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.photodegradable hydrogel | human mesenchymal stem cell | spatial matrix stiffness

The Functional Response of Mesenchymal Stem Cells to Electron‐Beam Patterned Elastomeric Surfaces Presenting Micrometer to Nanoscale Heterogeneous Rigidity

“…Interestingly, it was also noted in this study that paxillin intensity was increased in FAs formed on regions of increased rigidity. [45] Further studies employing stiff islands of (approx. 36 µm 2 ) concluded that although the island were too large to address the minimal adhesion area required to trigger FA formation, as long as adhesion sites are well-anchored to resist traction forces, the area of adhesion is limited only by the minimal area required to support focal complex initiation, [46] Recently Meacci et al reported that it is local FA contraction mechanics mediated by myosin II and α-actinin, and not intracellular tension that plays the central role in FA reinforcement in response to local rigidity sensing.…”

Three‐Dimensional Models of the Human Brain Development and Diseases

“…Advances in the field of photochemistry have enabled the researchers to engineer 3D spatial and temporal patterning of mechanical and biochemical signals of the synthetic ECM. [186,190,202–207] This profoundly impacted the way we study the biology of cells. For example, PEG hydrogels tethered locally with a ‘caged’ synthetic peptide helped study cell migration.…”

Atomic Force Microscopy in Characterizing Cell Mechanics for Biomedical Applications: A Review

“…Mesenchymal stem cells cultured on substrate with stiffness 0.1-1 kPa differentiate into neurons, stem cells cultured on substrate with stiffness 8-17 kPa differentiate into myoblasts, and stem cells cultured on substrate with stiffness 25-40 kPa differentiate into osteoblasts. In 2016, Yang et al [84] investigated the stem cells on mechanically patterned hydrogel surfaces with different stiff-to-soft ratios by AFM. Hydrogels with tunable mechanical properties were synthesized by photodegradation reaction.…”