Substrate Stiffness Controls the Cell Cycle of Human Mesenchymal Stem Cells Via Cellular Traction

Abstract

The microenvironment of human mesenchymal stem cells (hMSCs) regulates their selfrenewal and differentiation properties. Previously it was shown that hMSCs remained quiescent on soft (0.25 kPa) polyacrylamide (PA) gels but re-entered into cell cycle on a stiff (7.5 kPa) gel. However, how cells behave on intermediate stiffness and what intracellular factors transmit mechanical changes to cell interior thereby regulating cell cycle remained unknown. In this work we demonstrated that PA gels between 1 and 5 kPa act as a mechanical switch in regulating cell cycle of hMSCs. By experiments on cell-cycle exit and re-entry, we found that hMSCs demonstrated a sharp transition from quiescence to proliferation between 1 and 5 kPa. Further studies with ROCK inhibitor Y-27632 revealed that contractile proteins, but not cell spread area, accounts for the sensitivity of hMSCs towards substrate stiffness and hence correlates with their changes in cell cycle. These observations therefore suggest that substrate stiffness regulates hMSC proliferation through contractile forces as generated by cellular contractile proteins in a unique pattern which is distinct from other cell types as studied.

Crosslinker Structure Modulates Bulk Mechanical Properties and Dictates hMSC Behavior on Hyaluronic Acid Hydrogels

“…[32,60,65,66] Notably, previous work found that cellular contractility may regulate cell proliferation in an intermediate (1-5 kPa) stiffness range. [67] Contractility usually increases with cell spread area on stiff hydrogels; however, it is unknown how the variation in molecular stiffness of the peptoid-crosslinked hydrogels affects contractility here.…”

Recent Advancement in Elimination Strategies and Potential Rejuvenation Targets of Senescence

“…[38] Kureel et al [205] show that mesenchymal stem cells cultured on soft polyacrylamide gels delay the onset of senescence and regulate cell-cycle dynamics. [206] Surface stiffness also manages the quiescence of MSCs. [207] Gilbert and Chaudhary groups have shown that substrate stiffness controls proliferation and maintains differentiation potential in muscle stem cells.…”