Cell contractility arising from topography and shear flow determines human mesenchymal stem cell fate

Abstract

Extracellular matrix (ECM) of the human Mesenchymal Stem Cells (MSCs) influences intracellular tension and is known to regulate stem cell fate. However, little is known about the physiological conditions in the bone marrow, where external forces such as fluid shear stress, apart from the physical characteristics of the ECM, influence stem cell response. Here, we hypothesize that substrate topography and fluid shear stress alter the cellular contractile forces, influence the genetic expression of the stem cells and hence alter their lineage. When fluid shear stress was applied, human MSCs with higher contractility (seeded on 1 μm wells) underwent osteogenesis, whereas those with lower contractility (seeded on 2 μm gratings) remained multipotent. Compared to human MSCs seeded on gratings, those seeded on wells exhibited altered alignment and an increase in the area and number of focal adhesions. When actomyosin contractility was inhibited, human MSCs did not exhibit differentiation, regardless of the topographical feature they were being cultured on. We conclude that the stresses generated by the applied fluid flow impinge on cell contractility to drive the stem cell differentiation via the contractility of the stem cells.

Attenuated Glial Reactivity on Topographically Functionalized Poly(3,4‐Ethylenedioxythiophene):P‐Toluene Sulfonate (PEDOT:PTS) Neuroelectrodes Fabricated by Microimprint Lithography

“…Understanding the glia interactions as key contributors in the glial scar formation is essential, and in addition to influencing cytoskeleton‐linked proteins, substrate topography has been previously shown to affect cellular function and the synthesis of cytokines and signaling molecules in neural cells . To elucidate further the roles of topographical functionalization on the neural response in vitro, changes in the expression of proinflammatory cytokines and chemokine factors were assessed via multiplex enzyme‐linked immunosorbent assay (ELISA) analysis.…”

Keratinocytes are mechanoresponsive to the microflow‐induced shear stress

“…For this, prior to shear stress exposure, we inhibited major mechanotransducers (actin, myosin, and lipid raft) individually with chemical inhibitors namely (a) cytochalasin D (CytoD) that causes the shortening of actin filaments by preventing polymerization (Boraas, Pineda, & Ahsan, ), (b) blebbistatin (Bleb) that decreases actin–myosin interactions by inhibiting the binding of myosin with actin (Boraas et al, ), and (c) methyl β‐cyclodextrin (MBCD) removes cholesterol and causes disruption of lipid rafts (Behera et al, ). All these cytoskeletal inhibitors have previously been shown to compromise with the mechanoresponsiveness of cells toward flow‐induced shear stress and inhibit the expression and activation of FAK (Sonam, Sathe, Yim, Sheetz, & Lim, ). Herein, the total expression and localization of pFAK were taken as indicators of shear stress‐induced modulation in the keratinocyte behavior (Figure a).…”

“…For this, prior to shear stress exposure, we inhibited (Behera et al, 2016). All these cytoskeletal inhibitors have previously been shown to compromise with the mechanoresponsiveness of cells toward flow-induced shear stress and inhibit the expression and activation of FAK (Sonam, Sathe, Yim, Sheetz, & Lim, 2016). Herein, the total expression and localization of pFAK were taken as indicators of shear stress-induced modulation in the keratinocyte behavior ( Figure 5a).…”

Manufacturing Cell Therapies Using Engineered Biomaterials

“…The ECM can present different ligands, apply mechanical forces, and dynamically interact with cells, instructing their behavior. Multiple ECM properties, such as fibrous structures, matrix composition and elasticity [35–37], geometry [38], nanotopography [39] and shear flow [40], have been shown to dramatically direct cellular behavior in the absence of other soluble chemical stimuli. The culturing and processing of cell populations in vitro, within environments vastly different from their native niche can introduce large epigenomic and functional heterogeneities in these populations, often severely hampering clinical translation [41].…”