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Acto-myosin based mechano-sensitivity of cells - comparing human mesenchymal stem cells and differentiated cells

dc.contributor.advisorRehfeldt, Florian Dr.
dc.contributor.authorKudryasheva, Galina
dc.titleActo-myosin based mechano-sensitivity of cells - comparing human mesenchymal stem cells and differentiated cellsde
dc.contributor.refereeRehfeldt, Florian Dr.
dc.description.abstractengWithin the last decades it was discovered that the cellular microenvironment plays an important role in cellular processes and cell fate can be directed by mechanical properties of the extracellular matrix (ECM), which can have various elasicities. Cells can sense mechanical properties of their surrounding with contractile acto-myosin stress fibers through focal adhesions and generate force throughout the cell. Human mesenchymal stem cells (hMSCs) are a striking example for mechano-sensing and transduction. They can differentiate into various cell lines by plating them on substrates with different elasticities for several days up to weeks. Interestingly, morphological changes of the acto-myosin fibers and the global cell shape appear already within the first 24 hours of culture. In this thesis, we compare morphological changes of hMSCs, which were chemically and mechanically driven towards differentiation into muscle cells. We present that both, chemical preculture (in addition of dexamethasone or transforming growth factor β1) and mechanical preculture (seeding on elastic substrate with muscle-like rigidity) changes stem cell morphology, measured by the cell area and aspect ratio. I found that the morphology of these treated cells is close to muscle cell’s shape. Moreover, after a week of culture on muscle-like rigidity hMSCs did not lose their ability to readapt to new environment. Furthermore, we investigate spreading mechanics of various already committed cell types on elastic substrates. We found that cell spread area on a 2D surface monotonically increases with the substrate elasticity independent of cell type and size, which is in good agreement to recently stated theoretical predictions. Though the extracted parameters from the theoretical predictions differ between the cell lines, we confirm that the spreading process is not cell type specific. The presented results support the importance of non-muscle myosin II’s (NMMII) for cellular mechano-sensing and -transduction. We show that addition of low concentrations of the NMMII inhibitor blebbistatin affects cell morphology only on soft substrates. This mild blebbistatin treatment facilitates cell spreading on soft substrates and prevents formation of focal adhesions, whereas cellular morphology on stiff substrates is not affected. The results suggest a model emphasizing the importance of contractile forces in the acto-myosin cortex during cell
dc.contributor.coRefereeSalditt, Tim Prof. Dr.
dc.subject.engcell mechanicsde
dc.subject.engHuman mesenchymal stem cellsde
dc.subject.engcell spreadingde
dc.subject.engeffect of blebbistatin on cell mechanicsde
dc.subject.engfluorescence microscopyde
dc.subject.engelastic substratesde
dc.affiliation.instituteGöttinger Graduiertenschule für Neurowissenschaften, Biophysik und molekulare Biowissenschaften (GGNB)de
dc.subject.gokfullBiologie (PPN619462639)de

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