UNamur – SCK●CEN PhD student Naomi Daems wins a Young Investigator Award and a Poster Award at the ERRS-GBS Conference 2017

Gold nanoparticles are coated with organic polymers and antibodies specifically targeting the tumor cells. Naomi Daems investigates the in vitro cytotoxicity profile of these gold nanoparticles on healthy cell types, which is crucial prior to move to clinical testing. This work is performed in the context of a close collaboration between the SCK●CEN (Dr. An Aerts & Dr. Karen Van Hoecke) and the University of Namur (Prof. Carine Michiels and Prof. Stéphane Lucas).

Naomi Daems was awarded a Young Investigator Award granted by the European Radiation Research Society (ERSS) to attend its annual meeting in Germany on 17-21 September 2017. On this occasion, she presented a poster communication entitled "Hybrid gold nanoparticles coated with organic polymers and antibodies as a platform for cancer theranostics: Cytotoxicity assessment" (see abstract), which brought her a poster award.

ABSTRACT

Hybrid gold nanoparticles coated with organic polymers and antibodies as a platform for cancer theranostics: Cytotoxicity assessment

noami.daems@sckcen.be

Noami Daems, S. Li, O. Fichera, K. Van Hoecke, S. Baatout, T. Cardinaels, C. Michiels, S. Lucas and A. Aerts

Radiobiology Unit, Institute for Environment, Health and Safety, SCK•CEN, Belgian Nuclear Research Centre, Mol, Belgium/ Unité de Recherche en Biologie Cellulaire (URBC)-NARILIS, University of Namur, Belgium

In cancer radiotherapy, gold nanoparticles (AuNPs) have emerged as promising radiosensitizers, which accumulate in the tumor and are believed to increase the effectiveness of external beam radiotherapy by local production of reactive oxygen species (ROS) and secondary electrons upon irradiation. At UNamur, 5 nm gold nanoparticles coated with an organic shell of polyallylamine are produced by plasma vapour deposition (AuNPs@PPAA) (1). Optionally, the AuNPs@PPAA can be conjugated to anti-EGFR antibodies (Cetuximab) (mAb-AuNPs@PPAA) which actively target EGFR-overexpressing cancer cells in vitro and in vivo (2-3) and for which in vivo biodistribution studies have demonstrated a significant accumulation in the liver and the spleen. Therefore, the cytotoxicity profile of the gold nanoparticles should be investigated properly in healthy cell types prior to use the mAb-AuNPs@PPAA in clinical applications. Human kidney (HK-2) cells and telomerase-immortalized microvascular endothelial (TIME) cells were studied as first examples of healthy cells. We performed MTS tetrazolium cytotoxicity assays after 3 hours of incubation and live cell imaging with apoptotic markers Annexin V and caspase 3/7 during 48 hours of incubation with AuNPs@PPAA. The nanoparticle concentrations tested ranged from 8 μM to 254 μM of gold. The MTS cytotoxicity assay resulted in a significant dose-dependent reduction of cell viability in TIME cells. In contrast, an increased tetrazolium-to-formazan conversion was seen in HK-2 cells, which could represent an enhanced enzymatic activity as a response to AuNPs@PPAA. During live cell imaging, a concentration of 254 μM of gold resulted in an increase of Annexin V and caspase 3/7 signaling after 10 and 8h in HK2 and TIME cells, respectively. Lower concentrations, even down to 8 μM, also lead to apoptosis in TIME cells after longer incubation times. In the future, we will assess the cellular AuNPs@PPAA uptake by means of ICP-MS and TEM. Furthermore, ELISA and western blot can identify which underlying pathways may be modulated by the AuNPs@PPAA. Oxidative stress induced by exposure to AuNPs@PPAA will by evaluated by means of ROS measurements. Finally, the toxicity evaluation will be completed with studies testing a liver cell line and we will investigate if the AuNPs@PPAA are able to activate splenic macrophages. Experiments will be repeated with mAb-AuNPs@PPAA.

Acknowledgements: N Daems is supported with a 2-years FRIA PhD grant of F.R.S-FNRS (National Fund for Scientific Research, Belgium).

References:

(1) Moreau N, et al. Plasma Process Polym. 2009;6(1):S888-S892

(2) Marega R, et al. J Mater Chem. 2012;22(39):21305-21312

(3) Karmani L, et al. Contrast Media Mol Imaging. 2013;8(5):402-8