Chiral polypeptide nanoparticles as nanoadjuvants of nanovaccines for efficient cancer prevention and therapy

The chirality of bioactive molecules is closely related to their functions. D-amino acids commonly distributed in the bacterial cell walls trigger a robust anti-infective immune response. Inspired by that, two kinds of chiral polypeptides, poly(L-phenylalanine)-block-poly(L-lysine) (P_L-K) and poly(L-phenylalanine)-block-poly(D-lysine) (P_D-K), were synthesized and used as nanoadjuvants of nanovaccines for cancer prevention and therapy. The amphiphilic polypeptides self-assembled into nanoparticles with a diameter of about 30 nm during ultrasonic-assisted dissolution in phosphate-buffered saline. The nanovaccines P_L-K-OVA and P_D-K-OVA were easily prepared by mixing solutions of P_L-K or P_D-K and the model antigen chicken ovalbumin (OVA), respectively, with loading efficiencies of almost 100%. Compared to P_L-K-OVA, P_D-K-OVA more robustly induced dendritic cell maturation, antigen cross-presentation, and adaptive immune response. More importantly, it effectively prevented and treated the OVA-expressed B16-OVA melanoma model. P_D-K-OVA achieved a tumor inhibition rate of 94.9% and even 97.0% by combining with anti-PD-1 antibody. Therefore, the chiral polypeptide nanoparticles represent simple, efficient, and extensively applicable nanoadjuvants for various nanovaccines.

Osteoimmunity-regulating biomaterials promote bone regeneration

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Nucleic acid nanoassembly-enhanced RNA therapeutics and diagnosis

RNAs are involved in the crucial processes of disease progression and have emerged as powerful therapeutic targets and diagnostic biomarkers. However, efficient delivery of therapeutic RNA to the targeted location and precise detection of RNA markers remains challenging. Recently, more and more attention has been paid to applying nucleic acid nanoassemblies in diagnosing and treating. Due to the flexibility and deformability of nucleic acids, the nanoassemblies could be fabricated with different shapes and structures. With hybridization, nucleic acid nanoassemblies, including DNA and RNA nanostructures, can be applied to enhance RNA therapeutics and diagnosis. This review briefly introduces the construction and properties of different nucleic acid nanoassemblies and their applications for RNA therapy and diagnosis and makes further prospects for their development.

3D Printed Personalized Nerve Guide Conduits for Precision Repair of Peripheral Nerve Defects

The treatment of peripheral nerve defects has always been one of the most challenging clinical practices in neurosurgery. Currently, nerve autograft is the preferred treatment modality for peripheral nerve defects, while the therapy is constantly plagued by the limited donor, loss of donor function, formation of neuroma, nerve distortion or dislocation, and nerve diameter mismatch. To address these clinical issues, the emerged nerve guide conduits (NGCs) are expected to offer effective platforms to repair peripheral nerve defects, especially those with large or complex topological structures. Up to now, numerous technologies are developed for preparing diverse NGCs, such as solvent casting, gas foaming, phase separation, freeze-drying, melt molding, electrospinning, and three-dimensional (3D) printing. 3D printing shows great potential and advantages because it can quickly and accurately manufacture the required NGCs from various natural and synthetic materials. This review introduces the application of personalized 3D printed NGCs for the precision repair of peripheral nerve defects and predicts their future directions.

Stimuli-Responsive Nanoparticles for Controlled Drug Delivery in Synergistic Cancer Immunotherapy

Cancer immunotherapy has achieved promising clinical progress over the recent years for its potential to treat metastatic tumors and inhibit their recurrences effectively. However, low patient response rates and dose-limiting toxicity remain as major dilemmas for immunotherapy. Stimuli-responsive nanoparticles (srNPs) combined with immunotherapy offer the possibility to amplify anti-tumor immune responses, where the weak acidity, high concentration of glutathione, overexpressions of enzymes, and reactive oxygen species, and external stimuli in tumors act as triggers for controlled drug release. This review highlights the design of srNPs based on tumor microenvironment and/or external stimuli to combine with different anti-tumor drugs, especially the immunoregulatory agents, which eventually realize synergistic immunotherapy of malignant primary or metastatic tumors and acquire a long-term immune memory to prevent tumor recurrence. The authors hope that this review can provide theoretical guidance for the construction and clinical transformation of smart srNPs for controlled drug delivery in synergistic cancer immunotherapy.

