Dendritic cell-mediated delivery of doxorubicin-polyglycerol-nanodiamond composites elicits enhanced anti-cancer immune response in glioblastoma

Targeted brain tumor imaging by using discrete biopolymer-coated nanodiamonds across the blood-brain barrier

Short circulation lifetime, poor blood-brain barrier (BBB) permeability and low targeting specificity limit nanovehicles from crossing the vascular barrier and reaching the tumor site. Consequently, the precise diagnosis of malignant brain tumors remains a great challenge. This study demonstrates the imaging of photostable biopolymer-coated nanodiamonds (NDs) with tumor targeting properties inside the brain. NDs are labeled with PEGylated denatured bovine serum albumin (BSA) and tumor vasculature targeting tripeptides RGD. The modified NDs show high colloidal stability in different buffer systems. Moreover, it is found that discrete dcBSA-PEG-NDs cross the in vitro BBB model more effectively than aggregated NDs. Importantly, compared with the non-targeting NDs, RGD-dcBSA-PEG-NDs can selectively target the tumor site in U-87 MG bearing mice after systemic injection. Overall, this discrete ND system enables efficacious brain tumor visualization with minimal toxicity to other major organs, and is worthy of further investigation into the applications as a unique platform for noninvasive theragnostics and/or thermometry at different stages of human diseases in the brain.

Enhancing TNBC Chemo-immunotherapy via combination reprogramming tumor immune microenvironment with Immunogenic Cell Death

Tumor-associated fibroblasts (TAFs) play an important role in tumor progression and therapeutic response, especially in the immunosuppressive tumor microenvironment (TME). To remodel immunosuppressive TME of 4T1 tumor, we developed a nano liposome to deliver silybin (SLN, an anti-liver fibrosis Chinese Traditional Medicine). Liposomal silybin (SLN/LIP) possessed a spherical shape with particle sizes of 75.2 nm, high stability, and good accumulation in the tumor site. After treated with SLN/LIP, α-SMA positive TAFs and the deposition of stroma were decreased significantly. SLN/LIP also changed the tumor immune microenvironment through the increase of IFN-γ and IL-12, as well as reduced of TGF-β, SDF-1, IL6 and TNF-α. Importantly, SLN/LIP enhanced the infiltration of cytotoxic T cells (CTLs) and transformed a "cold" tumor into a "hot" tumor. To achieve the higher antitumor efficacy, an immunogenic cell death (ICD) inducer, liposomal doxorubicin (DOX/LIP) was combined with SLN/LIP. The combination treatment led to trigger immunogenic tumor apoptosis, and enhance antitumor immunity, therefore, improved anti-tumor efficiency, and further prolonged survival duration. The combination of liposomal silybin and liposomal doxorubicin might be a new chemo-immunotherapy approach for triple negative breast cancer (TNBC) tumor treatment.

Cell primitive-based biomimetic functional materials for enhanced cancer therapy

Cell primitive-based functional materials that combine the advantages of natural substances and nanotechnology have emerged as attractive therapeutic agents for cancer therapy. Cell primitives are characterized by distinctive biological functions, such as long-term circulation, tumor specific targeting, immune modulation etc. Moreover, synthetic nanomaterials featuring unique physical/chemical properties have been widely used as effective drug delivery vehicles or anticancer agents to treat cancer. The combination of these two kinds of materials will catalyze the generation of innovative biomaterials with multiple functions, high biocompatibility and negligible immunogenicity for precise cancer therapy. In this review, we summarize the most recent advances in the development of cell primitive-based functional materials for cancer therapy. Different cell primitives, including bacteria, phages, cells, cell membranes, and other bioactive substances are introduced with their unique bioactive functions, and strategies in combining with synthetic materials, especially nanoparticulate systems, for the construction of function-enhanced biomaterials are also summarized. Furthermore, foreseeable challenges and future perspectives are also included for the future research direction in this field.

Tumor microenvironment-activated therapeutic peptide-conjugated prodrug nanoparticles for enhanced tumor penetration and local T cell activation in the tumor microenvironment

Nanomedicine-based chemoimmunotherapy has shown a great potential for cancer therapies application in recent years. However, most nanoparticles still face a problem of low accumulation and limited penetration of chemotherapeutic drugs and immunotherapeutic drugs into solid tumors. Here, we developed a tumor microenvironment (TME)-activable therapeutic peptide-conjugated prodrug nanoparticle for enhanced tumor penetration and synergistic antitumor effects of chemotherapy and immune checkpoint blockade therapy. The prodrug nanoparticle is composed of a short D-peptide antagonist of PD-L1 (^DPPA) conjugated doxorubicin (DOX) prodrug and a PEGylated DOX prodrug, which can dissociate into small DOX nanoparticles (<30 nm) and release ^DPPA antagonist in TME. The prodrug nanoparticles could co-deliver DOX and ^DPPA antagonist by one nanocarrier and improve tumor accumulation and penetration of the prodrug nanoparticels via a transcytosis process. It is demonstrated that co-delivery of DOX and ^DPPA antagonist directly killed tumor cells, promoted the tumor-infiltrating cytotoxic T lymphocytes, reduced the tumor-infiltrating regulatory T cells, and elicited a long-term immune memory effect to prevent tumor recurrence and metastasis. This TME-activable prodrug nanoparticle holds promise as a co-delivery nanoplatform for the improved chemoimmunotherapy of solid tumors.

