Intradermal air pouch leukocytosis as an in vivo test for nanoparticles

Jennifer Vandooren,¹ Nele Berghmans,¹ Chris Dillen,¹ Ilse Van Aelst,¹ Isabelle Ronsse,¹ Liron Limor Israel,² Ina Rosenberger,³ Jörg Kreuter,³ Jean-Paul Lellouche,² Shulamit Michaeli,⁴ Erica Locatelli,⁵ Mauro Comes Franchini,⁵ Miren K Aiertza,⁶ Laura Sánchez-Abella,⁶ Iraida Loinaz,⁶ Dylan R Edwards,⁷ Louis Shenkman,⁸ Ghislain Opdenakker<sup>1

1</sup>Rega Institute for Medical Research, University of Leuven, Leuven, Belgium; ²Department of Chemistry and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Tel Aviv, Israel; ³Institut für Pharmazeutische Technologie, Johann Wolfgang Goethe-Universität, Frankfurt, Germany; ⁴The Mina and Everard Goodman Faculty of Life Sciences and Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat Gan, Tel Aviv, Israel; ⁵Department of Industrial Chemistry Toso Montanari, University of Bologna, Bologna, Italy; ⁶New Materials Department, Fundación CIDETEC, San Sebastián, Spain; ⁷School of Biological Sciences, University of East Anglia, Norwich, UK; ⁸Tel Aviv University, Ramat Aviv, Tel Aviv, Israel

Abstract: The need for test systems for nanoparticle biocompatibility, toxicity, and inflammatory or adaptive immunological responses is paramount. Nanoparticles should be free of microbiological and chemical contaminants, and devoid of toxicity. Nevertheless, in the absence of contamination, these particles may still induce undesired immunological effects in vivo, such as enhanced autoimmunity, hypersensitivity reactions, and fibrosis. Here we show that artificial particles of specific sizes affect immune cell recruitment as tested in a dermal air pouch model in mice. In addition, we demonstrate that the composition of nanoparticles may influence immune cell recruitment in vivo. Aside from biophysical characterizations in terms of hydrodynamic diameter, zeta potential, concentration, and atomic concentration of metals, we show that – after first-line in vitro assays – characterization of cellular and molecular effects by dermal air pouch analysis is straightforward and should be included in the quality control of nanoparticles. We demonstrate this for innate immunological effects such as neutrophil recruitment and the production of immune-modulating matrix metalloproteases such as MMP-9; we propose the use of air pouch leukocytosis analysis as a future standard assay.

Keywords: nanoparticles, biocompatibility, toxicity, air pouch, immunology


A Letter to the Editor has been received and published for this article.