Rational construction of polycystine-based nanoparticles for biomedical applications

Polypeptide-based nanoparticles are one of the promising excipients of nanomedicines due to their excellent biosafety and flexible modification. Among all the types of polypeptide nanoparticles, polycystine (PCys2)-based ones draw increasing...

An oxidative stress-responsive electrospun polyester membrane capable of releasing anti-bacterial and anti-inflammatory agents for postoperative anti-adhesion

Peritendinous adhesion, secondary to the repair surgery of tendon rupture or injury, is one of the most common causes of reoperation, owing to the proliferation of fibrous tissue and excessive collagen synthesis caused by the residing inflammatory cells. In this study, a smart oxidative stress-responsive electrospun polyester membrane (EPM) was fabricated as both physical barrier and reservoir of curcumin/celecoxib (CUR/CEL) to prevent peritendinous adhesion. The multicomponent EPM was designed to release the encapsulated drugs in response to oxidative stress of the local microenvironment induced by inflammation. Specifically, sulfides in the EPM were able to react with reactive oxygen species (ROS) and become hydrophilic sulfoxide or sulfone to accelerate the release rate of drugs and regulate oxidative stress level in the inflammatory site intelligently. The oxidation-sensitive multicomponent EPM loaded with CUR and CEL was tested for anti-adhesion capacity in vitro and in vivo. An excellent ROS-sensitive degradation behavior and good cytocompatibility with cell viability of above 85% were presented with the fabricated EPM. The CUR- or CEL-loaded EPM possessed a better anti-adhesion ability compared with EPM without the drugs. Nevertheless, they were inferior to the EPM simultaneously loaded with both drugs, where the adhesion rate and fibrous adhesion number in the EPM+CUR/CEL group were close to extremely low values of about zero, demonstrating that CUR and CEL could synergistically prevent peritendinous adhesion. More interestingly, the multicomponent EPM was able to react with the local oxidative stress, leading to a smart and sustained behavior of releasing approximately 80% of the drug within 20 days. Overall, the smart multicomponent EPM offers a promising barrier strategy to prevent peritendinous adhesion.

Polypeptide nanoformulation-induced immunogenic cell death and remission of immunosuppression for enhanced chemoimmunotherapy

Many conventional chemotherapeutics play an immune-modulating effect by inducing immunogenic cell death (ICD) in tumor cells. However, they hardly arouse strong antitumor immune response because the immunosuppressive lymphocytes are present in the tumor microenvironment. These immunosuppressive lymphocytes include regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). We used a low dose of doxorubicin (DOX) to induce ICD in combination with immune regulator 1-methyl-DL-tryptophan (1MT) to suppress indoleamine 2,3-dioxygenase and overcome Treg- and MDSC-associated immune suppression. By co-encapsulation of DOX and 1MT into a reduction-responsive polypeptide nanogel, the drugs were simultaneously released in the tumor cells and synergistically performed antitumor efficacy. After treatment, recruitment of Tregs and MDSCs was inhibited, and the frequency of tumor-infiltrating CD8⁺ T cells was remarkably enhanced. These results demonstrated that the chemoimmunotherapy strategy effectively suppressed tumor growth without causing evident adverse effects, indicating its great potential in clinical cancer therapy.

