Exploring the roles of integrin binding and cytoskeletal reorganization during mesenchymal stem cell mechanotransduction in soft and stiff hydrogels subjected to dynamic compression

Abstract

Mesenchymal Mechanobiology Cytoskeleton Mechanotransduction Focal adhesion a b s t r a c tThe objective of this study was to explore how the response of mesenchymal stem cells (MSCs) to dynamic compression (DC) depends on their pericellular environment and the development of their cytoskeleton. MSCs were first seeded into 3% agarose hydrogels, stimulated with the chondrogenic growth factor TGF-β3 and exposed to DC ( $10% strain at 1 Hz) for 1 h on either day 7, 14, or 21 of culture. At each time point, the actin, vimentin and tubulin networks of the MSCs were assessed using confocal microscopy. Similar to previous results, MSCs displayed a temporal response to DC; however, no dramatic changes in gross cytoskeletal organization were observed with time in culture. Vinculin (a membrane-cytoskeletal protein in focal adhesions) staining appeared more intense with time in culture. We next aimed to explore how changes to the pericellular environment, independent of the duration of exposure to TGF-β3, would influence the response of MSCs to DC. To this end, MSCs were encapsulated into either 'soft' or 'stiff' agarose hydrogels that are known to differentially support pericellular matrix (PCM) development. The application of DC led to greater relative increases in the expression of chondrogenic marker genes in the stiffer hydrogels, where the MSCs were found to have a more well developed PCM. These increases in gene expression were not observed following the addition of RGDS, an integrin blocker, suggesting that integrin binding plays a role in determining the response of MSCs to DC. Microtubule organization in MSCs was found to adapt in response to DC, but this effect was not integrin mediated, as this cytoskeletal reorganization was also observed in the presence of RGDS. In conclusion, although the PCM, integrin binding, and cytoskeletal reorganization are all involved in mechanotransduction of DC, none of these factors in isolation was able to completely explain the temporal mechanosensitivity of MSCs to dynamic compression.& 2013 Elsevier Ltd. All rights reserved. j o u r n a l o f t h e m e c h a n i c a l b e h a v i o r o f b i o m e d i c a l m a t e r i a l sPlease cite this article as: Steward, A.J., et al., Exploring the roles of integrin binding and cytoskeletal reorganization during mesenchymal stem cell mechanotransduction in soft and stiff hydrogels subjected to dynamic compression.

Cyclic Tensile Strain Can Play a Role in Directing both Intramembranous and Endochondral Ossification of Mesenchymal Stem Cells

“…Furthermore, it has been reported that tensile strain and dynamic compression differentially regulate MSC differentiation (Haudenschild et al, 2009 ), with CTS upregulating osteogenic markers BMP1, ALP , and NELL1 , whereas compression was found to promote chondrogenesis of MSCs encapsulated in 3D alginate matrices. This latter finding agrees with a number of separate studies demonstrating that compressive loading can enhance chondrogenesis of MSCs (Huang et al, 2004 ; Campbell et al, 2006 ; Thorpe et al, 2012 ; Steward et al, 2014 ; Luo et al, 2015 ). Additionally, it has been demonstrated that high magnitudes of cyclic hydrostatic pressure and dynamic compression can suppress hypertrophy and endochondral ossification of MSCs (Bian et al, 2012 ; Thorpe et al, 2013 ; Carroll et al, 2014 ; Luo et al, 2015 , Zhang et al, 2015 ).…”

Mechanical regulation of mesenchymal stem cell differentiation

“…MSCs seeded in the stiffer hydrogels displayed a more pro‐chondrogenic response to the application of DC compared with those seeded in softer hydrogels (Steward et al. ). Furthermore, inhibition of integrin binding suppressed the beneficial response to DC in the stiff hydrogels (Steward et al.…”

“…Furthermore, inhibition of integrin binding suppressed the beneficial response to DC in the stiff hydrogels (Steward et al. ). Overall, differences in scaffold type, cell type and loading regime (Maul et al.…”

Modeling the effect of ascites-induced compression on ovarian cancer multicellular aggregates

“…Pressure was conveyed at 25 mmHg to the test vessel using an Instron, as previously reported for chondrocytes ( Fig. 1 C) ( Wagner et al, 2008 ; Steward et al, 2014 ). Control EOC MCAs were sealed and incubated in an identical pressure vessel that was temperature controlled and maintained at atmospheric pressure.…”