treatment Using iRGD-Modified RBC Membrane-Camouflaged Nanoparticles

Introduction

Triple-negative breast cancer (TNBC) has the high degree of malignancy and aggressiveness. There is no targeted therapy drug. Many studies have shown that RBC membrane-coated nanoparticles achieve biological camouflage. In addition, the RGD module in the iRGD mediates the penetration of the vector across the tumor blood vessels to the tumor tissue space. Therefore, we developed iRGD-RM-(DOX/MSNs) by preparing MSNs loaded with doxorubicin as the core, and coating the surface of the MSNs with iRGD-modified RBC membranes.

Methods

iRGD-RM-(DOX/MSNs) were fabricated using physical extrusion. In addition, their physical and chemical characterization, hemolytic properties, in vivo acute toxicity and inflammatory response, in vitro and in vivo safety, and qualitative and quantitative cellular uptake by RAW 264.7 cells and MDA-MB-231 cells were evaluated and compared. Furthermore, we examined the antitumor efficacy of iRGD-RM-(DOX/MSN) nanoparticles in vitro and in vivo.

Results

iRGD-RM-(DOX/MSNs) have reasonable physical and chemical properties. iRGD-RM-(DOX/MSNs) escaped the phagocytosis of immune cells and achieved efficient targeting of nanoparticles at the tumor site. The nanoparticles showed excellent antitumor effects in vivo and in vitro.

Conclusion

In this study, we successfully developed biomimetic iRGD-RM-(DOX/MSNs) that could effectively target tumors and provide a promising strategy for the effective treatment of TNBC.

Intelligent photothermal dendritic cells restart the cancer immunity cycle through enhanced immunogenic cell death

Dendritic cells (DCs) play a pivotal role in initiating antigen-specific tumor immunity. However, the abnormal function of DCs owing to the immunosuppressive tumor microenvironment (TME) and the insufficient number of tumor infiltrating DCs could promote immune tolerance and tumor immune escape. Thus, there is great potential to employ DCs to induce efficient antitumor immunity. In this paper, we developed intelligent DCs (iDCs), which consist of nanoparticles loaded with photothermal agents (IR-797) and coated with a mature DC membrane. The DC cell membrane on the surface of iDCs preserves the ability to present antigens and prime T cells. The iDCs can also enter the lymph node and stimulate T cells. The activated T cells reduced the expression of heat shock proteins (HSPs) in tumor cells, rendering them more sensitive to heat stress. Subsequently, we used mild photothermal therapy (42-45 °C) to induce immunogenic cell death and contribute to a synergistic antitumor effect. iDCs as a refined and precise system in combination with DC-based immunotherapy and thermal therapy can be stored long-term and on a large scale, so they can be applied in many patients.

Optimizing the Design of Blood-Brain Barrier-Penetrating Polymer-Lipid-Hybrid Nanoparticles for Delivering Anticancer Drugs to Glioblastoma

PURPOSE

Chemotherapy for glioblastoma multiforme (GBM) remains ineffective due to insufficient penetration of therapeutic agents across the blood-brain barrier (BBB) and into the GBM tumor. Herein, is described, the optimization of the lipid composition and fabrication conditions for a BBB- and tumor penetrating terpolymer-lipid-hybrid nanoparticle (TPLN) for delivering doxorubicin (DOX) to GBM.

METHODS

The composition of TPLNs was first screened using different lipids based on nanoparticle properties and in vitro cytotoxicity by using 2³ full factorial experimental design. The leading DOX loaded TPLNs (DOX-TPLN) were prepared by further optimization of conditions and used to study cellular uptake mechanisms, in vitro cytotoxicity, three-dimensional (3D) glioma spheroid penetration, and in vivo biodistribution in a murine orthotopic GBM model.

RESULTS

Among various lipids studied, ethyl arachidate (EA) was found to provide excellent nanoparticle properties e.g., size, polydispersity index (PDI), zeta potential, encapsulation efficiency, drug loading, and colloidal stability, and highest anticancer efficacy for DOX-TPLN. Further optimized EA-based TPLNs were prepared with an optimal particle size (103.8 ± 33.4 nm) and PDI (0.208 ± 0.02). The resultant DOX-TPLNs showed ~ sevenfold higher efficacy than free DOX against human GBM U87-MG-RED-FLuc cells in vitro. The interaction between the TPLNs and the low-density lipoprotein receptors also facilitated cellular uptake, deep penetration into 3D glioma spheroids, and accumulation into the in vivo brain tumor regions of DOX-TPLNs.

