Ultrasound-nanovesicles interplay for theranostics.

Nanovesicles (NVs) are widely used in the treatment and diagnosis of diseases due to their excellent vascular permeability, good biocompatibility, high loading capacity, and easy functionalization. However, their yield and in vivo penetration depth limitations and their complex preparation processes still constrain their application and development. Ultrasound, as a fundamental external stimulus with deep tissue penetration, concentrated energy sources, and good safety, has been proven to be a patient-friendly and highly efficient strategy to overcome the restrictions of traditional clinical medicine. Recent research has shown that ultrasound can drive the generation of NVs, increase their yield, simplify their preparation process, and provide direct therapeutic effects and intelligent control to enhance the therapeutic effect of NVs. In addition, NVs, as excellent drug carriers, can enhance the targeting efficiency of ultrasound-based sonodynamic therapy or sonogenetic regulation and improve the accuracy of ultrasound imaging. This review provides a detailed introduction to the classification, generation, and modification strategies of NVs, emphasizing the impact of ultrasound on the formation of NVs and summarizing the enhanced treatment and diagnostic effects of NVs combined with ultrasound for various diseases.

A nucleus-targeting peptide antagonist towards EZH2 displays therapeutic efficacy for lung cancer.

EZH2 is an overexpressed nuclear protein associated with relatively poor survival and chemoresistance in lung cancer. In this study, a nucleus-targeting peptide antagonist EIP103 capable of penetrating cell membrane and nuclear envelope was identified, and has high binding affinity towards EZH2 localized in the nucleus of lung cancer cells. To improve the stability and therapeutic efficacy of EIP103, PEG-PE micelle encapsulated EIP103 (M-EIP103) was successfully conducted. In vitro results indicated that M-EIP103 exhibited better stability, higher intracellular uptake and stronger cytotoxicity than free EIP103 in H446 and A549 cells. Mechanistic studies suggested that M-EIP103 inhibited proliferation by down-regulating the H3K27me3 expression level in cancer cells. In vivo assays further confirmed that both EIP103 and M-EIP103 significantly inhibited lung cancer progression. Notably, enhanced therapeutic efficacy of EIP103 by PEG-PE micelle encapsulation could be identified. The observed anti-tumor activity of EIP103 and M-EIP103 demonstrated a promising therapy to improve clinical treatment of lung cancers as well as other EZH2-overexpressing malignant cancers. This study also illustrates the feasibility of developing targeted delivery of therapeutic peptides to nucleus for cancer therapy.

Peptide-based coacervates in therapeutic applications.

Coacervates are droplets formed by liquid‒liquid phase separation. An increasing number of studies have reported that coacervates play an important role in living cells, such as in the generation of membraneless organelles, and peptides contribute to condensate droplet formation. Peptides with versatile functional groups and special secondary structures, including α-helices, ß-sheets and intrinsically disordered regions, provide novel insights into coacervation, such as biomimetic protocells, neurodegenerative diseases, modulations of signal transmission, and drug delivery systems. In this review, we introduce different types of peptide-based coacervates and the principles of their interactions. Additionally, we summarize the thermodynamic and kinetic mechanisms of peptide-based coacervates and the associated factors, including salt, pH, and temperature, affecting the phase separation process. We illustrate recent studies on modulating the functions of peptide-based coacervates applied in biological diseases. Finally, we propose their promising broad applications and describe the challenges of peptide-based coacervates in the future.

Enhancement of gold-nanocluster-mediated chemotherapeutic efficiency of cisplatin in lung cancer.

A novel delivery system for cisplatin was constructed based on electrostatics-mediated assemblies of gold nanoclusters and PEGylated cationic peptide (cisplatin@GC-pKs). Encapsulated cisplatin in the as-formed micelle like assemblies was observed to demonstrate improved cellar uptake and enhanced chemotherapeutic efficiency in the cisplatin-resistant lung cancer cells. In vivo assays further confirmed that cisplatin@GC-pKs had profound anti-tumor efficiency due to deep penetration and accumulation of nanoscale cisplatin@GC-pKs via the enhanced permeability and retention (EPR) effect at tumor tissues. The constructed cisplatin@GC-pKs in this work demonstrated enhanced anti-tumor activity for lung cancer therapy, as well as a potential treatment strategy for a variety of cisplatin-resistance related malignancies.

