Self-assembled amphiphilic copolymers as dual delivery system for immunotherapy

Gas-Responsive and Gas-Releasing Polymer Assemblies

In order to explore the unique physiological roles of gas signaling molecules and gasotransmitters in vivo, chemists have engineered a variety of gas-responsive polymers that can monitor their changes in cellular milieu, and gas-releasing polymers that can orchestrate the release of gases. These have advanced their potential applications in the field of bio-imaging, nanodelivery, and theranostics. Since these polymers are of different chain structures and properties, the morphology of their assemblies will manifest distinct transitions after responding to gas or releasing gas. In this review, we summarize the fundamental design rationale of gas-responsive and gas-releasing polymers in structure and their controlled transition in self-assembled morphology and function, as well as present some perspectives in this prosperous field. Emerging challenges faced for the future research are also discussed.

A sugar modified amphiphilic cationic nano-adjuvant ceased tumor immune suppression and rejuvenated peptide vaccine induced antitumor immunity in cervical cancer

Human papilloma virus (HPV), one of the most common cancer-causing viruses, accounts for more than 90% of human anal and cervical cancers. Clinical studies have focused on adjuvant therapy with vaccines to improve therapeutic outcomes in patients with late-stage HPV-related cancers. In the present study, a mannose receptor (CD206) targeting a lithocholic acid-modified polyethylenimine (PEI) nano-adjuvant delivering the toll-like receptor 7/8 agonist, resiquimod (R848) (mLAPMi-R848), in a HPV E6- and E7-expressing TC-1 tumor murine model was developed. Peritumoral administration of mLAPMi resulted in enhanced accumulation in tumor/tumor-draining lymph nodes and significantly targeted antigen presenting cells like macrophage and dendritic cells. PEI-based nanocarriers can exploit the adjuvant potency of R848 and improve the antitumor immunity. Hence, co-administration of mLAPMi-R848 along with an E6E7 peptide in TC-1 tumor mice eradicated tumor burden and elicited splenocyte-induced cytotoxicity in TC-1 cancer cells. In a bilateral TC-1 tumor model, administration of mLAPMi-R848 and E6E7 peptide significantly suppressed both primary and secondary tumor burdens and improved the overall survival rate. Immune cell profiling revealed elevated levels of mature DCs and CD8+ T cells but reduced levels of tumor-associated immunosuppressive cells (TAICs) like myeloid derived suppressor cells (MDSCs) and regulatory T (Treg) cells in distal tumors. Overall, this study demonstrated that mLAPMi-R848 has improved the antitumor immunity of the peptide antigen against HPV-induced cancers by targeted immunodulation of antigen presenting cells (APCs) and reducing TAICs. Furthermore, this nano-adjuvant has the potential to offer a new treatment option for patients with cervical cancer and can be applied for the treatment of other HPV induced cancers.

A Polylactide-Based Micellar Adjuvant Improves the Intensity and Quality of Immune Response

Micelles from amphiphilic polylactide-block-poly(N-acryloxysuccinimide-co-N-vinylpyrrolidone) (PLA-b-P(NAS-co-NVP)) block copolymers of 105 nm in size were characterized and evaluated in a vaccine context. The micelles were non-toxic in vitro (both in dendritic cells and HeLa cells). In vitro fluorescence experiments combined with in vivo fluorescence tomography imaging, through micelle loading with the DiR near infrared probe, suggested an efficient uptake of the micelles by the immune cells. The antigenic protein p24 of the HIV-1 was successfully coupled on the micelles using the reactive N-succinimidyl ester groups on the micelle corona, as shown by SDS-PAGE analyses. The antigenicity of the coupled antigen was preserved and even improved, as assessed by the immuno-enzymatic (ELISA) test. Then, the performances of the micelles in immunization were investigated and compared to different p24-coated PLA nanoparticles, as well as Alum and MF59 gold standards, following a standardized HIV-1 immunization protocol in mice. The humoral response intensity (IgG titers) was substantially similar between the PLA micelles and all other adjuvants over an extended time range (one year). More interestingly, this immune response induced by PLA micelles was qualitatively higher than the gold standards and PLA nanoparticles analogs, expressed through an increasing avidity index over time (>60% at day 365). Taken together, these results demonstrate the potential of such small-sized micellar systems for vaccine delivery.

Review: Development of SARS-CoV-2 immuno-enhanced COVID-19 vaccines with nano-platform

Vaccination is the most effective way to prevent coronavirus disease 2019 (COVID-19). Vaccine development approaches consist of viral vector vaccines, DNA vaccine, RNA vaccine, live attenuated virus, and recombinant proteins, which elicit a specific immune response. The use of nanoparticles displaying antigen is one of the alternative approaches to conventional vaccines. This is due to the fact that nano-based vaccines are stable, able to target, form images, and offer an opportunity to enhance the immune responses. The diameters of ultrafine nanoparticles are in the range of 1-100 nm. The application of nanotechnology on vaccine design provides precise fabrication of nanomaterials with desirable properties and ability to eliminate undesirable features. To be successful, nanomaterials must be uptaken into the cell, especially into the target and able to modulate cellular functions at the subcellular levels. The advantages of nano-based vaccines are the ability to protect a cargo such as RNA, DNA, protein, or synthesis substance and have enhanced stability in a broad range of pH, ambient temperatures, and humidity for long-term storage. Moreover, nano-based vaccines can be engineered to overcome biological barriers such as nonspecific distribution in order to elicit functions in antigen presenting cells. In this review, we will summarize on the developing COVID-19 vaccine strategies and how the nanotechnology can enhance antigen presentation and strong immunogenicity using advanced technology in nanocarrier to deliver antigens. The discussion about their safe, effective, and affordable vaccines to immunize against COVID-19 will be highlighted.

