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Description
Introduction: YAP/TAZ complex is considered to be the main player in the mechanotransduction process. It shuttles between cell nuclei and cytoplasm depending on the stiffness of the growth substrate, dimensionality and cell shape. Stem cells in their natural environment, called niche, grow in three dimensional soft tissue but in standard in vitro culture are maintained mostly on flat stiff culture substrates as plastic or glass. These changes of microenvironmental cues have a great impact on the stem cells developmental processes, such as proliferation, differentiation and production of therapeutically active, immunomodulatory factors. Thus to improve and direct the pro-regenerative potential of stem cells, it is highly important to identify the molecular mechanisms involved in sensing the niche by stem cells. Methodology: Here we used two different populations of human stem cells regarding their biology and therapeutic outcome: neural stem cells derived from induced pluripotent stem cells (hiPSC-NSC) and mesenchymal stem cells derived from Wharton’s Jelly of umbilical cord (WJ-MSC). Using immunocytochemical analysis we have shown the localization of YAP/TAZ in cells grown on 2D substrates and 3D aggregates and/or fibrin and geltrex- based hydrogel scaffolds in the time dependent manner. In addition, using immunoassay test, we have verified the level of released immunomodulatory proteins after exposition of stem cells to the YAP/TAZ complex inhibitor in different microenvironmental conditions. Results: In both tested human stem cell populations grown in 2D conditions we have confirmed mostly nuclear localization of YAP/TAZ. Already 30 minutes after 3D cell aggregates were created from 2D culture, changes in the distribution of YAP/TAZ complex in the nuclear vs cytoplasmic compartment were observed. Moreover, in 2D conditions, exposure of stem cells to verteporfin (YAP/TAZ inhibitor) induced changes in cell morphology and localization of investigated complex to the cytoplasmic compartment, similar to that found in 3D cell aggregates as well as scaffolds based structures. Spatial conditions of the culture and treatment with verteporfin, both influenced the secretion of immunomodulatory factors (TSG-6, TGFβ, IL-11, and COX2) and differentiation of hiPSC-NSC and WJ-MSC. Conclusions: Mechanotransducer complex YAP/TAZ is involved in fast response of the stem cells to the changes in the spatial organization of the microenvironment with implication on the production of factors that may contribute to their regenerative potential.
Acknowledgment: The work was supported by National Science Centre grant Miniatura-3 (2019/03/X/NZ3/01109) and statutory funds to MMRI PAS
20941879839