Enhanced lymphatic delivery of nanomicelles encapsulating CXCR4-recognizing peptide and doxorubicin for the treatment of breast cancer.

Lymph node metastases in cancer patients are associated with high aggressiveness, poor prognosis, and short survival time. The chemokine receptor 4 (CXCR4)/stroma derived factor 1α (CXCL12) biological axis plays a critical role in the spread of cancer cells. Designing effective delivery systems that can successfully deliver CXCR4 antagonists to lymph nodes, which are rich in CXCR4-overexpressing cancer cells, for controlling cancer metastasis remain challenging. In this study, we demonstrated that such a challenge may be alleviated by developing nanometer-sized polyethylene glycol-phosphatidylethanolamine (PEG-PE) micelles for the co-delivery of the CXCR4 antagonistic peptide E5 and doxorubicin (M-E5-Dox). This nanomicelle platform enables the preferential accumulation of cargos into lymph nodes and thus can better inhibit cancer metastasis and enhance antitumor efficacy than either free drugs or single drug-loaded micelles in breast cancer-bearing mouse models. Hence, M-E5-Dox is expected to be a potential therapeutic agent that would improve the clinical benefits of breast cancer therapy and treatment of various CXCR4-overexpressing malignancies.

Synthetic CXCR4 Antagonistic Peptide Assembling with Nanoscaled Micelles Combat Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is the most common adult acute leukemia with very low survival rate due to drug resistance and high relapse rate. The C-X-C chemokine receptor 4 (CXCR4) is highly expressed by AML cells, actively mediating chemoresistance and reoccurrence. Herein, a chemically synthesized CXCR4 antagonistic peptide E5 is fabricated to micelle formulation (M-E5) and applied to refractory AML mice, and its therapeutic effects and pharmacokinetics are investigated. Results show that M-E5 can effectively block the surface CXCR4 in leukemic cells separated from bone marrow (BM) and spleen, and inhibit the C-X-C chemokine ligand 12-mediated migration. Subcutaneous administration of M-E5 significantly inhibits the engraftment of leukemic cells in spleen and BM, and mobilizes residue leukemic cells into peripheral blood, reducing organs' burden and significantly prolonging the survival of AML mice. M-E5 can also increase the efficacy of combining regime of homoharringtonine and doxorubicin. Ribonucleic acid sequencing demonstrates that the therapeutic effect is contributed by inhibiting proliferation and enhancing apoptosis and differentiation, all related to the CXCR4 signaling blockade. M-E5 reaches the concentration peak at 2 h after administration with a half-life of 14.5 h in blood. In conclusion, M-E5 is a novel promising therapeutic candidate for refractory AML treatment.

Modulation of ß-amyloid aggregation by graphene quantum dots.

Misfolding and abnormal aggregation of ß-amyloid peptide is associated with the onset and progress of Alzheimer's disease (AD). Therefore, modulating ß-amyloid aggregation is critical for the treatment of AD. Herein, we studied the regulatory effects and mechanism of graphene quantum dots (GQDs) on 1-42 ß-amyloid (Aß1-42) aggregation. GQDs displayed significant regulatory effects on the aggregation of Aß1-42 peptide as detected by thioflavin T (ThT) assay. Then, the changes of confirmations and structures induced by GQDs on the Aß1-42 aggregation were monitored by circular dichroism (CD), dynamic light scattering (DLS) and transmission electron microscope (TEM). The in vitro cytotoxicity experiments further demonstrated the feasibility of GQDs on the regulation of Aß1-42 aggregation. Meanwhile, the structural changes of a Aß1-42/GQDs mixture in different pH revealed that electrostatic interaction was the major driving force in the co-assembly process of Aß1-42 and GQDs. The proposed mechanism of the regulatory effects of GQDs on the Aß1-42 aggregation was also deduced reasonably. This work not only demonstrated the potential feasibility of GQDs as therapeutic drug for AD but also clarified the regulatory mechanism of GQDs on the Aß1-42 aggregation.

