Bioprinting-associated pulsatile hydrostatic pressure elicits a mild proinflammatory response in epi- and endothelial cells

During nozzle-based bioprinting, like inkjet and microextrusion, cells are subjected to hydrostatic pressure for up to several minutes. The modality of the bioprinting-related hydrostatic pressure is either constant or pulsatile depending on the technique. We hypothesized that the difference in the modality of hydrostatic pressure affects the biological response of the processed cells differently. To test this, we used a custom-made setup to apply either controlled constant or pulsatile hydrostatic pressure on endothelial and epithelial cells. Neither bioprinting procedure visibly altered the distribution of selected cytoskeletal filaments, cell-substrate adhesions, and cell-cell contacts in either cell type. In addition, pulsatile hydrostatic pressure led to an immediate increase of intracellular ATP in both cell types. However, the bioprinting-associated hydrostatic pressure triggered a pro-inflammatory response in only the endothelial cells, with an increase of interleukin 8 (IL-8) and a decrease of thrombomodulin (THBD) transcripts. These findings demonstrate that the settings adopted during nozzle-based bioprinting cause hydrostatic pressure that can trigger a pro-inflammatory response in different barrier-forming cell types. This response is cell-type and pressure-modality dependent. The immediate interaction of the printed cells with native tissue and the immune system in vivo might potentially trigger a cascade of events. Our findings, therefore, are of major relevance in particular for novel intra-operative, multicellular bioprinting approaches.