Engineered drug-loaded cells and cell derivatives as a delivery platform for cancer immunotherapy

Recent advances in improving cancer immunotherapy have been summarized with a focus on using functionalized intact cells and cell derivatives.

Her2-Targeted Multifunctional Nano-Theranostic Platform Mediates Tumor Microenvironment Remodeling and Immune Activation for Breast Cancer Treatment

Purpose

The treatment of breast cancer is often ineffective due to the protection of the tumor microenvironment and the low immunogenicity of tumor cells, leading to a poor therapeutic effect. In this study, we designed a nano-theranostic platform for these obstacles: a photothermal effect mediated by a gold shell could remodel the tumor microenvironment by decreasing cancer-associated fibroblasts (CAFs) and promote the release of doxorubicin (DOX) from nanoparticles. In addition, it could realize photoacoustic (PA)/MRI dual-model imaging for diagnose breast cancer and targeted identification of Her2-positive breast cancer.

Methods

Her2-DOX-superparamagnetic iron oxide nanoparticles (SPIOs)@Poly (D, L-lactide-co-glycolide) acid (PLGA)@Au nanoparticles (Her2-DSG NPs) were prepared based on a single emulsion oil-in-water (O/W) solvent evaporation method, gold seed growing method, and carbon diimide method. The size distribution, morphology, PA/MRI imaging, drug loading capacity, and drug release were investigated. Cytotoxicity, antitumor effect, cellular uptake, immunogenic cell death (ICD) effect, and targeted performance on human Her2-positive BT474 cell line were investigated in vitro. BT474/Adr cells were constructed and the antitumor effect of NPs on it was evaluated in vitro. Moreover, chemical-photothermal therapy effect, PA/MRI dual-model imaging, ICD effect induced by NPs, and tumor microenvironment remodeling in human BT474 breast cancer nude mice model were also investigated.

Results

Nanoparticles were spherical, uniform in size and covered with a gold shell. NPs had a photothermal effect, and can realize photothermal-controlled drug release in vitro. Chemical-photothermal therapy had a good antitumor effect on BT474/Adr cells and on BT474 cells in vitro. The targeting evaluation in vitro showed that Her2-DSG NPs could actively target and identify Her2-positive tumor cells. The PA/MRI imaging was successfully validated in vitro/vivo. Similarly, NPs could enhance the ICD effect in vitro/vivo, which could activate an immune response. Immunofluorescence results also proved that photothermal effect could decrease CAFs to remodel the tumor microenvironment and enhance the accessibility of NPs to tumor cells. According to the toxicity results, targeted drug delivery combined with photothermal-responsive drug release proved that NPs had good biosafety in vivo. Chemical-photothermal therapy of Her2-targeted NPs has a good antitumor effect in the BT474 nude mice model.

Conclusion

Our study showed that chemical-photothermal therapy combined with tumor microenvironment remodeling and immune activation based on the Her2-DSG NPs we developed are very promising for Her2-positive breast cancer.

Polymer-lipid hybrid nanovesicle-enabled combination of immunogenic chemotherapy and RNAi-mediated PD-L1 knockdown elicits antitumor immunity against melanoma

Immunotherapy has revolutionized cancer treatment; however, only a limited portion of patients show responses to currently available immunotherapy regimens. Here, we demonstrate that RNA interference (RNAi) combined with immunogenic chemotherapy can elicit potent antitumor immunity against melanoma. Specially, we developed cationic polymer-lipid hybrid nanovesicles (P/LNVs) as a new delivery system for doxorubicin and small interfering RNA (siRNA) with extensive cytotoxicity and gene silencing efficiency towards B16 cells. The deployment of doxorubicin-loaded P/LNVs augmented the expression and presentation of endogenous tumor antigens directly in situ by inducing the immunogenic cell death of B16 cells through poly(ADP-ribose) polymerase 1-dependent (PARP1) apoptosis pathway; thereby, eliciting remarkable antitumor immune responses in mice. Leveraging dying B16 cells as a vaccination strategy in combination with RNAi-based programmed cell death ligand 1 (PD-L1) knockdown showed efficacy in both prophylactic and metastasis melanoma settings. Strikingly, PD-L1 blockade synergized with a sub-therapeutic dose of doxorubicin triggered robust therapeutic antitumor T-cell responses and eradicated pre-established tumors in 30% of mice bearing B16 melanoma. Our findings indicated that this combination treatment provided a new powerful immunotherapy modality, characterized by markedly increased infiltration of effector CD8⁺ T cells and effective alleviation of the immunosuppressive microenvironment in tumors. P/LNVs is a versatile and highly scalable carrier that can enable a broad combination of nanomedicine and RNAi, providing new therapeutic strategies for advanced cancers.

