Multicolor flow cytometry-based immunophenotyping for preclinical characterization of nanotechnology-based formulations: an insight into structure activity relationship and nanoparticle biocompatibility profiles

Nanoparticles may influence mast cells gene expression profiles without affecting their degranulation function

An in vitro method for monitoring nanoparticle effects on IgE-dependent mast cell degranulation was developed and validated. The assayed nanoparticles included four clinical-grade nanomedicines (Abraxane, Doxil, AmBisome, and Feraheme) and three commercial research-grade nanomaterials (generation 5 PAMAM dendrimers with carboxy-, hydroxy-, or amine- surface functionalities). Most of the tested materials did not alter IgE-dependent mast cell degranulation, suggesting that nanoparticles and nanomedicines are unlikely to worsen pre-existing allergies to other antigens. Two clinical-grade formulations containing cytotoxic oncology drugs-Abraxane and Doxil-decreased degranulation. Abraxane but not Doxil decreased FcεR expression on the cell surface. Single-cell sequencing revealed the most differentially expressed genes (DEG) in Abraxane and Doxil-treated cultures. Interestingly, Feraheme and amine-terminated dendrimers induced DEG without affecting degranulation. These data demonstrate that some nanomaterials have more effects on immune cells than can be detected by a functional immunoassay.

Changes in Generations of PAMAM Dendrimers and Compositions of Nucleic Acid Nanoparticles Govern Delivery and Immune Recognition

Nucleic acid nanoparticles (NANPs) are promising immune modulators due to their well-established structural properties and distinct structure-activity relationship with the immune system. We previously identified that NANPs' size, shape, composition, and type of delivery vehicle define their uptake by immune cells and subsequently induced cytokine profile. In this work, we examined the delivery efficiencies and immunological impacts of two representative NANPs─DNA cubes and RNA cubes─complexed with a benchmark delivery vehicle, Lipofectamine 2000 vs. different generations of amine-terminated poly(amidoamine) dendrimers. Using molecular dynamics simulations, we modeled dendrimer interactions with nucleic acid cargos. Next, we used traditional 2D and more recently established 3D cell cultures to assess dendrimers' influence on NANPs uptake. Immune activation was evaluated in several cell lines engineered with reporter genes driven by key immune signaling pathways. Specifically, HEK-lucia reporter cells were used to evaluate RIG-I activation, while THP1-Dual cells provided quantitative readouts for both IRF and NF-κB transcription factor activity. Our findings demonstrate that both dendrimer generation and NANP composition influence cellular uptake and immune responses. This study underscores the importance of formulation in shaping NANPs' biological properties and further advances the understanding of their immunological properties critical for the development of NANPs-based adjuvants.

Role of physicochemical properties in silica nanoparticle-mediated immunostimulation

Immunostimulation caused by nanoparticles may be beneficial or adverse depending on their intended application. Activation of immune cells is beneficial for indications targeting the immune system for therapeutic purposes, such as tumor microenvironment reprogramming, immunotherapy, and vaccines. When it is unwanted, however, immunostimulation may lead to excessive inflammation, cytokine storm, and hypersensitivity reactions. The increasing use of silica nanoparticles (SiNPs) for the delivery of drugs, imaging agents, and antigens warrants preclinical studies aimed at understanding carrier-mediated effects on the number, activation status, and function of immune cell subsets. Herein, we present an in vitro study utilizing primary human peripheral blood mononuclear cells (PBMC) to investigate the proinflammatory properties of four types of SiNPs varying in size and porosity. Cytokine analysis was performed in resting and LPS-primed PBMC cultures to understand the ability of silica nanoparticles to induce de novo and exaggerate preexisting inflammation, respectively. Changes in the number and activation status of lymphoid and myeloid cells were studied by flow cytometry to gain further insight into SiNP-mediated immunostimulation. Nonporous SiNPs were found to be more proinflammatory than mesoporous SiNPs, and larger-sized particles induced greater cytokine response. LPS-primed PBMC resulted in increased susceptibility to SiNPs. Immunophenotyping analysis of SiNP-treated PBMC resulted in T and B lymphocyte, natural killer cell, and dendritic cell activation. Additionally, a loss of regulatory T cells and an increase in γδ TCR T cell population were observed with all particles. These findings have implications for the utility of SiNPs for the delivery of drugs and imaging agents.

Immunophenotyping, Part II: Analysis of Nanoparticle Effects on the Composition and Activation Status of Human Peripheral Blood Mononuclear Cells

The use of nanoparticles as drug delivery carriers requires analysis of their safety, which among other tests, includes immunotoxicity. Nanoparticles are also increasingly used for applications intended to specifically activate, inhibit, or modify the immune system's responses to improve the treatment of inflammatory and autoimmune disorders, cancer immunotherapy, and vaccines targeting cancer cells and viral and bacterial pathogens. In addition to the safety, the analysis of nanoparticles intended for immune system targeting includes mechanistic immunology investigations. Immunophenotyping provides researchers with a tool to assess the immune cell viability and activation status. These results provide mechanistic insights into nanoparticle efficacy and toxicity and therefore are of interest to the biomedical nanotechnology field. However, no standardized approaches exist due to the breadth of methods and instruments available for this analysis. This chapter provides detailed instructions for applying this methodology to analyze nanoparticle effects on subsets of immune cells present in peripheral blood. While this experimental strategy is specific to the NovoCyte 3005 flow cytometer, it can be adapted to other instruments. Instructions for instrument setup, calibration, and antibody qualification are described in this book's Chapter 24 , Immunophenotyping, part I.