Data for: Rigidity sensing of inclusions directs differentiated cell elongation and force generation across phenotypes

Fibrosis is driven in part by the transition of healthy fibroblasts to a
contractile phenotype, called myofibroblasts. The mechanics of the
extracellular matrix play a crucial role in regulating the cell fates and
behaviors during this transition. However, most studies to date focus on
cells grown on 2D surfaces and matrices with homogeneous properties. This
leaves open how local rigidity differentially regulates the behaviors of
both phenotypes in 3D environments, including polarization, contraction,
and maintenance of phenotypes, during remodeling. Here, we engineer 3D
microgel-in-collagen composites by embedding low-volume fractions of
cell-scale microgels with two levels of rigidity, mimicking healthy and
pathological tissues, that are stiffer than the surrounding collagen but
do not significantly change the bulk modulus. We find that microgels serve
as mechanical centers: both phenotypes polarize toward microgel
inclusions. The polarization response decays as a power-law with distance
∼ r−n, decreasing more slowly for myofibroblasts (n ≈ 0.35) than
fibroblasts (n ≈ 0.81), indicating that myofibroblasts are more sensitive
to small mechanical variations. In-situ measurement finds that
forces are highest for myofibroblasts near stiff microgels and lowest for
fibroblasts near soft microgels. Local rigidity also stabilizes the
myofibroblast phenotype: Both the ordering of the proinflammatory marker
α-SMA and nuclear YAP localization persist for cells cultured with stiff
microgels over several days, but diminish quickly for those cultured with
soft microgels and in pure collagen. Together, these results reveal a
rigidity- and phenotype-dependent feedback loop: stiff inclusions induce
cell polarization and collagen remodeling via contractile force, which in
turn, maintain the myofibroblast phenotype. Our study positions mechanical
heterogeneity as a useful and sensitive handle to probe and potentially
modulate early fibrotic progressions.