Injectable biomaterials for treatment of glioblastoma

Despite ongoing advancements in the field of medicine, glioblastoma multiforme (GBM) is presently incurable, making this advanced brain tumor the deadliest tumor type in the central nervous system. The primary treatment strategies for GBM (i.e. surgical resection, radiation therapy, chemotherapy, and newly incorporated targeted therapies) fail to overcome the challenging characteristics of highly aggressive GBM tumors and are presently given with the goal of increasing the quality of life for patients. With the aim of creating effective treatment solutions, research has shifted toward utilizing injectable biomaterial adjuncts to minimize invasiveness of treatment, provide spatiotemporal control of therapeutic delivery, and engage with cells through material-cell interfaces. This review aims to summarize the limitations of the current standard of care for GBM, discuss how these limitations can be addressed by local employment of injectable biomaterial systems, and highlight developments in the field of biomaterials for these applications.

A review of recent advances in nanodiamond-mediated drug delivery in cancer

INTRODUCTION

Nanodiamond (ND) refers to diamond particles with sizes from few to near 100 nanometers. For its superb physical, chemical and spectroscopic properties, it has been proposed and studied with the aims for bio imaging and drug delivery. Many modalities on conjugating drug molecules on ND to form ND-X for more efficient drug delivery have been demonstrated in the cellular and animal models.

AREA COVERED

Many novel drug delivery approaches utilizing nanodiamond as a platform have been demonstrated recently. This review summarizes recent developments on the nanodiamond facilitated drug delivery, from the ND-X complexes preparations to tests in the cellular and animal models. The outlook on clinical translation is discussed.

EXPERT OPINION

Nanodiamond and drug complexes (ND-X) produced from different methods are realized for drug delivery; almost all studies reported ND-X being more efficient compared to pure drug alone. However, ND of particle size less than 10 nm are found more toxic due to size and surface structure, and strongly aggregate. In vivo studies demonstrate ND accumulation in animal organs and no confirmed long-term effect studies on their release from organs are available. Standardized nanodiamond materials and drug delivery approaches are needed to advance the applications to the clinical level.

pH-triggered intracellular release of doxorubicin by a poly(glycidyl methacrylate)-based double-shell magnetic nanocarrier

Two core-double-shell pH-sensitive nanocarriers were fabricated using Fe₃O₄ as magnetic core, poly(glycidyl methacrylate-PEG) and salep dialdehyde as the first and the second shell, and doxorubicin as the hydrophobic anticancer drug. Two nanocarriers were different in the drug loading steps. The interaction between the first and the second shell assumed to be pH-sensitive via acetal cross linkages. The structure of nanocarriers, organic shell loading, magnetic responsibility, morphology, size, dispersibility, and drug loading content were investigated by IR, NMR, TG, VSM, XRD, DLS, HRTEM and UV-Vis analyses. The long-term drug release profiles of both nanocarriers showed that the drug loading before cross-linking between the first and second shell led to a more pH-sensitive nanocarrier exhibiting higher control on DOX release. Cellular toxicity assay (MTT) showed that DOX-free nanocarrier is biocompatible having cell viability greater than 80% for HEK-293 and MCF-7 cell lines. Besides, high cytotoxic effect observed for drug-loaded nanocarrier on MCF-7 cancer cells. Cellular uptake analysis showed that the nanocarrier is able to transport DOX into the cytoplasm and perinuclear regions of MCF-7 cells. In vitro hemolysis and coagulation assays demonstrated high blood compatibility of nanocarrier. The results also suggested that low concentration of nanocarrier have a great potential as a contrast agent in magnetic resonance imaging (MRI).

Application prospect of peptide-modified nano targeting drug delivery system combined with PD-1/PD-L1 based immune checkpoint blockade in glioblastoma

Glioblastoma (GBM) is a type of primary malignant brain tumor with low median survival time, high recurrence rate and poor prognosis. The blood-brain barrier (BBB) and the diffuse infiltration of invasive GBM cells lead to a lower efficacy of traditional treatment. Recently, nanocarriers have become a promising method of brain drug delivery due to their ability to effectively cross the BBB. Especially, the peptide-modified nanocarriers can enhance the permeability, targeting and efficacy of chemotherapeutic agents against GBM. Moreover, the clinical application of immune checkpoint blockade (ICB) therapy in cancer treatment has attracted increasing attention, and the programmed death-1 receptor (PD-1) and PD-ligand-1 (PD-L1) monoclonal antibodies are considered to be a possible therapy for GBM. Consequently, we review the advances both in peptide-modified nano targeted drug delivery system and PD-1/PD-L1 based ICB in GBM treatment, and propose a new strategy combining the two methods, which may provide a novel approach for GBM treatment.

