Biodistribution of 125I-labeled polymeric vaccine carriers after subcutaneous injection

A genetically engineered neuronal membrane-based nanotoxoid elicits protective immunity against neurotoxins

Given their dangerous effects on the nervous system, neurotoxins represent a significant threat to public health. Various therapeutic approaches, including chelating agents, receptor decoys, and toxin-neutralizing antibodies, have been explored. While prophylactic vaccines are desirable, it is oftentimes difficult to effectively balance their safety and efficacy given the highly dangerous nature of neurotoxins. To address this, we report here on a nanovaccine against neurotoxins that leverages the detoxifying properties of cell membrane-coated nanoparticles. A genetically modified cell line with constitutive overexpression of the α7 nicotinic acetylcholine receptor is developed as a membrane source to generate biomimetic nanoparticles that can effectively and irreversibly bind to α-bungarotoxin, a model neurotoxin. This abrogates the biological activity of the toxin, enabling the resulting nanotoxoid to be safely delivered into the body and processed by the immune system. When co-administered with an immunological adjuvant, a strong humoral response against α-bungarotoxin is generated that protects vaccinated mice against a lethal dose of the toxin. Overall, this work highlights the potential of using genetic modification strategies to develop nanotoxoid formulations against various biological threats.

Radiolabelling of nanomaterials for medical imaging and therapy

Nanomaterials offer unique physical, chemical and biological properties of interest for medical imaging and therapy. Over the last two decades, there has been an increasing effort to translate nanomaterial-based medicinal products (so-called nanomedicines) into clinical practice and, although multiple nanoparticle-based formulations are clinically available, there is still a disparity between the number of pre-clinical products and those that reach clinical approval. To facilitate the efficient clinical translation of nanomedicinal-drugs, it is important to study their whole-body biodistribution and pharmacokinetics from the early stages of their development. Integrating this knowledge with that of their therapeutic profile and/or toxicity should provide a powerful combination to efficiently inform nanomedicine trials and allow early selection of the most promising candidates. In this context, radiolabelling nanomaterials allows whole-body and non-invasive in vivo tracking by the sensitive clinical imaging techniques positron emission tomography (PET), and single photon emission computed tomography (SPECT). Furthermore, certain radionuclides with specific nuclear emissions can elicit therapeutic effects by themselves, leading to radionuclide-based therapy. To ensure robust information during the development of nanomaterials for PET/SPECT imaging and/or radionuclide therapy, selection of the most appropriate radiolabelling method and knowledge of its limitations are critical. Different radiolabelling strategies are available depending on the type of material, the radionuclide and/or the final application. In this review we describe the different radiolabelling strategies currently available, with a critical vision over their advantages and disadvantages. The final aim is to review the most relevant and up-to-date knowledge available in this field, and support the efficient clinical translation of future nanomedicinal products for in vivo imaging and/or therapy.

Dual dye in-vivo imaging of differentially charged PLGA carriers reveals antigen-depot effect, leading to improved immune responses in preclinical models

The present in-vivo study investigated the behavior and performance of differently charged poly(lactic‑co‑glycolic) acid microparticles (PLGA MP) as vaccination platform. For this purpose, particles loaded with ovalbumin (OVA) as model antigen were subcutaneously (s.c.) injected in SKH1 mice. The utilized SKH1 hairless mice exhibit a fully operative immune system and allow parallel imaging investigations due to the lack of hair. Usage of this species enabled the combination of two investigations within a single study protocol, namely noninvasive in-vivo imaging and immune responses directed towards the antigen. All treatments were well tolerated, no safety drop-outs occurred. The fate of the model antigen OVA as well as the PLGA particles was monitored using a dual dye approach (CF660C & DiR) by multispectral fluorescence imaging (msFI). A depot effect for the OVA antigen adsorbed to the MP surface could be observed for the positively charged MPs. The immune response against OVA was then analyzed. OVA alone did not induce an immune response, whereas the positively charged as well as the neutral MP induced a strong and consistent humoral immune response with a clear favor of IgG1 over IgG2a subclass antibodies. In contrast, negatively charged MP were not able to induce measurable antibody responses. Cellular immune response was weak and inconsistent for all treated groups, which verifies previous in-vitro results conducted with the herein described microparticulate antigen platform. In conclusion, the characterization of the in-vivo performance yielded valuable information about antigen and carrier fate after application. The presented adjuvant platform is capable of inducing strong T_H2 dominated immune responses characterized by enhanced IgG1 subclass titers which are critical for vaccines aimed at promoting induction of neutralizing antibodies.

A holistic approach to targeting disease with polymeric nanoparticles

The primary goal of nanomedicine is to improve clinical outcomes. To this end, targeted nanoparticles are engineered to reduce non-productive distribution while improving diagnostic and therapeutic efficacy. Paradoxically, as this field has matured, the notion of targeting has been minimized to the concept of increasing the affinity of a nanoparticle for its target. This Opinion article outlines a holistic view of nanoparticle targeting, in which the route of administration, molecular characteristics and temporal control of the nanoparticles are potential design variables that must be considered simultaneously. This comprehensive vision for nanoparticle targeting will facilitate the integration of nanomedicines into clinical practice.