Figure 2
Hepatic stellate cells spread and assume myofibroblast morphology in response to in situ stiffening.
(a) Schematic of in situ stiffening process. (b) Phase contrast images of stellate cells on soft and stiff static substrates, as well as a dynamically stiffened soft-to-stiff substrate (in situ stiffening performed on day 4). Scale bars: 50 μm. (c) Representative stellate cell spread area quantification over 24 h time lapse following in situ stiffening on day 4 (n = 3 cells per group, each shape represents a single cell whose spread area was monitored every 15 min). Spread areas are relatively constant in soft and stiff static groups, but increase steadily in soft-to-stiff group, especially during the first 12 h. (d) To ensure that stellate cells were spreading in response to stiffness and not free radical generation, soft MeHA gels were fabricated where the remaining methacrylates were capped with a thiol, so that in the presence of light and initiator free radicals would be generated but no secondary crosslinking (stiffening) would occur. Representative phase contrast images showed no differences in cell spread areas between groups. Scale bars: 50 μm. (e) Quantification of cell area confirmed no differences in spread area between groups (n > 22 cells per group per time point, error bars represent s.e.m.).