Doxorubicin-loaded iron oxide nanoparticles for glioblastoma therapy: a combinational approach for enhanced delivery of nanoparticles

Although doxorubicin (DOX) is an effective anti-cancer drug with cytotoxicity in a variety of different tumors, its effectiveness in treating glioblastoma multiforme (GBM) is constrained by insufficient penetration across the blood–brain barrier (BBB). In this study, biocompatible magnetic iron oxide nanoparticles (IONPs) stabilized with trimethoxysilylpropyl-ethylenediamine triacetic acid (EDT) were developed as a carrier of DOX for GBM chemotherapy. The DOX-loaded EDT-IONPs (DOX-EDT-IONPs) released DOX within 4 days with the capability of an accelerated release in acidic microenvironments. The DOX-loaded EDT-IONPs (DOX-EDT-IONPs) demonstrated an efficient uptake in mouse brain-derived microvessel endothelial, bEnd.3, Madin–Darby canine kidney transfected with multi-drug resistant protein 1 (MDCK-MDR1), and human U251 GBM cells. The DOX-EDT-IONPs could augment DOX’s uptake in U251 cells by 2.8-fold and significantly inhibited U251 cell proliferation. Moreover, the DOX-EDT-IONPs were found to be effective in apoptotic-induced GBM cell death (over 90%) within 48 h of treatment. Gene expression studies revealed a significant downregulation of TOP II and Ku70, crucial enzymes for DNA repair and replication, as well as MiR-155 oncogene, concomitant with an upregulation of caspase 3 and tumor suppressors i.e., p53, MEG3 and GAS5, in U251 cells upon treatment with DOX-EDT-IONPs. An in vitro MDCK-MDR1-GBM co-culture model was used to assess the BBB permeability and anti-tumor activity of the DOX-EDT-IONPs and DOX treatments. While DOX-EDT-IONP showed improved permeability of DOX across MDCK-MDR1 monolayers compared to DOX alone, cytotoxicity in U251 cells was similar in both treatment groups. Using a cadherin binding peptide (ADTC5) to transiently open tight junctions, in combination with an external magnetic field, significantly enhanced both DOX-EDT-IONP permeability and cytotoxicity in the MDCK-MDR1-GBM co-culture model. Therefore, the combination of magnetic enhanced convective diffusion and the cadherin binding peptide for transiently opening the BBB tight junctions are expected to enhance the efficacy of GBM chemotherapy using the DOX-EDT-IONPs. In general, the developed approach enables the chemotherapeutic to overcome both BBB and multidrug resistance (MDR) glioma cells while providing site-specific magnetic targeting.

High expression of stromal signatures correlated with macrophage infiltration, angiogenesis and poor prognosis in glioma microenvironment

Glioma is one of the most fatal tumors in central nervous system. Previous studies gradually revealed the association between tumor microenvironment and the prognosis of gliomas patients. However, the correlation between tumor-infiltrating immune cell and stromal signatures are unknown. In our study, we obtained gliomas samples from the Chinese Glioma Genome Atlas (CGGA) and The Cancer Genome Atlas (TCGA). The landscape of tumor infiltrating immune cell subtypes in gliomas was calculated by CIBERSORT. As a result, we found high infiltration of macrophages was correlated with poor outcome (P < 0.05). Then functional enrichment analysis of high/low macrophage-infiltrating groups was performed by GSEA. The results showed three gene sets includes 102 core genes about angiogenesis were detected in high macrophage-infiltrating group. Next, we constructed PPI network and analyzed prognostic value of 102 core genes. We found that five stromal signatures indicated poor prognosis which including HSPG2, FOXF1, KDR, COL3A1, SRPX2 (P < 0.05). Five stromal signatures were adopted to construct a classifier. The classifier showed powerful predictive ability (AUC = 0.748). Patients with a high risk score showed poor survival. Finally, we validated this classifier in TCGA and the result was consistent with CGGA. Our investigation of tumor microenvironment in gliomas may stimulate the new strategy in immunotherapy. Five stromal signature correlated with poor prognosis also provide a strong predator of gliomas patient outcome.

Manganese-Based Nanoactivator Optimizes Cancer Immunotherapy via Enhancing Innate Immunity

Cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) are essential components of the innate immune sensors to cytosolic DNA and elicit type I interferon (IFN). Recent studies have revealed that manganese (Mn) can enhance cGAS and STING activation to viral infection. However, the role of Mn in antitumor immunity has not been explored. Here, we designed a nanoactivator, which can induce the presence of DNA in cytoplasm and simultaneously elevate Mn²⁺ accumulation within tumor cells. In detail, amorphous porous manganese phosphate (APMP) NPs that are highly responsive to tumor microenvironment were employed to construct doxorubicin (DOX)-loaded and phospholipid (PL)-coated hybrid nanoparticles (PL/APMP-DOX NPs). PL/APMP-DOX NPs were stably maintained during systemic circulation, but triggered to release DOX for inducing DNA damage and Mn²⁺ to augment cGAS/STING activity. We found that PL/APMP-DOX NPs with superior tumor-targeting capacity boosted dendritic cell maturation and increased cytotoxic T lymphocyte infiltration as well as natural killer cell recruitment into the tumor site. Furthermore, the NPs increased production of type I IFN and secretion of pro-inflammatory cytokines (for example, TNF-α and IL-6). Consequently, PL/APMP-DOX NPs exhibited excellent antitumor efficacy and prolonged the lifespan of the tumor-bearing mice. Collectively, we developed a PL-decorated Mn-based hybrid nanoactivator to intensify immune activation and that might provide therapeutic potential for caner immunotherapy.