X-ray-responsive polypeptide nanogel for concurrent chemoradiotherapy

Concurrent chemoradiotherapy (CCRT) is a standard treatment regimen for medically inoperable stage III non-small-cell lung carcinoma (NSCLC) owing to its superior prognostics compared with the sequential modality. Nevertheless, the current pattern of CCRT still fails to provide satisfactory survival outcome. Furthermore, CCRT is always accompanied by a higher risk of severe side effects, limiting the dose escalation. Herein, an X-ray-responsive polypeptide nanogel (PNG) was developed for on-demand delivery of chemotherapeutic agent triggered by radiotherapy to synergistically improve the efficacy of CCRT with reduced side effects. The smart PNG was formed by crosslinking methoxy poly(ethylene glycol)-block-poly(L-glutamic acid-co-γ-2-chloroethyl-L-glutamate) (mPEG-b-P(LG-co-CELG)) with a diselenide (Se-Se) bond. The doxorubicin (DOX)-loaded polypeptide nanogel (PNG/DOX) exhibited accelerated drug release when exposed to X-ray irradiation as a result of Se-Se bond degradation. With prolonged circulation and enhanced intratumoral accumulation in vivo, PNG/DOX combined with X-ray irradiation exhibited better synergistic antitumor efficacy and fewer side effects toward human A549 lung carcinoma-bearing nude mice. The smart X-ray-responsive nanogel provides a promising bridge between chemotherapy and radiotherapy and enhances the potential application of CCRT in clinic.

Synergistically Enhanced Mucoadhesive and Penetrable Polypeptide Nanogel for Efficient Drug Delivery to Orthotopic Bladder Cancer

Intravesical chemotherapy has been recommended after the gold standard of transurethral resection of the bladder tumor to prevent bladder cancer (BC) from local recurrence in the clinic. However, due to rapid urine excretion and barrier protection of the bladder wall, the clinical performances of chemotherapeutic drugs are severely compromised. In the present work, a smart positively charged disulfide-crosslinked nanogel of oligoarginine-poly(ethylene glycol)–poly(L-phenylalanine-co-L-cystine) (R₉-PEG–P(LP-co-LC)) was prepared to prolong the retention period and enhance the penetration capability of chemotherapeutic agent toward the bladder wall. PEG significantly improved the aqueous dispersibility of the 10-hydroxycamptothecin (HCPT)-loaded R₉-PEG–P(LP-co-LC) (i.e., R₉NG/HCPT) and enhanced the mucoadhesive capability by the nonspecific interaction between PEG chain and the bladder mucosa accompanied with the electrostatic interaction between the cationic R₉ and negatively charged bladder mucosa. Besides, R₉, as a cell-penetrating peptide, efficiently penetrated through the cell membrane and delivered carried cargo. The disulfide bond endowed the selective release behavior of HCPT triggered by the intracellular reductive microenvironment. As an advanced chemotherapeutic nanoformulation, the smart R₉NG/HCPT demonstrated superior cytotoxicity against human BC 5637 cells in vitro and remarkably enhanced tumor suppression activity toward orthotopic BC models of mouse and rat in vivo, indicating its great potential in the clinical intravesical BC chemotherapy.

Tackling autoimmunity with nanomedicines

Tolerogenic immunotherapy aims to blunt pathogenic inflammation without affecting systemic immunity. However, the anti-inflammatory drugs and immunosuppressive biologics that are used in the clinic usually result in nonspecific immune cell suppression and off-target toxicity. For this reason, strategies have been developed to induce antigen-specific immune tolerance through the delivery of disease-relevant antigens by nanocarriers as a benefit of their preferential internalization by antigen-presenting cells. Herein, we discuss the recent advances in the nanotechnology-based antigen-specific tolerance approaches. Some of these designs are based on nanoparticles delivering antigens and immunoregulatory agents to modulate antigen-presenting pathways, while others directly target T cells via nanoparticle-based artificial antigen-presenting cells. These antigen-specific therapies are hoped to replace systemic immune suppression and provide long-term disease remission.

Immunomodulatory Nanosystems

Immunotherapy has emerged as an effective strategy for the prevention and treatment of a variety of diseases, including cancer, infectious diseases, inflammatory diseases, and autoimmune diseases. Immunomodulatory nanosystems can readily improve the therapeutic effects and simultaneously overcome many obstacles facing the treatment method, such as inadequate immune stimulation, off-target side effects, and bioactivity loss of immune agents during circulation. In recent years, researchers have continuously developed nanomaterials with new structures, properties, and functions. This Review provides the most recent advances of nanotechnology for immunostimulation and immunosuppression. In cancer immunotherapy, nanosystems play an essential role in immune cell activation and tumor microenvironment modulation, as well as combination with other antitumor approaches. In infectious diseases, many encouraging outcomes from using nanomaterial vaccines against viral and bacterial infections have been reported. In addition, nanoparticles also potentiate the effects of immunosuppressive immune cells for the treatment of inflammatory and autoimmune diseases. Finally, the challenges and prospects of applying nanotechnology to modulate immunotherapy are discussed.

