title: Problems and challenges in the development and validation of human cell-based assays to determine nanoparticle-induced immunomodulatory effects.
abstract: BACKGROUND
  With the increasing use of nanomaterials, the need for methods and assays to examine their immunosafety is becoming urgent, in particular for nanomaterials that are deliberately administered to human subjects (as in the case of nanomedicines). To obtain reliable results, standardised in vitro immunotoxicological tests should be used to determine the effects of engineered nanoparticles on human immune responses. However, before assays can be standardised, it is important that suitable methods are established and validated.
  
  
  RESULTS
  In a collaborative work between European laboratories, existing immunological and toxicological in vitro assays were tested and compared for their suitability to test effects of nanoparticles on immune responses. The prototypical nanoparticles used were metal (oxide) particles, either custom-generated by wet synthesis or commercially available as powders. Several problems and challenges were encountered during assay validation, ranging from particle agglomeration in biological media and optical interference with assay systems, to chemical immunotoxicity of solvents and contamination with endotoxin.
  
  
  CONCLUSIONS
  The problems that were encountered in the immunological assay systems used in this study, such as chemical or endotoxin contamination and optical interference caused by the dense material, significantly affected the data obtained. These problems have to be solved to enable the development of reliable assays for the assessment of nano-immunosafety.
authors.affiliation: Department of Molecular Biology, University of Salzburg, 5020 Salzburg, Austria. geja.oostingh@sbg.ac.at
authors.forename: Gertie J
authors.initials: GJ
authors.lastname: Oostingh
authors.forename: Eudald
authors.initials: E
authors.lastname: Casals
authors.forename: Paola
authors.initials: P
authors.lastname: Italiani
authors.forename: Renato
authors.initials: R
authors.lastname: Colognato
authors.forename: René
authors.initials: R
authors.lastname: Stritzinger
authors.forename: Jessica
authors.initials: J
authors.lastname: Ponti
authors.forename: Tobias
authors.initials: T
authors.lastname: Pfaller
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Kohl
authors.forename: Daniëlla
authors.initials: D
authors.lastname: Ooms
authors.forename: Flavia
authors.initials: F
authors.lastname: Favilli
authors.forename: Hilde
authors.initials: H
authors.lastname: Leppens
authors.forename: Davide
authors.initials: D
authors.lastname: Lucchesi
authors.forename: François
authors.initials: F
authors.lastname: Rossi
authors.forename: Inge
authors.initials: I
authors.lastname: Nelissen
authors.forename: Hagen
authors.initials: H
authors.lastname: Thielecke
authors.forename: Victor F
authors.initials: VF
authors.lastname: Puntes
authors.forename: Albert
authors.initials: A
authors.lastname: Duschl
authors.forename: Diana
authors.initials: D
authors.lastname: Boraschi
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism; D001681:Biological Assay / Q000379:methods* / Q000592:standards*; D002477:Cells / Q000166:cytology / Q000276:immunology*; D002478:Cells, Cultured; D006801:Humans; D007155:Immunologic Factors / Q000276:immunology*; D016209:Interleukin-8 / Q000235:genetics / Q000276:immunology; D053768:Metal Nanoparticles / Q000009:adverse effects / Q000737:chemistry; D011401:Promoter Regions, Genetic; D015203:Reproducibility of Results; D012997:Solvents
chemical_list: D001672:Biocompatible Materials; D007155:Immunologic Factors; D016209:Interleukin-8; D012997:Solvents