Doxorubicin-polyglycerol-nanodiamond conjugates disrupt STAT3/IL-6-mediated reciprocal activation loop between glioblastoma cells and astrocytes

Astrocytes are key stromal components in glioblastoma (GBM) and have complex interactions with the GBM cells (GBC) promoting the survival, progression and therapy resistance of GBM. In this study, we first demonstrated the existence of a reciprocal activation loop mediated by the STAT3/IL-6 signaling between GBC and astrocytes. This loop of reciprocity was found to be initiated by the constitutive activity of STAT3 and downstream expression of IL-6 in the GBC. GBC-derived IL-6 activated STAT3 and thereby upregulated IL-6 expression in the astrocytes. Astrocyte-derived IL-6 acted back on the GBC causing further activation of STAT3 and leading to enhanced downstream events that promote proliferation, migration, invasion and apoptosis resistance of the GBC. Next, we showed that doxorubicin-polyglycerol-nanodiamond conjugates (Nano-DOX), which could be delivered via GBM-associated macrophages, suppressed STAT3 activity in the GBC reducing their IL-6 output to the astrocytes and thereby abolished the astrocytes' feedback activation of the GBC. Moreover, Nano-DOX also suppressed stimulated activation of STAT3 and IL-6 induced by temozolomide, a first-line anti-GBM chemotherapy, resistance to which critically involves STAT3 activation. In conclusion, Nano-DOX could disrupt the STAT3/IL-6-mediated reciprocal activation loop between the GBC and astrocytes. Nano-DOX also provides a novel approach to therapeutic modulation of the GBM microenvironment.

Single-dose in situ storage for intensifying anticancer efficacy via combinatorial strategy

Metronomic cancer chemotherapy has displayed the potential to ameliorate immunosuppressive tumor microenvironment (TME) and facilitate antitumor immunotherapy, but this strategy requires uninterrupted administration of low-dose chemotherapeutic agents and suffers from rapid drug clearance. Here, we developed a single-dose in situ immune stimulator storage to achieve prolonged retention and sustained release of drugs in tumor parenchyma. Importantly, this storage could initiate immune responses through photothermal therapy (PTT) and simultaneously remodel TME. In detail, the storage framework (NGOPC) with size of ~60 nm, was composed of Ala-Ala-Asn-Cys-Lys modified nano graphene oxide (NGO-PEG-pep) and 2-cyano-6-aminobenzothiazole modified NGO (NGO-PEG-CABT), and could sufficiently penetrate into deep tumor region. Once NGOPC arrived at the core field, legumain overexpressing in TME could trigger click cycloaddition reaction of NGO-PEG-pep with NGO-PEG-CABT to form network, leading to aggregation and augmented retention in tumor. Additionally, paclitaxel (PTX) that can block immunologic escape was loaded in NGOPC (NGOPC@PTX), which synergistically worked with PTT-generated antitumor immunity. We found that NGOPC@PTX possessed the superior ability to accumulate in tumor and generate antitumor immunological efficacy by improving immune factors: induction of HSP70-mediated immunogenic cell death, reduction of regulatory T cells, and activation of cytotoxic T lymphocyte. This in situ storage, which exhibited excellent tumor growth inhibition effect and prolonged lifespan in combination with PTT, displays the potential for intensified cancer immunotherapy.

Photothermal-Chemotherapy Integrated Nanoparticles with Tumor Microenvironment Response Enhanced the Induction of Immunogenic Cell Death for Colorectal Cancer Efficient Treatment

Inducing immunogenic cell death (ICD) that enhances the immunogenicity of dead cancer cells is a new strategy for tumor immunotherapy, but efficiently triggering ICD is the biggest obstacle to achieving this strategy, especially for distant and deep-seated tumors. Here, a new therapeutic system (Pd-Dox@TGMs NPs) that can effectively trigger ICD by combining chemotherapy and photothermal therapy was designed. The nanosystem was fabricated by integrating doxorubicin (Dox) and a photothermal reagent palladium nanoparticles (Pd NPs) into amphiphile triglycerol monostearates (TGMs), which showed specific accumulation, deep penetration, and activation in response to the tumoral enzymatic microenvironment. It was proved that codelivery of Dox and Pd NPs not only effectively killed CT26 cells through chemotherapy and photothermal therapy but also promoted the release of dangerous signaling molecules, such as high mobility group box 1, calreticulin, and adenosine triphosphate, improving the immunogenicity of dead tumor cells. The effective ICD induction mediated by Pd-Dox@TGMs NPs boosted the PD-L1 checkpoint blockade effect, which efficiently improved the infiltration of toxic T lymphocytes at the tumor site and showed excellent tumor treatment effects to both primary and abscopal tumors. Therefore, this work provides a simple and effective immunotherapeutic strategy by combining chemical-photothermal therapy to enhance immune response.

