Folate-receptor mediated pH/reduction-responsive biomimetic nanoparticles for dually activated multi-stage anticancer drug delivery.

How to overcome the cell membrane barriers and achieve release payloads efficiently in the cytoplasm have been major challenges for anticancer drug delivery and therapeutic effects with nanosystems. In this study, bovine serum albumin (BSA) was modified with folate acid and histamine, which was then used as the nanocarrier for the antitumor agent doxorubicin (DOX). The DOX-loaded nanoparticles (DOX/FBH-NPs) were prepared via a crosslinking method, and the release of DOX from these nanoparticles (NPs) exhibited pH/reduction-responsive behaviors in vitro. These NPs interacted with the folate receptor overexpressed on the cell membrane of 4 T1 cells and achieved enhanced endocytosis. Afterwards, these NPs exhibited pH-responsiveness within endo-lysosomes and escaped from endosomes due to the "proton sponge" effect, and then completed release of DOX was triggered by high concentration of glutathione (GSH) in cytoplasm. Thus, DOX/FBH-NPs exhibited excellent cytotoxicity against 4 T1 cells in vitro. Benefited from the enhanced permeability and retention (EPR) effect and folate receptor-mediated endocytosis, these NPs gained satisfied tumor-targeting effects in vivo and efficient delivery of DOX to tumor tissues. As a result, these NPs exhibited enhanced antitumor effects and reduced side effects in vivo. In conclusion, these BSA-based NPs modified with both folate acid and histamine showed enhanced tumor-targeting effects in vivo with good biocompatibility and intracellular pH/reduction-responsive behaviors, providing a promising strategy for the efficient delivery of antitumor agents.

Stimuli-responsive nanoparticles for the codelivery of chemotherapeutic agents doxorubicin and siPD-L1 to enhance the antitumor effect.

Cancer cells have been reported to exhibit high resistance against immune system recognition through various cell intrinsic and extrinsic mechanisms. Considerable challenges have been encountered in monotherapy with chemotherapeutics to attain the desired antitumor efficacy. In this study, a nanodelivery system was designed to incorporate doxorubicin (DOX) and programmed death-ligand 1 (PD-L1) small interfering RNA (siRNA), that is, siPD-L1. DOX and siPD-L1 were formed from a stimuli-responsive polymer with a poly-L-lysine-lipoic acid reduction-sensitive core and a tumor extracellular pH-stimulated shedding polyethylene glycol layer. The codelivery system was stable under physiological pH conditions and demonstrated enhanced cellular uptake at the tumor site. Moreover, the combined treatment of DOX and siPD-L1 exhibited improved antitumor effect in vitro and in vivo compared with either modality alone. The combination of chemotherapy and immunotherapy presented in this work through the codelivery of a chemotherapeutic agent and a gene-silencing agent (siRNA) may provide a new strategy for cancer treatment.

Co-delivery of VEGF siRNA and Etoposide for Enhanced Anti-angiogenesis and Anti-proliferation Effect via Multi-functional Nanoparticles for Orthotopic Non-Small Cell Lung Cancer Treatment.

Targeting tumor angiogenesis pathway via VEGF siRNA (siVEGF) has shown great potential in treating highly malignant and metastatic non-small cell lung cancer (NSCLC). However, anti-angiogenic monotherapy lacked sufficient antitumor efficacy which suffered from malignant tumor proliferation. Therefore, the combined application of siVEGF and chemotherapeutic agents for simultaneous targeting of tumor proliferation and angiogenesis has been a research hotspot to explore a promising NSCLC therapy regimen. Methods: We designed, for the first time, a rational therapy strategy via intelligently co-delivering siVEGF and chemotherapeutics etoposide (ETO) by multi-functional nanoparticles (NPs) directed against the orthotopic NSCLC. These NPs consisted of cationic liposomes loaded with siVEGF and ETO and then coated with versatile polymer PEGylated histidine-grafted chitosan-lipoic acid (PHCL). We then comprehensively evaluated the anti-angiogenic and anti-proliferation efficiency in the in vitro tumor cell model and in bioluminescent orthotopic lung tumor bearing mice model. Results: The NPs co-delivering siVEGF and ETO exhibited tailor-made surface charge reversal features in mimicking tumor extracellular environment with improved internal tumor penetration capacity and higher cellular internalization. Furthermore, these NPs with flexible particles size triggered by intracellular acidic environment and redox environment showed pinpointed and sharp intracellular cargo release guaranteeing adequate active drug concentration in tumor cells. Enhanced VEGF gene expression silencing efficacy and improved tumor cell anti-proliferation effect were demonstrated in vitro. In addition, the PHCL layer improved the stability of these NPs in neutral environment allowing enhanced orthotopic lung tumor targeting efficiency in vivo. The combined therapy by siVEGF and ETO co-delivered NPs for orthotopic NSCLC simultaneously inhibited tumor proliferation and tumor angiogenesis resulting in more significant suppression of tumor growth and metastasis than monotherapy. Conclusion: Combined application of siVEGF and ETO by the multi-functional NPs with excellent and on-demand properties exhibited the desired antitumor effect on the orthotopic lung tumor. Our work has significant potential in promoting combined anti-angiogenesis therapy and chemotherapy regimen for clinical NSCLC treatment.

Doxorubicin and siRNA-PD-L1 co-delivery with T7 modified ROS-sensitive nanoparticles for tumor chemoimmunotherapy.

