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Sascha Niclas Klimosch,1,* Marbod Weber,1,* Jordi Caballé-Serrano,2,3 Thomas Knorpp,1 Antonio Munar-Frau,2 Birgit Margareta Schaefer,4 Manfred Schmolz1 1HOT Screen GmbH, Reutlingen, Germany; 2Department of Oral and Maxillofacial Surgery, Universitat Internacional de Catalunya, Barcelona, Spain; 3Department of Periodontology, School of Dental Medicine - University of Bern, Bern, Switzerland; 4Geistlich Pharma AG, Wolhusen, Switzerland*These authors contributed equally to this workCorrespondence: Manfred Schmolz, HOT Screen GmbH, Aspenhaustr. 25, Reutlingen, 72770, Germany, Tel +49 7121 628705-0, Fax +49 7121 628705-90, Email m.schmolz@hot-screen.deIntroduction: Common in vitro cell culture systems for testing implant material immune compatibility either rely on immortal human leukocyte cell lines or isolated primary cells. Compared to in vivo conditions, this generates an environment of substantially reduced complexity, often lacking important immune cell types, such as neutrophil granulocytes and others. The aim of this study was to establish a reliable test system for in vitro testing of implant materials under in vivo-like conditions.Methods: Test materials were incubated in closed, CO2-independent, tube-based culture vessels containing a proprietary cell culture medium and human whole blood in either a static or occasionally rotating system. Multiplex cytokine analysis was used to analyze immune cell reactions.Results: To demonstrate the applicability of the test system to implant materials, three commercially available barrier membranes (polytetrafluoroethylene (PTFE), polycaprolactone (PCL) and collagen) used for dental, trauma and maxillofacial surgery, were investigated for their potential interactions with immune cells. The results showed characteristic differences between the static and rotated incubation methods and in the overall activity profiles with very low immune cell responses to PTFE, intermediate ones to collagen and strong reactions to PCL.Conclusion: This in vitro human whole blood model, using a complex organotypic matrix, is an excellent, easily standardized tool for categorizing immune cell responses to implant materials. Compared to in vitro cell culture systems used for materials research, this new assay system provides a far more detailed picture of response patterns the immune system can develop when interacting with different types of materials and surfaces.Keywords: whole blood cultures, in vitro material testing, immune cells, cytokines, barrier membranes