Zwitterion-Functionalized Detonation Nanodiamond with Superior Protein Repulsion and Colloidal Stability in Physiological Media

Nanodiamond (ND) is a versatile and promising material for bioapplications. Despite many efforts, agglomeration of nanodiamond and the nonspecific adsorption of proteins on the ND surface when exposed to biofluids remains a major obstacle for biomedical applications. Here, the functionalization of detonation nanodiamond with zwitterionic moieties in combination with tetraethylene glycol (TEG) moieties immobilized by click chemistry to improve the colloidal dispersion in physiological media with strong ion background and for the simultaneous prevention of nonspecific interactions with proteins is reported. Based on five building blocks, a series of ND conjugates is synthesized and their performance is compared in biofluids, such as fetal bovine serum (FBS) and Dulbecco's modified Eagle medium (DMEM). The adsorption of proteins is investigated via dynamic light scattering (DLS) and thermogravimetric analysis. The colloidal stability is tested with DLS monitoring over prolonged periods of time in various ratios of water/FBS/DMEM and at different pH values. The results show that zwitterions efficiently promote the anti-fouling properties, whereas the TEG linker is essential for the enhanced colloidal stability of the particles.

Development of cancer immunotherapy based on PD-1/PD-L1 pathway blockade

Programmed death receptor 1 (PD-1)/programmed death ligand 1 (PD-L1) blockade therapy has achieved considerable success in various tumours. However, only a fraction of patients benefit from its clinical application, and some patients might be suffer from tumour resistance against PD-1/PD-L1 blockade therapy after the original response. In this review, we summarized the main reasons that caused the low response rate of PD-/PD-L1 blockade therapy: firstly, the off-target of PD-1/PD-L1 blocking agents, which is also the main factor of the side effect of autoimmune disorders; secondly, the insufficient infiltration of T cells in a tumour microenvironment; thirdly, the low immunogenicity of tumor cells; fourth, other immunosuppressive components impairing the therapeutic efficacy of the immunotherapy based on the PD-/PD-L1 blockade, and introducing some updated the delivery system of PD-1/PD-L1 blocking agents and the combination therapy based on PD-1/PD-L1 inhibitors and other therapeutics that can complement and promote each other to achieve improved immune response.

Doxorubicin-polyglycerol-nanodiamond conjugate is a cytostatic agent that evades chemoresistance and reverses cancer-induced immunosuppression in triple-negative breast cancer

BACKGROUND

Triple negative breast cancer (TNBC) has the poorest prognosis of all breast cancer subtypes and is one of the most fatal diseases for women. Combining cytotoxic chemotherapy with immunotherapy has shown great promise for TNBC treatment. However, chemotherapy often leads to the development of chemoresistance and severe systemic toxicity compromising the immune functions that are crucial to anti-TNBC immune therapy. Tumor-induced immunosuppression also poses a great hindrance to efficacious anti-TNBC immunotherapy. Nanomedicine holds great promise to overcome these hurdles.

RESULTS

Doxorubicin-polyglycerol-nanodiamond conjugate (Nano-DOX) was firstly found to be a cytostatic agent to the 4T1 cells and displayed a lower apparent therapeutic potency than DOX. However, the tumor-bearing animals, particularly some key immune cells thereof, showed good tolerance of Nano-DOX as opposed to the severe toxicity of DOX. Next, Nano-DOX did not induce significant upregulation of P-gp and IL-6, which were demonstrated to be key mediators of chemoresistance to DOX in the 4T1 cells. Then, Nano-DOX was shown to downregulate tumor-derived granulocyte-colony stimulating factor (G-CSF) and suppresses the induction and tissue filtration of myeloid-derived suppressor cells (MDSCs) that are the principal effectors of cancer-associated systemic immunosuppression. Nano-DOX also alleviated the phenotype of MDSCs induced by 4T1 cells. Finally, Nano-DOX induced the 4T1 cells to emit damage associated molecular patterns (DAMPs) that stimulated the tumor immune microenvironment through activating key immune effector cells involved in anti-tumor immunity, such as macrophages, dendritic cells and lymphocytes in the tumor tissue.

CONCLUSIONS

Nano-DOX is a cytostatic agent with good host tolerance which is capable of evading chemoresistance and reversing cancer-induced immunosuppression both at the systemic level and in the tumor microenvironment in TNBC. Our work presents Nano-DOX as an interesting example that a chemotherapeutic agent in nano-form may possess distinct biochemical properties from its free form, which can be exploited to join chemotherapy with immunotherapy for better treatment of cancer.

