Damaging Tumor Vessels with an Ultrasound-Triggered NO Release Nanosystem to Enhance Drug Accumulation and T Cells Infiltration.

INTRODUCTION: Limited by tumor vascular barriers, restricted intratumoural T cell infiltration and nanoparticles accumulation remain major bottlenecks for anticancer therapy. Platelets are now known to maintain tumor vascular integrity. Therefore, inhibition of tumor-associated platelets may be an effective method to increase T cell infiltration and drug accumulation at tumor sites. Herein, we designed an ultrasound-responsive nitric oxide (NO) release nanosystem, SNO-HSA-PTX, which can release NO in response to ultrasound (US) irradiation, thereby inhibiting platelet function and opening the tumor vascular barrier, promoting drug accumulation and T cell infiltration. METHODS: We evaluated the ability of SNO-HSA-PTX to release NO in response to US irradiation. We also tested the effect of SNO-HSA-PTX on platelet function. Plenty of studies including cytotoxicity, pharmacokinetics study, biodistribution, blood perfusion, T cell infiltration, in vivo antitumor efficacy and safety assessment were conducted to investigate the antitumor effect of SNO-HSA-PTX. RESULTS: SNO-HSA-PTX with US irradiation inhibited tumor-associated platelets activation and induced openings in the tumor vascular barriers, which promoted the accumulation of SNO-HSA-PTX nanoparticles to the tumor sites. Meanwhile, the damaged vascular barriers allowed oxygen-carrying hemoglobin to infiltrate tumor regions, alleviating hypoxia of the tumor microenvironment. In addition, the intratumoral T cell infiltration was augmented, together with chemotherapy and NO therapy, which greatly inhibited tumor growth. DISCUSSION: Our research designed a simple strategy to open the vascular barrier by inhibiting the tumor-associated platelets, which provide new ideas for anti-tumor treatment.

Self-assembled FeS-based cascade bioreactor with enhanced tumor penetration and synergistic treatments to trigger robust cancer immunotherapy.

Major challenges for cancer treatment are how to effectively eliminate primary tumor and sufficiently induce immunogenic cell death (ICD) to provoke a robust immune response for metastasis control. Here, a self-assembled cascade bioreactor was developed to improve cancer treatment with enhanced tumor penetration and synergistic therapy of starvation, chemodynamic (CDT) and photothermal therapy. Ultrasmall FeS-GOx nanodots were synthesized with glucose oxidase (GOx) as template and induced by paclitaxel (PTX) to form self-assembling FeS-GOx@PTX (FGP) via hydrophobic interaction. After accumulated at tumor sites, FGP disassembles to smaller FeS-GOx for enhanced deep tumor penetration. GOx maintains high enzymatic activity to catalyze glucose with assistant of oxygen to generate hydrogen peroxide (H2O2) as starvation therapy. Fenton reaction involving the regenerated H2O2 in turn produced more hydroxyl radicals for enhanced CDT. Following near-infrared laser at 808 nm, FGPs displayed pronounced tumor inhibition in vitro and in vivo by the combination therapy. The consequent increased exposure to calreticulin amplified ICD and promoted dendritic cells maturation. In combination with anti-CTLA4 checkpoint blockade, FGP can absolutely eliminate primary tumor and avidly inhibit distant tumors due to the enhanced intratumoral infiltration of cytotoxic T lymphocytes. Our work presents a promising strategy for primary tumor and metastasis inhibition.

Surface Decoration via Physical Interaction of Cupric Diethyldithiocarbamate Nanocrystals and Its Impact on Biodistribution and Tumor Targeting.

