Rashidi, N.; Harasymowicz, N.; Savadipour, A.; Steward, N.; Tang, R.; Oswald, S.; Guilak, F.

Progressive fibrosis causes tissue malfunction and organ failure due to the pathologic accumulation of a collagen-rich extracellular matrix. In vitro models provide useful tools for deconstructing the roles of specific biomechanical or biological mechanisms involved in these processes and identifying potential therapeutic targets. In particular, recent studies have implicated cellular mechanosensing of substrate micro- and nanoscale architecture as a regulator of fibrosis. In this study, we investigated how the mechanosensitive ion channel PIEZO1 and intracellular mechanotransduction pathways influence fibrotic gene and protein expression in adipose-derived stem cells (hASCs). Specifically, we examined the role of PIEZO1 and the mechano-sensitive transcription factors YAP/TAZ in sensing aligned or non-aligned substrate architecture to regulate collagen formation. We utilized both 2D microphotopatterned substrates and 3D electrospun polycaprolactone (PCL) substrates to study the role of culture dimensionality. We found that PIEZO1 regulates collagen production in hASCs in a manner that is sensitive to substrate architecture. Activation of PIEZO1 induced significant morphological changes in hASCs, particularly when they were cultured on aligned substrates. While YAP translocated to the cytoplasm following PIEZO1 activation, depleting YAP and TAZ did not change collagen expression significantly downstream of PIEZO1 activation, implying that YAP/TAZ translocation out of the nucleus and increased collagen production may be independent outputs of PIEZO1 activation. Our studies demonstrate a role for PIEZO1 in cellular mechanosensing of substrate architecture and provide targetable pathways for treating fibrosis as well as for enhancing tissue-engineered and regenerative approaches for fibrous tissue repair.