Advances in Engineering Cells for Cancer Immunotherapy

Cancer immunotherapy aims to utilize the host immune system to kill cancer cells. Recent representative immunotherapies include T-cell transfer therapies, such as chimeric antigen receptor T cell therapy, antibody-based immunomodulator therapies, such as immune checkpoint blockade therapy, and cytokine therapies. Recently developed therapies leveraging engineered cells for immunotherapy against cancers have been reported to enhance antitumor efficacy while reducing side effects. Such therapies range from biologically, chemically and physically -engineered cells to bioinspired and biomimetic nanomedicines. In this review, advances of engineering cells for cancer immunotherapy are summarized, and prospects of this field are discussed.

Leveraging the interplay of nanotechnology and neuroscience: Designing new avenues for treating central nervous system disorders

Nanotechnology has the potential to open many novel diagnostic and treatment avenues for disorders of the central nervous system (CNS). In this review, we discuss recent developments in the applications of nanotechnology in CNS therapies, diagnosis and biology. Novel approaches for the diagnosis and treatment of neuroinflammation, brain dysfunction, psychiatric conditions, brain cancer, and nerve injury provide insights into the potential of nanomedicine. We also highlight nanotechnology-enabled neuroscience techniques such as electrophysiology and intracellular sampling to improve our understanding of the brain and its components. With nanotechnology integrally involved in the advancement of basic neuroscience and the development of novel treatments, combined diagnostic and therapeutic applications have begun to emerge. Nanotheranostics for the brain, able to achieve single-cell resolution, will hasten the rate in which we can diagnose, monitor, and treat diseases. Taken together, the recent advances highlighted in this review demonstrate the prospect for significant improvements to clinical diagnosis and treatment of a vast array of neurological diseases. However, it is apparent that a strong dialogue between the nanoscience and neuroscience communities will be critical for the development of successful nanotherapeutics that move to the clinic, benefit patients, and address unmet needs in CNS disorders.

A Characterization of Dendritic Cells and Their Role in Immunotherapy in Glioblastoma: From Preclinical Studies to Clinical Trials

Glioblastoma (GBM) is the most common and fatal primary central nervous system malignancy in adults with a median survival of less than 15 months. Surgery, radiation, and chemotherapy are the standard of care and provide modest benefits in survival, but tumor recurrence is inevitable. The poor prognosis of GBM has made the development of novel therapies targeting GBM of paramount importance. Immunotherapy via dendritic cells (DCs) has garnered attention and research as a potential strategy to boost anti-tumor immunity in recent years. As the “professional” antigen processing and presenting cells, DCs play a key role in the initiation of anti-tumor immune responses. Pre-clinical studies in GBM have shown long-term tumor survival and immunological memory in murine models with stimulation of DC activity with various antigens and costimulatory molecules. Phase I and II clinical trials of DC vaccines in GBM have demonstrated some efficacy in improving the median overall survival with minimal to no toxicity with promising initial results from the first Phase III trial. However, there remains no standardization of vaccines in terms of which antigens are used to pulse DCs ex vivo, sites of DC injection, and optimal adjuvant therapies. Future work with DC vaccines aims to elucidate the efficacy of DC-based therapy alone or in combination with other immunotherapy adjuvants in additional Phase III trials.

Natural compound inducers of immunogenic cell death

Accumulating evidence shows that the anti-cancer potential of the immune response that can be activated by modulation of the immunogenicity of dying cancer cells. This regulated cell death process is called immunogenic cell death (ICD) and constitutes a new innovating anti-cancer strategy with immune-modulatory potential thanks to the release of damage-associated molecular patterns (DAMPs). Some conventional clinically-used chemotherapeutic drugs, as well as preclinically-investigated compounds of natural origins such as anthracyclines, microtubule-destabilizing agents, cardiac glycosides or hypericin derivatives, possess such an immune-stimulatory function by triggering ICD. Here, we discuss the effects of ICD inducers on the release of DAMPs and the activation of corresponding signaling pathways triggering immune recognition. We will discuss potential strategies allowing to overcome resistance mechanisms associated with this treatment approach as well as co-treatment strategies to overcome the immunosuppressive microenvironment. We will highlight the potential role of metronomic immune modulation as well as targeted delivery of ICD-inducing compounds with nanoparticles or liposomal formulations to improving the immunogenicity of ICD inducers aiming at long-term clinical benefits.

Doxorubicin-polyglycerol-nanodiamond composites stimulate glioblastoma cell immunogenicity through activation of autophagy