The vascular wall is the first physiologic barrier that circulating nanoparticles (NPs) encounter, which also is a key biological barrier to cancer drug delivery. NPs can continually scavenge the endothelium for biomarkers of cancer, and the chance of NPs' extravasation into the tumors can be enhanced. Here, we envision P-selectin as a target for specific delivery of drug nanocrystals to tumors. The cupric diethyldithiocarbamate nanocrystals (CuET NCs) were first prepared by an antisolvent method, and then nanocrystals were coated with fucoidan via physical interaction. The fucoidan-coated CuET nanocrystals (CuET@Fuc) possess high drug loading and have the ability to interact with human umbilical vein endothelial cells expressing P-selectin, which transiently enhances the endothelial permeability and facilitates CuET@Fuc extravasation from the peritumoral vascular to achieve higher tumor accumulation of drugs than bare CuET NCs. The CuET NC shows poorer anticancer efficacy than CuET@Fuc at the same dose of CuET. Upon repeated dosing of CuET@Fuc for 2 weeks, no mortality was observed in treated melanoma-bearing mice, while the mortality in the control group and excipient-treated groups reached 23%. The growth rate of melanoma in the CuET@Fuc-treated group was significantly lower than those in other groups. Furthermore, an acute toxicity study revealed that CuET@Fuc is a safe formulation for cancer treatment.

Mitochondria targeted nanoparticles to generate oxygen and responsive-release of carbon monoxide for enhanced photogas therapy of cancer.

Carbon monoxide (CO) based gas therapy has been an emerging strategy for cancer treatment. However, the uncontrolled release of CO and limited therapeutic efficacy of monotherapy are two major obstacles for clinical application. To overcome these issues, human serum albumin (HSA) nanoparticles combined with manganese dioxide (MnO2) were developed to deliver a photosensitizer (IR780) and CO donor (MnCO) for a synergistic therapy combining CO gas therapy and phototherapy. The nanoparticles (HIM-MnO2) formed catalyze hydrogen peroxide to produce oxygen for hypoxia relief. With laser irradiation, it can increase the generation of reactive oxygen species for the enhancement of photodynamic therapy (PDT). Furthermore, the generated heat of photothermal therapy (PTT) induced by nanoparticles could trigger the release of CO to achieve a therapeutic window for enhanced gas therapy. Due to the co-localization of IR780 in mitochondria, HIM-MnO2 could accumulate in mitochondria for the synergistic therapy combining CO gas therapy and phototherapy, and could oxidize the mitochondrial membrane and induce more apoptosis. After intravenous injection into tumor bearing mice, HIM-MnO2 could accumulate at tumor sites and with laser irradiation, tumor growth was significantly inhibited due to the enhanced PDT, PTT, and CO gas therapy. This study provides a strategy with oxygen generating and thermal-responsive CO release to combine phototherapy and CO gas therapy for cancer treatment.

Blockade of Platelets Using Tumor-Specific NO-Releasing Nanoparticles Prevents Tumor Metastasis and Reverses Tumor Immunosuppression.

The tumor microenvironment maintains a sufficient immunosuppressive state owing to the existence of the immunosuppressive factors. The most prominent such factor is transforming growth factor ß (TGF-ß), which is mainly provided by platelets. Moreover, platelets have been shown to be the main accomplice in assisting tumor metastasis. Therefore, blocking tumor-associated platelets is endowed with functions of enhancing immunity and reducing metastasis. Herein, we designed a tumor microenvironment-responsive nitric oxide (NO) release nanoparticle, Ptx@AlbSNO, which was able to specifically and safely co-deliver the antiplatelet agent NO and the chemotherapeutic agent paclitaxel (Ptx) into tumor tissues and inhibit platelet-tumor cell interactions. We discovered that Ptx@AlbSNO could successfully block tumor-specific platelet functions, thereby suppressing the process of tumor epithelial-mesenchymal transition (EMT), preventing platelet adhesion around circulating tumor cells (CTCs) and reducing distant metastasis. In vivo studies demonstrate that the co-delivery of NO and Ptx can suppress primary tumor growth. With the ability to effectively inhibit activated platelets and TGF-ß secretion in tumors, Ptx@AlbSNO can enhance intratumoral immune cell infiltration to reverse the immunosuppressive tumor microenvironment.

Starvation-amplified CO generation for enhanced cancer therapy via an erythrocyte membrane-biomimetic gas nanofactory.

