title: Spatially patterned matrix elasticity directs stem cell fate.
abstract: There is a growing appreciation for the functional role of matrix mechanics in regulating stem cell self-renewal and differentiation processes. However, it is largely unknown how subcellular, spatial mechanical variations in the local extracellular environment mediate intracellular signal transduction and direct cell fate. Here, the effect of spatial distribution, magnitude, and organization of subcellular matrix mechanical properties on human mesenchymal stem cell (hMSCs) function was investigated. Exploiting a photodegradation reaction, a hydrogel cell culture substrate was fabricated with regions of spatially varied and distinct mechanical properties, which were subsequently mapped and quantified by atomic force microscopy (AFM). The variations in the underlying matrix mechanics were found to regulate cellular adhesion and transcriptional events. Highly spread, elongated morphologies and higher Yes-associated protein (YAP) activation were observed in hMSCs seeded on hydrogels with higher concentrations of stiff regions in a dose-dependent manner. However, when the spatial organization of the mechanically stiff regions was altered from a regular to randomized pattern, lower levels of YAP activation with smaller and more rounded cell morphologies were induced in hMSCs. We infer from these results that irregular, disorganized variations in matrix mechanics, compared with regular patterns, appear to disrupt actin organization, and lead to different cell fates; this was verified by observations of lower alkaline phosphatase (ALP) activity and higher expression of CD105, a stem cell marker, in hMSCs in random versus regular patterns of mechanical properties. Collectively, this material platform has allowed innovative experiments to elucidate a novel spatial mechanical dosing mechanism that correlates to both the magnitude and organization of spatial stiffness.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, CO 80303; BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303;
authors.forename: Chun
authors.initials: C
authors.lastname: Yang
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305;
authors.forename: Frank W
authors.initials: FW
authors.lastname: DelRio
authors.affiliation: BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303; Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303;
authors.forename: Hao
authors.initials: H
authors.lastname: Ma
authors.affiliation: BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303; Department of Materials Science and Engineering, University of Colorado Boulder, Boulder, CO 80303;
authors.forename: Anouk R
authors.initials: AR
authors.lastname: Killaars
authors.affiliation: Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303;
authors.forename: Lena P
authors.initials: LP
authors.lastname: Basta
authors.affiliation: BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303; Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303;
authors.forename: Kyle A
authors.initials: KA
authors.lastname: Kyburz
authors.affiliation: BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303; Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303 Kristi.Anseth@colorado.edu.
authors.forename: Kristi S
authors.initials: KS
authors.lastname: Anseth
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods*; D002454:Cell Differentiation; D000066673:Cell Self Renewal; D002478:Cells, Cultured; D004548:Elasticity; D000071063:Endoglin / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D006801:Humans; D020100:Hydrogels / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D014157:Transcription Factors; D000091102:YAP-Signaling Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C064206:ENG protein, human; D000071063:Endoglin; D020100:Hydrogels; D010750:Phosphoproteins; D014157:Transcription Factors; D000091102:YAP-Signaling Proteins; C088374:YAP1 protein, human; D000469:Alkaline Phosphatase
keywords: human mesenchymal stem cell; photodegradable hydrogel; spatial matrix stiffness