Honokiol-Based Nanomedicine Decorated with Ethylene Glycols Derivatives Promotes Antitumor Efficacy

Honokiol-loaded nanoparticles (HK-loaded NPs) exhibit potential antitumor activity; however, the factors affecting their antitumor efficacy are still unclear and need to be explored. This research was aimed to systematically estimate the influence of feed weight ratio (FWR) and nanocarrier structure on antitumor activity. Accordingly, three types of ethylene glycol derivatives, including linear poly(ethylene glycol) with molar mass of 2000 (PEG₄₅), first and second generation oligo(ethylene glycol) dendrons (G1 and G2) were used as nanocarriers, and a series of HK-loaded NPs with different FWR were prepared successfully using the evaporation-ultrasonication method. These NPs showed similar stability but demonstrated differences with respect to particle size, morphology, cumulative profile, and antitumor efficacy. The influence of the FWR was studied using G1 dendrons as nanocarriers; the results indicated that the particle size and morphology of G1 NPs were significantly affected, and G1 NPs (8/1), with the FWR of 8/1 for HK versus G1 dendron, exhibited the highest antitumor activity among all G1 NPs. Furthermore, the influence of nanocarrier structure was investigated at the FWR of 4/1; the findings revealed reduction in the particle diameter from 280 nm to 109 nm and change in morphology from sphere to flower-like structure with an increase in the branch degree from linear to dendron. Moreover, G2 NPs (4/1), with the FWR of 4/1 for HK versus G2 dendron, carrying the highest branch degree exhibited the greatest antitumor efficacy among all. These results are suggestive of influence of particle size and morphology on antitumor efficacy of HK-loaded NPs. Conclusively, this study demonstrated nanocarrier structure and the FWR significantly affect the antitumor efficacy of NPs, which should be optimized for designing nanoscale delivery systems.

Recent Advances and Future Perspectives in Polymer-Based Nanovaccines

Vaccination is the most valuable and cost-effective health measure to prevent and control the spread of infectious diseases. A significant number of infectious diseases and chronic disorders are still not preventable by existing vaccination schemes; therefore, new-generation vaccines are needed. Novel technologies such as nanoparticulate systems and adjuvants can enable safe and effective vaccines for difficult target populations such as newborns, elderly, and the immune-compromised. More recently, polymer-based particles have found application as vaccine platforms and vaccine adjuvants due to their ability to prevent antigen degradation and clearance, coupled with enhanced uptake by professional antigen-presenting cells (APCs). Polymeric nanoparticles have been applied in vaccine delivery, showing significant adjuvant effects as they can easily be taken up by APCs. In other words, polymer-based systems offer a lot of advantages, including versatility and flexibility in the design process, the ability to incorporate a range of immunomodulators/antigens, mimicking infection in different ways, and acting as a depot, thereby persisting long enough to generate adaptive immune responses. The aim of this review is to summarize the properties, the characteristics, the added value, and the limitations of the polymer-based nanovaccines, as well as the process of their development by the pharmaceutical industry.

Polymeric nanostructure vaccines: applications and challenges

INTRODUCTION

The use of biocompatible polymers, from natural or synthetic sources, opened the door for a new era in vaccine research. These polymers offer the possibility to develop nanostructured antigen carriers that can be easily internalized by antigen-presenting cells, due to their nanometric size. Besides, the incorporation of an adjuvant allows increasing and modulating the immune response for both, polymers with or without self-adjuvant properties.

AREAS COVERED

The historical background and the state-of-the-art in the use of polymers as antigen carriers are addressed in the first part of this review. Then, an overview of the immunology of vaccination is provided. Finally, the main advances in the field, based on the prototypes that are licensed or undergoing clinical trials, but also the challenges that limit the translation of many polymer-based nanostructure vaccines with promising preclinical results, are discussed.

EXPERT OPINION

Polymeric nanostructured vaccines have a great potential in modern vaccinology. However, the translation into the market is hampered due to several limitations. Studies on correlates of protection to provide suitable biomarkers, new and better methods of synthesis to produce more reproducible nanovaccines, a deeper knowledge in the immune system and in the physiopathology of the infectious diseases will surely improve and boost the field in the next years.

Wedelolactone-Loaded Micelles Ameliorate Doxorubicin-Induced Oxidative Injury in Podocytes by Improving Permeability and Bioavailability

Wedelolactone (WED) is commonly used for the treatment of doxorubicin (DOX)-induced kidney damage, but its efficacy is limited by its poor solubility and bioavailability. In this study, we developed a novel delivery system of WED-loaded micelles (WED-M) with Solutol^® HS15 and lecithin at an optimized ratio of 7:3 to improve the poor permeability and bioavailability of WED and to enhance its efficacy. The spherically shaped WED-M (particle size: 160.5 ± 3.4 nm; zeta potential: −30.1 ± 0.9 mV; entrapment efficiency: 94.41 ± 1.64%; drug loading: 8.58 ± 0.25%; solubility: 1.89 ± 0.06 mg/ml) has continuous stability over 14 days and a sustained release profile. The permeability of WED-M in Caco-2 cells indicated a significant 1.61-fold higher Papp AP to BL ratio than WED alone. Additionally, pharmacokinetic evaluation of WED-M demonstrated that the bioavailability of WED was increased 2.78-fold. Both HE staining and transmission electron microscopy showed an obvious improvement of pathological damage in WED-M treatment. Moreover, WED-M significantly enhanced the ROS level in mice and MPC5 podocytes. We concluded that using this micelle delivery system for WED could improve its permeability and bioavailability to attenuate DOX-induced oxidative injury in podocytes. This study provided important information on the fact that the micelle delivery system, WED-M, showed a significant improvement of renal damage.