The effect of stiff substrates on the collective migration of A549 cells

Abstract

The Young’s modulus of normal lung tissues ranges from 1 to 5 kPa, whereas fibrotic or lung tumor tissues can be ~30 times stiffer. However, the lung parenchyma microscopically consists of various tissues, and cancer cells in tumors contact stiff collagen-containing fibers during invasion. In this study, we investigated the effect of stiff substrates on A549 cell migration. We fabricated stiff polydimethylsiloxane (PDMS) substrates with different stiffness levels (1.4, 3.4, and 18.3 MPa) by adjusting the cross-linking agent ratio. We examined the distance and the trajectory orientation of A549 cell migration on PDMS substrates and much stiffer 7.7 GPa glass with scratch-wound assays. A549 cells exhibited a collective sheet-like migration pattern toward the wounded area on stiff substrates. The migration range at 18.3 MPa was significantly higher than at 1.4 and 3.4 MPa, and that on glass was significantly higher than that at 18.3 MPa. The cell trajectory orientation on stiff PDMS substrates gradually increased and became constant, whereas that on glass was constant from the initial migration. Our results revealed that stiff substrates affect A549 cells migration in this range.