PEGylated Polyurea Bearing Hindered Urea Bond for Drug Delivery

In recent years, polyureas with dynamic hindered urea bonds (HUBs), a class of promising biomedical polymers, have attracted wide attention as a result of their controlled hydrolytic properties. The effect of the chemical structures on the properties of polyureas and their assemblies has rarely been reported. In this study, four kinds of polyureas with different chemical groups have been synthesized, and the polyureas from cyclohexyl diisocyanate and tert-butyl diamine showed the fastest hydrolytic rate. The amphiphilic polyurea composed of hydrophobic cyclohexyl-tert-butyl polyurea and hydrophilic poly(ethylene glycol) (PEG) was synthesized for the controlled delivery of the antitumor drug paclitaxel (PTX). The PTX-loaded PEGylated polyurea micelle more effectively entered into the murine breast cancer 4T1 cells and inhibited the corresponding tumor growth in vitro and in vivo. Therefore, the PEGylated polyurea with adjustable degradation might be a promising polymer matrix for drug delivery.

Inhibition of CaMKIIα Activity Enhances Antitumor Effect of Fullerene C60 Nanocrystals by Suppression of Autophagic Degradation

Fullerene C60 nanocrystals (nano-C60) possess various attractive bioactivities, including autophagy induction and calcium/calmodulin-dependent protein kinase IIα (CaMKIIα) activation. CaMKIIα is a multifunctional protein kinase involved in many cellular processes including tumor progression; however, the biological effects of CaMKIIα activity modulated by nano-C60 in tumors have not been reported, and the relationship between CaMKIIα activity and autophagic degradation remains unclear. Herein, nano-C60 is demonstrated to elicit reactive oxygen species (ROS)-dependent cytotoxicity and persistent activation of CaMKIIα in osteosarcoma (OS) cells. CaMKIIα activation, in turn, produces a protective effect against cytotoxicity from nano-C60 itself. Inhibition of CaMKIIα activity by either the chemical inhibitor KN-93 or CaMKIIα knockdown dramatically promotes the anti-OS effect of nano-C60. Moreover, inhibition of CaMKIIα activity causes lysosomal alkalinization and enlargement, and impairs the degradation function of lysosomes, leading to autophagosome accumulation. Importantly, excessive autophagosome accumulation and autophagic degradation blocking are shown to play an important role in KN-93-enhanced-OS cell death. The synergistic anti-OS efficacy of KN-93 and nano-C60 is further revealed in an OS-xenografted murine model. The results demonstrate that CaMKIIα inhibition, along with the suppression of autophagic degradation, presents a promising strategy for improving the antitumor efficacy of nano-C60.

Evaluation of Polymer Nanoformulations in Hepatoma Therapy by Established Rodent Models

Hepatoma is one of the most severe malignancies usually with poor prognosis, and many patients are insensitive to the existing therapeutic agents, including the drugs for chemotherapy and molecular targeted therapy. Currently, researchers are committed to developing the advanced formulations with controlled drug delivery to improve the efficacy of hepatoma therapy. Numerous inoculated, induced, and genetically engineered hepatoma rodent models are now available for formulation screening. However, animal models of hepatoma cannot accurately represent human hepatoma in terms of histological characteristics, metastatic pathways, and post-treatment responses. Therefore, advanced animal hepatoma models with comparable pathogenesis and pathological features are in urgent need in the further studies. Moreover, the development of nanomedicines has renewed hope for chemotherapy and molecular targeted therapy of advanced hepatoma. As one kind of advanced formulations, the polymer-based nanoformulated drugs have many advantages over the traditional ones, such as improved tumor selectivity and treatment efficacy, and reduced systemic side effects. In this article, the construction of rodent hepatoma model and much information about the current development of polymer nanomedicines were reviewed in order to provide a basis for the development of advanced formulations with clinical therapeutic potential for hepatoma.