Abstract

Mesenchymal stem cells adopt differentiation pathways based upon cumulative effects of mechanosensing. A cell’s mechanical microenvironment changes substantially over the course of development, beginning from the early stages in which cells are typically surrounded by other cells and continuing through later stages in which cells are typically surrounded by extracellular matrix. How cells erase the memory of some of these mechanical microenvironments while locking in memory of others is unknown. Here, we develop a material and culture system for modifying and measuring the degree to which cells retain cumulative effects of mechanosensing. Using this system, we discover that effects of the RGD adhesive motif of fibronectin (representative of extracellular matrix), known to impart what is often termed “mechanical memory” in mesenchymal stem cells via nuclear YAP localization, are erased by the HAVDI adhesive motif of the N-cadherin (representative of cell-cell contacts). These effects can be explained by a motor clutch model that relates cellular traction force, nuclear deformation, and resulting nuclear YAP re-localization. Results demonstrate that controlled storage and removal of proteins associated with mechanical memory in mesenchymal stem cells is possible through defined and programmable material systems.

Highlights

  • Mesenchymal stem cells adopt differentiation pathways based upon cumulative effects of mechanosensing

  • The PEG hydrogel system presented either HAVDI/RGD, or non-functional scrambled HAVDI sequence (Scram) combined with RGD (Scram/RGD) (Fig. 1). 8-arm PEG maleimide (PEG-MAL) modified with monothiolated peptides was subsequently crosslinked by 8-arm PEG thiol (PEG-SH) via Michael addition) (Fig. 1a)[41]

  • As with analogous HA hydrogels, PEG hydrogels modified with 1 mM RGD and 1 mM non-functional scrambled HAVDI sequence (Scram/ RGD) established only integrin adhesions, while PEG hydrogels modified with 1 mM RGD and 1 mM HAVDI enabled both integrin and N-cadherin mediated interactions (HAVDI/RGD) (Fig. 1b and Supplementary Fig. 1)

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Summary

Introduction

Mesenchymal stem cells adopt differentiation pathways based upon cumulative effects of mechanosensing. When we seeded cells on the hydrogels with different stiffness and peptide, cell area increased with increasing substrate stiffness, in accordance with previous studies[43,44]; no significant difference was observed between the Scram/RGD and HAVDI/RGD groups (Supplementary Fig. 4).

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