The YAP profile of lung fibroblasts differs when subjected to cyclic stretch in a 2D and 3D environment

<bold>Background:</bold> Cells of the lung are subjected to mechanical cues transmitted through the extracellular matrix, induced by cyclic stretch when breathing. The impact of cyclic stretch on the mechanobiology of fibroblasts has mostly been characterised in 2D, but remains to be explored in a lung-mimetic 3D environment. We aim to evaluate the mechanobiology of fibroblasts under lung-mimetic cues by the localization of the mechanosensitive co-transcription factor YAP. <bold>Method:</bold> Healthy primary lung fibroblasts were cultured in 2D on collagen-I coated flexible membranes or in 3D in healthy decellularized lung slices. The cells were pre-cultured statically for 72h, followed by 72h of cyclic stretch (mimicking breathing) or maintained as a static culture. Actin/paxillin staining and the ratio of nuclear/cytoplasmic (N/C) YAP localization were evaluated with confocal microscopy. <bold>Preliminary results:</bold> In the initial phase of the pre-culture, all conditions had activated YAP, with an N/C ratio > 1. When subjected to cyclic stretch, cells cultured in 2D and 3D initially displayed a distinct YAP N/C profile. Stretched cells cultured in 2D had an increased nuclear YAP N/C ratio of 1.65 compared to 1.25 when cultured statically. Whereas in 3D, the static and stretched conditions had a YAP N/C ratio of ~1.5. <bold>Conclusion:</bold> Our preliminary data suggests that the initial mechanoresponse is induced by the cell adhesion to the 2D and 3D substrates and that the substrates influence how cells sense and respond to cyclic stretch. The knowledge of mechanobiology in a healthy 3D environment could be used to determine how cells sense mechanical cues in the altered microenvironments of chronic lung diseases.