Evaluation of Proinflammatory Response to Polymeric Materials Using a Macrophage Cell Line Genetically Tagged with a Luminescent Peptide

Investigation of biological response to materials is important in understanding their biocompati-bility and cell-material interactions for biomaterial applications. Macrophages are important for early biological response. Responses of macrophages to materials have previously been investigated by quantitating inflammatory and anti-inflammatory cytokines using ELISA and RT-PCR assays, and by assessing phenotype changes using flow cytometry and immunohistochemistry. In this study, we developed a method to evaluate the proinflammatory response to polymeric materials using a macrophage cell line (THP-1) genetically tagged with a luminescent peptide (HiBiT). The gene for the luminescent peptide was inserted into IL-1β in THP-1 cells using the CRISPR/Cas9 system. Upon stimulation of HiBiT-tagged THP-1 cells with lipopolysaccharide, IL-1β secretion could be detected using highly sensitive measurement of luminescence as well as using ELISA and RT-PCR assays. We found that IL-1β production by HiBiT-tagged THP-1 cells differed in response to nylon, cellulose, and polytetrafluoroethylene. Moreover, the time course of IL-1β secretion also differed for these materials. These results indicate that IL-1β production over time in HiBiT-tagged THP-1 cells exposed to a material can be measured. We believe that this method for evaluation of proinflammatory response using genetically engineered macrophages would complement ELISA and RT-PCR in investigating cellular response to different materials.