Grad Seminar: Development of an in vitro model to characterize neutrophil extracellular traps formation under shear in the presence of a biomaterial

Abstract

To enable the design of materials with improved blood biocompatibility, there is a need to better understand the interactions between biomaterials and blood components, such as neutrophils, which play key roles in inflammation. In addition to their inflammatory response, neutrophils engage in an antibacterial strategy known as NETosis (the formation of neutrophil extracellular traps known as NETs), consisting of released DNA and antimicrobial proteins. NETs can be induced by a variety of synthetic and physiological stimuli. Although NETs and blood-biomaterial interactions have separately been reported to contribute to thrombosis and inflammation, there is a need to develop a model and methods that support the investigations of the mechanisms involved in material-induced activation and NETs under physiological flow conditions. In this work, an in-vitro model was developed to study the effect of shear and the presence of a biomaterial on HL-60 cells (a neutrophil-like model cell line) and blood-isolated neutrophils. A parallel plate flow chamber was used to expose cells to a biomaterial environment at a physiological shear rate over 1-2 hours, either with or without a known NETosis inducer. As NET formation occurred in the in vitro model, NETs were found to aggregate on the biomaterial surface, all the more so with blood-isolated neutrophils. Our results suggest that the NET signal in the bulk, as measured by flow cytometry, did not accurately reflect the level of NETosis occurring in the system as NETs remained attached to the material surface. The distribution of NETs between the biomaterial surface and circulation highlights the complexity of assessing NETosis in blood-material interactions. Given the difference in NETosis response between HL-60 cells and PMNs, the HL-60 cell line may not be an accurate and appropriate proxy to investigate neutrophil-material interactions in an vitro flow model.

Presenter

Andreea Maria Palage, MASc candidate in Systems Design Engineering 

Attending this seminar will count towards the graduate student seminar attendance milestone!