Carbon monoxide (CO)-based gas therapy has emerged as an attractive therapeutic strategy for cancer therapy. However, the main challenges are the in situ-triggered and efficient delivery of CO in tumors, which limit its further clinical application. Herein, we developed an erythrocyte membrane-biomimetic gas nanofactory (MGP@RBC) to amplify the in situ generation of CO for combined energy starvation of cancer cells and gas therapy. This nanofactory was constructed by encapsulating glucose oxidase (GOx) and Mn2(CO)10 (CO-donor) into the biocompatible polymer poly(lactic-co-glycolic acid), obtaining MGP nanoparticles, which are further covered by red blood cell (RBC) membrane. Because of the presence of proteins on RBC membranes, the nanoparticles could effectively avoid immune clearance in macrophages (Raw264.7) and significantly prolong their blood circulation time, thereby achieving higher accumulation at the tumor site. After that, the GOx in GMP@RBC could effectively catalyze the conversion of endogenous glucose to hydrogen peroxide (H2O2) in the presence of oxygen. The concomitant generation of H2O2 could efficiently trigger CO release to cause dysfunction of mitochondria and activate caspase, thereby resulting in apoptosis of the cancer cells. In addition, the depletion of intratumoral glucose could starve tumor cells by shutting down the energy supply. Altogether, the in vitro and in vivo studies of our synthesized biomimetic gas nanofactory exhibited an augmentative synergistic efficacy of CO gas therapy and energy starvation to inhibit tumor growth. It provides an attractive strategy to amplify CO generation for enhanced cancer therapy in an accurate and more efficient manner. STATEMENT OF SIGNIFICANCE: Carbon monoxide (CO) based gas therapy has emerged as an attractive therapeutic strategy for cancer therapy. In this study, we developed an erythrocyte membrane biomimetic gas nanofactory to amplify the in-situ generation of CO for combined cancer starvation and gas therapy. It is constructed by coating glucose oxidase (GOx) and CO donor-loaded nanoparticles with erythrocyte membrane. Due to the erythrocyte membrane, it can effectively prolong blood circulation time and achieve higher tumor accumulation. After accumulated in tumor, endogenous glucose can be effectively catalyzed to hydrogen peroxide, in-situ amplified CO release to induce the apoptosis of cancer cells. In addition, depleting glucose can also starve tumor cells by shutting down the energy supply. Overall, our biomimetic gas nanofactory exhibits an augmentative synergistic efficacy of CO gas therapy and starvation to increased tumor inhibition. It provide a novel strategy to deliver CO in an accurate and more efficient manner, promising for combined cancer therapy in future clinical application.

A modified hydrophobic ion-pairing complex strategy for long-term peptide delivery with high drug encapsulation and reduced burst release from PLGA microspheres.

Poor encapsulation and high initial burst were two major obstacles for the water-soluble peptide drug loaded microspheres preparation using the industrial emulsification method. In the present study, we hypothesized that the hydrophobic ion-pairing (HIP) complex strategy with a further healing of the pores within the microspheres may improve drug encapsulation and initial burst release. DSS was chosen as the most suitable one among the three test ion-pairing agents (SDS, DSS and STC) due to its high binding efficiency with drug and reversible dissociation capacity in presence of counter ions. The formation of HIP complex between octreotide acetate and DSS successfully reversed the highly water-soluble nature of the drug. A specific S/O/W method was adopted to encapsulate such drug containing HIP complex. The encapsulation efficiency of the drug was greatly improved compared with the conventional W1/O/W2 method (from 44% to 90%). Under the optimal healing conditions (the healing time 6 h, temperature 40 °C and 4% DEP content), the pores within the microspheres were effectively healed. Initial burst amount of octreotide acetate in S/O/W microspheres decreased to 3.56%. The pore healing effect was further confirmed by the scanning electron microscopy and fluorescence microscopy results. In the process of testing the drug release performance of such new strategy in vitro and in vivo, a more satisfactory single phase release profile with sustained and steady drug release was observed. These results suggested that the modified HIP strategy could be a promising platform for water-soluble peptide encapsulation with high encapsulation efficiency, low initial burst and stable drug release mechanism.