Tumor cells avoid immunosurveillance during the tumorigenesis, metastasis and recurrence periods thanks to the overexpressed immunosuppressive molecules on their surface. For instance, the programmed cell death 1 ligand (PD-L1) binds with the T-cells' programmed cell death receptor 1 (PD-1) impairing the anti-tumor activity of the host T cells. In this study, a new reactive oxygen species (ROS) responsive nanoparticle (NP), modified with the HAIYPRH (T7) peptide, was developed for the co-delivery of siRNA-PD-L1 and doxorubicin (Dox). These NPs can block the inhibitory signal responding to T cells and enhance cytotoxicity of Dox against tumor cells. The T7 modification binds to the overexpressed transferrin receptor on tumor cells facilitating its cellular uptake. Dox rapid release is then triggered by the high tumor cells cytoplasmic concentration of ROS, leading to cell apoptosis. Our results demonstrated these NPs exhibited a T7-mediated cellular uptake and an intracellular ROS-triggered payloads release in vitro. They also suggested an improved in vivo 4T1 tumor targeting efficiency and chemoimmunotherapy. Most notably, the co-delivery system exhibited a significantly enhanced antitumor effect over Dox-only loaded NPs following prompting the proliferation of T cells by siRNA-PD-L1. In conclusion, these ROS-responsive NPs provided a promising strategy to combine siRNA-PD-L1 immunotherapy and Dox chemotherapy.

A Novel 3D in Vitro Tumor Model Based on Silk Fibroin/Chitosan Scaffolds To Mimic the Tumor Microenvironment.

Drug development involves various evaluation processes to ascertain drug effects and rigorous analysis of biological indicators during in vitro preclinical studies. Two-dimensional (2D) cell cultures are commonly used in numerous in vitro studies, which are poor facsimiles of the in vivo conditions. Recently, three-dimensional (3D) tumor models mimicking the tumor microenvironment and reducing the use of experimental animals have been developed generating great interest to appraise tumor response to treatment strategies in cancer therapy. In this study, silk fibroin (SF) protein and chitosan (CS), two natural biomaterials, were chosen to construct the scaffolds of 3D cell models. Human non-small cell lung cancer A549 cells in the SF/CS scaffolds were found to have a great tendency to gather and form tumor spheres. A549 cell spheres in the 3D scaffolds showed biological and morphological characteristics much closer to the in vivo tumors. Besides, the cells in 3D models displayed better invasion ability and drug resistance than 2D models. Additionally, differences in drug-resistant and immune-related protein levels were found, which indicated that 3D models might resemble the real-life situation. These findings suggested that these 3D tumor models composed of SF/CS are promising to provide a valuable biomaterial platform in the evaluation of anticancer drugs.

Targeted Delivery of Doxorubicin via CD147-Mediated ROS/pH Dual-Sensitive Nanomicelles for the Efficient Therapy of Hepatocellular Carcinoma.

Low accumulation in tumor sites and slow intracellular drug release remain as the obstacles for nanoparticles to achieve effective delivery of chemotherapeutic drugs. In this study, multifunctional micelles were designed to deliver doxorubicin (Dox) to tumor sites to provide more efficient therapy against hepatic carcinoma. The micelles were based on pH-responsive carboxymethyl chitosan (CMCh) modified with a reactive oxygen species (ROS)-responsive segment phenylboronic acid pinacol ester (BAPE) and an active targeted ligand CD147 monoclonal antibody. The Dox-loaded micelles provided rapid and complete drug release in pH 5.3 incubation conditions with 1 mM H2O2. In addition, an in vitro cell uptake study revealed that CD147 modification significantly enhanced cellular internalization due to the high affinity to CD147 receptors, which are overexpressed on tumor cells. An in vivo study revealed that CD147-modified micellar formulations exhibited high accumulation in tumor sites and markedly enhanced antiproliferation effects with fewer side effects than other formulations. In conclusion, this CD147 receptor targeted delivery system with ROS/pH dual sensitivity provides a promising strategy for the treatment of hepatic carcinoma.

Enhanced Cellular Internalization and On-Demand Intracellular Release of Doxorubicin by Stepwise pH-/Reduction-Responsive Nanoparticles.

The efficient delivery of antitumor agents to tumor sites faces numerous obstacles, such as poor cellular uptake and slow intracellular drug release. In this regard, smart nanoparticles (NPs) that respond to the unique microenvironment of tumor tissues have been widely used for drug delivery. In this study, novel charge-reversal and reduction-responsive histidine-grafted chitosan-lipoic acid NPs (HCSL-NPs) were selected for efficient therapy of breast cancer by enhancing cell internalization and intracellular pH- and reduction-triggered doxorubicin (DOX) release. The surface charge of HCSL-NPs presented as negative at physiological pH and reversed to positive at the extracellular and intracellular pH of the tumor. In vitro release investigation revealed that DOX/HCSL-NPs demonstrated a sustained drug release under the physiological condition, whereas rapid DOX release was triggered by both endolysosome pH and high-concentration reducing glutathione (GSH). These NPs exhibited enhanced internalization at extracellular pH, rapid intracellular drug release, and improved cytotoxicity against 4T1 cells in vitro. Excellent tumor penetrating efficacy was also found in 4T1 tumor spheroids and solid tumor slices. In vivo experiments demonstrated that HCSL-NPs exhibited excellent tumor-targeting ability in tumor tissues as well as excellent antitumor efficacy and low systemic toxicity in breast tumor-bearing BALB/c mice. These results indicated that the novel charge-reversal and reduction-responsive HCSL-NPs have great potential for targeted and efficient delivery of chemotherapeutic drugs in cancer treatments.