Correction: Improving the inhibitory effect of CXCR4 peptide antagonist in tumor metastasis with an acetylated PAMAM dendrimer.

[This corrects the article DOI: 10.1039/C8RA08526A.].

Improving the inhibitory effect of CXCR4 peptide antagonist in tumor metastasis with an acetylated PAMAM dendrimer.

The metastasis of breast cancer is one of the main factors resulting in the high fatality of patients. Although many antagonists have been developed to inhibit the metastasis of breast cancer, their practical application has been limited because of the poor solubility of many chemotherapeutic drugs in the physiological environment. Herein, a complex of E5 peptide antagonist and acetylated PAMAM G5 (PAC80) has been constructed to enhance the solubility of the peptide antagonist. The E5 peptide antagonist has been designed and it was confirmed that it could specifically bind to CXCR4, which is a chemokine receptor involved in the metastasis of several types of cancers, in our previous work. The results demonstrated that PAC80 could significantly increase the solubility of the E5 peptide in the physiological environment, as well as the affinity of the E5 peptide to CXCR4-positive cell lines, and the inhibitory effect of the E5 peptide for cell migration in vitro. Meanwhile, the passive lung metastasis model of breast cancer was established and the anti-tumor metastasis of the PAC80-E5 complex was evaluated in vivo. The results show that the PAC80-E5 complex demonstrated excellent inhibition for the tumor metastasis at an E5 dosage of 10 and 20 mg kg-1. These effects indicate a feasible strategy to apply the PAC80-peptide complex in cancer therapies to improve the solubility and bioavailability.

Correction: Improving the inhibitory effect of CXCR4 peptide antagonist in tumor metastasis with an acetylated PAMAM dendrimer.

[This corrects the article DOI: 10.1039/C8RA08526A.].

Physicochemical properties of liposomal modifiers that shift macrophage phenotype.

Liposomes are one of the most widely studied drug carriers due to their relative biocompatibility, lack of immune system stimulation, ability to be cell specific, and serve as a protective drug carrier. Due to several physicochemical properties such as size and charge, liposomes naturally target the phagocytic capabilities of macrophages. In the tumor microenvironment, macrophages strongly influence growth and progression, making them an appealing target for drug delivery. Using the natural capability of liposomes to target macrophages, and the knowledge that material properties can alter cellular responses, this work aims to influence macrophage phenotype with arginine-like surface modified DOPE:DOPC liposomes. These liposomes were incubated with interleukin-4 (IL-4) or lipopolysaccharide (LPS) stimulated macrophages and naïve RAW 264.7 macrophages. Macrophage phenotype was determined through arginase activity, tumor necrosis factor (TNF)-α secretion, and nitrite production. With significant variations in the molecular profiles of each activated cell type, these findings suggest that macrophage responses could be altered with small variations in surface functionality of liposomes.

Improving selective targeting to macrophage subpopulations through modifying liposomes with arginine based materials.

The effects of surface modifications on liposomes using a library of arginine derivatives for improved drug delivery were examined. Both unmodified and modified liposomes were tested for their drug delivery properties and propensity for internalization by macrophages. All materials were characterized by dynamic light scattering (DLS) and zeta potential. The resulting liposomes were able to encapsulate doxorubicin with a loading efficiency greater than 90% and cumulative releases of less than 15% after 144 h. The internalization of these particles was examined by loading the liposomes with fluorescein or doxorubicin to test internalization through fluorescence level and half maximal inhibitory concentration (IC50), respectively. RAW 264.7 macrophages were activated with lipopolysaccharide (LPS) or interleukin-4 (IL-4) to induce M1- or M2-like phenotypes. Naïve macrophages were also studied. Most modified liposomes enhanced the cytotoxicity of doxorubicin compared to unmodified liposomes. Macrophage phenotype was also observed to influence the cytotoxicity of doxorubicin entrapped in modified liposomes, with some samples enhancing the cytotoxicity in LPS stimulated macrophages and some enhancing toxicity in IL-4 stimulated cells.