Immunosuppression is a salient feature of GBM associated with the disease's grim prognosis and the limited success of anti-GBM immunotherapy. Stimulating immunogenicity of the GBM cells (GC) is a promising approach to subverting the GBM-associated immunosuppression. We had previously devised a drug composite based on polyglycerol-functionalized nanodiamonds bearing doxorubicin (Nano-DOX) and demonstrated that Nano-DOX effectively modulated GBM's immunosuppressive microenvironment through stimulating the immunogenicity of GC and initiated anti-GBM immune responses. The present study now explored the mechanism of Nano-DOX's immunostimulatory action. Nano-DOX was found to induce autophagy rather than apoptosis in GC and stimulated GC to emit antigens and damage-associated molecular patterns (DAMPs) that are potent adjuvants, which resulted in enhanced activation of dendritic cells (DC). Heightened autophagosome release was observed in Nano-DOX-treated GC but was shown not to be a major channel of antigen donation. Blocking autophagy in GC not only reduced Nano-DOX-stimulated GC antigen donation and DAMPs emission, but also efficiently attenuated DC activation stimulated by Nano-DOX-treated GC. Taken together, these findings suggest that activation of autophagy is a central mechanism whereby Nano-DOX stimulates GC's immunogenicity. Our work provides new insight on how nanotechnology can be applied to therapeutically modulate the GBM immune microenvironment by harnessing autophagy in the cancer cells. STATEMENT OF SIGNIFICANCE: Immunosuppression is a salient feature of GBM associated with the grim prognosis of the disease and the limited success of anti-GBM immunotherapy. We demonstrated that Doxorubicin-polyglycerol-nanodiamond composites could activate autophagy in GBM cells and thereby stimulate the immunogenecity of GBM cells. This discovery 1, sheds new light on how nanotechnology could be applied to therapeutically modulate the tumor immune microenvironment, and 2, provides a powerful tool for subverting the GBM's immunosuppressive microenvironment, which has great therapeutic potential for the treatment of GBM.

Targeting EGFR of triple-negative breast cancer enhances the therapeutic efficacy of paclitaxel- and cetuximab-conjugated nanodiamond nanocomposite

Breast cancer is the most common malignancy and a leading cause of cancer-related mortality among women worldwide. Triple-negative breast cancer (TNBC) is characterized by the lack of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2). However, epidermal growth factor receptor (EGFR) is highly expressed in most of the TNBCs, which may provide a potential target for EGFR targeting therapy. Nanodiamond (ND) is a carbon-based nanomaterial with several advantages, including fluorescence emission, biocompatibility, and drug delivery applications. In this study, we designed a nanocomposite by using ND conjugated with paclitaxel (PTX) and cetuximab (Cet) for targeting therapy on the EGFR-positive TNBC cells. ND-PTX inhibited cell viability and induced mitotic catastrophe in various human breast cancer cell lines (MDA-MB-231, MCF-7, and BT474); in contrast, ND alone did not induce cell death. ND-PTX inhibited the xenografted human breast tumors in nude mice. We further investigated ND-PTX-Cet drug efficacy on the TNBC of MDA-MB-231 breast cancer cells. ND-PTX-Cet could specifically bind to EGFR and enhanced the anticancer effects including drug uptake levels, mitotic catastrophe, and apoptosis in the EGFR-expressed MDA-MB-231 cells but not in the EGFR-negative MCF-7 cells. In addition, ND-PTX-Cet increased the protein levels of active caspase-3 and phospho-histone H3 (Ser10). Furthermore, ND-PTX-Cet showed more effective on the reduction of TNBC tumor volume by comparison with ND-PTX. Taken together, these results demonstrated that ND-PTX-Cet nanocomposite enhanced mitotic catastrophe and apoptosis by targeting EGFR of TNBC cells, which can provide a feasible strategy for TNBC therapy. STATEMENT OF SIGNIFICANCE: Current TNBC treatment is ineffective against the survival rate of TNBC patients. Therefore, the development of new treatment strategies for TNBC patients is urgently needed. Here, we have designed a nanocomposite by targeting on the EGFR of TNBC to enhance therapeutic efficacy by ND-conjugated PTX and Cet (ND-PTX-Cet). Interestingly, we found that the co-delivery of Cet and PTX by ND enhanced the apoptosis, mitotic catastrophe and tumor inhibition in the EGFR-expressed TNBC in vitro and in vivo. Consequently, this nanocomposite ND-PTX-Cet can be applied for targeting EGFR of human TNBC therapy.

Doxorubicin conjugated with nanodiamonds and in free form commit glioblastoma cells to heterodromous fates

Aim: To mechanistically compare the effects of doxorubicin (DOX) and DOX conjugated with nanodiamonds (Nano–DOX) on human glioblastoma cells (GC). Materials & methods: GC viablity, proliferation and activation of apoptosis and autophagy was assayed in response to DOX and Nano–DOX. Expression and release of HMGB1 were measured and its role in apoptosis and autophagy probed in response to DOX and Nano–DOX.  Results: DOX induced apoptosis in GC while Nano–DOX induced autophagy. Inhibition of autophagy in Nano–DOX-treated GC promoted apoptosis. DOX suppressed the emission of HMGB1 while Nano–DOX stimulated HMGB1 emission which was attenuated when autophagy was repressed. Blocking of HMGB1 emission mitigated autophagy and enhanced apoptosis in Nano–DOX-treated GC. Exogenously administered HMGB1 promoted autophagy and protected against apoptosis in both Nano–DOX-treated GC and DOX-treated GC. Conclusions: Nano–DOX is a potent autophagy activator as opposed to DOX as an apoptosis inducer. Nano–DOX initiates a mutual reinforcement loop between autophagy and HMGB1 in GC and thereby protects GC against apoptosis.