CONCLUSION

This work demonstrated that the TPLN system can be optimized by rational selection of lipid type, lipid content, and preparation conditions to obtain DOX-TPLN with enhanced anticancer efficacy and GBM penetration and accumulation.

Tuning the Elasticity of Polymersomes for Brain Tumor Targeting

Nanoformulations show great potential for delivering drugs to treat brain tumors. However, how the mechanical properties of nanoformulations affect their ultimate brain destination is still unknown. Here, a library of membrane-crosslinked polymersomes with different elasticity are synthesized to investigate their ability to effectively target brain tumors. Crosslinked polymersomes with identical particle size, zeta potential and shape are assessed, but their elasticity is varied depending on the rigidity of incorporated crosslinkers. Benzyl and oxyethylene containing crosslinkers demonstrate higher and lower Young's modulus, respectively. Interestingly, stiff polymersomes exert superior brain tumor cell uptake, excellent in vitro blood brain barrier (BBB) and tumor penetration but relatively shorter blood circulation time than their soft counterparts. These results together affect the in vivo performance for which rigid polymersomes exerting higher brain tumor accumulation in an orthotopic glioblastoma (GBM) tumor model. The results demonstrate the crucial role of nanoformulation elasticity for brain-tumor targeting and will be useful for the design of future brain targeting drug delivery systems for the treatment of brain disease.

Glycosylation of PAMAM dendrimers significantly improves tumor macrophage targeting and specificity in glioblastoma

Glioblastoma is among the most aggressive forms of cancers, with a median survival of just 15-20 months for patients despite maximum clinical intervention. The majority of conventional anti-cancer therapies fail due to associated off-site toxicities which can be addressed by developing target-specific drug delivery systems. Advances in nanotechnology have provided targeted systems to overcome drug delivery barriers associated with brain and other types of cancers. Dendrimers have emerged as promising vehicles for targeted drug and gene delivery. Dendrimer-mediated targeting strategies can be further enhanced through the addition of targeting ligands to enable receptor-specific interactions. Here, we explore the sugar moieties as ligands conjugated to hydroxyl-terminated polyamidoamine dendrimers to leverage altered metabolism in cancer and immune targeting. Using a highly facile click chemistry approach, we modified the surface of dendrimers with glucose, mannose, or galactose moieties in a well-defined manner, to target upregulated sugar transporters in the context of glioblastoma. We show that glucose modification significantly enhanced targeting of tumor-associated macrophages (TAMs) and microglia by increasing brain penetration and cellular internalization, while galactose modification shifts targeting away from TAMs towards galectins on glioblastoma tumor cells. Mannose modification did not alter TAMs and microglia targeting of these dendrimers, but did alter their kinetics of accumulation within the GBM tumor. The whole body biodistribution was largely similar between the systems. These results demonstrate that dendrimers are versatile delivery vehicles that can be modified to tailor their targeting for the treatment of glioblastoma and other cancers.

RVG-functionalized reduction sensitive micelles for the effective accumulation of doxorubicin in brain

BACKGROUND

Glioblastoma is a lethal neoplasm with few effective therapy options. As a mainstay in the current treatment of glioma at present, chemotherapeutic agents usually show inadequate therapeutic efficiency due to their low blood brain barrier traversal and brain targeting, together with tumor multidrug resistance. Novel treatment strategies are thus urgently needed to improve chemotherapy outcomes.

RESULTS

Here, we report that nanomedicines developed by functionalizing the neurotropic rabies virus-derived polypeptide, RVG, and loading reduction-sensitive nanomicelles (polymer and doxorubicin) enable a highly specific and efficacious drug accumulation in the brain. Interestingly, curcumin serves as the hydrophobic core of the polymer, while suppressing the major efflux proteins in doxorubicin-resistant glioma cells. Studies on doxorubicin-resistant rat glioma cells demonstrate that the RVG-modified micelles exhibit superior cell entry and antitumor activity. In vivo research further showed that RVG modified nanomicelles significantly enhanced brain accumulation and tumor inhibition rate in mice, leading to a higher survival rate with negligible systemic toxicity. Moreover, effective suppression of recurrence and pulmonary metastatic nodules were also determined after the RVG-modified nanomicelles treatment.

CONCLUSIONS

The potential of RVG-modified nanomicelles for glioma was demonstrated. Brain accumulation was markedly enhanced after intravenous administration. This unique drug delivery nanoplatform to the brain provides a novel and powerful therapeutic strategy for the treatment of central nervous system disorders including glioma.