DAMPs‐coated Prussian blue nanoparticles as photothermal‐nanoimmunotherapy agents for cancer

Abstract

Nanoparticle-based photothermal therapy (PTT) has been widely investigated in cancer therapy as a rapid and minimally invasive tumor ablation technique. In this treatment modality, the intrinsic photothermal conversion property of synthesized nanoparticles allows the conversion of incident light into heat, which generates cell temperature increases, thereby killing cancer cells in contact with the nanoparticles. Here, Prussian blue nanoparticles (PBNPs) are used as photothermal agents, as they exhibit strong absorbance at near-infrared (NIR) wavelengths, are stable, non-toxic, and have 20.5% photothermal conversion efficiencies. In studies using PBNPs to administer photothermal therapy (PBNP-PTT) to localized tumors in a neuroblastoma model, PBNP-PTT generates local heating, resulting in decreased tumor growth and significantly improved survival. Importantly, we have shown that under certain conditions, PBNP-PTT generates immunogenic cell death (ICD), a favorable cell death phenotype characterized by concurrent cytotoxicity and immune cell engagement, enabling a potentially robust and long-lasting immune response and allowing for immunological memory against recurrent or metastatic disease. ICD is defined by the release or exposure of danger-associated molecular patterns (DAMPs), such as calreticulin, adenosine triphosphate (ATP), and high mobility group box 1 (HMGB1) from dying cancer cells. DAMPs are critical for the maturation, antigen uptake, and presentation of dendritic cells, and serve as powerful immunological adjuvants to activate a cytotoxic T lymphocyte response; these markers must be present for a cell to be classified as undergoing ICD. Previous studies in our lab show that the PBNP-PTT-stimulated release of DAMPs from dying cancer cells is both disease- and stimulus-specific; that is, depending on the cell type and conditions of PBNP-PTT, DAMPs may or may not be released sufficiently to generate downstream responses. To ensure that PBNP-PTT induces the release and expression of the correct DAMPs to induce ICD, we synthesized DAMPs-coated PBNPs to use in PBNP-PTT. Our hypothesis is that PBNP-PTT allows to heat cancer cells, causing exposure of some DAMPs, while simultaneously releasing other DAMPs from the PBNPs, augmenting the immunogenic effect. Here, we show the synthesis strategy for coating PBNPs with DAMPs, the number of DAMPs bound to PBNPS using the Bio-Red Protein Assay, and the stability of the DAMPs-PBNPs over several days. We present consistent data showing the cytotoxic capability of DAMPs-PBNP-based PTT using CellTiter-Glo® Luminescent Cell Viability Assay. Additionally, we compare the effects of applying PBNP-based PTT on the surface versus interstitially, to further optimize our photothermal nanoimmunotherapy. Support or Funding Information UPR-Ponce RISE (NIH-NIGMS R25GM096955) Hypothesis The stability of PBNPs and PBNPs-DAMPs measured over 7 days using a Dynamic Light Scattering. Cytotoxicity capabilities of PBNPs and DAMPs-PBNPs.The viability of treated neuroblastoma cells with PBNPs and DAMPs-PBNPs at different concentrations using CellTiter-Glo® Luminescent Cell Viability Assay. Cytotoxicity capabilities of PBNP-PTT and DAMPs-PBNP-PTTThe viability of tumor cells of neuroblastoma under PBNPs-PTT and DAMPs-PBNPs-PTT, after 24h of incubation, treated at different concentrations of the nanoparticles (0–0.1 mg/mL) using a 0.75W (A) and 1.00W laser power (B). Reached temperatures at 0.75W (C) and 1.00W (D) laser power for the treated tumor cells under PTT for 10 min. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.